Topic: CB750 K1 project

[mwvachon]

Yeah, the crimping is tough, that is why I used a soft cloth - was hoping to absorb some of the impact when tapping those back over. I also had a bit of internal grit shake loose when I did the gold K1, but as you said, it's since settled out of sight. 
Gauges looking good so far! You got the faces from?
Also, you might want to check w/Z1PARTS.net [http://www.z1parts.net/product/cb750-wiring-harness] for your wiring harness - think that's where I'll get mine.

[Dunk]

Fighting the tach to get the ring on. The speedo had a one piece gasket around the edge of the white/turquoise inner part that reflects the light. The tach has two gaskets, one ring above and one below. This stacks thicker and the crimp ring is not tall enough to crimp nicely on it. The rubber ring gaskets were slightly differing thicknesses so I was able to use two of the thinnest ones and it's barely enough to crimp, though not as much as I'd like.

So I get it crimped on and the needle had fallen off. Took it apart and put the needle back on firmly. Tapped more gently while crimping and now about halfway around and it's coming loose, needle is not pointing right at zero. Should I use a dab of some sort of adhesive on the needle? Superglue or similar? Maybe nail polish? I would prefer to be able to get it off in case the gauge ever needs to be opened again, but it seems to need something more than just the slight friction fit to not fall off or move when crimping the ring. Speedometer did not have this problem. I feel like these gauges are fighting me every step of the way.

Faces came from CB750faces.com / Lecram. I think the wiring harness is from Z1parts. Not 100%, I'd have to look at receipts.

[tweakin]

That is so discouraging...  I hate messing with the gauges.  I always put  tiny bit of clear silicone on the needle to help secure it when I rebuild gauges.

Fighting the tach to get the ring on. The speedo had a one piece gasket around the edge of the white/turquoise inner part that reflects the light. The tach has two gaskets, one ring above and one below. This stacks thicker and the crimp ring is not tall enough to crimp nicely on it. The rubber ring gaskets were slightly differing thicknesses so I was able to use two of the thinnest ones and it's barely enough to crimp, though not as much as I'd like.

So I get it crimped on and the needle had fallen off. Took it apart and put the needle back on firmly. Tapped more gently while crimping and now about halfway around and it's coming loose, needle is not pointing right at zero. Should I use a dab of some sort of adhesive on the needle? Superglue or similar? Maybe nail polish? I would prefer to be able to get it off in case the gauge ever needs to be opened again, but it seems to need something more than just the slight friction fit to not fall off or move when crimping the ring. Speedometer did not have this problem. I feel like these gauges are fighting me every step of the way.

Faces came from CB750faces.com / Lecram. I think the wiring harness is from Z1parts. Not 100%, I'd have to look at receipts.

[Dunk]

Finally done with the gauges. Used a dab of super glue on the tach needle to keep it in place, then since it was so tight getting the cover crimped on I put it in my press, with only a very small amount of pressure, and got it crimped much better than I could on the bench. New backing plates on, one original style for the speedometer and one new replacement style for the tach. Don't like the new style which has the extra hole for the speedometer and is slotted between the gear drive and wire grommet... Though it makes installing the wires and grommet faster.





I'm glad to be done with gauges, it has been tedious. I feel like the to do list is getting much smaller, which is great.

[Dunk]

Nothing major today but a little progress. My wiring connectors from vintageconnections.com arrived last week so I figured I'd try to get more wiring done. Had to de-butcher some of the connections on the controls and got most of the headlight bucket wiring attached in what I think is the correct way. The connectors and crimper from vintage connections are all excellent quality and easy to use. I'm very pleased.

Also looked through some bins of spare parts I've acquired over the years and found a second triple tree washer. I only had one on this bike when I got it, but now can rest at ease having found a second and have it securely on the bike since these seem to be made of unobtainium. It was on the outside on the cracked tree here, maybe that's why it was needlessly damaged.



Slow and steady...

[mwvachon]

I hear ya, Cad, on the top fork bridge. I've now collected a small stash of these 'D' washers. I ordered some from a dealer in NC and then I found out the project bike actually had the original ones (I really need to check all these little sandwich bags before I go ordering stuff!), I also found a few more in my other salvage stuff, so I'm good for a couple more bikes - I think!

[Dunk]

A little more progress. Pegs ready to go on...

Cleaned, painted, and new rubber. Slow progress, but these are the sort of odds and ends which need to get done to wrap up.

[cheftuskey121]

Beautiful work as usual. One step at a time!

[Dunk]

Not sure what I'm doing here. Got an order of misc parts to wrap up most of the chassis. A bit to go with that but I support it's mostly there. Horn, throttle cables and grips, coils, finish wiring in headlight bucket, clean and mount oil tank...misc other little things. It's mostly there and more or less ready to have an engine dropped in.







This is what's left of my pile from disassembly. When I took it apart I laid everything out in this area more or less as it came off the bike. Anything replaced with spare/NOS/reproduction was put in my spare parts boxes as parts went on the bike. As you can see there's really not much left to be cleaned/restored/replaced and put back on.


So with the pleasantly warm weather and the garage tied up with the bike I spent the morning doing some things with my truck which has been neglected most of the winter. After that I took advantage of the remaining daylight and above freezing temperatures to lug the engine outside and go at it with engine bright, brused, and a hose, then following that up with a few cans of brake cleaner. Ready for whatever I'm doing to it. At minimum I'll be polishing the bright covers, painting, and replacing a few gaskets.





I'd like to replace the oil pump o-rings and stopper plug/spring but Elan seems to be out of stock at the moment. Hopefully he'll have them back in stock before I wrap up the engine. Is there anything I should do before putting this back in? I'm thinking clutch just because. I was considering doing the cam tensioner and all associated parts until I figured out that involves pulling the head and jugs. Not sure now. If I do that I'd replace the chain as well, and probably the rings at minimum, do some head porting, maybe change the cam... At that point I might want to do a big bore kit...

At that point I'd be better off pulling the engine from the other K1 which is totally unknown everything to me, but is like an on/off switch at 8k and pulls hard past the end of the tach. Of course that engine needs the same cleanup as this one and at the least should be checked out. Besides, I'd like to build that bike next winter either as a cafe or just a nice rider with some modern upgrades and not so worries about staying original like this bike.

So what do you guys think I should do with this engine beyond just making it look good? It ran well, had a little of the typical clutch and timing chain rattle but nothing alarming. While I'd like to do some performance improvements I'd also be happy to be able to be riding soon since it's starting to warm up.

[edhaeuser]

If I had not found a big poorly patched hole in my case, I would have cleaned it up, painted it, and thrown it back in the frame.

[cheftuskey121]

If I had not found a big poorly patched hole in my case, I would have cleaned it up, painted it, and thrown it back in the frame.

I remember when I first saw the patch job on my K1 motor. my heart sank. thankfully it turned out to be ok. too bad the damn motor mounts at the rear busted off in my wreck. actually going to rebuild the K1 motor in new unstamped cases with Bill Benton soon. unstamped...you know what that means...matching numbers

can't wait to see this thing finished. man I wish I could ride up and visit!

[seanbarney41]

the cam tower pucks will go bad relativaly(how the #$%* do you spell this word?) soon, and then you got an oily mess....everything else is just icing on the cake

[Dunk]

OK, so at the least I'm thinking reseal the major parts and the covers I have off to polish. Doing the pucks under the cam towers I think would be prudent, so at that point I'll have the cam out. At that point it's not much more to pull the head and jugs, do a cleanup, measure taper, re-ring, lap valves, etc. while it's off.

At that point maybe it would be worth just doing a quickie top end freshening up as that's what I'm looking at. Hopefully just cleanup, reseal, lap valves, etc. Replace valve seals and so forth. Check guides for excessive play and if anything looks bad bite the bullet and bring it to a machine shop.

If I go that route I'd like to port the head. I've done several port jobs on Ford small blocks and 385 series. Anyone have some resources for what areas need work and what works best on these heads?

Also if I've got the top end apart what is involved in doing a big bore kit like an 836? Is it as simple as get the pistons and have the jugs bored to size for them? Not sure at what point thicker sleeves are required. What kits are good if I go that route? I'm under the impression from some quick searching the cost isn't terribly much, ranging from $100 ebay kits (quality?) to a few hundred from various other vendors.

Still undecided as to my exact course of action, but I'd like to get input on my options. Biggest thing is I don't want to deal with any leaks after this goes in, engine in and out of the frame is not my idea of fun.

Anyhow here's what I've got...



What is this number? U 422


After removing the intake boots I found this fin bent. Never noticed it before, I'm guessing some hack got a bit rough breaking the head loose previously. After doing the rest of the bike I suspect it was laid down on the right side before. No damage I've noticed to the engine to indicate that, though it did have (undamaged) case guards on it.


Looks like some rubbing on the top of all the intake ports. Not sure if that's factory or not. Maybe some minor flashing or mismatch between the screw in ports and the head someone cleaned up previously?






Can anyone recommend a engine stand adapter so I can put this on my stand? I'd rather work on a stand, but worst case it'll be on my bench at some point.

[Dunk]

If I had not found a big poorly patched hole in my case, I would have cleaned it up, painted it, and thrown it back in the frame.

I remember when I first saw the patch job on my K1 motor. my heart sank. thankfully it turned out to be ok. too bad the damn motor mounts at the rear busted off in my wreck. actually going to rebuild the K1 motor in new unstamped cases with Bill Benton soon. unstamped...you know what that means...matching numbers

can't wait to see this thing finished. man I wish I could ride up and visit!

Sounds like you're making progress on yours. Any plans for more power when you get it together in the new cases? If you ever find yourself in the Philadelphia area give me a shout.

[seanbarney41]

your intake port pics show factory port cleanup of the casting.  Interesting, as I was under the impression that k1 era bikes had a nicer job of this from the factory.  Supposed to be several ponies buried in that casting flash and mis-match.  Hondaman's book has excellent info on what to do with this and engine rebuilding in general.

[edhaeuser]

Can anyone recommend a engine stand adapter so I can put this on my stand? I'd rather work on a stand, but worst case it'll be on my bench at some point.

I made this one with longer arms for painting.  It fits my Harbour Freight 1000 lb stand.  I might be convinced to send it out your way as I am not using it right now.  I would need it back when you are finished, though. 

[Dunk]

I actually ordered Hondaman's book this morning... Says something like 15-30 days. Hoping to be done with this in a month or two for when it's consistently warm out. It's tough finding time, or it's wait for the next part, or it's while I'm in here I may as well... You know how it goes. The book should come in handy as this won't be my last CB750, I'm hoping to do my other K1 next winter and I doubt that'll be the last one, though I'd like to do a '69 450 eventually as I always liked them and that was the first bike I ever rode.

I wish I still had my welder, that stand looks pretty simple to make. Had two stolen so I'm out $1600+ worth of welders. Hardened the garage a bit but afraid to buy another because clearly I'm being cased. Whoever is stealing my welders doesn't seem to be interested in tools, parts, etc. that are worth a fortune but a lot more volume and weight to dollar ratio and harder to sell compared to a welder. Many little projects I wish I had one but waiting for another big project and I think the next one will be secured to the floor or structure or dragged inside after each use. I'll see what I can find premade if not I may take you up on that offer.

My back is killing me today, I hurt it a couple days ago and while it's getting better, it's hard to be bent over or working on the floor for long. Yesterday hurt too, I was fine while working on this but woke up feeling like I got in a fight with a freight train. I've got the side covers off, seals out, gaskets cleaned off, and soaking in the parts cleaner. In a bit I'll finish scrubbing them and begin polishing. Doing this will give me some time to decide what to do with the engine and see if anyone else comments on it.

After taking the valve cover off I checked the timing chain and after rotating so all the slack was on one side there was a significant amount of slack. I could pull the chain up off 1/4 of the cam sprocket. Loosened the adjuster and it did take out most of the slack, just a small amount but has tension on it now. Not sure how to tell what's alright or not but I don't think I'd need to replace the chain. Despite appearing to adjust as it should I will remove and clean the tensioner at minimum. Can't really tell condition of the tensioner wheels from the top but they don't look chewed up. No idea on the guide as I can't see it.

How do I set the cam timing? I looked through the shop manual and for removing/reinstalling the cam it said something about lining up the marks on the cam to horizontal in the tower to tell cam position. I assume this coincides with a particular crank position maybe TDC #1? Not entirely sure, it's probably mentioned in another section of the manual. This is my first time pulling part a 4 stroke bike engine and first time with anything overhead cam so a bit of a learning curve.

[Terry in Australia]

G'Day Mate, your rolling chassis is looking great, well done. As has been previously mentioned, the cam pucks under the cam towers should be replaced, and it's not a huge job. Rotate your cam to the "T" mark for 1&4 cylinders, (looking thru the hole in your points plate) and check that those marks on the end of the cam are horizontal.

Remove your cam chain tensioner to take the slack off the chain, undo the two bolts that hold your cam sprocket onto your cam (don't drop them down the camchain tunnel!) pull the cam sprocket off the cam, remove the chain, undo all your cam tower bearing caps and hold-down bolts, remove the cam and sprocket (attach a piece of wire to your camchain to stop it falling down the hole) lift the cam towers off, and you'll see the old pucks.

Before you replace them, take the opportunity to back off and re-tension your head. Just back the nuts off a few turns, then put a drop of oil on each cylinder stud, then retension them as per the diagram in your manual, using a good quality torque wrench in no more than 5 foot/pound increments to start, then no more than 2 foot/pound increments as you get over 10 foot/pounds, and the four 6mm bolts under the pucks, plus the two 6mm bolts fore and aft of the camchain tunnel. (I think from memory you only tighten the 6mm bolts down to around 6-8 foot pounds, but check your manual first)

I torque the standard cylinder studs to 19 foot/pounds (3 more than the manual recommends) I then leave it overnight, loosen them all off and then retension them again to 19 foot/pounds, and my head gaskets don't leak.

If your engine ran well before you pulled it out, chances are you're wasting your time cleaning valves and lapping them in again, so if it was me, I'd just leave it alone.

Pull your camchain tensioner apart though, the spring loaded rod is prone to seizure, and often just loosening it off will do nothing. Give the shaft a good clean and a light polish and hit it with some engine oil or WD40 to ensure that it will slide back and forth with no hindrance. When you re-install it, do what you did previously and turn it so the slack is at the rear of the engine and install the tensioner and make sure it's taken up the tension, tighten the bolt and the locknut, and you'll be good to go. Cheers, Terry.  

[calj737]

Cadunkle - for the stand adapter, if you just need something "quick and dirty" use angle iron. Some 1x1 or better, cut into 4" lengths. Drill 1/2" holes offset on either edge of angle iron (1 hole 1-1/2" from top, 1 same distance from bottom in other side) this allows you to use the engine stand mounting arms, pass some 8" long carriage bolts through the arms, then thru the "bottom" hole of angle iron. Use your hangar bolts thru top hole.

4 pieces like this will serve your immediate needs. It's not as elegant as the one offered, but for the cost of shipping, you could probably fab it up at home.

FWIW

[Dunk]

I cleaned up a little grime I hasn't got to with the carb boots on and covered, used brake cleaner and scrub brush. Then some time later set to try to straighten that bent fin on the head. Applied heat and the whole shebang went up in flames! Was using some new brand cheaper brake cleaner I've never seen before as they were out of the stuff I usually get. I think it's environmentally friendly so doesn't evaporate so quickly, though it seemed to have dried up. Was burning pretty good and lit the pad I had it laying on fire along with some oily rags and so forth. Threw a towel over it and the smothering mostly worked, then got a hose and put out what little was left. Never a dull moment!



So after making sure I wasn't gonna burn the garage down I figured I ought to do something that doesn't involve heat or fire, so set to finishing polishing the engine covers. I've found a few hours this week to get these cleaned up this week. Not a show perfect mirror finish but a lot better than they were.

My motivation for perfection isn't quite there at the moment. I'm bummed as there were a lot of firings at work this week so just trying to plug along with something to keep me busy and my mind from wandering too much.









I may get to the cam tower pucks soon as I need to at least replace those. I'm debating whether it's worth it to replace the cam tensioner rollers and guide as well. As best I can tell mine are intact and still rolling. If I do that I think it'll be an 836 kit and head porting while it's apart. Tough decisions. There are $120 cast ebay kits with little detail provided, $250 coated ebay kits with coated pistons at 10:1 and little other detail so I assume cast, and Wiseco at $450 for forged pistons 10.25:1.

Or just pull the head and jugs and see what I have, port the head a bit, and if everything looks good and measures out within spec throw it back together. Maybe with HD studs since that's fairly cheap and easy at that point and a known weakness. From that damage to the one fin on the head I'd guess that was likely done with the head off, maybe dropping it. So no idea on miles or what I have as gauges were likely not original and I've seen a few indications at least the top end has been apart before. Any way to tell what casting the head is and if it's an original K1 head or has been replaced with a later head?

[calj737]

Try spraying the engine down with oven cleaner. Works pretty well, and you can wipe off the grime that doesn't seep off. And, no flame required ;-)

[Terry in Australia]

Be very careful with oven cleaners, any caustic based cleaner will turn your alloy cases a horrible black colour which won't come off! I use non-caustic automotive paint stripper and it rips the old paint off and leaves the alloy nice and shiny.

Re: the big bore kits, the 120 dollar eBay pistons are fine, I've got them in my engine with no issues. Cheers, Terry.

[calj737]

I have heard that too, Terry. I did use it on an engine BEFORE I had heard that, but never encountered that result. I gave it down to the clear cost still being on the engine, perhaps? But I would wholly agree that a raw aluminum part can be adversely affected by the wrong type of chemical.

Perhaps a different cleanser would be the better choice all around. I know that Simple Green makes an aluminum specific cleaner and that has also worked well for many people.

[Dunk]

Yes I'm aware some cleaners will discolor or stain aluminum. I use either simple green or purple power in my parts cleaner and both will discolor aluminum if exposes for an extended period. I do a brief soak then scrub, as long as I don't leave anything aluminum in overnight it tends to be fine. I may go back to a petroleum based cleaner next time I drain/clean/replace fluid as they tend to work better and be less of an issue with parts, but are more expensive and available at fewer stores.

I was reading some of the threads here on those $120 836 kits and generally seems to be decent quality from reports there, though haven't seen anyone post who has run one for an extended time. Still on the fence with that. I'll research a bit more and figure if I'll do the 836 and if so which pistons. How many miles on yours Terry and what are your impressions of quality? Any issues? Did you do any head work, cam, etc. while it was apart? Worthwhile upgrade?

Lifting this sucked... How can aluminum be so heavy? Oh yeah, it's full of steel.


One of these things is not like the other... Stay classy. Clutch looks good and plenty of meat on it comparing to spec. so I'll probably just clean and reuse. Did have some of the typical hard to find neutral/clunk into gear issues. I've had bikes that did it worse and completely resolved with just a disassembly, cleaning and readjustment so I think I'll be fine with this. I am considering doing the clutch basket mod which amounts to adding a few holes. I believe it's supposed to help with the dragging issue.




Disassembled...






Pucks didn't look to be leaking, but hard to tell since the engine has been cleaned, degreased, and so forth. No sealant was used on the old ones. This has been done before, an old cam tower puck hiding in this cavity.



Cam chain guide and rollers, hard to see but they look intact.





Should I clean up this casting flash in the fins? It's similar in several areas which I imagine would restrict airflow and cooling.



I think I'm going to pull the head and figure out what I have and what has been done before. Tempting to just slap it back together but I hate not knowing and I'd hate pulling it out again even more.

[Dunk]

Got the head and jugs pulled and cleaning parts.

First things that struck me is the outer two pistons, 1 and 4, have the pistons installed backwards. The arrow is pointing towards the intake side. The inner cylinders 2 and 3 have the arrow pointing towards the front/exhaust side of the engine as normal. Why might this have been done? Just a screwup by someone who had it apart before? Doesn't look like any valve to piston contact so I guess despite different valve reliefs they're close enough.

Did some quick measurements and cylinders look like 2.401"-2.4015". Taper is about .0005" on most with one having significantly less. The pistons are all 2.400" at the skirt. So the taper looks pretty good, well within spec of .002" to bore to next size. I've seen engines with .007" taper and usually see a lot more then .0005", though usually I'm working on 4" or greater bores so not sure what is a lot of taper for a small piston and bore. Piston to wall clearance is within spec of .0004"-.0016" Bores don't look bad... No ridge catching my fingernail, though there is one spot mid bore on #1 that I can feel. Looks like maybe it sat in that spot for a long time and had a little moisture. It's not bad enough that I'd worry though.

I removed the studs and will be using HD studs. Hopefully that will keep everything together and sealed up. So the decision now is should I ruin with these pistons and just a quick hone and rering and put 1 and 4 back the correct orientation? Or 836?  Either way I will check the head and valves, clean up the ports a bit, and a quick lap of the valves.