This jetting issue is driving me knuts!
Jul 3, 2002 | 12:53 AM
#12
Pro Rider
Joined: Oct 2001
Posts: 2,776
Likes: 0
Yeah, alltoys. I may try it tomorrow, after my job interview.
I have 138, 142 and 145 keihin sizes. Maybe that will do the trick.
Thanks, surveyor, for the aussie bike site. I may ask them some stuff about the main air jets. I ordered a main air jet from the dealer, so in a week I will have one in my hand without having to disable my ride. I can then show pic of it and measure it. Maybe I will even mail it to my contact at Keihin, so he can help us out.
I have 138, 142 and 145 keihin sizes. Maybe that will do the trick.
Thanks, surveyor, for the aussie bike site. I may ask them some stuff about the main air jets. I ordered a main air jet from the dealer, so in a week I will have one in my hand without having to disable my ride. I can then show pic of it and measure it. Maybe I will even mail it to my contact at Keihin, so he can help us out.
Jul 5, 2002 | 09:14 PM
#14
Thread Starter
|
Range Rover
Joined: Apr 2002
Posts: 188
Likes: 0
Man, this just gets stranger. Ran the 132 and 138 for awhile. Did a couple of plug chops and the color of the insulators never changed from the original grey. Bought a new set of plugs thinking that the originals were permantly colored. Rode 45 miles yesterday on the new plugs. Did a 62mph plug chop on road to the house. Pulled the front plug and the insulator was just as white as the day I put in. Scared me, so today I put in a 135 and a 140. It doesn't run as well with these jets in and I lost about 4mph on top end. With the smaller jets I was getting 62mph on the hill up to the house. Today I got 58 and its 20 degrees cooler than yesterday. Cut the ignition and coasted in to the driveway, pulled the plug and they were still white as yesterday.
What gives? I know I'm making a change because of the way the quad runs. I'm wondering if there isn't some bizarre additive in our fuel around here that has more effect on plug color than jetting.
I was told once that reading the insulators wasn't reliable and you should look at the ring on the negative electrode. Proper mixtures will form a ring at almost the same height as the center electrode. Today this ring is almost to the bend in the electrode. Yesterday it was dead even with center one.
I saw no signs of overheating with the leaner mixtures. The fan didn't run anymore than normal. But I'm not sure that lean mixtures will show up as heat in the engine.
In all three jetting configs I've tried the quad runs good with no hesitation, stumble or backfire. It ran best on the lean jets! I also know that an engine will make the most horsepower when it is jetted lean, almost to the point of meltdown.
All this is with factory jets. I've thought about dynojet. With the experiences I'm having now a kit with even more stuff to change and adjust doesn't sound too appealing!
Sign Me CORNFUSED!
What gives? I know I'm making a change because of the way the quad runs. I'm wondering if there isn't some bizarre additive in our fuel around here that has more effect on plug color than jetting.
I was told once that reading the insulators wasn't reliable and you should look at the ring on the negative electrode. Proper mixtures will form a ring at almost the same height as the center electrode. Today this ring is almost to the bend in the electrode. Yesterday it was dead even with center one.
I saw no signs of overheating with the leaner mixtures. The fan didn't run anymore than normal. But I'm not sure that lean mixtures will show up as heat in the engine.
In all three jetting configs I've tried the quad runs good with no hesitation, stumble or backfire. It ran best on the lean jets! I also know that an engine will make the most horsepower when it is jetted lean, almost to the point of meltdown.
All this is with factory jets. I've thought about dynojet. With the experiences I'm having now a kit with even more stuff to change and adjust doesn't sound too appealing!
Sign Me CORNFUSED!
Jul 5, 2002 | 09:34 PM
#15
Pro Rider
Joined: Jun 2002
Posts: 348
Likes: 0
I have been in the same situation. That is why I prefer to use Dynojet over home jetting. They know the best setup for the engine & the main thing is that you will not be too lean. Engine rebuild cost a hell of alot more than jet kit. Also, I would have to say those NGK's are adding up, not to mention the time it is taking to dial it in. Good luck!
Jul 22, 2002 | 02:10 PM
#16
Range Rover
Joined: Feb 2002
Posts: 200
Likes: 0
<< I just re-jetted yesterday and for me it was a nightmare. I have the worst luck with phillips screws! I know this and I will not buy nor use a Craftsman phillips screwdriver, they are the worst ones made! ....The bottom right hand screw on the rear carb would not come out and as carefull as I tried to be I ended up stripping the head. >>
Damn...I did the same thing yesterday. That SAME screw, which just happened to be the VERY LAST ONE to come off, got semi-stripped as I tried to take it out. It's probably about 60-70% stripped, I gave up on it b/c I was so frustrated last night. I couldn't get a good enough screw driver on it and couldn't get enough leverage to break the sucker loose. Hopefully I'll be able to get it out tonight w/out having to drill it out. I'm not sure how I'm gonna do it.
Anyone have any suggestions on changing the main air jets? Anything I should look out for. I didn't have my service manual on my yesterday but I think they go in the carb on the opposite the access side of the needles/floats.
Anyone have any suggestions if I can't get the stripped screw out?
Jul 22, 2002 | 07:45 PM
#18
Pro Rider
Joined: Oct 2001
Posts: 2,776
Likes: 0
Whoops, try the small flat blade like scoot said.
Go buy a new, good quality screwdriver with the ridges on it if you think it will save you from drilling.
I used a driver bit on a 1/4 ratchet. Don't drill, is there room to take carbs off and try a vice grip (new one, good quality teeth)?
I almost got in trouble but my screw drivers were new and they all made it but one screw, which I used the ratchet and bit to get loose.
I am changing my main fuel jets back to the kawasaki ones (I have 142 and 145) to see if it gives me back any top speed.
The main air jets are not changeable according to a Keihin service technician.
Go buy a new, good quality screwdriver with the ridges on it if you think it will save you from drilling.
I used a driver bit on a 1/4 ratchet. Don't drill, is there room to take carbs off and try a vice grip (new one, good quality teeth)?
I almost got in trouble but my screw drivers were new and they all made it but one screw, which I used the ratchet and bit to get loose.
I am changing my main fuel jets back to the kawasaki ones (I have 142 and 145) to see if it gives me back any top speed.
The main air jets are not changeable according to a Keihin service technician.
Jul 25, 2002 | 11:36 AM
#19
Pro Rider
Joined: Apr 2002
Posts: 304
Likes: 0
Wolley,
sorry this is so long..
(cut & paste from 2 posts)
<< I live and ride at 6400 feet.>>
(ok per kaw jetting in manual 132/138 stock jets 135/138)
<<I've modified my intake and installed a UNI filter. This helped bottom end and midrange, no noticeable effect on top end.
I keep doing plug reads and ever since I opened up the intake the insulators are about a half shade lighter than the background area where the profile, email, edit, thumbs-up icons are on the message window. There is no carbon of any type on the electrode or the metal area below the threads, just a nice grayish blue color. The inside of my exhaust pipe is dark but there is no soot/carbon that will wipe off on your finger. The quad runs fine. It doesn't bog, has no flat spots, and doesn't do anything but burble a little on deacceleration.>>
turn the mix screw out a little if stock pipes..
<< These three indicators tell me that my jetting should probably be left alone.>>
ok, you are pretty close here..within a jet size or so.. possibly shim the needles..adjust the mix screws a little, synch the carbs(a must before further diagnosing or tweaking) (mikunis take .020 shims or a #4 washer will work..)
<<Still I want it to be faster! I've gotten quite used to the factory power now and I want MORE!!!!! At least gain back the 4.5-5 horsepower that I lose at this altitude. Jetting ain't gonna get that back. It needs more air! Lately it's been hot (97) with single digit humidity and although it doesn't run bad it sure is doggy compared to 50 degree days>>
you know that a temp change really affects the way jets work..a lot more than elevation..
roughly a jet size for 2000', but also a jet size for each 30 degrees in temp CHANGE..so if you get it right at 80 degrees, then ride at 50 degrees, it will be a jet size rich..or a jet size lean at 110 degrees..
if you liked it at 50 degrees (lets use a 135 as an example) at 80 degrees it would be like a 132.5, 100 degrees like a 130.5
so that is 2 jet sizes off...
<<Man, this just gets stranger. Ran the 132 and 138 for awhile. Did a couple of plug chops and the color of the insulators never changed from the original grey. Bought a new set of plugs thinking that the originals were permantly colored. Rode 45 miles yesterday on the new plugs. Did a 62mph plug chop on road to the house. Pulled the front plug and the insulator was just as white as the day I put in. Scared me, so today I put in a 135 and a 140. It doesn't run as well with these jets in and I lost about 4mph on top end. With the smaller jets I was getting 62mph on the hill up to the house. >>
bikes make more power running on the lean side, than the rich side, but if too lean, BIG problem$$$ happen..
<<Today I got 58 and its 20 degrees cooler than yesterday.>>
the 132 is acting like a 133.5 due to the temp..
<<In all three jetting configs I've tried the quad runs good with no hesitation, stumble or backfire. It ran best on the lean jets! I also know that an engine will make the most horsepower when it is jetted lean, almost to the point of meltdown.
All this is with factory jets.>>
what was the best it ran, I mean that you were the happiest with, and at what temperature was it..
then if a temperature change of 20-30 degrees happens (50 one day & 80 the next) the jets are off 1 size due to that..
it is REALLY hard to do jetting with BIG temp changes..
<<I've thought about dynojet.>>
think about spending 3 bux for a mikuni carb calculator from dennis kirk, while it is for a diffrent carb, it will tell you what temperature changes & elevations have effects on what size jets..
sorry this is so long..
(cut & paste from 2 posts)
<< I live and ride at 6400 feet.>>
(ok per kaw jetting in manual 132/138 stock jets 135/138)
<<I've modified my intake and installed a UNI filter. This helped bottom end and midrange, no noticeable effect on top end.
I keep doing plug reads and ever since I opened up the intake the insulators are about a half shade lighter than the background area where the profile, email, edit, thumbs-up icons are on the message window. There is no carbon of any type on the electrode or the metal area below the threads, just a nice grayish blue color. The inside of my exhaust pipe is dark but there is no soot/carbon that will wipe off on your finger. The quad runs fine. It doesn't bog, has no flat spots, and doesn't do anything but burble a little on deacceleration.>>
turn the mix screw out a little if stock pipes..
<< These three indicators tell me that my jetting should probably be left alone.>>
ok, you are pretty close here..within a jet size or so.. possibly shim the needles..adjust the mix screws a little, synch the carbs(a must before further diagnosing or tweaking) (mikunis take .020 shims or a #4 washer will work..)
<<Still I want it to be faster! I've gotten quite used to the factory power now and I want MORE!!!!! At least gain back the 4.5-5 horsepower that I lose at this altitude. Jetting ain't gonna get that back. It needs more air! Lately it's been hot (97) with single digit humidity and although it doesn't run bad it sure is doggy compared to 50 degree days>>
you know that a temp change really affects the way jets work..a lot more than elevation..
roughly a jet size for 2000', but also a jet size for each 30 degrees in temp CHANGE..so if you get it right at 80 degrees, then ride at 50 degrees, it will be a jet size rich..or a jet size lean at 110 degrees..
if you liked it at 50 degrees (lets use a 135 as an example) at 80 degrees it would be like a 132.5, 100 degrees like a 130.5
so that is 2 jet sizes off...
<<Man, this just gets stranger. Ran the 132 and 138 for awhile. Did a couple of plug chops and the color of the insulators never changed from the original grey. Bought a new set of plugs thinking that the originals were permantly colored. Rode 45 miles yesterday on the new plugs. Did a 62mph plug chop on road to the house. Pulled the front plug and the insulator was just as white as the day I put in. Scared me, so today I put in a 135 and a 140. It doesn't run as well with these jets in and I lost about 4mph on top end. With the smaller jets I was getting 62mph on the hill up to the house. >>
bikes make more power running on the lean side, than the rich side, but if too lean, BIG problem$$$ happen..
<<Today I got 58 and its 20 degrees cooler than yesterday.>>
the 132 is acting like a 133.5 due to the temp..
<<In all three jetting configs I've tried the quad runs good with no hesitation, stumble or backfire. It ran best on the lean jets! I also know that an engine will make the most horsepower when it is jetted lean, almost to the point of meltdown.
All this is with factory jets.>>
what was the best it ran, I mean that you were the happiest with, and at what temperature was it..
then if a temperature change of 20-30 degrees happens (50 one day & 80 the next) the jets are off 1 size due to that..
it is REALLY hard to do jetting with BIG temp changes..
<<I've thought about dynojet.>>
think about spending 3 bux for a mikuni carb calculator from dennis kirk, while it is for a diffrent carb, it will tell you what temperature changes & elevations have effects on what size jets..
Jul 26, 2002 | 02:08 AM
#20
Pro Rider
Joined: Oct 2001
Posts: 1,435
Likes: 0
Wolley
Surveyor has the answer right on the money. If all you have done to mod your bike is the air inlet you will not get a big increase in power so refetting is not an important issue. Unless you mod the muffler you will not get a big power incease. When you rejet go smaller and if you don't notice any improvement then jet larger. I ride consistently from 3000ft to 9000ft I use stock Kawi jets with 142f and 145r with the best results but that's after moding the muffler. If you go to Nyrocs web site and see how he did his all it will cost you is time and if you now a welder a box of bubbly. The bike is generally rich from factory and you want this for higher altitudes just adjust your air screws when you get miss it will work fine.
Surveyor has the answer right on the money. If all you have done to mod your bike is the air inlet you will not get a big increase in power so refetting is not an important issue. Unless you mod the muffler you will not get a big power incease. When you rejet go smaller and if you don't notice any improvement then jet larger. I ride consistently from 3000ft to 9000ft I use stock Kawi jets with 142f and 145r with the best results but that's after moding the muffler. If you go to Nyrocs web site and see how he did his all it will cost you is time and if you now a welder a box of bubbly. The bike is generally rich from factory and you want this for higher altitudes just adjust your air screws when you get miss it will work fine.