Can't start my 125 pro!

[alexdukes]

Hi*guys,*

I am new to bikes and have run into a problem!

I purchased a second hand Gas Gas 125 pro 2003, evrything was good with the bike although there was a small issue with the clutch, i bleed the system, *no real change so put it down to warped plates.*

Rode the bike this*morning, no problems, went out again this afternoon, bike started fine, started riding down the road then the 2 strike sound suddenly got very loud! Now the bike won't start!

Any ideas??

Thanks in advance for any help

 

[alexdukes]

Just spoken to my son, he said that he put the wrong fuel in, he just put in*straight 98 unleaded*that was meant for the ride on lawnmower! Is that the issue???

 

[Davehuge]

Just spoken to my son, he said that he put the wrong fuel in, he just put in*straight 98 unleaded*that was meant for the ride on lawnmower! Is that the issue???

Hmmm, could be, in fact probably definately...

It's a competition 2 stroke engine, you need to pre-mix the fuel and 2 stroke oil. I hate to tell you but you've probably damaged the engine, best you take it to a reputable workshop and explain what's happened.

 

[cbutler]

Yes it has more than likely seized the motor. Would it kick over when it first died or was the motor locked up

 

[(F5)]

I think with Amsoil you can run 0:1 can't you?

So why were you running 98 in the lawnmower?

 

[alexdukes]

Thanks guys

Yes the motor would turn offer and did not seize.

Taken the head off today with lots of grease on the piston and bore, the crank seems to be complete.

 

[alexdukes]

The 98 is for my john deere ride on lawnmower!

 

[alexdukes]

Sorry forgot this image

 

[alexdukes]

When it went, it sounded almost as if the exhaust had fallen off, the usual engine running sound and rhythm just gear louder

 

[Anders]

The cylinder, head and even the piston looks OK. I think the pure petrol was not the problem. Just put it back together and put some premix in the tank. Then look for other problems if it still don't start.

 

[alexdukes]

I did try running it again before taking it apart, couldn't get it to stay running and sounded as if the exhaust had fallen off, far louder than usual?

So you think there is nothing wrong? Is it worth me changing the piston or seals at least?

 

[Anders]

I did try running it again before taking it apart, couldn't get it to stay running and sounded as if the exhaust had fallen off, far louder than usual?

So you think there is nothing wrong? Is it worth me changing the piston or seals at least?

Yes, of course there is something wrong. But I don't think the fuel alone caused it.
Regarding the loud noise, does it come from rear of the silencer or does it come from a leak some place close to the engine? Could it be just the silencer itself that is your problem?

Regarding new seals; yes, when you put it togehther you should use new o-rings and gaskets. If you measure the piston and ring gap you will get an idea of how worn it is, at least if you have some numbers to compare your measurements to. Unfortunately, I have no knowledge of the wear limits of the 125cc trials engines.

 

[alexdukes]

The loud sound is 100% coming from the exit of the exhaust, no holes or breakages