I am reposting some stuff from the MSN group here so we don't loose it forever.
From: bobm (Original Message) Sent: 1/18/2008 10:45 AM
I am in the process of tuning a '73 CB 450. Starting with the valves, I have not been able to find a .0012 feeler gauge in any auto shop. The best any of them can do is .0015. Any thoughts on where to get one?
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Recommend Message 2 of 7 in Discussion
From: MSN Nicknamestillstanding462 Sent: 1/18/2008 10:59 AM
I'll probably get flamed for this, but I always use a tight .002 on these bikes.
I don't think.0012 is even achievable for most of us, and a tight .002 seems to yield no more noise or wear.
Recommend Message 3 of 7 in Discussion
From: MSN Nicknameoldcycle Sent: 1/19/2008 2:17 AM
0.03mm Starrett feeler gage is available at the link below for about $4.00.
Recommend Message 4 of 7 in Discussion
From: MSN Nicknameelvis__evans Sent: 1/20/2008 11:44 AM
I've always used 0.0015". It's close enough. Elvis
Recommend Message 5 of 7 in Discussion
From: aries_58 Sent: 2/7/2008 9:20 PM
Don't know if this will help at all. Wish I could say I have tried it but my bike started acting funny so I never got the chance. I found this on a website and it sound like it might work.
The old Honda 350 and 450cc twins had what are called eccentric rocker arm shafts. That is, the center of the shaft is ground off center so that as you turn it, the rocker arm that rides on it, moves back and forth. This increases and decreases the valve clearance. If you adjust the valves on these engines the regular way with a feeler gauge you will be ok But, there is a better way.
Start and warm the engine up enough so that it idles good. Loosen each valve adjuster lock nut and turn the adjuster shaft with a screw driver. The valve will get noisy and the engine RPM will go up. You want the highest engine RPM with the lowest tappet noise. Do this on each valve. You will notice that the engine RPMs go way up. Sometimes as much as 1000 to 1500 RPM gain. Now back the idle down with the throttle stop screws and do it again. We want the highest RPMs and the least tappet noise, with the emphasis on the RPM. Yes, they will be noisy but, where do you think that RPM is coming from ? Stock clearance too tight ? I learned this trick from a factory mechanic when I worked in a Honda shop in 1968. I have never heard of it from any other source. It works though. I've used it on a lot of 350s/450s with no ill effects.
Recommend Message 6 of 7 in Discussion
From: MSN Nicknamestillstanding462 Sent: 2/7/2008 10:07 PM
I'm sorry, but never, EVER do this on a 450.
Works OK with a 350, but not a 450 - you'll toast your followers and cams.
We did it on 350's all the time back in The Day, but I've seen the results on a 450, not pretty.
In point of fact, tight intakes on a 450 will cause uncontrollable reving - I've seen it more than once.
Recommend Message 7 of 7 in Discussion
From: MSN Nicknamehonda3370 Sent: 2/8/2008 12:14 AM
I agree with Bill Lane, his suggestion is valid,when you give the rocker & cam lobe more room, there is MUCH better oil flow between the too. I have been using 004 on the intakes and 005 on the exhaust, for 14 years now, always trying to get better oil flow thru these motors, and if you think the motor is making noise, you can always tighten them up, nothing will be hurt by trying it. I never have been able to figure out why Honda made the clearance so tight ( that would be a good subject of discussion on the site ). maybe someone out there knows for sure ...with out guessing.