KT100 Carb Tuning

Dave Malloy · Joined: 18 Jul 2001 Posts: 675

Please explain and give input on setting and adjusting the Walbro jets. Some tell me 1/8 Hi & 2 - 2 1/2 Lo. Jean Genibrel's book says 3/4 Hi & 7/8 Lo and to lean the Hi and richen the Lo on tight tracks, but that much?. I hear the differences may have to do with carb mods. I run with a wet clutch and a sportsman can. Thanks.

Jimmy Moore · Joined: 26 Jul 2001 Posts: 664

Start with the high needle at 1/4 turn and the low at 2 turns. At the end of the straight the engine should start 4 stroking. If it doesn't, open the high a little 'till it does. This gives you a reference point. Then lean the high down 'till it runs clean at high end but, don't go less than 1/8 turn open. Next start leaning down the low needle untill you feel it stop pulling coming out of turns, you may also feel a dead spot half way down the straight. That gives you a reference point on the low. When you find that setting open the low another 1/4 turn and you've got it. In the race, watch the temp gage, usually when the flag man give me the half way sign I open the low another 1/8 turn. There are many ways to tune a wB3a and still have it work so, find those reference points to get the settings that work best at your track.

David Mayhew · Joined: 31 Jul 2001 Posts: 209

I wouldn't run the high and the low where Jean's book recomends. I run mine at 2 1/4 to 2 3/4 on the low and between a 1/8 to closed on the high. All of this changes a bit with each carb and the settings your engine builder uses but these are some common settings. Good luck.

David Mayhew

David Mayhew · Joined: 31 Jul 2001 Posts: 209

John,
That is a good point. First ask your engine builder as he should know but most builders I know run them really close to the same settings. The settings I recomended should work for most carbs though unless your builder does something that nobody else does. Good luck and talk to your engine builder.

David

John Bosanek · Posted: Mon Aug 13, 2001 10:24 pm Post subject: KT100 Carb Tuning

How about settings for a long track (road racing)? I've been running about 1/4 high and 2 1/2-2 3/4 low.....is this way off??

John Wehrheim · Posted: Mon Aug 13, 2001 10:35 pm Post subject: KT100 Carb Tuning

Dave:
I know you don't want to hear this, but your engine builder should tell you exactly where you should set it. Every engine builder blue prints their carbs differently, therefore anyones suggestions are going to be off the optium. Get the info from your engine builder and make slight adjustments depending on the air density. Read your plug once the motor has cooled so you don't ruin the threads in your head. If your engine builder can't tell you that, then I would suggest you get another one.

To show you how far everyone is, I set my supercans with the high closed and the low at 2 turns. But that is because the way the carb and motor were built.

[ August 13, 2001: Message edited by: John Wehrheim ]