[Minibikaa]

I have a Piranha 125 motor bored out to a 131 with a big valve head thats ported and polished. i have a 26mm chinese mikuni with a oval-bore lever-choke. the bottom end to mid range isn't bad and runs good, but the top end sputters and chokes. I cannot get the jetting on this thing! Right now im running a 25 pilot jet and a 130 main jet. when i go up to a 135 main jet it just runs worse. any advice on jetting? is it the crappy china carb? i could use some help

 

[Drz638]

It sounds like you need a smaller main jet try going down a size and if it gets better keep goin down till it runs clean.

 

[Marconi22]

learn to ride

 

[kdm197]

I have a Piranha 125 motor bored out to a 131 with a big valve head thats ported and polished. i have a 26mm chinese mikuni with a oval-bore lever-choke. the bottom end to mid range isn't bad and runs good, but the top end sputters and chokes. I cannot get the jetting on this thing! Right now im running a 25 pilot jet and a 130 main jet. when i go up to a 135 main jet it just runs worse. any advice on jetting? is it the crappy china carb? i could use some help

This is the site we use for a jetting guide



www.scootrs.com



Left side you will see



Parts

Scooters

Other - open this link, choose Tech - then #3a tune Keihin/mikuni carbs



Hope this helps,

Good luck

 

[deputyperk]

yea dude, way to high on main, you need around a main between 110 and 117 max



those 26 mikunis that have the oval bore are more like a 24. was the 130 the stock mainjet?

 

[phatfiddy]

Four-Stroke Carburetor Jetting Tricks on 4Strokes.com

 

[GAjonn]

learn to ride

What brilliant advice

 

[sibo]

Mine did the same thing. Then I went to a main jet about 15, maybe 20 sizes smaller. No joke. Ran fine.

 

[Minibikaa]

thanks for all the help. from what everyones telling me and what those sites say; it seems like my main jet is too big. i'm gonna try main jets from 125-110 tomorrow and see how that works out.

 

[deputyperk]

start with a 112.



those 22mm carbs come with a 15 pilot and a 95 main.

 

[Minibikaa]

start with a 112.



those 22mm carbs come with a 15 pilot and a 95 main.

its a 26mm. but it did come with that exact jetting

 

[themountain]

its a 26mm. but it did come with that exact jetting

as a starter: A 26mm carb is too big for that engine if the head isn´t ported

You will never get it dialed correctly, but as all said before , try a much smaller mainjet

 

[dirtbkr188]

Try a #17.5 pilot jet and a #100 or #105 main jet with the jet needle in the 3rd or 4th notch from the top of the needle. Set the fuel screw at 1-3/4 turns OUT from seated, as a baseline to work from.



PM Member OLDSCHOOL did a nice write up on jetting a few years ago, addressing the Mikuni-clone carb you probably have.

 

[Minibikaa]

i messed around with it yesturday and i ended up with a 25 pilot and a 110 main and left the needle in the same spot. it ran like a whole new bike! now i just need a little more fine tuning and it will run perfect