bultaco advise please

[jimg1au]

hi
i am looking at a 370 fronterra motor to go in a dirttrack project i have are these motors ok for this kind of racing.i know astros are tops for this but a little hard to get
cheers
jim

[lms6201]

no jim , no good for dirt track , would be far more suited for my frontera gold medal roller !

[jimg1au]

any more answers

[firko]

Go for it Jim. They're not all that different to the Pursang motor so it'll work well for DT.

[lms6201]

sorry jim , the wide ratio frontera ( same tranny as alpina except output drive uses roller bearings ) apparently works well on flat track , and the 370 has a very broad power range , i lost the gear lever on mine and did a whole race in 3rd , if it has an old wiesco piston like mine they vibrate a bit(heavy ) , i have been told that a die grinder can improve that  ,

[jimg1au]

thanks guys

[JC]

Jim,

Not all Frontera 370s had the wide ratio (matador/alpina) gear ratios. IIRC MK 9 did (M143), Mk 10 (M181) was supposed to have pursang gear ratios (but I'm not 100% sure) & MK 11 (M215) had  good ratios somewhere in between. MK 11 ratios would probably be best for DT. Top-ends are basically pursang on all three models.