Stuck Valve??? 82 GS850

[Anonymous]

Went to start bike and I am hearing a load knocking noise coming from the top of the engine. It just happend no warning.I took the cam cover off and removed the cams. Upon inspection I found there is a valve that did not look like the rest. It is seated much lower then the rest on the intake side. What could this be?? Did I break a stem or is it stuck. I just got it back from the shop where they put new ties on now this happens, I can't believe it!!!!!..

Any Idea's??? What is the fix I am going to have to tackel it myself..

Thanks

[redliner1973]

Does it now run like a 3 cylinder engine? if so, from your description, you sound like you ate a valve. dont run it, but turn crank by hand to make sure nothing is touching inside,if all is ok, run a compression test on it. you'll know right away then. post back and let us know what you find...

[focus frenzy]

That is very bad, the loud knocking was most likely the piston hitting the stuck valve. you will need to remove the head and closly inspect the piston for impact marks and wether the valve head broke off and damaged the piston and combustion chamber.
At the very least you will probably need to replace the stuck valve and valve guide, at worst you will need to replace the piston and head and posibly bottom end components.
Only close inspection will tell.......Sorry

Leon

[Anonymous]

Valves

So are all the shims on the valves should look the same when I tale the valve cover off Yes. One of them in a 1/2 inch lower then all the rest. I began to take the head off and of course snapped the bolts taking off the exaust, They were badly rusted so when I get the head off I think I will bring it to a machine shop to have them drill them out.

When taking the head off will any parts come blasting out of the head?? This is my first time digging this deep in the engine. Those bolts that hold on the head are quite rusted too. I have the soaking in WD40, is there a better way to get them out?? Thanks for you help. If anyone knows a traveling Bike Mechanic in Connecticut let me know!! It's starting to get ugly... Thanks

[Anonymous]

OK. Got the head off and what do you know. There was a screw keeping the valve open. Took the screw out inspected the piston. There are some marks on the piston from the screw but nothing major. How do I know if it needs to be replaced?? It is very dirty,what is the best way to clean the pistons and the head, Since I have it off I might as well clean it up.. Anything else you guys think I should replace?? I have a 81GS650 will any parts work from that

Thanks again all.....

[Anonymous]

You should lap the valve that was stuck. If you find that the pattern on the valve is uneven you'll need a new one. If you don't know what "lapping a valve" means you may need a little help from somebody. If you don't clean off the lapping compound extremely well you'll have a bunch of trouble later on.

Were you able to identify the screw? I always try to identify nails/screws that I find in my tires so I don't run over another one at the same place. The same thing could happen to you if there is a second screw in the intake somewhere.

Since you have already got another engine kicking around your cheapest way out would be to put that one in. You could also put in a new headgasket and see if it is okay without checking anything out. If it blows it blows...just make sure the engines mount the same way.


Steve

[Anonymous]

Any idea how a loose screw got in your engine?
Axel

[SqDancerLynn1]

Just clean the tops of the pistons, bottom end should be fine The piston would break before the bottom end. just make sure that you smooth down any marks so that you do not get any hot spots in the combustion chamber, Turn the cyl head up side down and pour some gas or solvent into the chamber and see if it leaks if it does you need to remove the valve and check further

[Hap Call]

You need to find out where that screw came from...I would guess it came from some component in the carb that feeds that cylinder or the air box. Something else will fail if you don't find the location that screw came from.

Hap

[redliner1973]

also, since you have the head off anyhow, whilst the machinist is getting out the broken bolts, why not just get it rebuilt 20+ years of running I would think it could use a good rebuild before going through all the truoble of putting it back on. Cheap insurance.