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Discussion Starter #1
I installed a dynojet stage 2 kit and I'm getting 40MPG. I dont think it worth the lost of mpg, there is several jets that come with the kit. Does anyone know which jet work better for MPG and still have some power gains.I'm running stock gears and a drilled out muffler, snorkel removed. I put the bigger jet for stage 2 there a smaller jet for stage 2 and there is still stage 1 jets also.Does anyone have any input on this dynojet kit. Thanks
 

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There are two ways that a jet kit can reduce your mpg.

First, it works real good and you use more throttle to get more thrills.

Second, it ain't working right and it's too rich.

I'm betting you're too rich. Reduce jet size and check again.

See, the only reason to increase jet size is because you've made some intake/exhaust mods and are running lean. Increasing the jet size brings you back to a proper mixture. Going overly large on a jet, such that it runs rich, does nothing but waste gas. It can't make more power without more air, which means more aggressive mods. I have no idea what the actual DJ jet sizes are that you're referring to. Do you have a cross reference to Keihin jet sizes? The most extreme mods that can be made to the KLR - intake, head, exhaust, are hard pressed to need more than a 147.5 jet with a KLX needle.

If you are at the proper mixture, the bike will not use more gas for a given situation. If you were getting 45mpg before the mods you should get 45mpg after the mods, as long as you don't change your driving style. The extra power that the mods made is potentially there, but doesn't come on (and use more gas) unless you twist the throttle.

T
 

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Discussion Starter #3
Dont know what size of jet I'm at work i think it a 165 jet not sure was getting 50 MPG before. The kit has many jets just was seeing if anyone had better luck picking a jet.
 

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I don't have a conversion for a 165. My table shows a 164 and 166. But no matter; a 164 is equivalent to a Keihin 182.5. Of course, without know the diameter and taper of a DJ needle (you're using a DJ needle, I presume) we can't really say anything about the size of the jet.

A jet is like a cat in that you don't pick a jet, it picks you. For your engine, there is a jet and needle position that is right - it will deliver the appropriate Air/Fuel Ratio. You need some way of ascertaining what your AFR. Probably the simplest is to read the plug. A plug from a rich running engine will be sooty and black. A lean engine will have a whitish and sorta glazed looking plug. An engine that is running at the right ratio will have a tan appearance.

Now, if you were getting 50 mpg before, I'd be willing to bet you were running a bit lean (unless you weigh about 125 pounds). My suggestion would be to go from your mid 160s jet down to something on the order of a mid 150s. That should be about 10% smaller in diameter. Take it out for a run and get yourself moving along in third or fourth at mid throttle for a good mile or so. Pull in the clutch and kill the engine. Pull the plug and look at it. In truth, if a roadside plug pull on the KLR is too big of a pain, just take it out for a good ride and come home and check the plug. Just don't let it idle for long when you get it home. If you have a tan plug, all's well. If it's whitish, change it immediately for a larger jet before you do any damage from running too lean.

T
 

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Dont know what size of jet I'm at work i think it a 165 jet not sure was getting 50 MPG before. The kit has many jets just was seeing if anyone had better luck picking a jet.

Stock the KLR is lean on the low speed circuits (pilot and needle) and rich on the main. I wouldn't go any larger on the main unless you've made intake/engine mods.

If you went larger on the main and stay >3/4 throttle for lengths of time yea your milage will drop.

Here's a good basic page: Motorcycle Carburetor Theory 101

Here's a more in depth CV carb resource: Keihin CVK40
 

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FYI re: Dynojet

FYI: Don't try getting a jet size off of your Dynojet kit's jet's. Dynojet uses a proprietary coding system to prevent people from duplicating their kits. The numbers on their jets and needles don't correspond to any standards.
 
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