Main Jet Size 147.5

[Smithjs35]

Would like to know if I purchased the right ones.

Mikuni Main Jets SBN 147.5 Part #: N102.221-147.5

Thanks for your help.

 

[maleko89]

Yes, that's the correct part number.

 

[Smithjs35]

Thanks so much, have been looking at too many jets and it affected my thinking and wanted a second opinion.

 

[Fire-medic]

That's what I run: Dynojet Stage 7 kit, w/Mikuni 147.5 main jets, and keeping the VBoost operational.

 

[Smithjs35]

I'm stock, do you see an issue with the 147.5's ? Thanks

 

[dannymax]

Might be a bit lean for stock pipes

 

[Fire-medic]

Might be a bit lean for stock pipes

Yes I didn't mention I have a full UFO 4/1 exhaust.

 

[Smithjs35]

So what size do you recommend? Stock or 150's, and thanks for your help.

 

[Fire-medic]

So what size do you recommend? Stock or 150's, and thanks for your help.

If you have a stock, OEM exhaust, or slip-on cans with OEM header pipes, try the 150 Mikuni main jets, 1 size smaller than stock, if you have a full custom exhaust (but NOT Cobra 4-into-4) then you can try the 147.5 Mikuni.

 

[Smithjs35]

Thanks Fire-medic, do you have a write up on carb rebuilding that I can use along with the manual. And last question, do you know what size guitar string to aide in jet cleaning.

 

[Fire-medic]

Our member Damon has dvd's for engine building and carb rebuilding. He used to have an ebay site, but I couldn't find it. Try contacting him through 'start a conversation' under his user name: Damon Damon

Geoff Lewie says, 'high-E'
https://www.vmaxforum.net/threads/carb-teardown.38182/page-2#post-484767
I recommend the Harbor Freight small drill bits. No you don't use 'em in a powered drill! Fingertips, or a 'pin vise.'

"When we refer to the gauge of a string we’re talking about its thickness. Strings are measured in thousandths of an inch - so for example, a gauge 9 high E measures .009 inches thick, whereas a standard 42 gauge low E measures .042 of an inch."
https://www.pmtonline.co.uk/blog/20...#:~:text=When we refer to the,042 of an inch.

 

[Smithjs35]

Thanks so much and you're more than a Fire medic. "Thanks to all Vmax medics"

 

[Sniffbooger]

I have Dale Walker Holeshot 4 into 2 full exhaust and I run 147.5s but I probably need to get the Factory Pro or Dynojet Stage 7 needles...it runs a bit lean right now...great on gas mileage, approx 40mpg hwy and 35 mpg combined city/hwy, but the power is a little off...seems a bit slower than before when I had the MIkuni 150s...but I will get some needles soon and see if it picks up a few hp. I already have the Factory Pro high dispersion emulsion tubes ready, just need some better needles and then I'll install them see how it goes.

 

[Hinterwaldler]

My 95 had been dyno tuned a few years back by a previous owner. It was tuned either with OEM pipes and mufflers or he might have had the supertrapp slip-ons (on OEM 4-2 pipes) on it at the time but in either it was essentially OEM exhaust. It also had a stock replacement K&N with full airbox. It got 147.5 mains and 1 washer shim under the stock needles (1 step richer) for best dyno tune which was right at 120 WHP (see avatar at left).

When I bought it 2 owners after the builder, it the Supertrapps had been fully gutted and had no end caps and badly needed a proper carb sync and tune. I bought a brand new classic Kerker 4-2-1 system on it with comp baffle and did a thorough carb tune and sync and it ran like the proverbial scalded dog from idle to redline. No runs, no drips, no errors. Top gear wot pulls from 40 mph no problem...no matter the gear or the rpm, there was not a complaint about the way it ran.

Being the 'never let it rest till our good is better and our better is best' kinda car/bike guy I am, I had to finish out the stock block potential by going the final step of the Morley Muscle kit....

After some trial and error and Sean's help via e-mai and more tuning and hair pulling, I finally got the Morley Muscle kit tuned fairly well.

For my 95 with Kerker 4-2-1 w/ comp baffle and complete Morley Muscle kit I found I had to go with 150 mains and stock needles (removed the washer from under the needle) with the DynoJet light springs from the kit and about 3-3.5 turns out of the mixture screw. (No matter how much tuning and trying I absolutely could not get the DynoJet needles to work across the range...at all.)

That is off from Sean's usual jetting recommendations for his 'Muscle Kit' but between he and I and many e-mails between us, my bike absolutely refused to cooperate with his recommendations. Apparently 99.9% of others are much more agreeable to his recommended jetting recommendations, I suppose mine is just hard-headed....it IS a Missouri (Show-Me) bike after all.

I think with 147.5 mains, if you richen midrange with needle tuning, I don't think you will be far off even with stock pipes.

 

[Smithjs35]

Thanks so much for that vmax knowledge. I'm going with 150's. Like you said, mine actually runs pretty well with stock set up. I have never put it on a dyno though. Just thought I would change jet size because it does run rich.