Author Topic: Main jet  (Read 961 times)

sissy mary

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Main jet
« on: November 17, 2014, 12:02:14 AM »
I finally got around to trying to re-jet my carb. It runs lean do to leo vice exhaust & K&N style air filter. Was surprised to see stock main jet was a 118? Thought it was a 108-110? Bought a 112.5 a while back, so I had to run out and buy a 120. Put it in and it still pop's, but I would say better. Ordered a 122 & 125. Has anyone else done this? Should I just forget the 122 & go with the 125? Most bikes I have jetted required going up 2 sizes just to over come the lean stock emissions systems. So I am thinking the 125? Any thoughts? Has anybody installed the 6sig or 6sigma jetting kit? How did it work? :-*

BettinANDlosing

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Re: Main jet
« Reply #1 on: November 17, 2014, 12:24:31 AM »
The Leo Vince always will pop, it's just part of having that exhaust. I wouldn't waste any money with those "custom jet kits" they just basically guess what jets you need. There's too many factors for them to get it right, altitude, exhaust, intake, condition of the engine etc etc. Last Leovince i installed on a x500 ended up with a 118 main, but that was with stock airbox. Pod filter you'll be closer to 130-140 and need to up the idle jet too.
2002 Kymco B&W 300; MRP 78MM "300CC", Naraku cam, Yoshimura rS3 exhaust, 17g Sliders, Yellow torque spring drilled airbox, stock carb #115 main #40 pj.

2001 "Yamaha" Zuma AKA MBK Booster; MHR OverRange, Dellorto 19mm BHBG, Polini "big" intake, RS-3 Rear shock, Stock cylinder.

sissy mary

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Re: Main jet
« Reply #2 on: November 17, 2014, 04:48:43 PM »
Thanks. It's not a pod filter. It is a DNA (K&N) style direct replacement (wire mesh and cloth gauze) filter. It fits into the same slot as the stock filter does. Air box has not been modified at all. Do u think a 122 will be fine, or should I go with the 125? It was lean as it runs better and with a little more power now with the 120. More smooth, not as much throttle needed as before etc. Bikes I have main jetted before required going up 2 sizes just to fix the very lean stock emission setting. So I am kind of leaning toward the 125, which would be going up 3 sizes. What do u think???? It's a pain in the azzz taking off the carb, box etc.

BettinANDlosing

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Re: Main jet
« Reply #3 on: November 17, 2014, 06:07:22 PM »
I hear ya, if it feels good at full throttle with the #125 i would stick on the rich side of things!
2002 Kymco B&W 300; MRP 78MM "300CC", Naraku cam, Yoshimura rS3 exhaust, 17g Sliders, Yellow torque spring drilled airbox, stock carb #115 main #40 pj.

2001 "Yamaha" Zuma AKA MBK Booster; MHR OverRange, Dellorto 19mm BHBG, Polini "big" intake, RS-3 Rear shock, Stock cylinder.

ce

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Re: Main jet
« Reply #4 on: November 17, 2014, 10:13:24 PM »
I have the Leo and I went with the 125 main jet but it seemed too rich and still had mad pops, so I went down to the 120 and it's real smoove, except after shutdown about one second later it gives a single pop.

It's like Leo likes poppin, and even after you get the carb tuned, it's still gotta get some pop somehow, so I just let 'im have it.

With 28 gram rollers in the Malossi 2000 variator it's a lot more fun than the stock setup, but the RPMs are kinda high throughout. I haven't tried top end yet, and I lost the speedometer so we'll have to see if it runs right.
Albuquerque, New Mexico

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