Poorly px125

[dirtyhandslopez]

Just had a P125 with exacly the same symptoms.
I put it down to atmosphere(scoots run crappy here in July- August. 95% humidity and no rain is not good for carb set-ups) and too large of an idle jet. Down jetted from 60 to 50, tweaked the mixture and away it went.
An hour later, he comes back, '''I think my motor siezed" "was running best it ever had" Bugger, what have I done
Turns out a poorly installed seal(done by someone else) had been rubbing on the crank and finally cut loose, bits had got up under the piston, wasting it. New top end needed...
I always put four dot punches around the seal, mechanically holding it in place. Never had one come out.
So, long story short, be careful, sounds like a seal coming out and it could lock up your motor.
Which is not good.

[squeakmillward]

Just had a P125 with exacly the same symptoms.
I put it down to atmosphere(scoots run crappy here in July- August. 95% humidity and no rain is not good for carb set-ups) and too large of an idle jet. Down jetted from 60 to 50, tweaked the mixture and away it went.
An hour later, he comes back, '''I think my motor siezed" "was running best it ever had" Bugger, what have I done
Turns out a poorly installed seal(done by someone else) had been rubbing on the crank and finally cut loose, bits had got up under the piston, wasting it. New top end needed...
I always put four dot punches around the seal, mechanically holding it in place. Never had one come out.
So, long story short, be careful, sounds like a seal coming out and it could lock up your motor.
Which is not good.

someone told me that 2 strokes liked the damp but I thought they were taking the p155

[Dazza]

Well, I replaced the rings tonight and with everything crossed tried it again - exactly the same

I stripped the carb down, as far as I can tell the float valve is working as it should, all jets cleared carb body checked and cleaned - exactly the same

I tried all sorts of combinations of throttle stop screw and mixture screw - it just wouldn't run right.

I think the next step is to try a known good carb , maybe exhaust - then what?? Engine rebuild?

How likely is it that the crank is worn?

Bit stumped on this one really

[Mr Grog]

Did you drain the gearbox oil and check it for petrol contamination?

[Dazza]

Mmm, no I didn't , that's a good point actually , the lad who owns it has oil on the back tyre and suspects the hub seal has gone, would petrol in the oil therefore making it thinner be more likely to leak?

[Mr Grog]

The oil on the back wheel may be the result of petrol in the gearbox but it usually comes out of the clutch breather and then spreads itself all over the clutch bell and then down onto the back wheel.

The more you run the scooter the more oil/petrol mixture is generated if the seal has gone and the more it flows out as it is a thinner viscosity.

[Dazza]

Yes, thats what I thought when you mentioned the seal going - think it's strip down time

[dirtyhandslopez]

I thought it was a seal coming out, one way or another

[goldeneye]

Dazza, run the engine , even with the choke out if needs be, then while its running, take the gearbox drain plug out. if the engine revs rise, its air getting sucked past the knackered seal while the oil or more likley petrol is draining from the gearbox.

[Dazza]

Thanks for the tip Goldeneye, will get him round and try that.