Author Topic: My 1975 CB550K build...550/650 Hybrid motor project  (Read 10891 times)

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Offline purf_man

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My 1975 CB550K build...550/650 Hybrid motor project
« on: November 24, 2012, 06:35:56 PM »
Well I figured now that I have my bike in the same state that I am living in I could start a thread.

Background of Bike:  Bought this off a friend shortly after getting out of college (he had upgraded to a Katana) as I had always wanted a SOHC Four (my father had some '69 750's back when he was in the Navy)  Bike had been sitting for a year or so in his parents garage.  I picked it up and after a couple rides the left crank seal started pissing oil.  Pulled the motor and replaced both seals but never got the motor back in.....7 years later and a couple moves I found out trash got in the cylinders because I had never put the plugs back in.....I got pissed and let it sit until I had the time to deal with it.

My Background:  Mechanical engineer working in the Power industry (Nuclear Power) I travel ALOT for work (pretty much every couple years it is a new project/location.  I keep a base of operations (where my personal projects live....the CB, a RD400, 1962 Fairlane and a V8 S10)  For my current work assignment I figured I would bring the CB since it travels alot easier than a full car and will not take much tool wise to work with (I did bring a small MIG and 4.5" grinder to detab the frame and weld on a couple new tabs for the solo seat/cowling)

The Plan:  I won't call it a Cafe build as they do seem a little over done and I hate trying to fit that stereo type in that you have to have a certain part or color or whatever or the trend is.  I am just building this the way I want to build it (I might cut some corners in buying something bolt on instead of fabbing as my time is limited and funds not as much)  On hand/in the mail already are some Tarozzi rearsets, a forkbrace, new monza cap for the tank and that is about it.

-  Relaced wheels (prob done by Buchanan's)  size yet to be determined.  Hubs and rims in black powder polished SS spokes.
-  Forks will get some new tubes from Franks (don't wanna bother with eBay for used tubes that are bent or have some pitting)  Looking to upgrade the valving.  Lowers to get black PC also (I do have some spare lowers that might get polished and might end up on the bike instead)
-  Dual SOHC front brakes.  I kinda like the vintage look of them.  Will get the centers PC'd and the disc drilled and ground.  Calipers refreshed with new pistons, more powdercoat.
-  Motor will be tore down and cleaned up, painted flat black and phillip heads replaced with small hex head bolts where I can (debating using a grey parkerized finish on the bolts)  a spare set of side covers were polished 6 years ago and will just a refresh to go on the motor.
-  Stock carbs (will get them refurbed) with stock boots to a custom airbox (prob a 2-piece Carbon deal with a cone filter up under the seat more)
-  Solo seat/cowling with the standard electronics relo under it.  Ballastic Battery, modern ATC fuse block, Dyna Ignition
-  Tarozzi rearsets as mentioned.

Looking into muffler options (have a 4-1 on the bike now) to swap out the steel cased muffler for something smaller and/or lighter.

My garage in my rental has no power (need to pick up a couple extension cords so I can get some light out there) so pics will come tomorrow.  I have already stripped down most of the bike (fusepanel is about the only think left on it right now) and have a couple sets of bars I want to test fit for when the rearsets get here later this week.  I think I have an aerotech seat picked out along with a belly tray. 

I am trying to fast track some of this build.  I would like to get most all of the mock-up down before Feb 4th when I go into a refueling outage that will be running 2-3 months in length and will have pretty much ZERO time for the bike (kinda hoping that will be my send stuff out for powder/paint/refurb and assemble it all this spring)
« Last Edit: December 04, 2012, 05:33:15 PM by purf_man »
1975 CB550
1978 RD400

Offline Tews19

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Re: My 1975 CB550 build...total teardown and rebuild
« Reply #1 on: November 24, 2012, 06:47:27 PM »
Sounds like you have a very detailed and thought out build. I will be keeping my eye on this.

I have a set of forks from forking by franks and they are mint. I actually got them in a stash I picked up from MN last summer. They were extended 6 plus inches. They had the forking by frank engraved. Called them up and for 60 bucks cut them down to stock length. Had them back within a week of me sending them off.

In regard to your exhaust. If you have a stick 4-1 550F header keep it. Run a reverse megaphone from cone engineering or you can pay 25 bucks more and get the same one from Lossa. Pretty sure lossa gets theirs from cone but they engrave LE in theirs. You have any pics of the bike or even of your dads 750?

We love pics!
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline purf_man

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Re: My 1975 CB550 build...total teardown and rebuild
« Reply #2 on: November 24, 2012, 07:18:30 PM »
I have a pic back at the house of him on one of his 750's (with big tall 70's style bars on it and him holding open an empty wallet)  I know we have a slide (in one of a couple dozen trays of slides) that shows the bikes lined up on the ordinance deck of the aircraft carrier (a few hundred bikes prob....handlebar to handlebar)

the exhaust is not stock 550F exhaust....just the typical painted aftermarket stuff.  Here is the bike after I found out about the oil leak on it.....If you could Id the exhaust that would be great (no markings on it)



The Airtech seat I am thinking of.


1975 CB550
1978 RD400

Offline 550Z

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Re: My 1975 CB550 build...total teardown and rebuild
« Reply #3 on: November 25, 2012, 01:33:45 AM »
Looks like a mac 4 into 1 very popular exhaust. Im looking into a carpy 4 into 1 they sound badass cafe racer 4 into 1 EXHAUST SYSTEM I MAKE

Offline purf_man

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Re: My 1975 CB550 build...total teardown and rebuild
« Reply #4 on: November 25, 2012, 10:20:16 AM »
so I poked around on it a bit this afternoon....still waiting on some parts to show up (it sucks living in the middle of nowhere)  wrestled the wiring in the headlight bucket to get the stock bars off and put on my clubmans (these are from Dime City and are the low angle bars....a little different than the traditional "Cafe" bars as the ends of the U are pinched down and welded instead of coped)

Before I started today:




GS tail mocked up:



Clubmans installed:

1975 CB550
1978 RD400

Offline purf_man

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Re: My 1975 CB550 build...total teardown and rebuild
« Reply #5 on: November 27, 2012, 04:37:40 PM »
well my rearsets (Tarozzi) and Fork Brace (also Tarozzi) came in.  Disappointed with the finish on the aluminum brackets (thin and spotty...guess I am sending them out for powder with everything else)  I think someone could rattle can them WAY better then they were out of the box.

need to get the brake rod all installed and set to length so I can match mark everything for when I take it apart.  I will get some pictures this weekend once it is light out (they were installed in my powerless garage via flashlight)  I might have to weld some tabs on the frame in place of the passenger ears and trim down the cast bracket to clean things up a bit or just install some spools on the old passenger peg bolts so they look like they have a reason to be there.

I had a sit on it (with no seat) and felt they were a little high for me but I think once I get a seatpan and some upholstery on there I should be pretty good to go.  The low rise Dime City Cycles clubmans felt pretty good to me too.  I might have to mark them and drill for the switches this weekend so I can get that all going too.
1975 CB550
1978 RD400

Offline Tews19

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Re: My 1975 CB550 build...total teardown and rebuild
« Reply #6 on: November 27, 2012, 04:43:53 PM »
If you are not happy with the parts I would send them back. IMO you should get what you expect. Especially if brand new. 
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline purf_man

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Re: My 1975 CB550 build...total teardown and rebuild
« Reply #7 on: December 04, 2012, 05:31:54 PM »
Quote from: the_dam_man;874970
Well I tore into the 650 motor a bit this morning.  The top end was loose as the guy I bought it from said it had a stuck piston and freed it up.  figured since I need to tear it down anyway I would get the top end off it and strip off the side covers on the motor (clutch, alternator, ignition, oil pump cover and starter)

seems with some minor clearancing the oil pump / sprocket covers will interchange (have to grind about 1/16" off a corner)  not sure if I like the smooth 550 cover of the "honda" cover on the 650.....prob will stick with my already polished 550 cover though.  3 pistons are in good shape but the third was pretty crusty.  going to hit it with some PB blaster and see if I can free u pthe rings on it (doesn't matter much as they will get cleaned up and tossed up for sale)

the 650 has a more agressive cam that can swap into the 550 but uses a different tach drive (did not come with the motor)  I have an extra 550 cam laying around I will prob send out as a core (while some run the 650 cam I wold rather have a larger one if I am upping the displacement to over 700 and looking to pick up some more power)

pulled my old switches off the stock handlebars....what a pain in the ass!!!  Will transfer them over tomorrow or later in the week so I can start getting a feel for this bike some more.

Tossed on a master I had picked up (chinese Brembo knock-off) for $30 a couple years ago....don't think I am goign to run it though....brake lever is WAY out front.  So the search for a master cylinder continues (swap to dual disc brakes up front so I need a larger bore master....that will clear the gauges)

Not sure what I am going to do for an ignition.  I cold get a dyna for the 550 and drill it out to fit the 650 crank end or just pick up the remaining pieces for the 650 ignition system (box and coils)  in the end the cost will be about the same.

Did a little shopping this morning online and a battery and fork tubes/seals/boots are on the way and shoul dbe here for next weekend.









Clearance is real tight on the fork brace.  This is with a stock sized 19" tire.  I am looking to step down to a 18" or maybe even a 17" combo so I should pick up a little clearance here.


Oh yeah a donor 750 cylinder is on the way for the big bore hybrid motor
1975 CB550
1978 RD400

Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #8 on: December 19, 2012, 04:28:23 PM »
figured it was time for an update:  well the first big item has showed up for the build.  My custom Excel wheels from Buchanan Spoke and Rim can in today.
 17x2.5 front and 17x3.5 rear.






Going back in their boxes to head to Twisted for some color (guy that does my powder coating)

I think my first set of EFI throttle bodies get in tomorrow and still waiting on the solo seat.

That is correct we are going to EFI a 550/650 hybrid motor with some GXSR parts and a Microsquirt.  I have a machinist lined out to do the big bore conversion (just need to split the cases on the 650 to get the crank out of it and for my VFR flywheel to get here)
1975 CB550
1978 RD400

Offline Tews19

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #9 on: December 19, 2012, 06:53:42 PM »
Pics! Hey what made you decide on 17 inch wheels?
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #10 on: December 19, 2012, 07:21:52 PM »
seemed most will drop the front to a 18 on a relace/rehoop.  I was looking for a shorter sidewalled tire and figured I would give the 17's a try since there seems to be an excellent selection on them.  I am building a spare set of hubs so I can always change the other set if I want to.

I know I will lose a little lean angle in the end from the bike dropping so much but I have nowhere near the minerals to ride this thing to its limit anyways.  I think with the rearsets raising the pegs I will gain back some of what I lose.

trying to figure out how to remount these rearsets now.  Was thinking of a lug welded to the frame to bolt to but it would have to be pretty heavy and a good sized hunk of steel so thinking of maybe just a pair of tabs and some 6061 I have laying here instead.

Don't get me wrong the Tarozzi rearsets are nice but I want to ditch the passenger peg mounts and not use the U-bolt to mount them.  The frame is getting powder coated so trying to get it as smoothed and trimmed as I can.
1975 CB550
1978 RD400

Offline Tews19

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #11 on: December 19, 2012, 08:16:19 PM »
What did the rims set you back if you do not mind?
1969 Honda CB750... Basket case
1970 Honda CB750 survivor.

Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #12 on: December 19, 2012, 08:44:45 PM »
after shipping it was right at $500 for the pair.

Pretty much all the rims from buchanans are about the same price (give or take based on width)  a set of 18's would have been about the same.
1975 CB550
1978 RD400

Offline Blackandsilver

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My 1975 CB550K build...550/650 Hybrid motor project
« Reply #13 on: December 20, 2012, 04:00:47 PM »
Sounds like you're in for a serious overhaul. Good luck! Subscribed!


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Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #14 on: December 20, 2012, 04:53:16 PM »
soo it seems I have a spigot size issue with the 650 rubbers to the GSXR throttles.  Seller said these were from a 600 but I am thinking they are from a 750 as they are way huge (750 guys say the 600 ones will fit their stock rubbers)




Surprisingly the spacing is pretty damn close out of the box.  I am thinking of maybe just using some stock GSXR rubbers (the flanged kind)  on a hunk of 3/8" alloy bar and another pair of the same to adapt to the 650 head (this is if I can't find an off the shelf single straight rubber that will work)

Where the bike sits now:




hopefully I can get some tabs trimmed off over the next couple weeks (need to get a heater and some PPE when I am in the city this week)  Trying to find a decent welder to get my factory welds gone over with a TIG and to add the new brackets I will be needing.
1975 CB550
1978 RD400

Offline sinister902

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #15 on: December 21, 2012, 07:56:12 AM »
subscribed! you're doing the exact engine build I've got in mind...

Offline Bluegreen

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #16 on: December 21, 2012, 12:45:36 PM »
subscribed! you're doing the exact engine build I've got in mind...

Me too. To both.

Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #17 on: December 27, 2012, 05:50:18 PM »
so my $15 shipped flywheel came in over the holiday.  Fitted it up on the upper case half with the crank in  it.  it will need a tapered spacer sleeve but will clear the stator housing (diameter wise)  I think I might see if I can find a stripped stock housing instead of taking one of my spares apart to gut out.

I guess I can go forward on getting a VFR800 winding to put in this frankenbike project.

My other EBAY win throttle body set showed up (both sets are GSXR 01-03)  This one has a one piece fuel rail instead of the pup pieces with o rings so it will be harder to re-space and assemble to fit the 650 head.  The spigots are also large so I need to figure something out there (either a stock boot that will go from the GSXR throttle to the 650 head, an adapter plate with a bunch of flanged rubber boots to adapt the two together or just have the 650 head bored and alloy sleeves welded in place and blended with epoxy.

Picked up an impact socket adapter for my hex driver so I can get the flywheel off the 650 crank and speed up taking the 650 motor apart to swap the cranks.  I might talk to my machinist when I drop off to see if he can do the final assembly on the motor too while he has it all since my workspace is not very clean (open soffit and windy Kansas weather)  I think it will be easier to take a sealed and professional assembled motor and just sit it in the corner of my living room until the frame is ready for it....well maybe some test stand time to dial in the tune and leak check before it goes in the frame.

1975 CB550
1978 RD400

Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #18 on: January 02, 2013, 12:39:59 PM »
Teaser Pics....



Hubs and Rotor pic from the powdercoater.  Said he is gonna redo one hub he didn't like (also has my rims)  Should have them back next week I think.  Will be mocking up the rotors and hub and having spacers/trimming done then.
1975 CB550
1978 RD400

Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #19 on: January 19, 2013, 06:43:25 PM »
things are picking up at work so finding less time for the bike (going to 6-12's for a couple months.....will help pay for the machine shop bill)

Cases and cylinder are at the shop for resleeving and boring.  Having an external oil setup done, VFR800 stator/flywheel, GSXR 600 throttles fitted, and the 65mm bigbore.

my seat finally came in after almost 6 weeks of waiting.



I spent today (was at work for 6 hours this morning) fixing the squeaky idler pulley on my truck and de-tabbing the frame.  I think I might make a run up to the city and pick up some steel so I can fab some new rearset mounts and start working on mounting this seat to the frame.

for the seat mount I am planning on some rubber grommets in the fiberglass section and then making a steal seatpan that will bolt through the fiberglass.  The rear section will be getting a lip glassed into it so I can bolt it from the bottom side.
1975 CB550
1978 RD400

Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #20 on: March 04, 2013, 11:49:02 AM »
So I am into my 6th week of working 6-12's+

Bike pretty much has come to a grinding halt (only a couple more weeks of these hours)

But I did manage to get my bearings installed in the hubs and shipped them back for lacing (should be a week until they get back)

My rotors are out for drilling and resurfacing.

Check on the way to my machinist to get my 65mm pistons on the 740cc big bore stroker motor.

I picked up a DOHC oil cooler setup and will be fitting it to the 550 cases (need to trim a couple spots and some new hoses and mounts)

I also grabbed a steering damper to install.

Box full of weld tabs from speedway motors for mounting things to the frame.

Also picked up a TIG welder so I am putting off putting anything on the frame with my mig until I ge the TIG up and going.  I still need to build my hoop on the frame but have been looking at maybe cutting down my cowl to fit the frame better (have mold making stuff at my house in TN)

so things are going a little bit slower than planned but I think by the end of May I should have most of my motor (will prob be waiting on head porting) 
1975 CB550
1978 RD400

Offline sinister902

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #21 on: March 04, 2013, 01:12:09 PM »
be sure to detail what you use and how you use it for the oil cooler setup....

what did the machine work run you for having the 550 cases modded, 750 liners modded and installed, bore, and hone?

Offline purf_man

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #22 on: March 04, 2013, 06:11:04 PM »
as far as mods (I mocked it up on the 650 donor cases) you will need to grind back a couple fins on the lower case half and spot face the adaptor or block (I am doing the adaptor)

I am waiting to get my final bill on the motor work.  But I want to say it was $90 a hole total (bore block and case, fit sleeve and bore sleeve) and I think the weisco pistons are around $120 a pop.

next on the list will be getting the head ported and tossing some better valve train parts in it.  Will be alot more money than I planned on for the build but have been wanting to do something like this for a couple years now.

I found a big bike salvage yard about 45 mins away so I need to go looking for a fuel pump donor for the EFI conversion.
1975 CB550
1978 RD400

Offline purf_man

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Re: My 1975 CB550K build 3-9-13 New Wheels
« Reply #23 on: March 08, 2013, 06:47:20 PM »
My wheels made it back from Buchanan's today (17" front and rear Excel wheels with polished SS spokes)

Went to OZ Powersports here in KS with the hope of finding a fuel pump.  Wouldn't let me in the yard.  Said if I wanted a measurement or to look at the part I had to buy it.  For $275 for a used fuel pump from them I figured my chances on ebay were better.

Anyways....here are the wheels.







I still need to clean up the edges from the powder and polish a couple exposed edges we didn't powder.  My rotors are on the way back from Truedisk LLC. after getting 72 holes punched in them (maybe tomorrow?) 

so the hunt for a fuel pump for the EFI continues....
1975 CB550
1978 RD400

Offline sinister902

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Re: My 1975 CB550K build...550/650 Hybrid motor project
« Reply #24 on: March 08, 2013, 07:23:50 PM »
nice work on the wheels!