Author Topic: RM500 jetting  (Read 2423 times)

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Offline tmkiwi

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RM500 jetting
« on: September 28, 2014, 05:11:29 pm »
Need a little advice.
Recently purchased a RM500D. First run was last weekend. Bike is a low hour one, all stock.
Currently running
280 main
35 idle
6FM46 needle. Top clip
Changed out the 45 idle jet for a 35 as it was running very rich down low. Still running too rich down low.
Once in the band it pulls well but the transition is a poor.
So my questions are.
Has anyone tried a 30 idle jet.?
Have just fitted a GMC exhaust system. Will this make it leaner.?
Haven't run it with the new exhaust yet.
I don't think the carb is worn as it's such a low hour bike. But I could be wrong.
What do you think.

Offline SON

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Re: RM500 jetting
« Reply #1 on: September 28, 2014, 05:39:12 pm »
First person I would talk to is GMC
It won't be the first RM500 pipe he has made and he will probably have had some feedback from previous clients
Don't forget the basics only change one thing at a time so you can measure the differences

Offline JohnnyO

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Re: RM500 jetting
« Reply #2 on: September 28, 2014, 05:56:17 pm »
Possibly needs a smaller needle jet if the needle is already on the leanest setting.
35 pilot should be close

Offline 80-85 husky

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Re: RM500 jetting
« Reply #3 on: September 28, 2014, 06:47:40 pm »
poor transition usually means rich on the needle. get the next one down (whatever that is.. :o)

Offline Lozza

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Re: RM500 jetting
« Reply #4 on: September 29, 2014, 08:02:50 am »
I would agree with needle jet/needle.If your needle is that far down, you need to change the needle and or the needle jet.
Jesus only loves two strokes

Offline shelpi

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Re: RM500 jetting
« Reply #5 on: September 29, 2014, 10:43:50 am »
Get the Sudco, Mikuni 5th Edition Tuning manual, only costs Around $14, its the bible, its all in there, tuneing, specifications, trouble shooting, parts catalogue,
so when ya order ya bits and or Carbies say from Ian Willians Tuneing you will have all the same part numbers for your RS, VM, HSR, TM, TMX, HS and BN carburetors ;)

Offline D project

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Re: RM500 jetting
« Reply #6 on: September 29, 2014, 12:47:01 pm »
I went two sizes leaner on the needle jet and one size down on the slide.
I think you should be ok around the 35/40 on the pilot.
These are what I am using with the standard pipe with all the other carb parts you have.

Offline tmkiwi

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Re: RM500 jetting
« Reply #7 on: September 29, 2014, 04:08:49 pm »
I went two sizes leaner on the needle jet and one size down on the slide.

Do you remember what the needle was.?

Offline D project

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Re: RM500 jetting
« Reply #8 on: September 30, 2014, 08:16:51 am »
Stock needle.