426 Jetting Question

[carlj75]

Ok, I have a 426 JE piston running 11:1 comp. Stage 2 Hotcam. No airbox lid with K&N filter. #42 pilot jet with choke removed. I ride mostly at sea level, between 55-80 degrees. What should I start with for the main jet, needle clip position, and air screw adjustment. Before the engine work, I was running a 170 dynojet main and it ran good. I was thinking about getting rid of the dynojet main and needle and starting from scratch. Any advice? Do I even have to rejet it for the bigger piston?

[Pappy]

im running almost the same set up...except with a lid and uni. i have a 152 main 42 pilot and 2 1/2 turns out on the air screw...needle in the stock position. i ran a 165 with no lid and it ran perfect......but id say start a bit higher then the 170 and do some jetting runs.

[Dune Surfer]

I had that same set up and ran a 172 regular main jet and a 42 pilot. I had the screw out 2.25 turns out at sea level. When it got hotter I would go up to a 175. This was mostly hard dune riding. Hope this helps. Oh stock needle position. Good luck:D

[carlj75]

Is that a dynojet 172? or a keihn 172?

[Dune Surfer]

Originally posted by carlj75
Is that a dynojet 172? or a keihn 172?

keihn

[carlj75]

So why the huge difference in Pappy's and Dune Surfer's jetting? I just bought some new Keihn jets: 165 through 175 and I'm going to use the stock needle. I guess I'll try Dune Surfer's jetting first.

[TRX_Thumper]

i got a je 416 kit in mine...stock muffler system with uni filter...and a 165 keihn main is lean...well its kinda brown..a light brown...but my question is since im running 3 gallons of 93 mixed to 1 gallon of 110 will this make the plug burn different color?

[carlj75]

I just put in the 172 Keihn main. Stock needle in 3rd clip. #42 pilot. And pilot screw 2.25 turns out. Removed choke and no airbox lid. I let it warm up and then let it idle for a while. It would idle fast for a few seconds and then slow down and almost die, then it would start idleing fast again. It just continued this cycle without me touching anything. What's the deal? Any help would be greatly appreciated, since I have to have this thing ready to go this weekend for Florence.

[Dune Surfer]

Originally posted by carlj75
I just put in the 172 Keihn main. Stock needle in 3rd clip. #42 pilot. And pilot screw 2.25 turns out. Removed choke and no airbox lid. I let it warm up and then let it idle for a while. It would idle fast for a few seconds and then slow down and almost die, then it would start idleing fast again. It just continued this cycle without me touching anything. What's the deal? Any help would be greatly appreciated, since I have to have this thing ready to go this weekend for Florence.

sounds like you have an air leak. Check your gaskets on the bowl and the intake boot. The difference in Pappy and my jetting could be elevation. I ride at sea level.

[Glamis400ex]

Pappy also had an airbox lid on and a UNI...


BTW...mine is doing the same thing as yours carlj75..:ermm:

Glamis

[carlj75]

bump

[carlj75]

I just checked the carb boot o-ring and carb bowl o-ring...not leaking as far as I could tell.

[Dune Surfer]

Glamis400 has exactly the same problem. Its strange, Let us know if you find an answer

[Dune Surfer]

bump

[carlj75]

I don't have my motor broken in yet, but it seems like the jetting is good when I ride it. When I come to a stop, the idle stays high for a few seconds and then slows down. Do you guys think that the #42 pilot jet is too big or something? Glamis400, have you figured it out yet? I don't know what else to try.

[Glamis400ex]

Carl,

You're describing what mine is doing also. Unfortunately, I have only been able to ride it for 3-4 hours, and that was almost 2 months ago.:(

I hope to get it all apart, clean everything and maybe try a new throttle cable.

Glamis