I am about to do some work on my 650 (K&N, Diamond G Snorkel and a pipe) and want to re-jet.

I was going to use the 145/148 Keihin jet setup, but am confused with all the talk of shimming jets. What does shimming do and why would I need to do it when I change over to the Keihin jets?

 

c5, I run 145/148 Keihin jets with the following mods: muffler modded with 6 - 1/2 inch holes, snorkle, 3 - 1 1/4 inch holes in the airbox lid and a Unifilter air filter. I had my needles shimmed when I was running the 142/145 jets. I don't know if it made any difference or not. I talked to Alltoys and he was wondering if there was any point in the shims. When I put my 145/148 jets in and ran my quad, I had some serious power, so I decided to take the shims out to see if it made any difference. It didn't. I'd do the mods you have listed and go with that for now. You will still need to do some tweaking in order to get your ride fine tuned but it should be a good start.

 

Thanks mastrblastr,

I'm ordering the jets today.

What will shimming do for me, and how will I know if I have to shim?

Will it richen the mix or lean it out?

Also, my parts guy said some Keihin jets were adjustable and didn't need shims, what does that mean?

Thanks.

 

Greg,

You would be shimming the needles, not the jets. This richens the mixture in the midrange by raising the level of the needle in the slide.

We did similar mods to one of our bikes this week. Diamondg snorkle, K&N filter, 3-1" holes in airbox lid and nyroc mod to pipe. We started with Keihin mains - 142f & 145r, no shims in needle and airscrews at 3.25f & 3.5r. The bike ran well but had a slight stumble just off idle. We left the mains the same, shimmed the needles about 0.05" (2 small flat washers) and dialed in the screws to 2.5f & 2.75r. Wow, no hesitation or stumble and extremely strong throughout the entire rpm range. It's hard to believe that such small changes can make such a big difference. I should mention that we ride at below 1000' elevation. As mastrblastr states, a little fine tuning will be needed but the end result is worth the trouble.

Some aftermarket needles are adjustable but the I think the only way to adjust the stock needles is by shimming them. Dial-a-jet is an adjustable jetting system that I think alltoys uses for large changes in elevation when riding. I think if you use the keihin jetting, and get it dialed in, you'll be quite pleased with the results.

Steve

 

You can cheat your carbs a little bit as you increase in elevation by opening more holes in your airbox lid. I made a piece that fits in my airbox lid that allows you to open up 2 more 1 inch holes in your airbox lid as it becomes necessary. It works not too bad as I have my 650 jetted for around 1500 feet, but I ride upwards of 5500 feet. When you get up in the bush, open up the extra holes to give it more air. It's way cheaper than dial-a-jets too!!!!

 

okay guys im only 15 and im curios to. what ''IS'' shimming the neddles, and what do you do when you shim the neddles

 

prairie,

You remove the needle from the slide in the carb and place a couple of small washers under the collar at the top of the needle. When you reinstall this in the carb the needle is now farther up in the slide and the gap at the bottom where the needle fits into the seat is larger which allows more gas to flow through the opening. More gas riches the mixture. The needles effect midrange, off idle to about 1/4 to 1/2 throttle. The main jets effect top end with the air screws adjusting bottom end.

Hope this helps a little. If you want to know more, ask away. It's the only way to learn. [img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-smile.gif[/img]

 

Thanks for all the help guys!

I feel much better about tuning my carbs.

I should be getting my jets in early next week. I'll pick up some shims this weekend and let you guys know how it turns out when the mods are done.

 

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I thought most jet needles had notches in them with an 'E' clip. Taking off the clip and replacing it in a different notch moves the needle up or down. Is the carb on the Kawasaki non-adjustable? You actually have to put washers in there?