Carb Issues

droopie69 · Jun 19, 2006

Can a carb be worn out????? Maybe the choke plunger? I've had the thing apart 6 or 10 times :bang: and have even taken wire to all the passages to make sure nothing is plugged. No matter what it will not idle..it's way too rich. I even got a 40 pilot jet and that didn't change the idle. Made it much snappier off idle but still won't idle. After studying the carb for a couple hours yesterday I decide that it could be pulling fuel thru the choke circuit. So I plugged the start jet (doesn't look replaceable) and now it idles and seems to run fine. I triple checked the float level and made sure it's not sinking and even set it about 5mm too low. If I take the plug out of the start jet, it just won't idle even with the idle screw all the way in. It's running too rich, so I don't think it's the slide, but I am wondering if the choke plunger can wear out??? I'm going to try to find a fitting to put in the bottom of the float bowl and make a float level gauge to see exactly where the fuel is at. Any ides?

I advanced the timing and put the 40 pilot in and it flat rips now off the bottom ,but it's a bitch to start cold with no choke and won't idle if the choke is working. Any ideas?

DirtDawger · Jun 19, 2006

Yes a choke plunger can wear out but usually take many years. Bad crank seals are another possibility. How old is the bike? Has the bottom or top end been rebuilt? How often/hard do you ride it?

Green Hornet · Jun 19, 2006

Did this problem occur before or after you advanced the timing??

droopie69 · Jun 19, 2006

DirtDawger said:
Yes a choke plunger can wear out but usually take many years. Bad crank seals are another possibility. How old is the bike? Has the bottom or top end been rebuilt? How often/hard do you ride it?

I got it in March and redid the top end and cleaned the KIPS. It had a bottom end last year and the seals are ok. It was leaking around the 3 indentions on the magneto side, but I epoxied those up. I've ridden it 4 times since March for a total of less than 100 miles.

1995-2006 is 11 years. Does that count as 'many'?

droopie69 · Jun 19, 2006

Green Hornet said:
Did this problem occur before or after you advanced the timing??

Before. Nothing has changed the idle-off idle transition. I've tried 2 different needles, 160-155-152 main jets and 45-42-40 pilot jets. Nothing changed it, until I plugged up the start jet. With the start jet plugged, it runs like a striped ape. I just don't want to have to carry a can of ether to start it! :)

My cheapest option appears to me to get a new choke plunger. About $23 from MxSouth. Unless someone has a used PWK 35 laying around.

droopie69 · Jun 19, 2006

Oh yeah, the other thing I noticed that tells me I am on the right track, is that once the start jet was plugged it eliminated 99% of smoking at idle. It runs crisp and clean and I could probably leave it like this and ride it for years. But I imagine it would take an hour to start on a cool day this fall.

kx200 · Jun 19, 2006

My 97 220 is doing the same thing! .I just thought it was because I have around 5000 miles on it. I will check out the choke plunger. I have a spare one I can try.

droopie69 · Jun 19, 2006

kx200 said:
My 97 220 is doing the same thing! .I just thought it was because I have around 5000 miles on it. I will check out the choke plunger. I have a spare one I can try.

Let me know if that simple fix fixes it!

Old Man Time · Jun 22, 2006

droopie69 said:
Before. Nothing has changed the idle-off idle transition. I've tried 2 different needles, 160-155-152 main jets and 45-42-40 pilot jets. Nothing changed it, until I plugged up the start jet. With the start jet plugged, it runs like a striped ape. I just don't want to have to carry a can of ether to start it! :)

My cheapest option appears to me to get a new choke plunger. About $23 from MxSouth. Unless someone has a used PWK 35 laying around.

I have the 35mm carb on my KDX220. I have the same problem as you when I jet it the way every one recommends. Here is what I found works in spite of what everyone says. 38 or 40 pilot (38 idles best) 142 or 145 on the main. Not only does it idle really nice but the air/fuel mix screw actually works. Usually 1 turn to 1 1/2 turns out. I am using a 1173K needle #2 which is a bit richer than the stock 1174K needle. If I were using the 1174K I think I could go up on the main to a 148 or 150 and still idle. I generally ride at 3000 to 6000 feet mostly in between those 2 elevations. The temp right now is in the upper 70s to 90 degrees.
Not only does the bike really idle nicely but it also does not load up so easily and has nice power.

I have also found when I jet the bike richer that it does not idle right or run as crisp and it also over heats on hilly situations. When jetted leaner it just pulls better and overheating is less an issue. I have given up on listening to the jetting experts because my bike just does not run right that way. I have not burned my motor up as some suggest. I think each bike is a bit different. Carbs wear differently and so on.

I too adjusted my carb floats to shut off a bit earlier. That had no effect on the idle problem.

I think I will try replacing my choke plunger with a new one since you have had some luck plugging yours. It would be nice if I could get the bike to handle bigger jets but for now I am doing it by the seat of my pants instead of what logically should work.

That's my 2 cents.

droopie69 · Jun 23, 2006

Thanks

Thanks Old Man Time. I've got a 1173 needle in it now. I think I have a 148 main laying around. I may try it and see what happens. I also found another float drain plug, so I am going to drill it and tap it for a nipple and make my own float level gauge. I may try that 148 with a 40 pilot and see what happens. I guess first I will just go out and start it now that it's sat around a few days and see how hard it is to start.

UFS207 · Jun 25, 2006

Very interesting thread. My 2000 220R exhibits very similar traits. Pretty much refuses to idle once hot for more than 5-10 seconds and fouls a plug every 150-200 miles even though I'm running a 40 pilot, 142 main, 2mm lower than stock float level, stock needle 1 clip from top (leaner) and 40:1 Yamalube R1. The bike is stock other than a FMF rev pipe, turbine core 2, wiseco piston and open airbox. It's runs pretty well otherwise and will get 55-60 miles to reserve on fast trails. It does tend to load up a bit if you don't keep the revs up somewhat though. I don't think it's sucking tranny oil through a bad main seal because I have done upwards of 250 miles on an oil change and never lost a drop. I rebuilt the topend a year ago and as of two weeks ago I still had over 160 psi and the Kips rotated by hand with ease.

I did a plug chop on the current jetting and the plug was tan colored so I guess it's fouling while putt-putting. I don't ride the bike very agressively (rarely more the 1/2 throttle, usually dictated by terrain) so I just figured maybe me and semi-racy 2 strokes make a bad combo.

I actually started to wonder if maybe my choke was malfunctioning as well so I pulled the carb apart today and cleaned the hell out of it with compressed air (even though it was already spotless). I inspected the choke plunger and couldn't really see anything wrong with it. Which one is the starter jet exactly? Is it long brass looking pipe deal on the intake/front side of the bowl? I would very much like to try your plugging idea out.

Anyways, please keep us posted Droopie69. I am just about ready to sell my bike and find a nice, used XR400R.

droopie69 · Jun 26, 2006

UFS207 said:
Very interesting thread. My 2000 220R exhibits very similar traits. Pretty much refuses to idle once hot for more than 5-10 seconds and fouls a plug every 150-200 miles even though I'm running a 40 pilot, 142 main, 2mm lower than stock float level, stock needle 1 clip from top (leaner) and 40:1 Yamalube R1. The bike is stock other than a FMF rev pipe, turbine core 2, wiseco piston and open airbox. It's runs pretty well otherwise and will get 55-60 miles to reserve on fast trails. It does tend to load up a bit if you don't keep the revs up somewhat though. I don't think it's sucking tranny oil through a bad main seal because I have done upwards of 250 miles on an oil change and never lost a drop. I rebuilt the topend a year ago and as of two weeks ago I still had over 160 psi and the Kips rotated by hand with ease.

I did a plug chop on the current jetting and the plug was tan colored so I guess it's fouling while putt-putting. I don't ride the bike very agressively (rarely more the 1/2 throttle, usually dictated by terrain) so I just figured maybe me and semi-racy 2 strokes make a bad combo.

I actually started to wonder if maybe my choke was malfunctioning as well so I pulled the carb apart today and cleaned the hell out of it with compressed air (even though it was already spotless). I inspected the choke plunger and couldn't really see anything wrong with it. Which one is the starter jet exactly? Is it long brass looking pipe deal on the intake/front side of the bowl? I would very much like to try your plugging idea out.

Anyways, please keep us posted Droopie69. I am just about ready to sell my bike and find a nice, used XR400R.

Yeah the start jet is the brass, non-removable thing...it feeds the passage at the bottom of the choke plunger. There is a passage in the side of the choke plunger hole that goes back to the air filter flange that feeds it. You may have better luck plugging that, since I think if no air is coming thru that passage, it can't suck gas up. But what I did was take vice grips and pull that brass piece off. There is a smaller tube under it. I cut a piece off an oring, stuck it in there and tapped the brass piece back on. I need to order a new choke plunger and see what happens. Tried to order it from MXSouth, but they said it was special order and not enough to make the minimum. Guess I'll try the dealer.

droopie69 · Jul 6, 2006

Carb Issues Update

Ok...I took it for some riding Monday and Tuesday. Temps about 96 with about 55% humidty (I lost 10lbs) and here's the results.

WOOO YAAAAA. I didn't know this thing could rip like it does now. Monday was a short 2 hr ride and I noticed about 3/8 a slight bog....but too friggin hot to worry about. Tuesday morning before we went out I moved the clip up from 3 to 2 and the bog is almost gone. It may have lost a tad on the rev, but there's always 6th gear! Just to recap, I took the 1174 needle out and now have an 1173 with a 40 pilot and a 155 main. But I guess it's sorta a moot point since i picked up a PWK 35 AS off ****. Should be here Friday.

fLyEnByU · Sep 15, 2006

droopie69 said:
Yeah the start jet is the brass, non-removable thing...it feeds the passage at the bottom of the choke plunger. There is a passage in the side of the choke plunger hole that goes back to the air filter flange that feeds it. You may have better luck plugging that, since I think if no air is coming thru that passage, it can't suck gas up. But what I did was take vice grips and pull that brass piece off. There is a smaller tube under it. I cut a piece off an oring, stuck it in there and tapped the brass piece back on. I need to order a new choke plunger and see what happens. Tried to order it from MXSouth, but they said it was special order and not enough to make the minimum. Guess I'll try the dealer.

did the plunger fix the problem, curious cause my bike does not idle when hot, but idles fine when warming up with no choke.

droopie69 · Sep 18, 2006

fLyEnByU said:
did the plunger fix the problem, curious cause my bike does not idle when hot, but idles fine when warming up with no choke.

Nope. I found an air striker on **** and bought it. It's been hot and I've been busy coaching football this fall to worry with it.

Carb Issues

Similar Topics

Privacy & Transparency

Privacy & Transparency