I recall someone saying the Raptor main jets were slightly different. My dealer can only get the hole sizes, and I would like to get the 142.5 and 147.5. Any suggestions where I can go and what the difference is? I think it had something to do with the taper?

 

Sudco International (323-728-5407, talk to Paul) has all of the jets for the Raptor in stock. I called Mikuni and they referred me to Sudco as a preferred supplier. I purchased 142.5, 147.5, 150, and 155 mains ($2.35/ea) and 25, 27 pilots ($4.95/ea) yesterday. My dealer could not get the 142.5's or the 147.5's. He said Yamaha said they are not available. There is no such thing as main jets with a tapered seat for the BSR Mikuni's. They are referred to only as small round main jets. This info comes direct from Mikuni. The pilots are tapered. The main jets must always be two sizes different. The right side carb (brake pedal side) has the larger size due to the fact that that carb feeds two of the three intake valves. Stock mains are 140 on the left and 145 on the right so the next size up to jet would be 142.5 on the left and 147.5 on the right. The pilots, needle clip position, air screw setting float height etc., are the same for both carbs. Take note there is a power jet in the left carb only. Stock size is 95. I would not change it right away. Do your mains and pilots first.

 

Good info. maynard

 

Both carbs have pilot jets-needles-and main jets, so where does the "power jet" come in (in relation o the throttle position) on the left carb and for what purpose? Thanks!

 

I'm not entirely sure yet. I have a call in to Joe Minton with Mikuni America and am awaiting an answer. I would suspect that jet works mainly in the midrange. I will post any info I receive from Mikuni.

 

Sorry to burst your bubble Maynard, but there is a difference in the jets. I know because I got the 150 main jet from my Yamaha dealer and it did not work. The jet was loose it it's sleeve. Upon further inspection, the original jet had a slight taper to the seat at the top of the threads. The replacement jet was flat. I then went to another shop and found a 150 jet with a taper and it fits snug like the original.

 

Thanks Maynard, that's just what I needed.

 

Thanks, for a second there I thought I was going senile. I thought I read something earlier in this forum about the mains having a taper. Good Catch.

Hay Maynard, the rest of the info was still good to get my hands on...

 

If you tell Mikuni or Sudco you want small round main jets with a tapered seat they will tell you there is no such thing. At least that is what they told me.