Is jetting THAT much better than shimming?

[diablo250]

I have done hours and hours of research on this subject- I have shimmed my needles with 3 washers, removed snorkel, installed 15t front sprocket, and de-cored my exhaust. The bike has been running well, no hesitation, no hiccups, but this isn't my first time riding a bike either, so I may not be noticing the 'little things'. .................Anyway, I ordered a Dynojet jet stage 2 kit and am wondering if I will notice any great gains over what I have now...

[VeX]

No. You will likely notice very little impact from the jet change. The jet is going to affect the very top part of your powerband. The needle shimming and idle mixture screws probably give you the biggest noticeable difference (as the low and mid throttle areas are typically lean from the factory).

Dynojet stage 2 jet kit? Is that the one for people who have their air box removed? If so you won't be able to use the jets unless you removed your airbox anyways.

[kkim]

lol... why don't people ask questions before they buy stuff???

[almost40]

Depending on which main jets you choose the biggest difference will be from 9000 rpm to redline. You will get a noticeable power increase in this rev range with a full exhaust and snorkel removal.

[diablo250]

Originally Posted by almost40

Depending on which main jets you choose the biggest difference will be from 9000 rpm to redline. You will get a noticeable power increase in this rev range with a full exhaust and snorkel removal.

I was thinking about going with the 096 main first, as I hear the dj 096 is a bit larger than the Keihin 096. The bike is running pretty much on point, I would like to just squeeze a bit of topend out of it.

[diablo250]

Originally Posted by kkim

lol... why don't people ask questions before they buy stuff???

By the time I got an answer, the money would have already burned through my pocket and into my savings account!

[kkim]

Originally Posted by diablo250

The bike is running pretty much on point, I would like to just squeeze a bit of topend out of it.

more top end as in speed or power?

[diablo250]

Originally Posted by kkim

more top end as in speed or power?

I'd like more power/ to move the powerband a bit. I am not a speed demon, nor do I have delusions of grandeur that my little 250 will ever keep up even with my GTI. I am getting some popping/backfire, but I believe it's from the clean air system as it's only on decel.

I'd like to have a bit more pickup from 8k+ when I'm on the freeway. I already have a 15t front, I plan to drop the rear 3t first, then jet. my current setup yields a 70mph cruising speed~ @ 8200rpm+/-.

[kkim]

The main advantages a jet kit offers over shimming are the proprietary needles that come with each manufacturer's kit and the adjustability ease the grooved needles provide. That plus the R&D the kit manufacturer puts in to show power gains.

you will need to remove the plugs that cover the mixture screws to gain a smooth powerband from idle to redline.

That said, to extract maximum gain from any rejetting, you will need to experiment a bit as results will differ on location and the particular mods done to the bike.

Going up and down from your present settings should reveal if you are headed in the right or wrong direction with each change. have you read this?

http://faq.ninja250.org/wiki/How_to_...e_your_jetting

[HKr1]

Originally Posted by diablo250

I'd like to move the powerband a bit.

Camshafts determine the powerband of a motor.

[almost40]

To get the most out of your Kit a Full exhaust is recomended. More fuel and air in and out will give you the most power. If your not planning on buying a full exhaust then dont expect miracles. A larger main will give you a bit more top end power. As far as the gearing goes, if you dont have the horsepower, you can over gear the bike. A 15/42 setup, in my opinion, is a little steep but will lower you highway rpms quite a bit. It should yeild a 1000 / 10 MPH ratio or somewhere thereaboults. (7000 = 70 mph) You can always downshift to 5th for better acceleration. I would suggest a 44t rear which would give you roughly the same ratio as I have. (8500 = 80 mph)