Scooterotica

I'm hoping someone might shed some light on a problem i'm having with my PX200.

Ive recently had a new piston and rebore which im still carefully running it in. Tonight travelling at a speed of no more than 45mph, my engine seemed to lose power. When I went to slightly increase the revs there was no more power. Pulled the clutch in and the engine dies completely.

My first thought is I've nipped it but it starts straight away after with good compression. It happened twice tonight- 10 minutes apart and once a few weeks ago. I've done 400 very careful miles since the rebore.

Bog standard set up with a SIP Road exhaust, 120 main jet.

Any ideas?

Fuel starvation?

Either fuel or CDI unit. Check all the electrical connections in the junction box and CDI unit are all good. Also make sure you have not nipped any of the electrical wires from the stator. Regards to the fuel, I've started to use clear fuel lines to see the fuel is getting to the carb. With the new fuel full of ethanol it is destroying fuel filters and fuel lines.
I lined my tank with petrol tank liner and the ethanol ate through it and it ended up in my filter and fuel line.
Gary

Have you tried checking the plug when it dies like that? it does sound like it's possibly nipping up, you would only notice a loss of compression if the rings were stuck in their grooves. What is the rest of the set up and doo you know what the piston to bore clearance was?

Ang, who did ya re-bore? Armstrongs? i"m running a 122 main with the SIP road, maybees upjet while your running in, you might have had a partial nip. whip the head off and have a look at the barrel, see if its got any marks on it. you going saturday? if so we"ll have a talk about it.

goldeneye wrote: whip the head off and have a look at the barrel, see if its got any marks on it.

Just take the exhaust mainiford off, if it has nipped it will have done so on the exhaust side and if you turn the engine over whilst looking thgrough the port you will be able see any sieze marks. At 45 MPH I wouldn't have thgought you would be on the main jet, I'd check the pilot and also check for air leaks and that you have the correct amount of ignition advance and grede of sparl plug. Check the clour of the plug before going any further though.

If there is an air leak, the engine usually whines like mad then shudder to a halt. The noise can be quite frightening and some times happens when you run out of petrol.
I think it's electrical and you are not getting a continual spark, hence it stopping and then you can start the scooter straight away.
Gary

I had similar with a dodgy LML 150 barrel i'd fitted to a mates px125 ,it was new and in LML packaging but it turned out to have virtually no clearance, this slowed down and felt really tight by the time i'd got into 3rd gear despite only doing 35 mph and it got worse and worse ,kept cutting out. I limped it home and up jetted another one up, still the same ; it turned out to be the clearance ,there was virtually none - i should have checked but new in packaging i'd just assumed it would be right.

So i'd say check the piston to bore clearance is ok as it sounds like it's seizing up.

I just had the same problem. Changed the flywheel oil seal and now runs perfect. Have you checked for any air leaks. Make sure everything is tight, cylinder head ect. If it still persist it wil be the flywheel seal. Unfortunately you have to split the casings to change the seal. If you try and do it without, the seal won't fit properly and you will damage the seal.
Gary

You can fit the flywheel seals without damage; it's fiddly but it's do-able, done it many times.

Hook the old one out with something like a clock makers screwdriver, taking care not to scratch the crank spigot, clean up the sealing surface with a clean cloth and check for damage, grease the area or the inside of the new seal lip, carefully push it home with something like a deep socket and take care that the lip does not fold out as you do.

It should be flush or just sub-flush about 0.5mm max with the casing hole.

Takes just a few minutes.