Jetting 4mm stroker

[JasonGOSU]

Mods: 4mm crank, ported, 35mm pwk, T-5 pipes, v-force 3, pod filters, cut domes, +4 timing, sea level, 80 degrees. I'm at a 135 main and have the nice tan ring around the insulator. I pretty sure the pilot is fat and the needle is in the wrong position. I can't start it without giving it some throttle. It sputters down below until about 3/4 throttle. It cuts out when I crack the throttle real quick to full throttle, then it comes back. Will the porting effect the main this much? Will the pilot have much effect on the main?

[23champ]

raise the needle as far as you can go.

[JasonGOSU]

does anyone else have any info?

[dajogejr]

What needles, what pilots and where is your air screw at?

[Snopczynski]

What needles, what pilots and where is your air screw at?

 

Main jet is top end, needle is 1/8-3/4 throttle, pilot jet is idle to just off idle.

 

What carbs are they?

[JasonGOSU]

thanks for the replies, but the questions still haven't been answered. They were answered for me on another website.

[Snopczynski]

thanks for the replies, but the questions still haven't been answered. They were answered for me on another website.

 

UMMMM???? You need to tell us what carbs your running. The answers can be entirely different between keihin, mikuni, lectron, stock bored with toomey needles, etc..... So no one can answer the question without the facts. It sounds like your running twin keihins, but that is something you need to tell us. If you have to crack the throttle to start it, its rich.

[wesw]

he said he was running pwk 35s. read his first post

 

 

138 mains are beyond small at sea level. you need to find out what pilot you have, what needle, what clip its on. the needle has letters on the side.

 

all that shit is needed before someone can throw info out for you.

 

 

 

so dont expect answers till you give more info.

 

 

but i wouldnt run it too long with that small of a main. 150ish you should be at most likely with the right setup.

[JasonGOSU]

Thanks WESW, I thought the main was too small. But after doing plug chops, the tan 2mm ring showed up at the base of the insulator, So I figured the main was good at 138. I thought the main was small, but I figured that maybe my porting wasn't pulling as much air as others. The pilot is a 48 and the needle is a DGK and it's in the middle slot. So, my questions were if I was at a 138 would a pilot effect the main a whole lot if it were real big? Would the needle position effect the main enough to make it 5 or 6 sizes too small?

 

Thanks for the info, much appreciated.

[wesw]

on keihin the circuit all over lap each other.

 

so big pilots feed into the mid, and to the mains.

 

but your pilots are small.

 

 

if you raised the needle it would put more fuel in yes. and it could throw your main off.

 

i would say

 

put a the needle on teh 4th and say 150 main and take it out for a ride.

 

put it in like 4th gear, and slowly open the throttle adn see how it acts. if it bogs out say 1/2 throttle it might be rich in the needle. butif it runs open it up and see how it acts on top and do a plug chop.

 

its a lot of playing with shit and change stuff. it might like more fuel, 5th clip might not.

 

 

 

who ported the juggs.

[JasonGOSU]

McDonald Pride Racing on the East Coast ported them

 

I pulled the choke when when I was riding, and it bogged all the way till it hit the powerband. The choke didn't seem to have any effect at all at WOT. So, maybe if I put a bigger main and lowered the needle, raising the clip, see what happens. But the thing that gets me is that the tan ring shows up on a 138 and when I go bigger it starts to color the insulator more. And I assume at WOT the needle is completely out of the main. Am I wrong about the needle being completely out?

 

maybe I should have just had passion port them. I'm thinking the porting isn't drawing enough air to pull a 150 or bigger main.

[dajogejr]

1st, WOT is all main.

2nd. Conventional wisdeom and Wes's own experience would tell you that main is too small..

 

However, porting can pull more fuel out of a smaller jet... Porting is just that.

Pulling more fuel/air efficiently and getting it out more efficiently.

 

I agree...put the 150 in. warm it up with old plugs. PUt the new ones in, and do a 1-5 (6th if you have enough room) WOT ride. HOld the throttle open, hit the kill switch. PUll the plugs, but the old back in.

 

Are you actually cutting these plugs, or just kinda looking? The insulator can take a while to color, and it's a good rough guide...but the 2mm tan ring is what you need to see...

 

If you did a WOT run and plug chop correctly, and the 138's still had that nice, tan ring along the bottom of the insulator, you're good to go.

[JasonGOSU]

yep, completely cut each plug after each change of the jets.