jetting

[macho comacho]

Hi all
I have been trying to get rid of a sputter at small openings on the throttle and have tried 45 and 42 pilots,but with these pilots the air screw had no effect either in or out.Then i tried a 40 pilot and the air screw now worked but only at 3.5 turns out.
My jetting is 178 main,40 pilot,CEK needle 4th clip,sea level and the temp is around 9 C. Reeds ok.
Could i use a 38 pilot or am i too lean at the moment with my current settings,also is there anything else that could cause this type of setting.
Many thanks Macho

[2 strokes 4 life]

Well best bet is the RBD carb mod. Best money you can spend if you can not get rid of the sputter.

[Eric K]

What carb slide do you have?

What year is the MC?

[macho comacho]

As i'm in the uk the rbd mod is out.The slide is a 7*.would a 38 pilot be too lean.

[iancp5]

Originally Posted by macho comacho

As i'm in the uk the rbd mod is out.The slide is a 7*.would a 38 pilot be too lean.

What bike is it - 300? How are you using it?

I used to have a 300 and best jetting I found was 40, CCK and 180. That was in cool temp. I would go to 38 & 178 in summer. That's for tight woods. If I was doing lots of fast stuff I'd probably have it richer to be safe after a bad experience! I tried going very lean once and it was great in the woods but seized on a fast bit. That was on 35p & clip 1 on an N1EF - a lesson learned.

I don't think you can completely eliminate 4 stroking if that is what you mean by sputtering but the bike shouldn't hesitate when you open the throttle after slow running. If you completely eliminate 4 stroking on tiny throttle you will be so lean you are going to seize.

[macho comacho]

Ok cheers iancp5 yes its a 300 and i use the bike for trail riding so i will stick with the jetting i have until it warms up.

[stay_upright]

Originally Posted by iancp5

What bike is it - 300? How are you using it?

I used to have a 300 and best jetting I found was 40, CCK and 180. That was in cool temp. I would go to 38 & 178 in summer. That's for tight woods. If I was doing lots of fast stuff I'd probably have it richer to be safe after a bad experience! I tried going very lean once and it was great in the woods but seized on a fast bit. That was on 35p & clip 1 on an N1EF - a lesson learned.

I don't think you can completely eliminate 4 stroking if that is what you mean by sputtering but the bike shouldn't hesitate when you open the throttle after slow running. If you completely eliminate 4 stroking on tiny throttle you will be so lean you are going to seize.

Ian - what throttle opening did your bike seize at? 3/4 or WOT? or more like 1/4 to 1/2..

As you read from my post below I'm running my bike a lot leaner than yours and have eliminated the 4 stroking, have ran this jetting for a couple of years and it works great. Mine is lean at teh bottom end and gets richer - back to stock at the top end. I would not worry about seizing the bike at low throttle openings only 3/4 throttle onwards but it sounds as if you have had other problems... Were the rings definately welded to the cylinder?