new exhaust-need rejetted? western pa area

5 replies to this topic
  • xrracer36

Posted September 18, 2002 - 05:18 AM


getting powerbomb header, and just bought a powercore IV muffler with spark arrestor.
will i need to rejet my ride once i install these?
i live in butler , western pa. (45 min. from pittsburgh)
guy i'm buying the header off of is local, and said he didn't need to rejet (only had header with stock yzf pipe on his 00 426), so not too worried bout header, just canister.
any help is appreciated. i have stock jetting now, no airbox lid, no throttle stop, stock yzf muffler (currently) and it's running good. backfires a little, but not bad.
racer36 :)
:D :D

[ September 18, 2002, 08:25 AM: Message edited by: xrracer36 ]

  • Bill

Posted September 18, 2002 - 01:51 PM


You can try the jetting in my signature, if you have yz timing. If not go with the DMM needle. This works well for me in Eastern Pa.


  • Steve_WR400F_#61t

Posted September 18, 2002 - 08:16 PM


Probably won't need to worry about changing anything. Many times people get to pushy looking for something more when getting a new pipe and end up screwing up the jetting. It's usually best to install the pipe and ride. If the power feels a little flat, especially up top, then go up one size in your main jet. If it's too rich, which I would doubt, then go down one size. From there take a good look at your manual and learn what changes do what before changing anything.

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  • xrracer36

Posted September 19, 2002 - 02:09 AM


thanks. good advice steve. maybe your right. my bro had a cr80, and when he got an fmf system, he had to rejet. maybe i was just assuming it would need done. i'll ride it first, and then take a plug reading or just go by power output or something.
thanks guys!

[ September 19, 2002, 05:10 AM: Message edited by: xrracer36 ]

  • Bill

Posted September 19, 2002 - 07:33 AM


Steve is correct but, why not optimize the power your trying to add (with the pipe) by getting your jetting correct?

Bill :)

  • xrracer36

Posted September 20, 2002 - 02:13 AM


not what i meant bill.
i'm gonna see how it runs with stock jetting, and if it doesn't run right/better than with stock pipe, then i'll look at rejetting. i been using top end a lot latley. feeling i'll be able to tell.
heck, my bike is probably jetted wrong to begin with. as far as i know, it's stock wr jetting, but i'm running a yzf pipe (higher flow?)


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