I think i may have a stuck valve problem, but I am really not sure.

Recently acquired an old 250 quad runner 4x4 for a new project. it was not running and previous owner said it was clicking at solenoid when he went to start it, but it ran normally before that. Sounded easy enough; Got a new starter on and fixed some wiring issues, but now the new starter squeals like a banshee and won't turn the engine when i go to start it. BUT, when i take the spark plug out, it turns the engine no problem.

Does this sound like a stuck valve? I have no experience with top end issues like this, but my feeling is that the exhaust valve is stuck and won't let the pressure escape from the cylinder, and that pressure is too much for the starter to overcome.

Also, there is a decompression lever on the head. I can pull it with the recoil easily with the lever down *its a bear if you don't use the lever*, but i did not use the decompression lever for the electric starter.

Any advice on where to go next would be appreciated. Its looking like I got a bigger project than expected, but it should make for a *hopefully* low cost education.

 

Sounds like the one way starter clutch is on it's way out. Try turning the engine over on the starter when de-compressed, my guess is it will, and I bet the previous owner has been starting it that way for a while. Valves don't stick shut, only open, as they are opened by the cam which applies massive force, but closed by a fairly light spring, and maximum cylinder pressure can't go over the compression ratio until the engine starts anyway.

 

Thanks merryman, I will give that a try and see what it does. I imagine it will crank over with the decompression lever on as you suggest. Valves are moving as the engine turns with the rope, so as you mentioned that definitely isn't the issue.

Do you know if the engine needs to be pulled to access the left hand crank case where the starter clutch and stator are housed? Manual seems to say that you should pull the engine, but to me it looks like the bolts to remove that cover are relatively accessible (might require a little persistence).

 

Don't know that engine, but Suzuki factory manuals are a bit odd, in that they go through a complete engine stripdown, but don't show how to do partial strips with engine in place. I would try removing the case, all Suzuki engine work I have done, (including Eiger flywheel removals) have been done with engine in frame.

 

haha yeah, the manual isn't the most user friendly. I should probably try to find a clymer or something not written in Japan instead of using the Suzuki service manual.

It does crank with the decomp lever on. Went to check the valve spacing and found a good amount of oil was inside the exhaust valve cover (1-2 oz). The intake valve was clean. Is it normal for oil to build in there? If the piston rings were good I shouldn't have that much oil getting to the valves in the first place, right? Not sure if this is just a common age-related-thing on these engines or if i should begin breaking down the top end and attempt a rebuild. A previous keeper of the bike clearly has messed around with the top end judging by the bang up gasket job, so my feeling is that top end and especially the valve need attention.




oil getting through exhaust valve.

 

After talking to my buddies at the bike shop, the exhaust valve pooling oil is pretty normal on these bikes in case anyone is not familiar...looked pretty suspect to me. glad its okay. Hopefully I'll get this thing fired up soon after all.