"Upgrading" to a Yoshimura Full CF exhaust v. Which Jet kit for my situation

[edxmon]

Welp, I was able to score a cf full yoshi exhaust for $220 shipped on ebay, it's got some scratches in the heat shield and the rectangular tag riveted to the can (nothing I can't repair, I think...), otherwise it looks mint and it comes with everything including the silencing insert.

I'm in SoCal (see "location"). I have the snorkel removed and using a K&N drop in filter, currently running a Dan Moto JISU, with the needles shimmed with 2 SAE #4 washers. I just found out today the bike runs better than I knew. Went to meet a guy for a sale through craigslist, I was hauling ass and the bike kept pulling all the way to 14k, while I remember it bouncing off the revs at around 13k before with the stock exhaust, K&N, w/o snorkel and shimmed. Of course I also recently had the valves adjusted and the carbs synched so that could have been it.

I'd like to install the new jets myself as to save as much $$ as possible. I know there is a kit that has assorted needles and jets but is a bit more expensive than buying specific ones. If any one lives around the same elevations as me and has a bike with the same mods, I would very much appreciate your input so that I can hopefully follow in your steps/ learn from your experiences with trying to get your bike jetted right.

P.S. I will soon be having my less than 3 months old Dan Moto JISU for sale if any one is interested.

Thank you all in advance and God Bless.

[csmith12]

word!

[edxmon]

Originally Posted by csmith12

word!

lol

[choneofakind]

ok, so your future setup will be:

no snorkel, K&N drop in filter, and full yoshi exhaust right?


Always run the bike on the same jetting specs after making intake/exhaust mods to make sure you know how/where it feels different and know what needs changed/what has improved.

So start with your current setup of 2 washers and 98 mains.

then test with 2 washers and 100 mains. From my experience, a full exhaust with a modded intake should run better with a step up on the mains.

You should then test 2 washers with 102.5 mains. Stick with the jets that worked the best.

Then move onto the washers. Add one. I'm guessing you'll be alright with 3 washers, but that's purely a guess. You may find that your bike runs better with a different number of washers.

There really is not a way to cut corners on jetting. Different bikes will potentially need different jetting, even if they are setup the same as another bike.

[edxmon]

Originally Posted by choneofakind

ok, so your future setup will be:

no snorkel, K&N drop in filter, and full yoshi exhaust right?


Always run the bike on the same jetting specs after making intake/exhaust mods to make sure you know how/where it feels different and know what needs changed/what has improved.

So start with your current setup of 2 washers and 98 mains.

then test with 2 washers and 100 mains. From my experience, a full exhaust with a modded intake should run better with a step up on the mains.

You should then test 2 washers with 102.5 mains. Stick with the jets that worked the best.

Then move onto the washers. Add one. I'm guessing you'll be alright with 3 washers, but that's purely a guess. You may find that your bike runs better with a different number of washers.

There really is not a way to cut corners on jetting. Different bikes will potentially need different jetting, even if they are setup the same as another bike.

Correct: No snorkel, K&N drop in, 2 washers
Just to clarify, 98s are the stocks, correct?

Seems like I will have to end up buying the Jet kit with that comes with the assortment of jets then, I just had the idea that if some one what my exact same set up they would be able to recommend me a particular size.

Time to sell my slip on to offset some of these costs. Thanks CH, appreciate your insight.

P.S. Ironic I'm now in the "full exhaust" camp after our little squabble about slip ons eh? lol I feel retarded now :P

[choneofakind]

98's are the stock size in the newgen bikes.

You should be able to get away with just a pair of 100 and a pair of 102 main jets. I've had great results with using washers and jets instead of a full jet kit. Saves too much money in my mind.

If you find someone with a similar setup, start there. Play around till it's right. That will likely save you time and get you close.

No need to feel retarded. You'll like the full system once it's jetted no worries about squabbles; that's just how people work. I squabble a lot if you hadn't noticed

[edxmon]

Originally Posted by choneofakind

98's are the stock size in the newgen bikes.

You should be able to get away with just a pair of 100 and a pair of 102 main jets. I've had great results with using washers and jets instead of a full jet kit. Saves too much money in my mind.

If you find someone with a similar setup, start there. Play around till it's right. That will likely save you time and get you close.

No need to feel retarded. You'll like the full system once it's jetted no worries about squabbles; that's just how people work. I squabble a lot if you hadn't noticed

When you say getting away with just jets, you mean I shouldn't even get the aftermarket needles? Because I think I saw a link to some place that sells just needles for a few bucks each, that would in fact save me a few bucks!

EDIT: interesting, the dynojet kit comes with different needles, but 2 out of 4 of the jets are smaller than stock. It comes with 94, 96, 98, 100. I'm assuming the bigger the needle number the larger the flow, why would any one need jets smaller than stock?

Doh! nvm, apparently stock 98 does not mean DynoJet 98

[choneofakind]

The smaller jets in the jet kit are for someone who uses the stock air box unmodified. The 98 mains are a tad rich. If someone is up in the mountains in Colorado for example, the air is more lean, and those 98 mains will be even more rich. A smaller main jet will help with that. The kit is meant for better jetting. Gotta have some different sizes to choose from to get it right for the location.

yeah, I would just buy the jets from jetsrus.com or a dealership and not worry about the aftermarket needles. The aftermarket needles are adjustable and the taper is different than the stock needles. That means the fuel delivery will be slightly different than the stock needle, but realistically, shimming the needles up gets 95% of the result at 1% of the price.

The aftermarket needles by themselves are hard to find. Were you looking at jetsrus for just the needles? That's going to be tricky because you'll have to measure the stock needles, the aftermarket needles (of a couple brands, I know the numbers are out there somewhere) and compare to the selection of needles that are in stock. If you're comfortable with finding your own aftermarket needles go for it, but I have no experience with that. It will be easiest to either use jets and washers, or get a full kit. Finding the right needles might be more work than it's worth, and idk if it will actually be that much cheaper in the end.

[edxmon]

Originally Posted by choneofakind

The smaller jets in the jet kit are for someone who uses the stock air box unmodified. The 98 mains are a tad rich. If someone is up in the mountains in Colorado for example, the air is more lean, and those 98 mains will be even more rich. A smaller main jet will help with that. The kit is meant for better jetting. Gotta have some different sizes to choose from to get it right for the location.

yeah, I would just buy the jets from jetsrus.com or a dealership and not worry about the aftermarket needles. The aftermarket needles are adjustable and the taper is different than the stock needles. That means the fuel delivery will be slightly different than the stock needle, but realistically, shimming the needles up gets 95% of the result at 1% of the price.

The aftermarket needles by themselves are hard to find. Were you looking at jetsrus for just the needles? That's going to be tricky because you'll have to measure the stock needles, the aftermarket needles (of a couple brands, I know the numbers are out there somewhere) and compare to the selection of needles that are in stock. If you're comfortable with finding your own aftermarket needles go for it, but I have no experience with that. It will be easiest to either use jets and washers, or get a full kit. Finding the right needles might be more work than it's worth, and idk if it will actually be that much cheaper in the end.

I didn't remember the site, but it probably was jetsrus, I just remember some one mentioning getting single jets was way cheap.

I think I'll follow your advice and stick with shimming the needles, unless some one comes around and tells me that a specific set up with mods like mine is tried and true.

[aShifty]

good thread! answered some questions that i had too

[choneofakind]

Buying jets and shimming needles is the cheap way to go!

[edxmon]

Ok, im looking at JetsRUs: http://jetsrus.com/a_jet_kit_street/...50R_Ninja.html

What's the difference between "main" and "pilot" jets? Pilot jets are the first half (top) of the page, while main jets are in the bottom half of the page.

Also, what's the difference between GENUINE Keihin jets and OEM EQUIVALENT Keihin jets? the oem equivalents are about half as expensive, which is very enticing.

[choneofakind]

Main jets are the jets that are used during WOT. these are the stock 98

pilot jets are the jets that are used during idle. these are the stock 38 (I think?)

Pilot jets are usually ok to keep stock, all you have to do is back the mix screws out a little. If you back the mixture screws out past like 3 turns, consider going up a size on the pilot jets.

I used the oem equivalent jets. No problems with them.

[edxmon]

Originally Posted by choneofakind

Main jets are the jets that are used during WOT. these are the stock 98

pilot jets are the jets that are used during idle. these are the stock 38 (I think?)

Pilot jets are usually ok to keep stock, all you have to do is back the mix screws out a little. If you back the mixture screws out past like 3 turns, consider going up a size on the pilot jets.

I used the oem equivalent jets. No problems with them.

I like the way this is looking, CH I owe you my man.

[menikmati]

Originally Posted by choneofakind

pilot jets are the jets that are used during idle. these are the stock 38 (I think?)

Pilot jets are usually ok to keep stock, all you have to do is back the mix screws out a little.

Correct, I just recently bought a Factory Pro Stage 3 kit and they include a 40 pilot jet to replace the stock 38 pilot jet if needed, but most of the ldle/low RPM tuning can be done by adjusting the idle mixture screws.