GS1100E piston to valve contact

[outofcontrol]

Does anyone know if valves will hit pistons on this motor if the timing is off?
I know some motors will collide, and some are designed not to.

I might have made a big boo boo last night when I was trying to start my motor.

About a month ago I took a wrench and hand turned my motor while it was sitting on the bench. I wanted to move some oil around because it had been sitting in a damp garage for so long with the side covers off.

Well, I had the cam chain tensioner off too and (I realize now) I totally screwed up the timing.

I had forgotten about that little incident until I was stumped last night when I found out my exhaust was sucking air when I tried to start it.

Dumb, dumb, dumb.

Well, if I have to replace 16 valves and 4 pistons I might as well get that big bore kit I was thinking about.

-KM

[RacingJake]

Did you have the sparkplugs out then you crank it over by hand, cause if you did and they did make contact hopefully you would feel the contact.

Best bet is to check the timing again and the rocker arm clearance. If it's a stuck/bent valve then when you pull the cam cover off you'll see one retainer lower than the others.

You may just want to pull the head just to make sure.

Good Luck

[BadBillyB]

Pull the valve cover off, remove the cams and then blow air into each cylinder. If you bent any valves you will hear the air escaping from either the intake or exhaust. If you do it this way, you dont have to hold the crank in a certain position to keep it from turning. You have to pull the cams out anyway to retime the chain.....Billy

[outofcontrol]

Thanks.

I'm going to leave work early today. I am so worried I can't get anything done anyway. I am expecting the worst.

-Kevin

[bradleymaynar]

I'm not sure if our engines are interference motors (meaning the valve train would come into contact with the pistons if the timing were off), but I'd think you'd have heard something nasty if the valves had tapped any pistons. Unfortunately the only way to be sure is to, at the very least, pull the valve cover and check the valves.

Good luck and hopefully it isn't catastrophic!

Brad tt

[silverhorse47]

Yes...there is a very nasty loud and ringing sound when a valve hits a piston on startup after a rebuild.
The timing chain would be quite out of whack ie. not adjusted according to the factory manual if one were to hear that sound...
S.

[RacingJake]

If the intake cam is advanced too far or the exhaust retarded too far, then they could hit the pistons. You can tell from the nice little rings on top of the pistons if the motor was running.

[outofcontrol]

There was contact between every exh valve and every piston.




When I was trying to start the motor (earlier) I didn't hear anything hitting. When I realized the valve timing was off, I shot compressed air in the plug hole with the cams off and I didn't hear anything come out. It even pushed the piston down. Also, none of the valves were stuck open. I then put the cams in (the right way) and started the motor. It started on the first kick (so to say), but it wasn't running great. I re-jetted the carbs, and I think the sync is all out of whack, but it was running. Then I got nervous and decided to take off the head and inspect some more. I took one of the exh valves out to inspect it and it looks normal.

Here's my question: How does the backyard mechanic inspect the valve to see if it's bent? I spun the valve in the seat and it didn't wobble.

Is there a chance that the valves can just barely hit the piston, just enough to knock the black stuff off? Should I buy all new valves?

-Kevin

[outofcontrol]

My mechanic told me while I have the head off to pour alcohol or something in the port to see if it would leak/seep/drip through the valve. It held WD40. I am thinking that things hit, but not real hard; at least not hard enough to bend things up; just enough to knock some deposits off.

-Kevin

[Clone]

If you have the head off and the valves look like they all seat, check for leak down like said, then clean up the pistons and heads, on any other motor I would lap the valves, here it seems to be a no-no. The first time you turned it over did it actually run? If it didn't I don't know if there is enough force to bend the valve, also it would depend on how far off the cams were as to the amount of contact.

[hungryman]

If you have the motor running, there is no need to pull the head to check for bent valves - just run a compression test. I'm afraid (while there is nothing wrong with it) you are taking the hard way on this one.

As for lapping the valves, if they are surfaced properly (fresh valve job), there is no need. If you need a valve job, get one, save the lapping for when you have no access to a professional valve job.

[RacingJake]

You could remove the keepers and retainers and springs. Then rotate the exhaust valve while watching the bottom of the valve rotate in the chamber. Does it stay center or does it rotate to one side???

Also push the valve open, rotate it 1/8 of a turn at a time, then pull it shut, do you see any daylight between the mating surface. A flashlight in the port helps.

Also check the valve guide. If the valve makes hard contact with the piston it can cause the valve stem to flex and the tip of the guide that protudes into the port can crack off and may find it way into the cylinder. Don't asked how I know that one.

[rphillips]

If the valves held WD-40, I don't see how you could have a problem. I'd say you got lucky by about .001 or .002

[outofcontrol]

You could remove the keepers and retainers and springs. Then rotate the exhaust valve while watching the bottom of the valve rotate in the chamber. Does it stay center or does it rotate to one side???

Also push the valve open, rotate it 1/8 of a turn at a time, then pull it shut, do you see any daylight between the mating surface. A flashlight in the port helps.

Also check the valve guide. If the valve makes hard contact with the piston it can cause the valve stem to flex and the tip of the guide that protudes into the port can crack off and may find it way into the cylinder. Don't asked how I know that one.

Jake,
I did exactly what you describe here. No wobble when I spun 3 of the valves in the seats. After 3 of them I sprayed WD40 in the ports and let it sit for a couple hours, and it still didn't leak through. I rode the bike tonight, and I think I got lucky; by a thou or two.

it sure does need a tune up though. I'm going to sync and tune the carbs tomorrow.

-Kevin

[Road_Clam]

Kevin, the other thing you can do is spray machinist's bluing around the valve seat, and while it's still wet, stick a valve in, and pull it out. If you have a full circle of bluing on the mating valve face, you are all set. I worked many moons ago in a automotive machine shop, and this was a crude, but effective method to check for bent valves. The best way is to place the valves on "V" blocks, and check them with an indicator. If you want, mail me your valves, and I will dial check them no charge.
Rich