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Discussion Starter #1
Hey everyone!

i have a 72 CL175. It had a blown head gasket so we (a buddy and I) decided to replace it. After fixing that and not knowing how to set the time properly, we assumed incorrectly and set the time 180 degrees off. Would this have lead to bent valves? I know the valves hit the pistons (you can see where the metal shines through carbon build up) but there is no pitting or destruction on the piston.

Once the time was corrected it seems that the valves may have still been hitting the pistons (a grinding sound, but an engine tear down assures nothing is in the case); which is where I draw the assumption the valves may be bent.

The valves are currently at a machinist awaiting reseating and and a valve job. (I have unbent valves I pulled out of a head from the junkyard). I guess I am just looking for reassurance that I diagnosed it properly. I don't know what else could be making this this noise when I crank it.

Thanks.
 

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Sensei
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Phone me as it's a grinding type noise, and camshaft bearing journals are the weak point of these engines....540-525-5199....Steve

Any chance the oil was fuel fouled (smelled of gasoline?)
 

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Discussion Starter #3
Phone me as it's a grinding type noise, and camshaft bearing journals are the weak point of these engines....540-525-5199....Steve

Any chance the oil was fuel fouled (smelled of gasoline?)
Hey Stephen.

I've called you a couple times actually. I'm the one with the 843 area code. I called about an electrical issue originally. I don't recall if the oil was fouled or not, if I were to bet I would say it wasn't. We had the bike running to get it home (needed that gasket and new fuel lines was all, but we ran into problems after we had the timing off). We did an acetone test like you recommended and one of the valves leaked.
 

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Sensei
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Problem is, they WILL run for awhile with bad cam bearings, and a grinding noise is typical......Check that it wasn't the camchain cutting into the "tunnel" front wall as well.....
 

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Discussion Starter #5
I guess I shouldn't have said a grinding noise. It's more of a thunk, like something hitting something else. And it will turn over without any noise. It's only when you give it throttle that this sound is made.
 

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Sensei
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Could be bad "big ends" on the con rods, bad fit of wristpin to small con rod end, or a piston just slightly touching a valve due to timing error from a loose or improperly timed-in camchain..Or a LOT of other possibles.....
Just guessing, I'd say piston to valve contact and your bent valve sort of indicates that.....However, while it's apart, you need to eliminate all the additional possibilities.......
 
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