Rejet a completely stock bike?

SirKng · 08-11-2022, 09:36 AM

Is it worth it to rejet a completely stock bike? Well, maybe with a pod filter and stock exhaust?

Reason I want to do this is the stock air box mountings are broken and my bike feels a bit sluggish with my new slightly taller heavier tires. I have regeared and it helps but was wondering if re-jetting will help more or if I should wait until I can get an exhaust. Bike does start a little hard and takes a long time to warm up so I was wondering if it'll help that too. Or can I just mess with the needle for richen it up during part throttle operation? I'm still learning about carbs so any input is appreciated.

This is on a XF250 if anybody is wondering.

**JerryHawk250** · 08-11-2022, 10:26 AM

Rejetting the main jet and adjusting the idle mixture will help with the hard starts. Also before you start messing with the jets, i would do a valve adjustment. Improper valve gap will make it damn near impossible to tune the carb correctly.

Bill Hilly · 08-11-2022, 02:19 PM

I have an aftermarket exhaust, and modified airbox on my TBR7, and have the stock carb jetted at what I think is as good as can be. I have a 115 main, and a 36 pilot jet , and two thin shims made from the lid if a potted meat can on the needle. I know not to expect great power from the bike, but it runs great, and it is definitely improved over the bike when I got it. It had stock exhaust, and the guy I got it from had a 110 main in it, and it had the 36 pilot in it ,I don't know if it was stock or not, but it's what I'm still using with the 115 main. It ran fine when I got it, but it definitely breathes better now. I was told by other more knowledgeable members on this forum, that with stock internals, and stock untouched head, that the stock carb can flow all the motor can draw.

08-11-2022, 09:36 AM	#1
SirKng Join Date: Apr 2020 Location: Eau Claire, WI Posts: 117	Rejet a completely stock bike? Is it worth it to rejet a completely stock bike? Well, maybe with a pod filter and stock exhaust? Reason I want to do this is the stock air box mountings are broken and my bike feels a bit sluggish with my new slightly taller heavier tires. I have regeared and it helps but was wondering if re-jetting will help more or if I should wait until I can get an exhaust. Bike does start a little hard and takes a long time to warm up so I was wondering if it'll help that too. Or can I just mess with the needle for richen it up during part throttle operation? I'm still learning about carbs so any input is appreciated. This is on a XF250 if anybody is wondering. __________________ 2018 SSR Motorsports XF250
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08-11-2022, 10:26 AM	#2
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,561	Rejetting the main jet and adjusting the idle mixture will help with the hard starts. Also before you start messing with the jets, i would do a valve adjustment. Improper valve gap will make it damn near impossible to tune the carb correctly. __________________ 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
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08-11-2022, 02:19 PM	#3
Bill Hilly Join Date: Feb 2021 Posts: 934	I have an aftermarket exhaust, and modified airbox on my TBR7, and have the stock carb jetted at what I think is as good as can be. I have a 115 main, and a 36 pilot jet , and two thin shims made from the lid if a potted meat can on the needle. I know not to expect great power from the bike, but it runs great, and it is definitely improved over the bike when I got it. It had stock exhaust, and the guy I got it from had a 110 main in it, and it had the 36 pilot in it ,I don't know if it was stock or not, but it's what I'm still using with the 115 main. It ran fine when I got it, but it definitely breathes better now. I was told by other more knowledgeable members on this forum, that with stock internals, and stock untouched head, that the stock carb can flow all the motor can draw.
	0