almost got the jetting right pleassse help

[bklyn400ex]

Here goes, i tried like 4 diff. main jets, i have basic mods alot of people told me to use a 155, i did, i left the needle and the air screw stock, plug was full of carbon then i tried a 152, plug was white, now i have the 155 back in air screw out 1 comlpete turn (3 1/2 turns) and i raised the needle clip one notch its still very lean but not as bad as the 152 what should i try next

thanx
chris

[cals400ex]

tell us what mods you have. going from a 155 to a 152 should not be a difference from carbon build up to white. you should see little difference when changing from these sizes. also, what speeds are you riding at? when you had a black plug, you may have been running at around half throttle or less. you could have ran it harder for instance with one main jet in versus the other. what i am getting at is that you could be getting carbon build up from the main jet on full throttle runs (or vice versa) and the plug could be whitish from riding at 3/4 throttle or less (or vice versa). so, you could be right on with your main jet and off with the pilot, needle, or fuel skrew or any combination inbetween. when checking for color with the plug on the main jet you need to 1. go buy a new plug. 2. get your self in a place where you can do some max speed for some time; i usually just go down a road. 3. change your plug when your at your open spot. 4. get on your bike and floor it and keep it maxed out for a little while. finally, pull in the clutch while your maxed out and turn the bike off. now its time to check the plug. caution: i would bring some heavy duty gloves or something because it will be hot. many people don't like doing these plug chops anymore because they don't get true readings from the plugs since the fuel has been getting worse and worse quality these days. however,this should tell you what you need to do with the mainjet because the mainjet is the one that is being used at full throttle. the needle is used for 1/4 to 3/4 throttle. the pilot jet is used for idle to 1/4 throttle. the fuel skrew is just used for idle to 1/4 throttle also. if you tell me what mods you have done, i would probally be able to give you a guess on what main jet to use. i also have a few minor mods and i usually run a 152 main jet but sometimes i run a 150 in the warmer summer months.

[bklyn400ex]

thanx for replying, i have a WB R4 slip on, ground out welds, holes in airbox, K+N air filter

[bklyn400ex]

when i do the plug test and shut the bike should i have it in 5th gear

[cals400ex]

you will want to be in 5th gear maxed out. also, don't just shut the bike off right when you get maxed out. keep it maxed out for several seconds at least. then when your ready, pull in the clutch and shut her off. with the mods you have, a 152 and a 155 are right in the ball park. with the mods you have you should be able to feel very little if any difference between these two size main jets. if i was you, i would run the 155. i don't know what temperatures you want this to be jetted for or what altitude your at. however, i run a 152 with no airbox lid, grinded welds, no choke, and a gutted factory pipe. if you have a friend or someone you know with a similar bike, you could race him with both jets in. i raced my friend with mine with the 152 and 155 and i made no difference in performance of the bike. in the hot summer months, you will usually go down one size on the main jet due to the density of the air. just try doing the plug chop and see what the plug looks like. the fuel is so bad around here it did not work too good for me. one brand of fuel here turns my plug a reddish over time and another brand of gas turns it yellowish over time with the same jets installed. if you have any other questions, let us know.