GS1100E piston to valve contact

[RacingJake]

Sounds like you got lucky indeed. If you were running stock cams that help too.

Get that thing dialed in and open her up.

[retrex]

Spring height ok?

You might want to check your springs to see if they are within spec. If they are too short this could explain the contact.

[shortlid]

My friends '82 GS850L bent valves and damaged pistons!

My friend Pete who is on this board was riding his '82 GS850L when the valaves hit the piston and made a mess of the motor! GS motors ARE interferance I guess.

[outofcontrol]

You might want to check your springs to see if they are within spec. If they are too short this could explain the contact.

Oh I know why they hit, I just don't know how hard they hit. The timing was so far off that the exhaust was sucking air when I tried to start it. It was basically timed to my random spinning of the motor with out the tensioner on. I knew something was weird when the motor spun so freely when I hit the button. it also wouldn't open the petcock (no vacuum) to let fuel in.

I guess they hit, but not very hard, and pretty slowly. the motor was not even close to starting. It probably would have been worse if the timing was just a 2-3 teeth off instead of totally wrong. I got lucky like a roulette gambler gets lucky – slim chances.

Thanks for the offer Clam, but I'm going to keep them in.

-Kevin

[massakins]

One way to check the valve sealing is to clean each valve using a steel wire brush (on a bench grinder is quick) and clean each of the seats using a brass wire brush (on a drill motor works well). Then apply a small amount of lapping compound to the sealing surface of the valve and reinstall it in its original hole without the spring or related keepers and retainers. Slide a piece of fuel line over the stem that grips it and spin it to lap the valve on its seat. Once lapped, wipe both seat and valve clean of all compound and visually inspect both for a complete contact circle of constant width. If present, it is sealing fine. If not, it may require more lapping, valve seat repair or replacement valve. I've had very good luck with this "tune-up" and replacement of valve seals.

Another check is to take the assembled cylinder head and position it so the port is vertical. Fill it with kerosene or gasoline (no smoking, duh!) enough to cover the valve seats and inspect the combustion chamber area for signs of leaking. No leakage is best, a small amount of seepage can be tolerated if no opportunity exists to correct it, a leak is not acceptable.

Obviously a racing motor would be built to tighter tolerances, but this would suffice for many a street ridden unit. Works well on my dragsters as well. Good luck.