EK

Member
Dec 3, 2000
66
0
Keihin tuning

Chris,

I assume your machine has a Keihin. Take a look at the Keihin carb tuning calibration chart at www.keihin.com --> Products --> Carburetors --> Tuning

Eric K
'01 GasGas 300XC
 

Chris-NJ

Member
May 26, 2000
20
0
I'll check today/tommorow and get back to all. thanks for the help. I'm trying to solve a nagging cold foul problem. someone suggest checking float bowl height first and maybe a cracked or damaged reeds?? i'll let you know.
 

cycleboy

Member
Sep 8, 1999
103
0
GlennP, I wasn't disputing the 16mm height, although I've never measured it. I was just quoting the manual.

Chris-NJ, I too have experienced this cold fouling problem. I noticed while I had the tank off the other day that the fuel tap does not completely stop the flow of gas. I'm wondering if this has anything to do with the fouling problem. After my next ride I am going to disconnect the fuel line and leave it off till I'm ready to ride it again to see if it has any effect. Are your plugs coming out all black and wet? Mine are, so I've rejetted leaner on the pilot and main. If you find out what causes this cold fouling please share it in this thread and I'll do the same.
 

Chris-NJ

Member
May 26, 2000
20
0
it only happens after the bikes been on the truck. has happened since new. never happens pulling out of the garage. i've only been to 4-5 races so it wasn't a huge deal, but after the 4-5 time i want it fixed. i'm thinking high float bowl height and the fuels getting dumped in during the truck ride. but someone also mentioned a faulty reed, which could be logical if the reeds normally hold the fuel splash back, unless they're partially opened or cracked allowing splash by during the truck ride. plugs are wet, second plug always works fine. taking it apart tonight. will report. fuel valve works fine. i've also tried the keep choke on/off things to no avial.
 

EK

Member
Dec 3, 2000
66
0
Twisted float

I noticed excess fuel going through the carb, especially at low throttle. It turned out the float was slightly twisted so the side that was easy to measure met the 16 mm spec. However, the other side was out of spec too close to the carb body preventing the float needle from seating fully. It was easy to tweak the float to the position it should be once I noticed the problem.

Eric K
'01 GasGas 300XC
 

Chris-NJ

Member
May 26, 2000
20
0
well, i took it apart and found nothing!!!! float level is perfect @ 16mm, from base to bottom of float. and reeds look new. dealer is scratching his head too and told me to try to polish the seat area with chrome cleaner. he said could be a burr or scratch, etc... allowing fuel by?? i'm going to try anyway. othwise i'll just bring plugs with me. ps i have 42 pilot, G needle in 3rd position and a 178 main. outer edge of plug clean, inner a little black but not wet, I will move to 175 main for summer.
 

tomthumb

Member
Apr 12, 2000
68
0
This all sounds so familiar. After jetting my bike and a couple of months of no problems, I also started experiencing fouled plugs on initial start up and found it to be two different things, my floats were set incorrectly and my gas was not shutting off completely. Sometimes, if the floats are set to low and the bike sets overnight and/or rides on a bumpy trailer, gas can collect in the bottom of your cylinder. Then on the first start of the day when applying a little throttle to clean it out, it pulls the fluid to the top and wets the plug. In my experience this combined with my gas not shutting off completely guaranteed me a fouled plug on initial start up 4 out of 5 times. I slightly overset the floats high to ensure the fuel was being shut off when the bike was bouncing on the trailer and replaced the o-ring in my petcock.

After setting my floats, I went to start the bike and it again the beast drenched another plug. Discourage, I went the house and sulked. After awhile of poor pitiful me I realized that the bike probable still had gas collected in the bottom of the cylinder. I put a new plug in it, fired it up rode it around the yard and I have not fouled a plug in seven months.

A trick I used on setting the floats was to mark 60 degree angle on the garage wall to ensure I was holding the carburetor at the right angle. You may also want try and set the floats a little higher than spec and see if the problem persist.

Good luck!

tomthumb

2000 KTM 300EXC
 

yarbonwick

Sponsoring Member
Mar 7, 2000
674
0
Okay Chris_NJ we need more, where are you? New Jersey?. If you're using a quality oil and 40:1 with quality fuel, you shouldn't be having much problems. However, since all KTM's come rich here's my opinion:


Get that G needle out. The pilot and main seem to be good. I would either replace the needle with a E or the I that came with your kit. However, some (most) have had great results with the single taper needles. Usually after several trial and errors but never the less. James Dean is the guru on that subject. After installing the E-3 I haven't had a plug foul in about eight months. Even though the E is supposed to be even richer than the G according to charts, it worked. Go figure. Also, the stock silencer was a big pain in my rear...and the bikes.

Incidently I highly recommend reading: http://www.eric-gorr.com/techarticles/carbtuning.html#h
 
Last edited:

Chris-NJ

Member
May 26, 2000
20
0
thanks for all the help so far. yes i'm in Northern NJ. i miked the h needle that came in my kit and it spec's out almost exact to the G needle in about the five places i measured them. i polished the seat last night, alot of black stuff came out on the q-tip!!?? anyway i think i will lower float level a mm or two, can't hurt???? i'm running Y2R at 40:1. never fouls a plug anytime other then starting it cold, coming off the truck. will keep posted on my efforts. i will read gorr's article.
 

yarbonwick

Sponsoring Member
Mar 7, 2000
674
0
Leave the float alone. If it's correct, it's correct. Some people swear by the Yahama oil however I have never-NEVER-EVER had good results with that in my KTM. Get rid of it. You're kit didn't include a NOZI needle? Or atleast a leaner needle? That's weird. KTM's come rich and the second needle is used after break in. Another thing that you try is to look at the back of the KTM manual. There are jetting specs for temp and altitude. That got me very close. Also, you could try a plug with a small electrode.
 

Chris-NJ

Member
May 26, 2000
20
0
bike camewith 45 pilot, G needle in 4th spot from top, and 178 main. back of book says even richer at my altitude and temp. however went to 3rd clip spot after first ride and all was well, still cold fouled once or twice. then recent warming up temps, i went to 42 pilot, cleaned up outer edge of plug nice,center still dark but not wet. only H needle came in kit and a 175 main. I will go to H in 3rd position with 175 this weekend to see what happens. but again it will run fine out of my garage (this weekend), just happens after a ride in the truck!!
 

tomthumb

Member
Apr 12, 2000
68
0
Chris-NJ,

I think you're on the right track. It is sometimes good practice to change one thing at a time to help determine which changes make the biggest differences. It may be a combination of a couple of things including jetting.

If you suspect that transporting your bike may have something to do with the problem, you may want to try draining the carburetor of it's gas before putting it in your truck. I suggest the following:

 Start the bike up let it worm up at home (ride it around a little if you can) before killing the motor, turn off the gas and let it run for a couple of minutes, then shut off the engine (try not to let it run out of gas, it can get too lean if your jetting is off).
 Pull gas line an ensure your gas is shutting off.
 Next find a good place to lay your bike on its side and lay it completely over and drain off the excess gas from the bowl through the vent tubes.
 If the gas shuts off properly, replace your fuel line and transport your machine.
 When you go to start the bike at your destination, turn on the gas, wait about 30 seconds and then lean your bike over far enough that gas comes out the vent tubes, choke, give it a couple of slow kicks and then the bike should fire on the first good kick. I generally turn it off the choke in less than 30 seconds after start up.

If your are successful, try it again on the way home and see if you can make it run without fouling the plug each time it is transported.

I also agree that you should consider replacing the stock bazooka silencer with a nice OEM version. Less spooge greater performance!

Here are my jetting specs

 2000 300 EXC
 600 to 1000 ft.
 # 6 slide
 R1466N needle 3rd clip
 175 main
 42 pilot and 40 pilot (summer) AM 2.0 to 2.5 turns.
 44:1 Mobil XT2, mixing 2.5 gallons of CAM gas to 2.5 gallons of 93 octane, the higher octane helps prevent power valve knock on deceleration.
 stock pipe
 FMF power core II

There are lots of posts on the subject of the #7 slide and the single taper Honda needles. You should search this forum and others on the subject. I purchased my bike four months old and the guy that I got it from had already worked out the jetting (with help from G.C.) and I love the way it performs.

Please let us know if you resolve your plug fouling problems.


tomthumb
 

Welcome to DRN

No trolls, no cliques, no spam & newb friendly. Do it.

FRESH VIDEO

Top Bottom