1998 us yamaha jog build

Hi evryone

I am in the process of building a street 1998 USA Spec Yamaha Jog with the horizontal Minarelli engine.

Don't know why but SIP wont ship Malossi to the US so the hard choice between Malossi vs Polini was made for me.

That being said I was leaning towards the Polini 70CC Evo kit but now I am having my doughts.

A) It says that it's a 15:1 Comp ratio and in Chicago pump gas is only 93 octane so... would that make the engine detonate?

B) I would like to keep the stock cranckshaft and the 10mm pin, would the evo kit (granted it would run on 93) be alright on the street with a 10mm pin?

C) what are some good alternatives?

Goal here is a DYNO proven 15HP at the wheel (Dynojet Dyno is what we use at the Harley Shop where I work)

Here is the projected set-up:

Polini Big Bore

21mm Carb

Koso intake CF reeds

Bidalot Exhaust

Polini variator (6 wqeights)

Thats it for now, what are the options for igniton management? Also please let me know if I overlooked something that is crucial to the build.


Thanks in advance

Excellent! You think I'l be alright running a the EVO kit on pump 93 Gas? I was thinking of a 21mm carb with a 105 or up main jet. Shoul I pre-mix more oil as well?

you could have a look on www.zumaforums.net and look in the forum section lots of info that motor. the site is USA based.

Yes you can run the 21mm carb with 93 gas just make sure its tuned well.

like the other post said your crank will not last long as its only designed to rev to about 8000-9000rpm where the evo kit creates power from 5000?-11000 rpm also with replacing the crank you can increase the primary compression in the motor.

Good luck with your build