starter jet buying?!

6 replies to this topic
  • dbrenize

Posted May 07, 2012 - 06:21 AM


i need a few sizes in starter jets and i cant seem to find them any were. can some one point me in the right direction please?!

  • grayracer513

Posted May 07, 2012 - 06:50 AM


You can order them through anyone who sells Yamaha parts.

But why would you want to change one?

  • dbrenize

Posted May 08, 2012 - 09:53 AM


alright, so heres the story this was my first rejet ever on any carb. and when i checked them and was putting them back in i made a woopsie and pout the starter jet over top of the pilot =0 and i had to gently drill it out and thankfully im good at removing bolts and such, so i didnt damage any threads and i kept the shavings out of the rest of the carb. but i got a leaner pilot jet because it wasnt idleing and it also wasnt starting which was cinfusing. so i wanted to get a stock and a 62 to maybe help a little. if this doesnt help and neither does the needle clip, then im sending it to the mechanics for him to check out the valves. im running to my local yamaha dealer tonight ill for sure have to order i called last week to all local parts stores and no one has the starter jet. please give me some feedback about the not starting/not idleing problem. thanks!

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  • grayracer513

Posted May 08, 2012 - 10:49 AM


Not until you give me some feedback about what kind of bike you're working on. Make, model, year.

  • dbrenize

Posted May 10, 2012 - 03:10 AM


Its a 1998 yz400f

  • grayracer513

Posted May 10, 2012 - 06:10 AM


Ouch. Not a good subject for your first carb tuning project. This is the stock jetting:

Main Jet: 175
Pilot Jet: 45
Starter Jet: 65
Leak Jet (if any): N/A
Fuel screw/Setting: 1.5 - 2.5 turns out
Needle/Position: OBDVR/4

I very much doubt that anyone riding anywhere in Pennsylvania would ever need a smaller pilot than what most YZF's came with stock unless they trip off to somewhere with a lot more elevation, so I don't think that's your starting trouble. Likewise, I doubt a smaller starter jet will help much. The only reason I can see for a larger one would be the extreme cold of your winters. Remember to that the starter jet only works when the "choke" is used.

Start with stock jetting. As for starting be sure you're using the right process:


Once it's running, turn the idle speed screw (usually a "knurled" black knob on the left side at the float bowl) in until it will idle on its own, and adjust the pilot screw:


During that process, you can gauge whether the pilot jet is about the right size:

But you may be fighting a losing battle with that old FCR. Sometimes they develop internal cross leaks and such that make them impossible to straighten out. In that case, a used carb from an '05-'09 YZ450 is an amazingly effective cure for it.

  • dbrenize

Posted May 10, 2012 - 05:52 PM


well im going to try my best. got the jets coming on monday. im trying to get it ready for some xc riding this summer. i really hope it will be ready by june. i will be posting here a lot for this reason. and i hope i can find some good knowlagable people like yourself that can help me!

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