Topic: 1970 CB450 restomod

[Maurice]

This plug still works, believe it or not. I will probably not ride with it, but somehow I knew one day this was going to happen. Those damn nuts are always on so tight.

[Maurice]

Almost popped a hernia trying to get the oil plug out. Sonofa. Had to use heat around it, then it came out. It's not the best design, directly underneath the bike, oil sump integral to the lower case, and a huge diameter guarantees oil splashing everywhere...



Also cleaned the inside of the tank, which was not too bad at all.

Before:



After:



WD-40 inside right now.

Waiting for muffler gaskets/clamps, I figured I'd rehabilitate the front brake. Expecting a rusted out piston, this is what came out:



Master was stuck, now rebuilt and bled. I'm still using the old hose, slingshot is closed for now...



The caliper paint is so-so, but I'll take care of it when the new hose is here or I'll get fluid on it. Also hopefully I can find the same color paint, it looks like a nice change from the black.

[Maurice]

I got to start it over the weekend.

First I rigged up an old battery, turned the motor around to lube up the cams. It really does not take much to build up oil pressure, soon there was oil pouring out the cam lobes.

Starter motor is not hooked up, so I kicked. This motor is high compression (I measured 170 and 160 PSI by leg), it takes some doing. Second kick it sputtered to life, then shut down. I tried to start it again to no avail, then lost some time rigging up proper exhaust since PO put longer shocks and the axle contacts the mufflers...

Next day I used a good battery, the motor fired up almost immediately, then went into too high an idle. Quickly adjusted the idle stops. Oil immediately started coming out one of the valve lash adjusters, I had forgotten to tighten it. Oops... Let it cool a bit, set the super tight lash (0.03mm, almost impossible to slide the gauge without wrinkling it). Runs fine now but smokes a bit under throttle, I'll see whether rings settle or it needs torn down. Compression looks ok so hopefully it's residual oil I poured in after I got the bike.

This engine revs quick, and was surprisingly easy to get to run ok initially. Kickstarter lever did leave the bottom of my foot sore from testing compression and starting, short lever and high compression: ouchy.

No time for pics or anything, it's all jumbled together anyway, was not expecting the exhaust to be such a PITA...

[faux fiddy]

I got to start it over the weekend.
 (0.03mm, almost impossible to slide the gauge without wrinkling it).

There is a thread at HondaTwins.net  that has a re-posted discussion of valve adjustment. Guys that worked with Team Hanson (Daytona winners back in the day) say a tight .002" is the way they do it. Another guy who I met at Barber says the same.

I did mine that way, as far as I know they might have never been adjusted since factory. It ran much better afterwards.

Not sure how that converts to MM off hand.

[tbpmusic]

Yeah, we all use 0.002" - the setting the manual calls for is nearly impossible for a normal human to achieve, and it's way too easy to be too tight. And I wouldn't suggest a real tight 0.002", but a moderate one. That gives a good margin of safety and still minimizes clatter.
Many folks who race them (like Terry Naughton at Hansen) actually use up to a 0.005" gap - but then they have plenty of parts available.

[Maurice]

Ah ok. The gauge I used is marked 0.0015", I'll go with .002 should be much easier. The engine does run quieter than I expected.

Started it up again and it did not smoke a bit this time. We'll see, need to clean the carbs again I think, after a while I could not start and was not getting any gas into the cylinders. The pilot circuit is a weird setup where gas comes in from the main, through a hole in between the towers and then into the slow jet tower. I was perplexed when cleaning the pilot and finding no hole at its tip

Is some starter freewheel noise normal when kicking while testing for compression for example? Once running I cannot hear any such noise.

[tbpmusic]

Ah ok. The gauge I used is marked 0.0015", I'll go with .002 should be much easier. The engine does run quieter than I expected.

Started it up again and it did not smoke a bit this time. We'll see, need to clean the carbs again I think, after a while I could not start and was not getting any gas into the cylinders. The pilot circuit is a weird setup where gas comes in from the main, through a hole in between the towers and then into the slow jet tower. I was perplexed when cleaning the pilot and finding no hole at its tip

Is some starter freewheel noise normal when kicking while testing for compression for example? Once running I cannot hear any such noise.

It could have been smoking because the tappets were a bit tight......

You are correct, ALL fuel for BOTH the main and idle circuits passes through the main jet first on these carbs, an unusual situation.
The "idle jet" that has the "38" stamped on it isn't a proper jet at all, more or less just a cover for the cross-drill between the two passages. The real idle jet is underneath the one stamped "38", and it's too small to bear any sort of stamped number.
Attached is an annotated diagram of how these carbs work......

If the starter is quiet when the engine runs, you're golden.

[faux fiddy]

I think I know the noise you're talking about when kicking.  I haven't had anything crater.  I've put half the mileage on the bike at 12k miles and it's done it from time to time.

Sometimes you'll hear the starter disingage and wind down, too.

[tbpmusic]

When the starter clutch starts to go out, you'll know it  - thing will start "whooping" and howling like crazy......

[Maurice]

Bike has been done for some time, maybe I'll cut the rear fender it's all dented anyway. Nice little bike has a lot of get up and runs great.

Next I'll be working on a '76 750, almost finished a DOHC 750 looks nice. I just don't feel like posting here anymore, sorry.