Re-jetting Carbs for New Exhausts

Little Loris · Post by **Little Loris** » Nov 17th, '06, 20:16

Thought I'd better start a new thread for this as it's a slightly different topic!

I've heard that I might have to re-jet the carbs for my new exhaust. Does anyone know if this is the case? Also, how will I know if they need re-jetting? Does it make a funny noise, down on horsepower maybe? I think the 400GreyBike forum are getting tired of my remedial, cape-tugging questions

Mike Daytona600 · Post by **Mike Daytona600** » Nov 17th, '06, 20:23

It helps. Get a k&n air filter as well if you can. Check out Dynojet and see what they do for your bike. The only way to see if it's been done before is to check the number on the jets in the carbs.

Little Loris · Post by **Little Loris** » Nov 17th, '06, 20:29

Mike Daytona600 wrote:It helps. Get a k&n air filter as well if you can. Check out Dynojet and see what they do for your bike. The only way to see if it's been done before is to check the number on the jets in the carbs.

Are Dynojet a local company? I don't suppose you have contacts for them or a web link?

Mike Daytona600 · Post by **Mike Daytona600** » Nov 17th, '06, 20:39

Here's the link but doesn't look ike they do one for yours. Might be worth giving them a ring.

http://www.dynojet.co.uk/jetkits/prices ... n-road.php

DynaMight · Post by **DynaMight** » Nov 17th, '06, 22:19

dynajet dont do a kit. fi international do, you can buy them from 400gb. its best to rejet so you get the best from the new exhaust, but theres a few cheaper ways or'rejetting' just up the the mainn jets to 115 or 118 all around and stick a .5 mm washer under the needles. that should be about right

Jon B · Post by **Jon B** » Nov 18th, '06, 11:40

A K&N filter will do nothing. They are just overpriced pieces of crap.

andy198712 · Post by **andy198712** » Nov 18th, '06, 17:41

the reason to rejet is, it'll be a bit lean in areas and will have flat spots in power, ie you'll accellerate and wen it hits say 8k rpm it'll feel down on power till say 10krpm stuff like that

and it might back fire more ect

svr-ash · Post by **svr-ash** » Nov 19th, '06, 00:18

andy198712 wrote:the reason to rejet is, it'll be a bit lean in areas and will have flat spots in power, ie you'll accellerate and wen it hits say 8k rpm it'll feel down on power till say 10krpm stuff like that

and it might back fire more ect

..and if it runs too lean, you'll [censored] your engine up bit time, you can make a bike overheat with a too lean mixture, this can cause problems like holing pistons, seizes etc

If i were you i'd do some rearch, i found DJ kits to be over priced crap, half the stuff they had in there stage 1 kits for my bike the carbs already had in them on a standard UK SV. The kits were designed for the US SVs running crappy K&N filters and after market exhausts.

Just putting in new jets won't be good enough either, it needs to be set up properly on a dyno to check the mixture is running right, to lean and as said it'll cause problems and too rich will cause performance and economy problems

corse saying all this i'm contradicting myself as i've not had mine dyno'd while i've been re-jetting mine, i've gone on feel

but i am planning a dyno run to check my fueling and adjust it to suit

Jon B wrote:A K&N filter will do nothing. They are just overpriced pieces of crap.

To true, BMC are far better

Little Loris · Post by **Little Loris** » Nov 19th, '06, 11:42

Dynomap in Exeter said they can test my bike and advise as to what needs to be done, if anything.

Would it be safe to fit the new exhaust and ride it there or is that going to really mess up my bike?

I have my Haines manual with me today so going to do some swotting up

Funky · Post by **Funky** » Nov 19th, '06, 12:29

Stick your exhaust on and ride it there. It shouldn't really do too much to it.