This is on a keihin PWK 36. I have a 91' lt250r with a couple of mods listed below. I just got it back together after putting in a new crank bearing and fixing about 5 other problems it had. I had it out and warmed it up and drove it a little. It won't idle, it will for a second or 2 but thats it with the idle screw turned all the way in, it won't idle at all with it turned 1 - 2 turns out. I could never get it to idle before I rebuilt it either. I am sure there are no air leaks. It smokes alot in the 0 1/2 throttle range I think it is rich because there is oil at the end of the exhaust pipe, not much but a little. About 1/2 to WOT it cleans out and doesn't smoke until you go under 1/2 throttle. It runs great but I can tell it is rich on the low end of the throttle. I run klotz R50 oil at 32:1. I did a plug chop at WOT and it came out just a hair rich, I need to go down a size or 2 on the main.

What should I adjust to make this smoke a little less and not be this rich? pilot jet, needle, air screw, idle screw?
Any help would be greatly appreciated,

chuck

 

Make sure the pilot jet is clean and the circuit is not stopped up, it should at least try to idle. Will it idle with the choke on? If so you need more fuel (larger pilot).

 

It trys to idle with the idle screw screwed in all the way but its not quite enough. If it is out a turn or 2 it won't even try to idle. How about the richness in the 0 - 1/2 throttle, should i adjust the needle? it currently has a 55 pilot jet in it, 165 main, and a DGJ needle on the 3rd clip.

chuck

 

Tomorrow I am going to try dropping the needle one clip do a plug chop and possibly drop a size or 2 down on the main jet. Yes it does idle for a little bit with the choke on (10 sec or so). What size pilot should I go to next I currently have a 55 in and the next 2 sizes are 58 and 60. Which one should I get. I have to buy it and there almost $5 a piece so I would like to get that right the first time.

any suggestions or tips?

chuck

 

on the PJ, and I pretty sure the same applies on the PWK, the idle speed / mix is set by rotating, yes screwing it in or out, the chock plunger. The plunger has a tapered needle which is the fine tune / idle speed setting on the idle circuit, up the plunger is lifted giving the bike a whack of gas, down, then the position of the needle sets the idle speed. Bet it's screwed fully down.

I used to adjust my idle speed on my 38 PJ equiped 92LT this way. keep winding it out / open until the idle picks up. adjusting the airscrew will not compensate if the needle is down.

 

The PWK's don't have that. They have a air screw and a idle screw. Does anyone have a keihin carb on there lt250 that is jetted? if so what are you running in yours?

I dropped the needle one clip and dropped the main to a 162. I noticed a little more power up 3/4 WOT. It does smoke a little less after I changed the needle the one clip but I still think it is rich.

Any suggestions with the 1/8 - 3/4 throttle? it seems rich yet, but should I try dropping the needle one more clip or not?


thanks alot,

chuck

 

I figured out the pilot jet and the main jet now, I am running a 65 pilot and a 160 main. I still need to figure out the needle though.

Should I try putting the needle to the leanest clip? or buy a differant needle and go from there?

The needle I have now is a DGJ and it is on the 2nd to leanest setting now and is still rich.

If I get a new needle should what should I change on it (Taper, Length, Diameter) ? It seems to be the richest from 1/8 to 3/4 throttle.

I also need a new/used axle for my quad. Mine is bent and only rideable at speeds under 6th gear.
Anyone have any info where I can get a good deal?

Please help,


Chuck

 

hey chuck,

I was wondering what you decided to go with on the needle, I have a keihin pwk 36 that I bought from a freind that I am trying to get set up on my 86 lt. I have a similar setup to yours, I have a fmf pipe and silencer, fmf reeds, and bored .040 over. My carb came with a dgk needle and it is on its leanest setting and running way to rich, anyway just hoping I could get an idea where to start.

 

I was thinking about going with a DGK but now if you say that I might try something differant. Mine came with a DGJ which is richer than yours. it depends on where yours is rich. The diameter affects 0 - 1/4 throttle, the length and clip positions affect 1/8 - 3/4 throttle (longer being richer), and the taper affects 1/4 - WOT.

I will most likely try a DGK or a or a DEL, a DEL is one size leaner on the diameter (bigger), and one size leaner on the length (shorter).


-chuck

 

I only had the carb on for a little while, and it was running rich from 1/4 on up, and the main was a 175. I am going to put the carb back on this week with a smaller main jet, and do some adjusting, and see if that helps, (I put the stocker on so I could ride this weekend). Ill let ya know if I have any luck