Leaded or unleaded

just a quick query. for mtl,ref the very troublesome polini 177,mtl, is there a difference in runnin leaded to unleaded in a 2 stroke engine?could this be my problem? i dont really no,this was suggested to me that it could be my problem,somthin about a head bein stamped or somethin,probably a load of you no what. checked my timin mate and its as far back as it can go on the stator.decided to take out the motor to do a flywheel bearing,as there was a bit of a harsh rattle from around that area even with the clutch in it didnt really change much, o rattle has come from first seizure,any way ive got a sticky tar on head and crown of piston that can be rubbed off with a cloth.plug burns lovely,is this the TTS oil,or another problem,all seals seam to be ok but im goin to change them any way while its split,…really thinkin of goin standard again totally peeeed off, taa

With leaded or unleaded its a question of how combustable they are, i.e. their octane rating. The higher the rating the more likley they are to combust from the heat alone which leads to pinking. On the Polini it runs very hot at high rpm so I would suggest that unleaded 95 would be the best to use.

What exactly have you done to your cylinder head? Get the combustion chamber enlarged and use a head gasket to lower the compression ratio. This should bring down the temparature a little.

There are really only 2 cures for the Polini and other cast iron kits thermal problems, the first is to buy an alu kit like the Malossi or get a liquid cooled head. The former being the cheaper option. Polini’s are fine for a short sprint, but if you want a reliable touring machine you have to go with the malossi or another alu kit.