Oh No!! I've got a big problem!

[Shawn27530]

I bought a new battery, installed it in the bike, and went to turn it over. And nothing it was like the starter hit a brick wall. I was going to pull a compression test as with all bikes I get. So I pulled all of the spark plugs, sprayed a whole can of liquid wrench into all the cylinders and let it sit for a beer while I cooled off and retrieved my screwdriver that flew out the garage door. I pulled the stator cover off and the crank would not make a full revolution either way aprox 3/4ths of a turn. At first I thought it might be a broke rod or wrist pin. So I stuck a long screwdriver into each cylinder while I turned the crank, all pistons are moving up and down as I turn the crank back and forth. It gets to a stop and won't go any further, the flywheel bolt breaks loose first. Any ideas what I have got myself into, I knew I should have spun it over before I bought it. But it had a dead battery and such so I just loaded it up and brought it home. Man this is such a bummer.

[skids]

Quit forcing it.
Remove the cam cover and see if you are lucky enough to line-up the arrows on the cam bosses with the dots (holes) on each cam --- without forcing it.

Where am I going with this? You may have slipped the cam chain. Contacting a valve with a piston crown is bad for valves and forcing it can actually damage a piston.

[2bhappy]

Shawn,

My guess is that you have a bent or stuck valve that is not allowing the piston to complete its cycle.


Marc

[Shawn27530]

Ok, I will pull the valve cover tomorrow for a better look. I called the original owner this afternoon, a fellow military man, he said he bought it right out of the crate, and it was running good when he parked it to go to Alaska.

[petejw]

Hey Shaun,
That happened to me not to long ago,
the result, 4 bent intake valves,
the chain had jumped a cog while i was cranking it,
the motor would still turn over if i cranked the engine
with the starter, but i couldnt turn the crank over by
hand.
the valve was protruding enough that when i removed the
spark plug i could c it hang over.
Its not a pretty site seeing 4 bent intake valves.
Prior to changing the battery did u do any work on the
motor, adj cam chain?
Do what skids says and remover the valve cover and see
if the dots line up.
Good luck with it.

[prometheus578]

with the valve cover off, check the valve clearances. Sure... you can't spin it completely, but check them anyway when the lobe's pointing away from the shim. HHmmm... you didn't mention what kind o' bike this was. maybe you don't have shims... but you get the idea. You may have a coupla real crazy readings.
I had a bent exhaust valve... the clearance was .035. Not too bad... not bad enough to stop a piston.
If you've got bent valves and they're hitting the pistons, you should see some compressed valve springs and REAL loose clearences.

[petejw]

heres a cpl of pics of the head from my bike.








and it worked lol

there is no cam at the back of the head.

[petejw]

sorry i didnt think the pics were that big.

[Shawn27530]

I went ahead and pulled the valve cover last night, because curiosity was killing me. The only valve springs that are compressed are the ones that should be open with the cam lobes down. I can lift the cam chain up off of the guide a little.

But now the engine will not budge either way. I was thinking maybe the transmission has it locked up somehow, but it shifts through all the gears and goes back to neutral.



I'm thinking boat anchor!!

[LoserShoes]

Have you tried it with the clutch pulled in? That will eliminate the transmission as a problem.

Steve

[John]

I recently had to drill a broken spark plug from the head of the 79SF that I am working on, and I noticed that the valves can be seen if they are just slightly open. Use a good bright light and look inside the spark plug hole. If a valve is stuck open, you should be able to see it.

[Shawn27530]

Alright I am convinced it is a transmission problem. I looked in all the spark plug holes and all the valves seem to be ok. Pulled the clutch lever in and zip tied it to the bar. Still the engine will not turn. I put the transmission in gear and the rear wheel won't move either.

[pggg]

Seized starter motor?

[Shawn27530]

Thats my next move, is to pull the starter motor. When I hit the starter you can hear it bump, but can it be that the gear is still engaged? I will find out tomorrow.

[John]

The gear on the starter shaft is always engaged with the starter clutch, which is in the engine case. The gear does not spin on the end of the shaft like it does on most auto starters. It is fixed in place. Try removing the starter, and turn it over by hand useing the 19mm square flange that is under the ignition cover. That way the bolt won't tend to loosen when you are turning the engine over. You could always remove the clutch cover and disassemble the clutch. That would eliminate transmission from the equation.