I'm getting ready to order a new set of jets to fix what I think to be lean condition on my 650. My cat. lists different types of keihn jets. What kind do I need? I see hex main, small round, slow jets, high speed, needel jets, main jets, pilot jets, low speed...

I'm looking in the newest chaparrel catalog.

Also if anyone can recommend a good combo for about 6-7k feet, I'd apprecate it. I know it was jetted a the dealer for elevation, but I think that just keeps the same lean condition as those sold at low elevation. I haven't pulled the carbs apart to check yet, haven't had the time.

 

AJ650,
Unfortuneatly there is no such thing as a quick jetting procedure maybe after 10-20 trys you will become faster that is about it LOL. If the dealer rejetted for you, you could be running lean. Try this take off the air box lid run the quad to see what it does backfire through the carbs or muffler. If it does this without removing the airbox lid then you are definatley lean. Also have you done a muffler modd yet this is the most important modd you can do to get more power and response to your 650. Let us know what you have. If you are going to rejett then use the Keihin jetts they are a better system than DJ jetts!!!!!

 

Alltoys,

I am in the same perdicament as AJ650. What company are you refering to when you say DJ? Dyno Jet or Dial a Jet?

 

I too am in the throes of rejetting for the same altitude as you. With just an airbox mod (shop vac hose, don't laugh it works as well as the DG snorkel) I have tried the recommended Kawai jets for this elevation. 132 front and 138 rear. This was too lean. 135 and 140 worked great. These are the jets recommended for 3-5K feet. I just installed a Supertrapp IDS-X and now it appears lean on the 135 and 140. So I went back to the 138 and 142 sea level jets and these are too rich. I guess! I did lose some top end with the bigger jets.
It actually runs best with 135 and 140 but a plug read indicates a marginally lean condition and since plug reads are really kind of fooky for accurate jetting I feel that to be on the safe side I should run a little richer.
Throughly confused now? So am I! Do I run the jets that perform best and take a chance on burning up or do I run the larger jets and lose some top end power? BTW plug reads on the larger 138/142 combo indicate an ideal mix but I still lose top end so they are obviously a little rich. Anybody have a portable exhaust gas analyzer they want to loan me?

 

Wolly,
You are at a point of fine tuning your jets and the way to do this is to open up the air box or put some washers behind the needle like Dyno Jets does. Some people use the DJ jet needle with the Keihin jets and they work ok. You will notice the angle of the piont of the needle is sharper than Keihins. Keihins will deliver more fuel than DJ's off the start to mid range where as the DJ needle has a slower engagement of fuel average mid range and more on top. You might gain slightly on top but definately not on bottom.

A spark plug test is still the most prevolent way to discover the amount of fuel mixture in the system. Running a little rich is better than a little lean but remember you can fine tune your jets. I lke to run a little lean when I race but somewhat on the rich side when I am running in the bush. I do this by installing a set of Dial A Jets it also helps with altitude sickness and modifying my Green Machine.

You will have to experiment with your jets untill you are a little on the lean side like Wolly then add a size to determine where the rich side is. Once you do this then you can play with washers on the needles, change needles, open the air box, this all equates to fine tuning. If you are a little on the rich side poke some holes into the airbox this will lean the system out. Thunder Products has a neet sliding vent unit that will mount into the airbox so you can let more in or close it to richen it up or close it to cross streams keepin water out. Hope this helps.

 

My bike is completely stock at the moment. If I let any more air into the box it backfires through the carb and I lose power and top end speed. When I first got the bike the dealer jetted for elevation and i had starting problems. Dealer assumed it was running rich, and jetted down. This made it next to impossible to start (15 minutes of on and off cranking) and I lost about 12mph on the top end once it was running. Took it back and requested it be jetted back to where it was, same old hard start, speed was back. I'm assuming it's still lean, as I said any change to air intake and major problems. I'm planning on either venting the lid, or running a full filtered lid so I should have considerably more air going in once that's done. New muffler or modded muffler will follow. right now I'd just like to get all the stock power I can so I'm starting at the right place once I start modding.

I'll try some of the combos wolly is playing with to get a better mix b4 and during any mods. My first post ? is what kind of Kehin jets do I need to get for the Kawi carb? My catalog shows different styles all by the same manufacturer, but they are only broken down by size, not application.

I actually have the parts for a portable analyzer, I just have to put it together and see if it works. In my mind it should work just dandy. If I have a chance this weekend I'll throw it together and see what happens. Since everything is in the garage already, I'd only be wasting time at this point. Got to love those mid-project change of plans that let you stockpile oddball parts.

 

Keep in mind these part numbers came from the service manual and are Kawi numbers.
The only jets that are serviceable are the mains. I think NYROC tried the air jets a while back and ran into some issues.
Smaller jet goes in the front carb.
size ----------Number ----------------altitude
138 -----------92063-1015 ------------0-1600ft
142 -----------92063-1016

135 -----------92063-1014 ------------1600-4900ft
140 -----------92063-1013

132 -----------92063-1076 ------------4900-8200ft
138 -----------92063-1015

130 -----------92063-1075 ------------8200-11500ft
132 -----------92063-1076

125 -----------92063-1069 ------------11500-14800ft
130 -----------92063-1075

I originally tried the 132/138 combo since I live at 6400ft. With the airbox mods this proved to be too lean. Up until I installed the muffler I was running the 135/140 combo and it worked well. Now I seem to be somewhere between the 138/142 and the 135-140. Maybe a 136/141? Do they come in half sizes?
You don't live near Durango Colorado do you?

One more thing try 3 turns on the pilot screws. It made mine start and idle better. To adjust these screw them all the way in and back them out 3 turns. Be carefull to not seat them hard when screwing them in or else you may damage the seats.

Hope this helps.

 

Wolly, AJ650,
Always start rich if possible then go down in size of jets untill your machine hits the lean side make note of this combo because you may go back to this some other time. AJ when you opened your air box it leaned it out you have found this out and can go up in size now. I beleive you are at stock now and the bike came that way because all manufactuers do this because they don't know where they are going and jet it for sea level. I found with stock jets on a modded muffler at 2200 ft worked well, a little lean that could be controlled by closing off any holes in the air box. I could go up to 9000ft with the stock jets just controlling how much air went into the air box more air greater lean mixture, less air of course you know what is next. I would suggest going to a 142fr & 145 combo for air intake modd and muffler modd at your alivation. Some will tell you this a rich position but you can lean it out with air box holes. Remember not to many as to much warm air and you will also richen the system there has to be a happy medium. No muffler modd I would stick with the stock set but open up the air intake make it breath it will perform almost %5 better. If it is still hard to start then go up in jet size to the 142 and 145 combo.

So far I have tried up to 195 fr & 200 r just see what happened. Now I am with a 45 mm carbon slide dual output carb with a 165 jet and Dial A Jets as a complement. Just remember to do a spark plug test after you jet to make sure you have the right results. I have worked with other fellows that are sled gurus and the same motor different sleds will have different jetting there is no set number for the motor or altitude just an approximation.

AJ650,
Be careful when using a exhaust anilyzer if you have never used one before the readings you get are just numbers unless you know how to use it. You may get false readings or interpret the readings falsly. Have someone help you that understands the system and you will be much farther ahead of the rest of us, good luck let me know how you make out.

 

The analyzer is just going to be a toy until I decide whether or not it works. Just another doohicky in the garage really. The display is segmented led's showing lean/rich or stoich (sp?). My cat. has jets for $3, so I guess I'll order a few to play with. Thanks for the info.

Wolley: thanks for the specs, I'd been looking for them but couldn't find them for some reason. I'm in cheyenne wy, 433.82 miles and 10 hours 4 minutes according to mapquest.

 

Hey AJ, I live in Thornton, CO, just north of Denver, we should get together and ride sometime.

Anyway, I have 142/145 in mine. I have a modded snorkle, 3 uni-vents in the airbox, stock filter and the Nyroc mod on the exhaust. With this setting it all works great. Not sure on top end, don't do much of that on the trail, all I know is I'm always being followed!