Any 2-stroke experts? Scorpa 250 troubles

[yorkie_chris]

Old-ish one with the rotax engine. I think 1998 ish.

It kicks up alright, but as it starts to warm up it will not tickover, or if you increase the slide-stop to the point where it will tick over, when you rev it it revs its nuts off and does not drop back to idle quickly at all.

Seems lean, the idle mixture screw does not make much difference that I can figure.

Not sure what the proper oil mixture is, would too much oil give these symptoms? (i.e making it go lean?) It's got 40:1 in it.

mixture should be 100ml to 5 litres

have you cleaned the carb and jets?

[yorkie_chris]

Yes carb has been cleaned out. Was not actually any sign of gunk in it.

[punyXpress]

What's changed since it last ran?
As Hovis says, clean carb - float may not be moving.
Also main bearing oil seals on old strokers can give up the ghost if dry for extended periods.

[yorkie_chris]

nothing changed it's just been stood awhile.

Anyone know stock position of slow speed screw?

could be coil or staterplate breaking down when hot

[yorkie_chris]

Still revs alright, just tickover and off-idle response.

Good fat spark when motor is well hot too.

[dizzyblonde]

I'll send matt down tomorrow if you want. He's getting under my feet, it'll give him something to do

[yorkie_chris]

OK should help, will give you a bell in the morra

Hi Chris,
Could be gummed up rings. stalling at tickover can be a sign of low compression (not as in low low, just low enought to casue a problem.

May be worth taking the pot off and checking they aren't all gummed up from being stood.

C