Carb question

[iwannaride]

I have a 2002 ZX-9R and I am changing out my carbs due a shop messing them up. i have a new set of carb with the factory pro jet kit and i am looking for some help in what size jets and other info.
thanks

[Billy]

This is going to be a little off topic but what shop did you go to that "messed" them up?

What did they exactily do?

[bobr]

jetting is going to be specifically related to the state your bike's in. IE: what mods are done to it. if your bike ran fine with the jetting in the old carbs.....swap those jets to the new carbs. be sure to check the springs in the carbs slides against the springs in the new carbs. sometimes those are changed with a kit. and be sure to check any of the holes in the slides. sometimes those get drilled. and no matter what, after installing the new carbs be sure to have them synced.

[iwannaride]

Thanks. i have a Muzzy Slip-on, Muzzy Timing Advancer, K& N filter, bigger fuel pump and lines, sprokets and carbs spacers on it as of now. The old carbs had a dynojet kit in it that i had a shop do and it never ran the same. it was smoother and quicker when it was stock. I talked to a few carb places and they said that drilling holes in the slides of the zx9r is a no no and it will slow the performance down. THey are vac advance carbs. so I got the factory pro but i was not sure if i should have the bigger jet on cyl. 2 and 3 and the smaller on 1 and 4.
(The kit only has 2 jet per size)
thanks again for you r help.
anthony

[iwannaride]

well the bike breaks up at high speeds, it will not start first time when i use the choke in the morning and it bogs out and when i get on it. the bog is quick and then it seems to be fine. i just took out the jet and they are a 155 and the stock ones i have are a 165 which the dealer tells me is stock. i am unsure why the 155 were used but when it was stock i had great throttle response, no bogging and it always started right away sometimes without using the choke.
thanks for any and all info.

[rebelpacket]

Are your old carb's in sync? Its very uncommon to have to replace them...

Bogging sounds like its lean... keep in mind that your bike will lean out a good deal in this colder weather... especially if it was running lean from the factory.

"Breaks up at high speeds", do you mean that it sputters and falls flat on its face at a certian RPM? That timing advance doohickey might be messing it up too... I thought you usually only use those if you've got fancy bits in your motor?

[iwannaride]

well after taking it apart last night i found that on the New needles there were two flat washers on top of the E-clip and there is supposed to be one on the top and one on the bottom. i am not sure if that could cause any of this but that was all i found so far. The carbs are in sync and the timing advance actually helped the bogging and breaking up, it was worse with out it.

[richw]

The washers are used to raise or lower the needles

If you believe you are lean then I would put 1 or both washers under the needle clip that effectively raises them. This is of course bullshit as we can not be sure that those are stock needles.

You also say your mains are smaller then stock which is weird as almost any mods need larger mains. Some thumpers do put thinner needles and smaller mains but that is rare.

I would check float levels, go 1 clip up needles, go 1 size bigger mains to start. 3 turns out on the airscrew.

[SSearchVT]

It looks like you are concentrating on the main jets and needle... Take a look at the pilot jets, float level, mixture screws, Vacuum lines, fuel filters, diaphrams, etc. Look at the slides to see if there are any scratches - junk in the bores not letting them work smoothly. Check to see if the shop that worked on them before used any RTV on the bowls - it breaks down in gas and will clog jets... Good luck...

[iwannaride]

thanks for the info. I check the Jet kit was the Dyno jet and they did change the needles and jets. why smaller mains i have no ideal. i check and there was no rtv or and lubricant use. all of the hoses, floats, springs etc are all brand new. i just put together a new set of carbs with the factory pro jet kit. i used 162 jets on #1 nad #4 and 168 on #2 and #3. I am going to start atthe same seetings as the other carbs to see how theses work compared to my other ones.

[KB]

Good luck carb issues on a street bike are a pain in the arse (having to take the tank on and off) and often time result in zero horwsepower gain.

KB

[Rye]

If you have a factory pro kit, then there should be a 1 page explanation of how to setup your carbs. If not call FP and they'll probably send a pdf. FWIW, don 't touch a Dynojet kit. They're shit and have always been. Having f'd with more carbs than I care to remember, this I can say with confidence. Your bike will benefit from a jet kit...if not from absolute hp gains...at least from a more linear powerband.