Valve Clearance - looking for your opinion

[X7eater]

Hi..this is my first post on this forum; hopefully the link below shows my bike

I'm currently working through a CB750F from 1980 that I recently imported into Australia from New York. It's a one owner bike with what, I believe to be, a genuine 11,000 miles. The bike has sat (indoors) for 10-15 years, so needs a fair amount of attention.

The bike starts easily with but runs quite rough. I'm now working my way through, timing, carbs, electrics etc.

However, my question is on valve clearances.

I know all about the factory specs, and how the general opinion is that .004"-.006" is now the preferred clearance in order to prolong valve life.

I've just measured my clearances, with the results shown below. Question:

On the face of it, I should be re-shimming any of the valves where the clearance is .003" or below? (i.e. it's only going to get worse from that point forward).......would you agree? or given I ride very conservatively these days, should it give it another 2-3,000 miles and recheck the clearances again?

 

[dirtdigger]

Definitely do any that are at .003. If it was mine I would do the ones at .004 as well. all of your exhaust are too tight. They will only get tighter.

 

[X7eater]

Thanks for the reply 'dirtdigger', I'll measure my existing shims and adjust as necessary up to 0.005"

 

[dirtdigger]

No problem. Clean looking bike!

 

[dmann707]

if you can find shims to get your clearances to 005 then you ll be in luck.... 003 to 006 will work fine ....the 003 ones will need attention soon ...anything less than 003 needs adjusting asap... i had one with 43000 miles , had one valve at 000... was losing about 30psi compression ...adjusted and came back to normal ....

 

[6pkrunner]

Keep all of the clearances at 0.005 0.003 is too tight on exhaust and will burn valves. Minimum of 0.005 all around.

 

[Davidson750]

General rule of thumb is .005 intake and exhaust.. Its been widely debated,...but at 9,000 rpm the answers come quickly