Author Topic: Mikuni Power Jet adjustment  (Read 73 times)

0 Members and 1 Guest are viewing this topic.

Offline 1983_Enduro_YAMI

  • C-Grade
  • **
  • Posts: 121
    • View Profile
Mikuni Power Jet adjustment
« on: Yesterday at 11:01:33 AM »
Hello all,

I have a Mikuni power jet kit installed on my TM38 flatslide carb and Mikuni recommends that original main jet should be reduced by 25% and the reduction will become the size of the power jet.

So in my case my bike is currently using a #380 main jet so i trimmed it back by 25% which now #95 will become the size of the power jet however this is a conversion from VM36 roundslide to TM flatslide with power jet kit so i started off in a richer side by installing a #320 main and a 97.5 power jet then go from there..

If the engine ever shows a rich/lean symptom which most likely it's gonna happen..should i be making the adjustment on the main jet first and leave the power jet alone until i have find a suitable main jet for it or should i be making changes on both simultaneously using the aforementioned Mikuni's formula? and for the future changing condition, should i only make changes on the main jet, power jet or both?

Best Regards,
Jack   
« Last Edit: Yesterday at 11:26:33 AM by 1983_Enduro_YAMI »

Offline TT5 Matt

  • Legend
  • *****
  • Posts: 1504
    • View Profile
Re: Mikuni Power Jet adjustment
« Reply #1 on: Yesterday at 02:01:52 PM »
an old tuner told me when i 1st started messing around with carbies to always start rich and go down but never lean and go up as by that time you may have siezed/grabbed the sides of the piston or burnt a hole in the top of your piston.using his advice of never lost a motor ;)

Offline 1983_Enduro_YAMI

  • C-Grade
  • **
  • Posts: 121
    • View Profile
Re: Mikuni Power Jet adjustment
« Reply #2 on: Yesterday at 02:31:15 PM »
I was told the same thing by a former dealer mechanic that i was working with during my high school years...for every single bike that i own now i always start with the biggest jet size possible and expect it to sputter then go down from there....It's the first time for me to try the power jet out though. Bought the kit a few years ago and never got around to use it until recently when i discovered a brand new TM38 in my file cabinet so might as well i will replace my VM36 roundslide with it.

I assume that the main jet is still the primary jet to be changed at 3/4 to WOT circuit with the power jet but when should i be changing the size of the power jet if necessary?