I have a scrambler 400 with a 39pwk and was wondering what jettign i should be running i have a hpd trail pipe, fmf turbine core 2 silencer, wiseco standard bore piston, reed spacer, velocity acceleraror, k&n clamp on. any help would be appreciated I am at sea level

 

You didn't say if you had it ported or not.Mine is race ported and i am at sea level too.My jetting is 178 main,35 pilot.I don't know if this will help you any.

 

It is not ported. before i put in the piston and added the spacer and filter. i was running a 175 main 42 pilot and middle position on clip

 

Scrambler123, Dam you got a lot of quads he!! 3 of them are03 models... Hows about sharing a 04 pred would be nice!!![img]i/expressions/face-icon-small-happy.gif[/img]

 

I got plenty for now but wouldn't mind a pred.


so is there anyone who can give me a rough estimate on where to start jetting?

 

can someone help me?

 

It definitely sounds like you are too rich on your jetting.Iwould think you should be around the 165 main jet range.Your pilot sounds too rich as well.Try the 35 pilot.Definitely do some plug checks.Let us know how it goes.

 

I don't think i'm rich i was running a 172 main and It burned a hole in my piston.

 

Check your case around the clutch side to make sure you don't have a crack,causing an air leak and a lean condition.I find it weird that you can run that jetting with no porting at all.And most people with race porting are running from a 172 to 178.I want you to check the case because i just cracked mine.Shoot me your e- mail and i will send you a pic.

 

I don't know which wayto tell you to go with this Jetting problem,but,you should always go up and make it as rich as you can ontill it smokes real bad then you know that it isn't going to burn up . then you can work your way down ontill it runs right.
Here is what I have on mine But, keep in mned that i have a full HPD race kit and port job. 35 pilot 170 main.
This should be used as a starting point BUT YOU CAN NOT GO BY WHAT ANYONE WILL TELL YOU because,every 400 is not the same.I myself havw been all the way down to a 160 main jet in the summer AND Before I went that far down everyone told me that it couldn't be right and that it would burn up . Even HPD couldn't believe that it had to go that lean to run right.For now I stay with the 35pilot jet and go from a 160 when very hot to a 180 when very cold.
so you see it can vary from Quad to Quad.
THE BEST THING YOU DO IS GET A exhaust gage (EGT) it will read the temps of the exhaust and that will help you get te jetting right.