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Discussion Starter · #1 ·
after having to pull the top end of my SL350 apart to replace the disintegrated cam chain tensioner roller, i noticed that 1 of the pistons has been kissing the exhaust valve fairly passionately. the other one had been kissing as well but looked more like it was married, just touching.
i think this has come about because of work i did to the motor 30 years ago when i used to race it. i had the cams reground to increase the lift, the head has been skimmed and i didn’t fit a bottom cylinder gasket. all of these together would have reduced the clearance tolerances a bit.
i guess that the valve clearance on that side might have been a bit tight as well, but it seemed ok when i serviced the bike when i got it going recently after it’s 30year rest. another problem that arose after it’s first run was that one of the coils fried. i just got back home after the short run to make some adjustments because it wasn’t running real good, and all the smoke leaked out of one of the coils. they were the originals so i have new coils, caps, plugs, points, condensers on order from the US of A, and a gasket set from China.
the camchain tensioner roller i made to Steve’s specifications is ready to go in and am looking forward to getting it all back together again.
cheers, Gary.
 

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You're pretty lucky, I guess after all these years you can determine that the valve didn't hit hard enough to bend, but I'd still check it since the engine is apart. You could double up the base gasket if you want to gain a little clearance.

........Paul
 

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"...the head has been skimmed and i didn’t fit a bottom cylinder gasket"

Actually, if he just put one base gasket in it the problem might be solved - but it would break up at least one romance. the married couple would end up not much worse off... :D
 

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You should have 0.060" clearance between the piston and valve. I doubt one gasket will give this. clearance. Might want to have a machinist remove some material from the piston.
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I was just referencing the fact that he got away with it before with no base gasket... but you're right, a single base gasket isn't going to get him the .060" commonly called for
 

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Discussion Starter · #6 ·
I was just referencing the fact that he got away with it before with no base gasket... but you're right, a single base gasket isn't going to get him the .060" commonly called for
do you know what the standard cam profile measurements are? I got the camshaft reground back in 1976, but the profile printout that came back with it has long gone. I will measure the cam when I get back to the shed. thinking its extra lift might be reducing the valve to piston clearance.
 
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