1998 US Spec Yamaha Jog

DukeOf290

Well-Known Member
Hello everybody

I have a 1998 Yamaha Jog here in Chicago USA. It has the horizontal Minarelli engine that I am going to build for street use.

Here is somewhat the game plan:

70CC Aluminum kit
21mm Carb
Sport Exhasut
Variator
Clutch
Intake+ CF reeds
Cranck???

Thats about it for now.

Here is the question

70cc kit? I was looking at Polini Evo but it says 15:1 Comp ratio! Would I even be able to run that on 93 octane gas (thats as high as it goes here)? If not what would be a good alternative? Malossi is hard to get as SIP wont shipp it to the States :/

CRANK!!! this is a grey area for me. I know stock I got the 10mm pin and I would imagine it wont last too long with a 70cc on it, so what would be a good streetable cranck? should I go with a 12mm?

Variator will most likely be Polini as well, maybe Hebo

Hebo clutch

21mm Dellorto or Polini carb (any advice on main jet would be appriciated)

Koso / Stage 6 intake with Carbon Fiber Reeds

Spark plug... Do I want to run a cooler plug?

What do people do with the ignition and timing on these?

Also do I need to premix more oil into the gas now? If possible I would like to keep it on auto-mix.

EXHAUST! Now this is a big one, I want MID RANGE! it will be very important for me as I will be doing a fair ammount in traffic. What are some exhausts that are less free flowing. I got a shitty Black Dragon now but it will most likely change.

Any help/advise is appriciated. Goal here is a Dyno proven 15 horses and a top speed of 70mph while still being a street scooter that I ride evryday.

Cheers
 
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The polini Evo is a High end cylinder wich I would not use for every day use. Curtainly not with the low octane fuel you have in the States.

You should look for a low rpm Iron cast 70 cc cylinder. (15 HP will be hard to achieve but 70mph should be no problem with longer gears.)

It is recommended to get a 12 mm. cranck. It is much stronger and will cause you no problems. What kind of brands can you get?

If you want another variator I would recommend the Polini.

With this kind of a setup you dont realy need a racing clutch but the Hebo wil do fine.

21 mm. dell'ortho is good enough. Dont spend to much money on a polini carb.

You can leave the ignition as it is.

With a low rpm 70 cc cylinder it is possible to keep the automated oil pump. But mixing it yourself will be best.

What brands of exhaust can you get in the states? If you can buy Yasuni I would buy a Yasuni R.

And just out of curiosity,wich brands can you get in the states if your talking about cranks, cylinders exhausts etc. And do you use a webshop?
 
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