Alright i would like start by saying that i have a 1986 Suzuki LT250r and well im trying to dial in the 36mm keihin pwk carb to my setup. My mods are fmf exhaust, boyesen reeds, some port work on a 71mm bore. I have it running pretty well but it just seems to smoke lots of blue when it idles. All of the engine oil seals have been replaced. Jetting consists of a 165 main jet, 42 pilot, DGN needle clip in the middle. I also noticed that the air screw does not get any rpm fluctuation when i tighten it all the way in or back it out 2 turns. I have nothing clogging the jets i have cleaned the carb many times. It runs perfect 1/4 to full throttle. Im guessing that the needle diameter is to rich 0 to 1/4 throttle as my pilot and air screw do not respond. If anyone has any suggestions please let me know. thanks
if your air screw isn't making a difference, then most likely you need to lean out the pilot a size or two, there is directions in how to tune these carbs under one of the 250 forums on here
thanks and ya i did try that also. I had a 35 pilot the lowest you can get and still no change. Im kinda stumped.
have u tried setting throttle slide just a hair above fully closed and adjusting air screw from there?
I want to keep the Keihin Carb but it just dont seem dial in perfect. I may have to go back to the stock Mikuni Carb
. The Keihin has awesome top end but is very lazy on the low end kinda sucks when i trail ride a lot. Still dont know why the air screw doesnt work?
yes i did try the throttle slide in many positions and the air screw does not respond . I did notice when i have the air screw 1 turn out and then turn it all the way in, the idle drops down a little which floods and then shuts off.
The air screw can be adjusted to make the engine idle at it highest rpm. If it idles at highest rpm at 0-1 turns the pilot is lean or if it idles at its highest rpm at over 2 turns out means that the pilot is rich. It does not want to idle up at all.
what are u mixing your oil too?
I wonder if it could be suckin alittle oil from the transmission side through the case halfs or somthin
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there is something different about kelhin carbs, try to send iceracer a pm
the air screw is different from a oe carb
actually you might be right changing the air screw could add more air but ya it has been trial and error with this carb. I want to freshen up the top end but cant untill its dialed in right.
zilla273 i have replaced the crank seals everything checks out okay, im just having trouble with the Keihin carb. I mix 32:1 and also tried 20:1 as the manual states.
Unless the engine is racing/surging/ hanging at Idle it's likely too rich Keihin's are EXTREMLY sensitive to Pilot settings. IF your doing all the jetting on a Tired engine your Pissin in the
wind, It dosent draw on the carb correctly or move the correct amount of Air. I suggest you rebuild it and start where your at now. Also a incorrectly set up head Will cause you fits dialing in jetting especially at low rpms.
You might be on to something there i have been running the same piston and bore for 2 years now but i don't ride it much because of the jetting. i was scarred of wearing down the cylinder. I pulled off the top end and i found the billet reed spacer halfway on there hanging by one screw. damn that could have been a disaster. but i think now i should either check the compression or rebuild as you said it might not be burning the fuel efficiently with low compression. I inspected the cylinder and there ain't a hair scratch on it. I still see the cross hatch hone left from the last time i did it when i replaced the piston rings. I just hope that 200 $ will solve the issue that i'm having with the carb not syncing in right.
also the head is stock and looks flawless with no nicks inside, still has original tan paint on it. how much compression should i have?