Bike was running 1 month ago...now won't start...

[kamikazi_kostka]

By seized you mean the piston is not moving up and down?

Well...I can peddle the bike if that makes any difference?

How do I check...remove the spark plug and peddle..and see if the piston moves up and down?

That seems as the only logical reason...what could I have done wrong with the clutch to cause this?

 

[Lukass]

Plenty of good advice in this thread.

So you can't get the engine to turn over at all?
If you lift the bike up a little and remove the plug you should be able to turn the rear tyre and have the piston move up and down easily, I would check that first.

Mine will lock the rear tyre on anything other than good road surface (slick tyre) so I have to make sure when I pop the clutch I push hard on the pedal at the same time to get it to start turning.

 

[kamikazi_kostka]

Ok...I just tried riding.

1) With spark plug in...rode it with gasline on until 10 mph..then released clutch...rear tire and motor chain locks and skids to stop

2) Took spark plug out...rode it with gasline until 10 mph...released clutch...rear tire and motor chain lockd and skidded to stop

3) Re-adjusted clutch lever...made it less tight...tried agin....still skids and locks.

4) Re-adjusted again...still skids and locks.

Without fuel or spark...I would still think it would have compression...and just be hard to peddle even though it wouldn't fire..but currently..it just locks when I release the clutch lever. I just don't understand how piston could seize after 1 month of non-use
I have adjusted clutch lever many times..and that makes no sense as to why it won't work.

Please help me...

 

[kamikazi_kostka]

It use to always catch fine...so it is not a too much compression issue.

 

[kamikazi_kostka]

Also...I have about 40 miles on this bike so far (some from the summer..then switched frames...then 30 miles this winter)...I have been running a 15:1 or 16:1 gas to oil mix with Synthetic oil.

Could this be a cause for the problems as well?

Thanks,
Chris

 

[Guest]

You say the wheel locked with the plug out? That can't cause the wheel to lock under normal conditions. (no compression)
That is one of two things....

1.) Seized piston, or other mechanical locking inside the engine, or

2.) Something in the driven side of the clutch/drive is locking.

These engines have some primary gears to them right? Take off the cover and see if there is something in the teeth of the gears.

Something is physicaly stopping the engine from turning, you must play detective and find it.

One last thing- you said the plug was REALLY carboned up? How much? Was it a glob of carbon? If so you could have stuck the rings and that can cause cylinder was scuffing and seizure.

 

[kamikazi_kostka]

when I pedal I hear the cylinder clanging around.

I don't understand how it could seize. Somthing must be causing it to not move up and down...piston seizure doesn't make sence...but ya....I don't know where to begin...I dont' want to take this entire engine apart...

I don't know how to do rings, points, ect...I don't want to take the head off...

What could have just caused this out of the blue?

-Chris

 

[kamikazi_kostka]

I took off the gearbox...and they line up..however...when I release the clutch..the inside part of the big gear stops rotating...the small gear won't turn..what could be the problem?

I am so confused.

Chris

 

[Guest]

Kamikazi....I'm trying to do long distance diagnostics here....

Taking the head off only requires removing a few head bolts I believe. You won't have to mess with the points or rings to do it.

First things first.

You say you hear clanking...what and where is that coming from? Do you have someone who can help you with this? I mean someone to push the bike while "in gear" and listen closely to the engine.

If the engine is seized, you won't be able to peddle it. If the crank or rod are broke, you may be able to peddle it until something inside catches. If you removed the plug and the engine still locks the back wheel when you let out the clutch, you got a problem. The only way to find it is a step by step assessment of the engine and drive line. Like it or not, you are going to have to go into the engine and clutch and find what's going on.

That or pay a mower shop or other to do it.

You say it ran fine the last time you rode it right?
When you say clutch lever, do you mean the handle bar lever, or the clutch actuating rod?

 

[kamikazi_kostka]

Basically...I think I might have found the problem.

It makes no sense as to why the piston would be frozen after one month of not sitting.

It was riding fine before. Before it broke...I tried to make clutch tighter..and actually messup up the lever (The handlebar one). I had to get a bike shop to repair it.

When I rehooked up the clutch cable...it looked.

I am guessing that even though it releases..the gear isn't lined up properly.

So I removed the gear cover, and found them to be lined up. Then I took off the clutch plate and then took out the clutch wire too. The inside this that goes from the lever to the gearbox thing had lost almost all of its lubrication. I am guessing if I relubricate it...it might work better. What I am guessing is yes it disengages, but doesn't come all the way back...therefore the gears don't transfer to spin.

Only conclusion I can make. I will work on it more tonight when I get home from school. I also talked to the shop teacher...who has rebuilt small engines many times...and he said he will give it a look with me. If I can't figure it out...I will have him look at it.

Chris