changed sprockets, now bike wont start

[Guest]

i did a sprocket and chain job on my 83 GS550L last year and it never started after that. i had it taken to a mechanic who said my pistons seized in the engine. ive decided its time to fix the bike, so i can learn and so i can get back out riding. after more examination i dont think its a piston problem. the camshaft didnt move much which is why the mechanic thought it was a piston problem. but, i did some work and the pistons do their thing just fine. the starter spins also. the bike rolls with the clutch engaged. any ideas on what i should start checking? im thinking it must be the clutch or transmission.
thanks

[dorkburger]

Ditch the mechanic first....
Not sure about that model, but some smaller GS bikes have a clutch push rod under the front sprocket cover. Maybe something to with that.
You say the starter spins.... as in cranks the engine?

[prem]

it doesnt crank the engine. when i take the cover off the left side. crankshaft cover i believe, i can see the starter gear spin if i take the reduction gear out that attaches to the crankshaft

[dorkburger]

Could be a starter clutch issue. Hold tight. Someone more familiar should be along. Also, that gear typically has a washer on each side which are easily lost when taking the gear off. They are easily lost.
The curous thing to me is why it happened after replacing the chain.

[gustovh]

With the bike in neutral, can you turn the engine over by hand using the big nut under the right side crank cover as you sit on the bike? Do not use the small bolt head. That will tell you if you have a seized engine or not. To make it easy pull the plugs.

V

[chuck hahn]

19 MM big nut on right side of crank. Take off the cam cover and observe if a valve is stuck closed as the lobes come into contact with the shim. If it turns a little then a lobe jams against a bucket I would pull the head and see if a springs broke or whatever else could jam up a valve. And I that point I would go that one step farther and pull the jug, hone them and put new rings in.

Of course look at the pistons and cylinder walls and marks before ordering rings etc etc. Find out whats wrong and order whats needed all at once.

[roeme]

With the bike in neutral, can you turn the engine over by hand using the big nut under the right side crank cover as you sit on the bike? Do not use the small bolt head. That will tell you if you have a seized engine or not. To make it easy pull the plugs.

V

Yup, do this.

Also, be more clear what exactly is going on. "Some work and piston did their thing" could mean anything.

Only thing I can imagine right now that would fit somewhat of rando descriptions would be a flooded cylinder.

[gsrick]

Good idea, a hydro locked cylinder will make for a bad day. Pulling the plugs and hitting the starter will t

ell that story real quick. Just don't look at the plug holes when you hit the button or you may get an eye full of fuel.

[fixmybrokecomputer]

Good idea, a hydro locked cylinder will make for a bad day. Pulling the plugs and hitting the starter will t

ell that story real quick. Just don't look at the plug holes when you hit the button or you may get an eye full of fuel.

You might want to do this outside of your garage. Take an air hose and blow around the plugs before you pull them to make sure debris doesn't fall down inside the cylinders. Disconnect the wires that power the coils and cover the spark plug holes with rags.

[prem]

i pulled the plugs and put zip ties in each hole. then i pulled the crank case, put a wrench to it and it turned and the zip ties went up and down nicely. i got a little resistance so i put some marvel mystery oil in for good measure. then i pulled out the gear that goes between the crank and what i believe to be the starter gear. when i pushed the starter button that little gear spun. this makes me think that the problem is not the head and might be in the clutch, clutch starter or transmission. i dont wanna pull parts apart that i dont need to.

[prem]

so i just took the right side crank cover off and the spark plugs out. i put a 19mm wrench on it and it would only go half way around. when i put a 17mm on the left side it does the same. i had gotten it to spin all the way around last time i had it open but it was with some force. i am going to take the gas tank off, remove the valve cover and examine it.
any tips or advice on what exactly to look for, or guidance.

[gustovh]

Remove the valve cover and start checking things out. Are you in time (has for some reason the cam chain skipped a tooth)? Look to see what happens when you try and turn the engine over and report back.

V

[prem]

i had put some Marvel mystery oil in the plugs and let it sit. i went to start it and it turned a little then locked up. i took the valve cover off and everything looks alright up there but i can see where the pistons get stuck. i am taking the head off now, removing the exhaust and carbs. i have never

[fixmybrokecomputer]

It's starting to sound an awful lot like hydrolock to me. This vid is from one of the gurus of the concours forum. Steve really knows his stuff! Watch the vid, do the test and report back with the results.

https://www.youtube.com/watch?v=4W6k3pTdAXw

[aclaytonb]

Once upon a time I heard something about clutch basket screws backing out and contacting the wall of the case. I'd check a few more things before a full teardown...