Stuck valve? How to free it?

[1979GS550stl]

I'm back to diagnosing my dead cylinder on my 79gs550e. I've got spark (although another unrelated spark issue I'm still working through), plug is good, and I'm 90 percent certain I'm getting fuel.

I don't have a compression gauge to check it, but I'm going to take off the valve cover, crank it over slowly with the kickstarter to see if she moves, and do the following if stuck:

"Shoot some lacquer thinner through the intake port to soften the crud up and if that fails give it a tug from up top by removing the valve cover and tugging on the retainer."

Will carb or intake cleaner work just as well as "laquer thinner?" Any other tips or tricks?

Also, if I do have a stuck valve, how hard should I pull on the "retainer? Is there risk of breaking it?

I've run the bike for far too long with no valve adjustments (10K), and I'm not sure when the PO had one before I did it back then. If it IS stuck and I unstick it, that's my first priority.

Hope its not more serious. I've had this bike for 9 years, and its my first one (20K on it, lots of sentimental value). Over the years I've overhauled just about everything but the engine with the help of a mechanic friend, but I'm not sure I can justify the expense of an engine overhaul (with myself or my wife). ;-)

[Nessism]

What makes you think you have a "stuck valve"? A condition like that is very unusual. More likely you have burned a valve from not adjusting them like you are suppose to.

[1979GS550stl]

Some other threads here mention backfires/backfire through air box/"pops" on decelleration etc. as potentially a stuck valve. Also, she was on the side stand for a bit. I got some white smoke on start up awhile back and a mechanic mentioned that could be an issue.

Any thoughts? I appreciate any and all advice. I just have a manual and enough curiosity and enough mediocre mechanical skills to get myself in trouble.

[rphillips]

A stuck valve would more likely be caused by not being ran for a long time. Burnt valves come from being too tight. Pull the cover & see if there is a tight valve.

[1979GS550stl]

I pulled the cover, and everything looked fine. It's the weirdest thing, though.

I put Marvel Mystery oil in the spark plug hole (as suggested here somewhere) before pulling the case, cranked it a few times. Then I pulled the case, checked out the valves, and they all seemed to be operating freely. I put everything back together again, got some white smoke for a bit, then everything seemed fine.

I still have a weak spark on ONE plug wire in ONE coil. Seems really weird. Wouldn't I have that issue in BOTH wires from that coil? I worked at night, turned off the lights, and didn't see arc from the wire. I trimmed the tips and put the caps back on, and same issue.

I'm considering ordering Dyna 3 ohm coils, wires and caps tomorrow. Even if it doesn't solve my issue it sounds like a good investment - especially if I want to upgrade the whole ignition later.

THANK YOU for all the advice. I'm one step closer, it seems. I'm going to try to fix the ignition issue then take it to a professional for the valve job. Even though I had everything off, the job seemed a bit to complex for my expertise - or lack there of.

[Nessism]

Did you check the valve clearances when you had the valve cover off. If you didn't, it's time to do it next. Do not wait any longer. If you don't already have a burnt valve, you will soon if you don't tend to this critical need.

[1979GS550stl]

Yeah, that's the plan, Nessism. I'm truly grateful for the input.

#1 didn't have spark, hence dead for an undetermined amount of time (causing the sticky valve, maybe?)

May indeed have a burnt valve as well. I really just wanted to get a feel for what the problem might be before taking it into a strange mechanic for the first time. (Sadly, my friend lost his transmission shop and moved on to other things).

These folks seemed nice, knowledgable and offered free, helpful advice over the phone when I was rebuilding my carbs. I not confident enough in my skills to attempt a valve adjustment myself.

I may take things apart again and check the valve clearances, but I didn't have the tool to do so. I'm going to try to fix my ignition woes and take it in for a valve job and general tune up before ANY more ride time.

Here's what will keep me up tonight: How long was I riding on one cylinder, and what damage could I have caused?

Thanks again for the advice from several folks throughout my various posts this week. A newbie appreciates the patients!

[Nessism]

One cylinder not firing will not damage the engine. Rest easy.

Back when I was in college my battery started to die which caused one cylinder to not fire (on a twin). I ran the bike flat out on one cylinder for 28 miles only to have it die one mile from home. Lucky for me some guy in a car stopped and gave me a lift. Bike suffered no damage at all.

[1979GS550stl]

Great news, Nessism. Thanks for putting my mind at ease.

I'd only ridden it occasionally last year because I just bought a house. Too busy fixing up a beater house to work on my beater motorcycle.

I took it on a few good rides (probably on three cylinders due to the ignition issue). Although it felt sluggish, once it warmed up, it ran surprisingly smooth for only running on three cylinders.

I'm a novice, and I never thought to check the temp on the head pipes until I reinstalled my carbs after replacing the float needle valves/seats. Once I isolated the spark issue, the valve must have been temporarily (hopefully) stuck.

I'll keep y'all updated once I get the spark issue resolved and a verdict on the valves from a the professionals at the Suzuki dealership. Thanks again.

[Guest]

Stick your finger in the spark plug hole and hit the starter. It should blow your finger out of the hole if you have compression.

[1979GS550stl]

Thanks, Chef1366. That's a nice little tip. Between this FANTASTIC site and my Clymer's manual, I'm learning a tremendous amount.

I've been able to do so much more this winter. It's amazing the difference having your OWN garage can make!!!!!!!!!!!! \\/