Speedzilla Forums banner
1 - 7 of 7 Posts

·
Registered
Joined
·
178 Posts
Discussion Starter · #1 ·
I'm checking the valves on my SP2 motor with about 3500 miles on it and one of the intake valves is on the low limit .13mm.

Can anyone tell me what the valve clearances do as the motor goes through its life?

If the slightly tight intake valve will get looser in the future I'll leave it alone, but if its only going to get tighter I'll pull the cam and adjust it now.

I guess I'm really asking two questions, one for intakes and another for exhaust valves since they probably behave differently.

I'm guessing the valves grow in length over time as the springs try to pull them out through and hammer them against the valve seats causing them to stretch a tiny bit making clearances get tight.

Maybe they don't change at all and I don't have to do anything since it's still on the edge but still within spec.

Thanks in advance!
 

·
:rolleyes
Joined
·
305 Posts
Unless you're revving the piss out of it all the time, the RC rarely needs adjustment. I'd leave it alone and check again in 20k miles ;).
 

·
Registered
Joined
·
1,515 Posts
I did an adjustment on a motor that had 20k give or take and only one exhaust in the front cylinder was loose. I'll check my other motor(150k) in a few weeks to see.
 

·
Registered
Joined
·
122 Posts
Typically, valves begin sitting tighter into the seats (the seats or valve face wears), thus the valve clearances get tighter.
 

·
Registered
Joined
·
178 Posts
Discussion Starter · #5 ·
Thanks for the advice.

Since I've got the motor out and am doing all the other usual modifications I figure I might as well go ahead and put all the valves at the correct clearances. Actually the forward intake valves are good so I'll only be pulling three cams.

I've got a good Starret set of inch feeler gauges, but figured I ought to get a metric set for doing as many bikes as I do lately. All I could find at the auto parts store was an import set.

Man do they vary! I got out my Mitutoyo digital micrometer and started measuring thicknesses; .05 was .054, .06 was .065, .15 was .162 and so on. I think I've discovered the key to chinese manufacturing efficiency - .09 was .097, and .10 was .097 also. Goddam communist chinese tools!

I think I'll be on the lookout for a good set of metric feelers.....in the meantime I've been using the mic to measure the feelers before each measurement. Slow but accurate.
 
1 - 7 of 7 Posts
Top