kt100 simple carb question

boostedsil40

New member
Im super new and im taking my kart out for the second time tomarrow,Im scared to damage the motor and from what I read the settings are 2 and 1/2 turns out with low speed needle and 1/4 or less on hi I tried this setting the other day and the motor seems to want to start at a half turn out on low speed,now my question is that as soon as its strated and ready to go Do i floor it THEN turn it the 2 and a halff turns then just leave it alone the rest of the time or will i have to turn the low jet tighter everytime i'm not flooring it to keep from floooding?

so basically can I start it at half turn on low, hi on 1/4 turn and as soon as i take off can i then turn the low jet out 2 more turns and leave it alone the rest of the day?how do you guys do it?will I have to turn the low tighter when im just cruising???

is it better and/or possible to start it at 2 1/2turns low speed needle and leave it alone the rest of the day,
 

Hoppy

Member
Do you have a tach/temp gauge? If not get one. That will tell you what your settings need to be and when you need to adjust them. Without that you may as well get an engine builders number.
A newbie will stick the engine nearly every time without accurate operating temperature monitoring.

Hoppy
 
2 1/2 is a lot to start and idle on, that's more of a setting to work up to as you get up to speed. You can also run less low and a little more high with good results and have a better idle and less tendency to load up off the bottom. 1/2 low is not enough to run on . I'd say 1 1/2 minimum on the low and open the high up to about 3/4 to start with. Run as much low as you can without it not reving up and just sitting there sputtering, that will give you the best throttle response and torque when under a load trying to get it up and going. Find the point on top end where it won't handle any more high side without breaking up or stuttering, that's a safe tune at that point and can be a little leaner, but leave it there until you get a little more experience with it. You'll find that as the weather changes, so will the needle settings need to change. The colder it gets the more fuel the engine will need because the air density will increase. More air needs more fuel. Jon
 
Read about what Steve O'Hara says to do, then try it I think you will be happy with it. Steve has been racing very successfully for longer than many on here have been alive.
 
Hoppy, I ran my first KT without any tach or temp for two years before it let loose. I also ran the carb with the low needle at about half turn and the high at 1 to 1-1/4 out before being told it was wrong. Now that I learned how to do it I stick about 2 a year. lol
 

boostedsil40

New member
actually i played with it for a few hours and I got so sick of fouling plugs...I started from rich to leaner and it seems 1/4 on high needle and 3/4 and 1 turn on low will bog so turning the high a hair lower made the top end more crisp with no bogging and low needle at 3/4 and its golden in all rpm so far,....till something gives but seems pretty rich on the safe side,other then soaked plugs the last time i checked plug was on the 3/4 on low speed and 3/4 on high and the plug had a nice brownish tint to it not to rich and not lean,I know its not a egr guage or wideband o2 sensor but this is what it is.thanks guys.
 

Don K

Member
Almost everyone who begins with the WB3A runs them too rich. Steve O's method works well because of the stock 18# pop-off. Lowering the pop-off is like raising the floats in an automobile carburetor. It creates more pressure in the fuel delivery system. Early on folks told me to use 8# pop-off and the carb was difficult to adjust and find the sweet spot. We usually looked for 11-12# pop-off and .045 lever height with the gasket in place. This setting offered a greater and easier range of adjustment.

Rule-of-thumb with the KT100 is; if it starts acting up go straight to the carb. Once you learn and become familiar with the WB3A it is easy to deal with and actually works quite well. Get the basic tools: pop-off gauge and height gauge, then google up Walbro WB3A rebuild and have fun.

DK:cool:

PS, the throttle shaft tends to wear the body causing air leaks and then they can become very temperamental.
 

Hoppy

Member
I wasn't so fortunate. But I must say that since the new Mychron I got a while back I resolved the stuck/hole in piston problem. Now my problem is missing my turning points because I can't stop looking at temp gauge!

Hoppy
 
To fix the throttle wear air leaks I put a big dab of silicone on the end of shaft over c-clip and open and close it as its drying to free up shaft. No more leak.
 
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