Topic: 1977 CB750F Super Sport "Cleaning out the attic"

[worst650ever]

Hi folks,

First off, thanks for the warm welcome to the site.  I've already gathered up so much helpful information! 

I've built many motorcycles, mostly Hondas, though a few Ducatis and Yamahas in there as well, but this is my first SOHC CB750.  It appears that some of my experience from my '79 CB650 will apply to this build, so that's good!

I wanted to build a bike that would be comfortable and confident at highway speeds - my little '76 CB360T is great around town, but despite all the mods and upgrades I've made to it, north of 70 miles an hour really starts to feel like I'm pushing it.  I decided on a Super Sport after lots of Craigslist poking and Google Image Searching

I picked up a roller '77 F frame (Comstars, forks, brakes, and that's about it) from one Craigslist guy, and picked up another roller frame and a '78 "K" motor from another Craigslist guy.  The second guy thought he had an "F" motor, but it turns out it's a plain old "K" motor with some black spray paint chipping off of it, but one that is in pretty good shape other than worn cylinder bores and rings.  I got a good deal on it, and the guy threw in all kinds of extras.  I later got a set of appropriate carbs and boots from him, as well as some other important bits and pieces.  He builds K bikes and Amen Savior choppers, so the Super Sport stuff wasn't really what he was looking for.  It was exactly what I was looking for, however!  He has been a very good resource, including letting me know about an Ebay auction where I was able to get a '77 Super Sport wiring harness for $10+$10 for the ride.  It is in amazing shape, with no cuts or splices or damage, and included the flasher, diode, and starter solenoid. 

Anyway, on to the pictures, which I know is what you folks really care about 

Here's the rolling frame - the other rolling frame was similar, but was painted blood red.  Note the brake calipers on the wrong side of the forks.





Here are the ID numbers.  Anyone know what the number in the head means?











Getting a new 5mm x 2.5mm O ring to help with oil pressure - the oil pump (on which the bolts were loose  ) got new O rings as well.



Head and bores off - new rings on order from Japan.



What's this?  Could it be an '83 CB1100F front end I had in my attic?  Yup!  Turns out it works with the original Comstars after I added spacers to the wheel to compensate for the longer axle.  I get twin piston brakes, TRAK (useless?), and bigger more modern forks.  Also, that click adjust thing on top of the tubes that no one knows what it really does.  Nifty. 



Lots of satin black paint.  It may not be a Super Sport motor, but it's going to get dressed up to look the part at least.  Paint covers a multitude of sins on the side covers as well.



I tore apart the head, cleaned it well in my kerosene parts washer, checked clearances (good!), lapped the valve seats, washed it again and again, and then put in new valve stem seals and put it back together.  I even remembered to pry out the old copper exhaust crush collars. 



Mocked up with the wrong tank and the original forks.  It's torn back down again.



Doh!  Anyone have a spare clutch lifter plate?  I also need the rear axle spacer that goes on the sprocket side if anyone has one of those floating around.



I also need gauges, side covers, chain and sprockets, and so on.  If anyone is selling, I'm buying!

[worst650ever]

My new stock size '77 - '78 rings arrived from cruzinimage_co on Ebay.  I think it took longer for the rings to get to me in the US than it took them to get from Japan to the US!  I understand that the folks here use his stuff a lot, and I've used his rings on my CB360T. 

With the rings alone test installed in the bores, the end gap was at 0.011" / 0.28mm.  The standard range is 0.2 - 0.4mm, with a max wear limit of 0.7mm, so I'm in pretty good shape.  I still need to give the bores a light hone to break the glaze and put a cross hatch on them, but it appears I have some room to do this in. 

I disassembled the air box to clean it out and found several wasps preserved in goopy blow-by.  Ew.  Into the parts washer it went!  I'm softening one of the velocity stacks in my wintergreen oil / xylene / acetone mix to see how it works.  At worst, I'll ruin one of them, at best it will be pliable and easy to install. 

The battery box was cleaned up, hit with Rustoleum Rusty Metal primer, and then more Satin Black.  I should buy Satin Black by the case with the amount I use! 

I'm waiting for new All Balls steering bearings to arrive to square away that part of the build.  With the rings, I can start putting the motor back together, paint it, and then, after I paint the frame, get it installed!  Closer and closer!

I'm not sure I want to use stock gauges for this build, so I'm considering using a TrailTech Vapor or something like that.  I really liked the Vapor on a CBR900RR I built, but it's pretty out of character for the CB750F.  Any suggestions? 

[Jerry Rxman Griffin aka MuthaF'er]

But that IS 'basically' a Super Sport engine. The 75/76 -392 variety just not the big valve problem head 77/78 variety. Your engine was derived from the 75 F with a beefier output shaft bearing. You have the best of all the years.

[worst650ever]

Jerry, I knew the '78 gained a bunch of improvements from the previous years, but that's wonderful to hear!  I feel better about painting it black as well    Thanks for the info!

I was also happy to not have to worry about a keeper going through a retainer like on the big valve heads.  What is a keeper that doesn't keep?  Sounds like a joke or something the Sphinx would ask. 

I didn't think to mention it before, but I did the HondaMan clutch hub additional hole modifications - this same mod on the CB360T is a big help.  The plates that came with it had plenty of beef left on them according to my digital calipers.  Do you folks love the Rotella 5w-40 T6 full synthetic as much as us CB360T folks love it?  On the 360s, the synthetic helps make up for the poor top end oiling and handles the high temperatures of the motor better.  Of course, I've modified the crap out of the oiling system on my 360 and am running a little on the rich side with 93 octane to keep it daily rider cooler.

Which brings me to a carburetor question.  The carbs I have, apparently off a '77, are jetted with #120 mains.  According to my factory service manual supplement, #115 mains were stock, but on the older K0-6 bikes, #120 mains were stock.  I'm running the stock '77-'78 airbox and going to be running the stock 4 into 1 Super Sport headers.  Are 120s ok for this application?

[HondaMan]

Jerry, I knew the '78 gained a bunch of improvements from the previous years, but that's wonderful to hear!  I feel better about painting it black as well    Thanks for the info!

I was also happy to not have to worry about a keeper going through a retainer like on the big valve heads.  What is a keeper that doesn't keep?  Sounds like a joke or something the Sphinx would ask. 

I didn't think to mention it before, but I did the HondaMan clutch hub additional hole modifications - this same mod on the CB360T is a big help.  The plates that came with it had plenty of beef left on them according to my digital calipers.  Do you folks love the Rotella 5w-40 T6 full synthetic as much as us CB360T folks love it?  On the 360s, the synthetic helps make up for the poor top end oiling and handles the high temperatures of the motor better.  Of course, I've modified the crap out of the oiling system on my 360 and am running a little on the rich side with 93 octane to keep it daily rider cooler.

Which brings me to a carburetor question.  The carbs I have, apparently off a '77, are jetted with #120 mains.  According to my factory service manual supplement, #115 mains were stock, but on the older K0-6 bikes, #120 mains were stock.  I'm running the stock '77-'78 airbox and going to be running the stock 4 into 1 Super Sport headers.  Are 120s ok for this application?

Running a 5w-[anything] oil in this engine will EAT the crank bearings in short order. The very least, in cool/cold weather only, should be 15w40. In particular, the black engine will run about 15-20 degrees hotter, so it is best to stay with the original CB750 oil weight spec of 20w50 above 50 degrees F, 14w40 down to 20 degrees, and 10w40 (or 10w50, which was the best bet in the 1970s) in winter riding.

The nasty "jinglish error" in the K4 manuals led to the "10w40 oil" stickers on some of these bikes, which at the time was supposed to mean, "No LESS than 10w40 oil", not intended to mean "USE 10w40 oil". Such was the language of the day... Those 750s that survived this error are the ones that you find running well after 25k miles, and can last up to 100k if the intervals were also kept short.

A few of our members like the Spectrol synthetic, if you're into synth. I have not had good luck keeping it inside the gaskets on my engines, though, it likes to weep out.

[worst650ever]

Thanks HondaMan, this is why I ask!  Any luck with the Rotella 15w-40 non-synthetic? 

It occurs to me my 360 has ball bearings on the crank versus the plain bearings on the 750.  Big difference there! 

Speaking of weeping, I read on Cycle X's website that they recommend using the copper coat spray on head and base gaskets, and using something like honda/yamabond on the side cover gaskets.  As I'm getting close to putting the jugs back on, is that good advice from them?

[worst650ever]

I also installed my All Balls roller head bearings, which tightened up the front end considerably.  I need to slap the new front wheel bearings on, and then the bearings will be dealt with.  When this bike is done, the 360 is going to get new bearings as well!

[70CB750]

IMHO 15W40 is still too light, not sure where you are but in Virginia, I use it only from November to February.   Go with 20W50 and you will never be sorry that you did.

[edwardmorris]

.........I read on Cycle X's website that they recommend using the copper coat spray on head and base gaskets, and using something like honda/yamabond on the side cover gaskets.  As I'm getting close to putting the jugs back on, is that good advice from them?

This is a must read for top end work  http://forums.sohc4.net/index.php/topic,107040.0.html

Which gaskets from CX are you using? If you have the cyls and head milled flat, then their MLS gasket works best and doesn't need any spray (I believe the instructions actually say not to use anything). I do however know that another member here had a base gasket leak without using the spray on an 836, so I'd recommend using the spray for the base. In addition to the spray, a little bit of hondabond around the oil return galley paths on the upper crankcase will ensure no leaks.

[HondaMan]

Thanks HondaMan, this is why I ask!  Any luck with the Rotella 15w-40 non-synthetic? 

It occurs to me my 360 has ball bearings on the crank versus the plain bearings on the 750.  Big difference there! 

Speaking of weeping, I read on Cycle X's website that they recommend using the copper coat spray on head and base gaskets, and using something like honda/yamabond on the side cover gaskets.  As I'm getting close to putting the jugs back on, is that good advice from them?

In your [hopefully] Vesrah gasket kit, there will be 4 O-rings all the same size for the oil passages. The pink ones go on the bottom, below the cylinders. The black ones may be too thin in cross-section to seal the area at the head gasket, causing a major oil leak soon (or immediately). Lay the head gasket on the cylinders, then lay the O-rings into those 2 holes at the oil passages, and measure how far above the head gasket those O-rings sit. If they are not AT LEAST 0.4mm higher, you have "the problem" with your (too thick) head gasket, very common today. This requires use of the 10.88x2.62mm O-rings, instead, be used in those 2 holes, or you WILL have a big oil leak. This has happened on many, many engines lately. The OEM gaskets used to be impregnated with sealant that melted and bonded the head and cylinders together for a while, reducing the possible leak sites if the tolerances got a little out-of-whack in production: that was Honda's "fix" for this issue. These sealants were outlawed (thank you, EPA...) in 2002, and vanished from our gasket kits. The head gaskets also became thicker when asbestos was outlawed (thank you, EPA...), using a less-strong and thicker fiber instead. So, we have to cope with it by using O-rings that are different from the original specs.

The "fixes", though temporary, have included things like, "glue the whole head gasket down" using sealant sprays like the one you mention. Not a great idea, IMHO. Fix the problem, and don't try to Band-Aid it together, or you will be taking the engine apart again very soon...

On the top of the head, in the 6 holes under the Rocker Towers, there are some rubber "pucks". Lately many of the gasket kits omit these, because Vesrah (among others) started shipping out pucks that were too thin (that actually fit later-model Honda engines), and they make for immediate oil leaks there, too. The best thing to do there is: measure the depth of the holes, and make sure your pucks are AT LEAST 0.3mm taller than the holes, or they will leak. You can get correct pucks from PartsNmore.com, which is where I have been getting mine.

In general, the gasket kits we are getting today are being made by people who were not yet born when the bikes came out. This has caused them to "miss" many important nuances about the gaskets and seals. Even Vesrah has 'fallen' in this area in the last 5 years, so measure each seal carefully, lest you end up with a leaky mess!

[edwardmorris]

Oh yeah, forgot about the o-rings (thanks Mark!). With mine, the Vesrah one's didn't pass the Hondaman test above, so I went with OE ones which were good. Same for the head pucks as well.

If you haven't already, I highly recommend grabbing a copy of Hondaman's 750 book, essential reading for any 750 owner

[HondaMan]

Thanks HondaMan, this is why I ask!  Any luck with the Rotella 15w-40 non-synthetic? 

It occurs to me my 360 has ball bearings on the crank versus the plain bearings on the 750.  Big difference there! 

Speaking of weeping, I read on Cycle X's website that they recommend using the copper coat spray on head and base gaskets, and using something like honda/yamabond on the side cover gaskets.  As I'm getting close to putting the jugs back on, is that good advice from them?

I use the Rotella 15w40 as break-in oil on new engines (new bearings) and on the smaller bikes sometimes, like the 350/360 Twins, the Baby fours, and the littlest ones like my CB125. They are not as hot as the Big Four.

[worst650ever]

<furiously takes notes>  Thanks guys, this is very helpful and timely information.  Sounds like I'll be doing some measurements and probably getting some new o-rings and maybe some new pucks.  I've used partsnmore a lot in the past for Nighthawk and Interceptor bits, so it's good to hear they can help me here as well. 

I have a very good local independent hardware store that stocks metric and standard o-rings in viton, nitrile, bunna-n, and God knows what else, so I'll have to see if they have the larger o-rings recommended, and I'll measure my new pucks.  They had the 5mm x 2.5mm cross section o-rings for the transmission side oiler mentioned earlier in this thread.

I've been using Permatex's MotoSeal instead of Honda or Yamabond lately and had good results, so I wanted to share that with the community.  I can get it off the shelf at my local auto parts stores, and it's stood up well in the past couple of motorcycle motors I've put together. 

HondaMan, your comment about asbestos reminded me of a recent Triumph TR3 (car) motor rebuild I did.  The new head gasket from the rebuild kit was definitely asbestos between copper sheet, as was the original one.  I wonder if it being a British sourced part was the reason for asbestos still being used?  It wasn't a NOS part, though I did end up with a NOS Lucas brand timing cover gasket.  2/3s of the holes in it were punched off center - "Trust Lucas" indeed    Now that motor rebuild was where we used LOTS of sealant on the gaskets, and no leaks yet.  We're a bit worried, cause no leaks on old English normally means no oil left in the motor...

Here are some pictures of the bike mocked up with VF750F Interceptor clip-ons.  I like the height and the look of those bars, so I think that's what I'll end up using for controls.  Sadly, my right hand one cracked as I was trying to straighten a nasty bend in it, so a new-to-me one is on its way.  Like I said, this build is being sponsored by the contents of my attic, so the clip-ons were another happy find.  They are 39mm, so they match the CB1100F forks.  I stumbled into some CBR954 forks and brakes, but I don't think those will work on this build.  The fork legs are too short, and the triple trees are too darn expensive for now.  The rotors for the brakes are about the same size as the front wheel as well!

[worst650ever]

This weekend I threw some more paint on the crankcase and cleaned up the pistons and installed the new rings.  I also took some measurements for cylinder o-ring purposes as we've discussed in this thread. 

According to my measurements, the head gasket and the o-ring depression in the top of the cylinder bores is 2.4 mm deep.  The base gasket and its o-ring depression in the top of the crankcase is also 2.4 mm deep.  This would seem to indicate that I should use o-rings at least 2.8 mm thick.  Does this seem correct or are the 2.62 mm o-rings still preferred in my case?

Also, my pucks are 2.63 mm thick.  The puck depression is 2.18 mm deep, so I feel comfortable that my pucks will work. 

Thoughts before I start turning wrenches?  Thanks!

[worst650ever]

So in between work, Bike Night, applying for a new job, and dealing with a hyperactive kitten teething on me while I sleep, I've managed to get some more work done on the Patchwork ManBike.

I ended up finding some nice 3mm thick o-rings, so I used them in the appropriate oil passageways.  I checked to make sure the "squish" didn't end up blocking the passageways as well.  The pucks I received in the rebuild kit were a good height, and also got a smear of Moto-Seal to make them stay sealed.  The o-rings got a light coat of the Moto-Seal as well to help keep the outside of the motor dry.  No one likes an oily boot or a stinky rider...

The bores went on the pistons pretty well with the help of a friend who has put in his time with Honda SOHC4s as well.  We torqued down the head and I retorqued it the next morning.  He's building a 750cc CB550 SOHC because there's something wrong with him 



HondaMan, I used your excellent guide to "freeing" the rocker arm shafts to modify my top end.  I cleaned up the rocker arm shafts with some green nylon pads and my kerosene parts washer, and they spin nice and free in their towers.  I also added the countersunk oil holes to increase lubrication to those parts. 



It's difficult to see, but I've slotted the stock cam gear enough to get a few degrees in each direction.  That MFer is hard to cut/grind/drill!  I'm going to degree in the cam, and from what I've read, it seems that setting it 5 degrees advanced (stock '78 cam) helps?  Thoughts?



I'm considering getting the headlight mounting bracket from a '79 CB650 to locate the headlight onto the triple trees from the '83 CB1100F.  As you can see, the mounting scheme is similar.  You can also see where I needed to remove the 1100's steering stops.  I'll have to add something back in later, I have a couple of ideas and a welder.  Note how the ignition switch bolts right up - I did need to enlarge the the holes in the switch from 6mm to 8mm to accommodate the 1100 upper triple tree.





I stopped by the local cycle shop - the owner though he had a Super Sport tank in his attic, but discovered it was a HondaMatic tank.  The tank is definitely longer than the "K" tank I have.  The "K" tank left such a gap between the Super Sport seat and the end of the tank I was afraid I'd slide into the gap and do some serious wedding tackle damage.  I already did enough damage with my time on a Ducati Monster, I'm not doing that any more! 



However, there is still a gap.  This may be dealt with by installing a new seat cover and moving the tank ever so slightly rearward on its front mounts.  Or using a ThighMaster so I can hold onto the bike better. 



I don't hate the tank on the bike, but it definitely changes the character of it.  I do get a fuel level sender, so I could add a fuel light or gauge.  Fancy!



What do you folks think of this tank?

[worst650ever]

I just finished degreeing the cam, and thought I'd share the data for what I believe to be a stock 1978 K cam - hopefully my math worked out right here:

Overlap: -16*
Intake Duration: 210*
Exhaust Duration: 199*
Intake Lobe Center: 110*
Exhaust Lobe Center: 110.5*
Lobe Center Seperation: 110.25*

So, based on that data, what, if anything, should I do with the cam?  Advance? Retard? Toss in the bin?

[worst650ever]

I ended up deciding to advance the cam 5* based on other posts on this board.  I worked really late into the night getting everything set up and installed and whatnot, and advanced the cam, stuck the valve cover on there, and called it good.

The next morning, I woke up and thought "did I advance or retard the cam?"

After shining a flashlight through the breather cover stuff, I realized I had retarded the cam 5*.  I didn't feel very advanced at that moment either, let me tell you.  I pulled the valve cover back off, set everything properly, and am waiting for a new valve cover gasket to arrive.  I guess if that's the worst that happens to me in this build I'll be happy! 

I've started to get the various bits and pieces bolted onto the side of the motor - I have a very nice condition points plate with what looks like nearly new Tek points on it, so that went on.  I'll dress the points and static time it to get it running and make the decision about electronic ignitions later.  I still have to test the condensers / capacitors however.  Those things do dry out over time.  A new to me points cover is on the way as well, as that was one part I was missing.

I also need a clutch "lifter" plate, as mine has the tip of one of the four "ears" broken off.  It looks like it would work, but I don't feel good about using it.  Anyone have a decent one for sale? 

[70CB750]

I did the cam timing several times for the F engine, never sure if I done it right 

Make sure to check valve clearances too.

The K0, when I took it apart, had one corner of the clutch lift plate missing and little pieces of aluminum in the oil pan; I suspect the PO cracked it on install and decided it will be "just fine".

[worst650ever]

I did the cam timing several times for the F engine, never sure if I done it right 

Make sure to check valve clearances too.

The K0, when I took it apart, had one corner of the clutch lift plate missing and little pieces of aluminum in the oil pan; I suspect the PO cracked it on install and decided it will be "just fine".

"Cut it off two times and it's still too short" huh? 

I have one of those nifty double ended feelers for valve clearances, but I normally do leave the exhaust a little loose so it doesn't tighten up too much when it heats up.  I set those clearances when the valve cover was off - that does make things easier. 

I found the corner of the plate in the oil pan as well (in addition to a rocker arm adjuster nut  ), and I think my PO did the same thing yours did.  Darn things are $$$ on Ebay too.  I'd think about welding it, but the opposite corner's casting is all pockmarked.  It's like the mold failed there and there was a lot of air introduced.  No sense in trying to fix junk. 

I need to take some more pictures - all the side covers are on the motor save the clutch cover and points cover (which is in the mail).  I should set the static timing as well now - it's not going to be any easier than now!  I'm stalling on stripping the few things I've put on the frame off so I can paint it as well.  I need to get some paint on the frame before the weather gets colder, or it will never get done! 

[70CB750]

I meant valve to piston clearance, there is some minimum space batween valve and the piston that should be maintained. You check it with play doh on top of the piston.

More here:

http://forums.sohc4.net/index.php?topic=86358.0

[worst650ever]

Oh yes, that!  The valve / piston clearance looks just fine, Honda left me some room there.  I almost feel like the 5* is barely enough to register, but we'll see. 

My #1 header pipe on the stock 4 into 1 Super Sport exhaust is seriously mashed, and I'm having trouble finding 1 3/8" / 35mm OD exhaust pipe to fix it.  I found a $50 aftermarket 4 into 1 exhaust on Craigslist with a hole near where the four pipes join, but it looks fixable with a piece of scrap steel.  On eBay, a replacement used #1 pipe starts at $44 before shipping.  I'd be glad to send $$$ if someone has a spare pipe or even about 12" of 1 3/8" OD exhaust tubing. 

[worst650ever]

Summit Racing saves the day:

http://www.summitracing.com/parts/kok-st13818steel/overview/

$12 shipped for 2' of the 1 3/8" / 35mm OD exhaust pipe.  Time to fire up the welder and the angle grinder and do some damage.  Of course, the exhaust gasket itself, which was in about 37 pieces, is another $11 shipped. 

I also ended up getting the rear axle spacers I needed, some good used control cables, the tool kit plastic holder, a battery strap, and a CB650 headlight bracket to work with the CB1100 triple tree from a local guy who parts out bikes.  $15 for all of that stuff, very reasonably priced!

[worst650ever]

My new valve cover gasket arrived yesterday, so that got installed along with the tappet covers.  I just need to pull the trigger on a clutch lifter plate and that side can get buttoned up too. 

I also stripped the frame down so I could clean off the surface rust and repaint it.  The rust isn't bad, but why do all this work only to leave the frame ugly?   













So on the rear swing arm, it doesn't appear to have the plastic bushings I was expecting to see - it appears to be fully sleeved with steel.  Huh?  Did the bushings disappear? 



I know I'm supposed to replace this grease fitting with a US standard one to get better flow.  I should probably put a couple more fittings in closer to each end so it's easier to grease as well.





Looks like boxing this in could help with stiffness.





Why isn't there a cross brace here to prevent the frame from squishing in on cornering?



To my amateur eye, I would think there should be something at / near the end of the frame to reinforce it as well. 



I've been doing some reading about installing gussets and other frame reinforcements, so I'll see what I can do.  The "F" frame seems better reinforced that the "K" frame, but there's always room for improvement, right?    Or at least room for me to mess it up...

[worst650ever]

The frame and swingarm got a coat of Rustoleum Rusty Metal Primer this evening, which I've had very good luck with in the past. 



I did finally figure out where the swing arm bushings are after I removed the metal sleeve / tube from the swing arm.  It was still well greased and came out pretty easy.  The stock bushings don't seem to have any play in them, so I'm on the fence about replacing them with bronze bushings. 

I noticed the kickstand is missing its rubber "finger."  I've never seen that happen before, I'll have to see if I have one in my inventory of Honda stuff.  I also pulled the trigger on a lot of clutch parts on Ebay, which included a good clutch lifter, basket, plates, cover, chrome cover cover, etc.  $40, not super cheap, but only about $5 - $10 more than what just the lifter was going for.  If anyone is looking for other clutch parts, let me know as I will have spares. 

[worst650ever]

So yea, this happened:



I put about three coats of semi gloss black enamel over the primer, and let it cook in the unusually warm and sunny weather before attempting this.









Somehow I only nicked the paint in a couple of places, and it was easy to touch up.  I thought of building an engine "hook" as described here, but I already had the frame down to the, uh, frame, so that decided things for me.  Having an engine crane to lift the motor off the stand and onto the motorcycle jack helped as well - I was able to do the whole thing by myself. 

I chased the threads on the frame and also fixed the bent threads on my nearly unobtanium F model motor mount / rider footpeg mount rod with a die.  M12 x 1.25 super fine thread, good thing I have a well stocked hardware nearby!  I have to pick up a M8 x 1.25 tap tomorrow, as one of the rear rider's right motor mount plate holes in the frame is being persnickety, likely due to some rust.  Sometimes I can chase the threads, sometimes I need to get out the tap or die. 

I also found I have a second front engine mount triangle, so I can install that to beef things up there as I have seen others (Hondaman) do.

I have acquired a large amount of spare and extra CB750 nuts and bolts, so now I need to make sure I get the right ones in the right places.  I've mostly kept the fasteners with the parts they go with, but in many cases, the parts didn't come with any fasteners.  I am estimating about 8 bikes have given parts to this build.  Perhaps I should call this build Frankenstein's Honster? 

[worst650ever]

More progress has happened, and it appears I'm going to need some kind of rear sets in order for the bike to be even moderately comfortable with the Interceptor clip ons. 

First off, pictures of the progress!



As you can see, the swingarm has been reinstalled, as have the shocks and front end.  I pretty much just popped the top triple off and rolled the front end away, so that reinstall was pretty easy.  I've fitted some temporary steering stops so that the tank doesn't get banged up by the forks. 



Here's a shot of it with the seat fitted for rear control location testing.  I also fitted my new 15T front sprocket and the chain, and that seems to be good enough for testing.  I'll get a new rear sprocket and chain when the thing runs enough to go up and down the street.  I suspect I won't wear the new front sprocket too badly in a few miles 



After dicking around with cardboard templates and whatnot, I realized I could just make a wood template, which would be strong enough for me to put my feet on the thing. 



The top rear control bolt hole is roughly 80mm center to center from the upper (swingarm) mount bolt.  The lower rear control bolt hole is about 160mm from the engine mount / stock foot peg bolt.  I'll share the drawings when I get things a bit more precise.  I'm going to see if my local materials and milling shop can create something in 1/2" aluminum.  I might even be able to keep the passenger pegs if I'm clever! 

[seanbarney41]

cool project...looks like you are having fun with all the "grab a part from the stash and make it fit" and looks like you are going to have a good functioning bike when you are done...did that 1100f frontend bolt right on?  I have ideas on using one someday on a cb750 sohc with "boomerang" comstars and all

[worst650ever]

cool project...looks like you are having fun with all the "grab a part from the stash and make it fit" and looks like you are going to have a good functioning bike when you are done...did that 1100f frontend bolt right on?  I have ideas on using one someday on a cb750 sohc with "boomerang" comstars and all

Yea, I have had to buy a good number of items for the build, but there's an awful lot of commonality between Honda stuff! 

The 1100f front end required that I swap the steering stem for the shorter unit from the SOHC 750, and that I grind off the steering stops on the lower triple tree.  It also requires using the 80's style headlight mounting brackets, as the "ears" from the SOHC bikes won't fit easily without modification, and then the headlight hits the key switch assembly.  The good news is that the ugly square headlights from the '80s had about the same width as the SOHC round headlight, so that should bolt up pretty easily. 

There's other tweaking - the 1100f forks are longer than the 750 forks, so I "choked up" the tubes to keep the caster the same.  This let me mount the clip ons a bit higher, which works well for my ergonomics. 

Oh, and if you want to use the SOHC 750 front wheel, you're going to have to fab some spacers for the front axle.  The brakes from the 1100f line right up with the dual front disks from the '77 - '78 F models, however, so you have that going for you 

So yea, they bolt right up* 



*Some assembly required

[seanbarney41]

are you going to use the cb750f2 comstars then?....I am assuming then, you don't have a viable set of the cb1100f "boomerang" comstars...

[worst650ever]

Yup, I'm using the stock Comstars.  I got the 1100f forks and triple along with some Nighthawk 650 forks I bought a couple years ago.  I didn't know what they were till I did some Googling.  The dual TRAC setup was fairly unique, so that helped me figure out what they were.  I also got the calipers with the forks, so it was an easy and cheap upgrade. 

[SOHC4 Cafe Racer Fan]

The 1100f brakes are a solid upgrade.

[worst650ever]

The 1100f brakes are a solid upgrade.

Indeed!  They are shared with the Nighthawks, the first gen Interceptors, and I believe some of the other '80s Honda "big" DOHC bikes.  Makes finding pads easy!

I think there's a how to around here somewhere about fitting these twin piston calipers to the SOHC bikes.  The only problem I've experienced with them (other than blown out seals and seized pistons from neglect) is the slider pins hanging up.  It's the same issue I've seen on GMs and Subarus and Fords and anything else with sliding calipers.  The sliding pins and their bores need to be cleaned out, damaged boots need to be replaced, and a good brake grease needs to be applied to the sliders. 

If I could easily fit the CBR954RR calipers and rotors I have, well...I'd probably do my best Superman impression over the front end 

[Buckskin Bandit]

I'm having fun watching this build! It's really neat.

[worst650ever]

I'm having fun watching this build! It's really neat.

Thanks for saying so!  It's nice to be able to take my time on it since I have another running bike (my CB360T) to keep me on two wheels.  There's been times when I've had four bikes and none of them ridable. 

I picked up an 8" x ~30" piece of 1/4" aluminum from my local materials supply house yesterday.  I thought I'd need to use 1/2" aluminum, but it's pretty clear that 1/4" will hold my weight and a passenger's if I go that route.

Here's the doodling that has resulted from my rear set test fitting with the wood - the graph paper squares are 5mm each:

EDIT: I've removed this image - the distance between the two mounting bolts (~115mm) appears to be too short.  I'll measure again and create a new drawing.

It mostly describes the relationship between the four holes in the plate - the two holes (14mm and 12mm) that go over the swing arm and stock foot peg bolts, and the two holes (8mm) that are in my CBR600RR rear sets.  Your leg length and Ebay purchased used rear sets may vary. 

[worst650ever]

Welllll, the distance between the two mounting bolts should be ~112mm, not 115mm.  I'll tweak the drawing. 

[worst650ever]

Long time no post, but I have a bunch of updates!

I finally got my aluminum rearset brackets fabbed up and installed after some tweaking of the mounting hole spacing.  There's still a little more adjustment to do, and they have some flex, so they will probably need to be reinforced, but at least I can test the bike a bit.

My local hardware store has metric rod ends and metric threaded rod, so I was able to fab up a new shift linkage using the stock parts from the '89 CBR600 rear sets.  It is very satisfying how nicely the bike "chunks" into gear - I'm glad I took the time to go through the internal shift mechanisms to make sure they were working right.



The brake side was pretty straightforward - I had to make a spacer for the CBR929 master cylinder, but the hole spacing was otherwise the same.  The master cylinder cost less than a rebuild kit for the old master cylinder shipped which was nice.  I had some troubles with the rear caliper till I realized I needed to disassemble it and clean it, which I had apparently not done.  It works great now, and I have another couple spares if I have any issues with it in the future.  There's a nice set of EBC pads back there now too, so that is pretty much buttoned up. 



The tail grab rail, tail light, and "trunk" are back on as well.  It seemed like every threaded hole back here had to be cleaned up, and I was missing the 85mm bolts that hold the rail in place, so back to the hardware store with me:



I also got the CB650SC Nighthawk oil cooler installed.  I was driving myself nuts trying to get the stock lines to fit until I realized I didn't have to use the stock lines and could just use the end fittings with new lines.  Duh.  The cooler is mounted pretty high up, but that way it will get clean air between the top of the wheel and the bottom of the headlight. 

Also, Hondaman's book arrived, so that is some good reading when it's too cold to work on the bike.  I did realize that I should have gone through the head while I had it off and port matched it, but I wanted to get the motor back together.  Ah well, next rebuild.  At least I did the clutch oiling mods, the rocker arm shaft oiling mods and the 5mm bolt delete mod, which should help longevity. 

The wiring harness is reinstalled as well, as is the battery box and some of its electronics.  I still need to build a pigtail for the new fuse box and set up the headlight and ignition relays.  I'm not sure if the headlight relay will be needed with the LED headlight bulb - it only pulls 24 watts.  It's probably best practice anyway in case I switch to another light setup.  The ignition relay is good for beefier coils, as long as I don't fry the points, right? 

I'm also looking for a place to install the solid state regulator / rectifier so it can get good cooling airflow.  Oddly, the rear set bracket might be a good spot for it, if it doesn't hit my foot. 

The oil tank is also plumbed, so I decided to fill the bike with oil and see if I could build pressure with the starter motor.  I cranked it over a bit, but couldn't get oil to come out the pressure sensor hole.  After doing some reading, I realized I did not prime the oil pump when I reinstalled it, oops.  Some more research suggested that I pressurize the oil tank with air to help force oil into the pump.  I used a rubber bung with a barbed fitting I have around for pulling vacuum and pressurizing stuff and carefully used my air compressor blow gun attachment to put some pressure on the tank.  I could hear the oil bubbling and the level went down about an inch or so in the tank, so I tried to crank it over again.  Ta da, black gold, Texas tea, all over my painted engine.  At least it's new oil. 

I reinstalled the oil pressure sensor and hooked my multimeter to it and to ground, and set it to the audible continuity mode.  The sensor grounds out when there's no pressure, and goes to high / infinite resistance when there is pressure, so I knew when the multimeter stopped beeping the sensor had enough pressure.  I cranked the motor over with the starter again, and what do you know, I had oil pressure.  I used Rotella 15w-40 diesel oil with Risoline for the ZDDP, and the level looks good.  It took about half a quart more to fill the cooler as well as the main system. 

[worst650ever]

Holy no updates in a year Batman!

I've been working on the bike occasionally when the mood strikes me.  A '75 Super Sport tank and seat in Sulphur Yellow came my way thanks to my eagle eyed Dad spotting a pile of 750F at a yard he was getting some car parts from.  A 4-1 MAC exhaust along with some early 750 exhaust spigots came my way from a friend who builds Amen Savior 750 choppers and has no need for "sport bike" parts, and I was able to get that installed this evening.

A 2006 Honda 599 "Hornet" also found its way to me after I sold my CB360, and it has been the daily rider.  An '87 CBR600F "Hurricane" also came to live with me, so I have the Hornet and the Hurricane.  Sounds like a band name...

On a whim, I filled the carbs with gas, jumpered power to the ignition, and shorted the solenoid with a screwdriver.  The damn thing fired right up and idled for 20ish seconds.  Son of a gun!  Guess I have to get back to work on this lump...