Jetting suggestions

[Fre530d]

Hello Guys

 

I installed my FAST ported cilinders last week. It is a agressive dune port.

 

I started with 360 mains , clip 4th pos., air screws 1,5 turns out.

 

Mod's are 20 cc domes Noss coolhead, trinity stage 4 pipes, V force 3 and POD filters.

 

It was bogging a little in the midrange but pulled out well from the lower range.

 

Now I've putten in 330 mains , rest is the same, the bogging stopped but when i am driving slowly

 

let's say 5000 rpm in 6th gear and I push the throttle , it revs super slowly , it takes ages to get to the

 

powerband. The engine feels like it's low on compession but it isn't.

 

Am i running too lean? I thought it was my compression but the compr is 170 Psi what's fine

 

at sea level I think. Any sugg?

 

Fred

[black sunshine]

When you say clip in the fourth position, do you mean lean or rich?

 

I'd start by talking to Jeff, he will probably recommend a good starting point for you and a plug chop!

[locogato11283]

have you done a wide open throttle plug check? you need to see what color your plugs are.. white is lean, black is rich and tan is right on.. i would think 320 or 330 would be pretty close. what pilot is in there? id put the clip back in the middle of the needle..

[black sunshine]

I would put those 360's back in for the first chop. That's what he put in mine and it was just a hair lean, or nervously spot on!! I put in 370's and didn't notice a difference except for a better ring on the plugchop. That was at 800' and about 80F out. Colder now, need bigger mains!!!!!!!!

[Fre530d]

I got a 27,5 pilot.

 

I am going to put the 360 mains back in and do a plug chop.

 

I'm going to do it next week and post some pics.

 

Thx guys for the answers.

[dajogejr]

I agree...put bigger mains, chop the plug.

And yes you need to run WOT through at least 5th gear, if not 6th. 2nd and 3rd gear plug chops DON'T Count.

 

Put the needle clip back in the middle as well.

 

http://www.dfn.com/benkaren/plugchop.html

[J-Madd]

I know of guy that runs 400 mains in one of Jeffs Dune ported motors, and it screams. Not sure of the pilots or needle clip position.

[Fre530d]

I know of guy that runs 400 mains in one of Jeffs Dune ported motors, and it screams. Not sure of the pilots or needle clip position.

 

 

The biggest main that Jeff has sent me is 360 so I think that's the one Jeff suggested me.

 

Thx for all the answers.

 

Maybe Jeff can shime in?

 

WFG

 

Fred

[FASTOYS]

Fred do you have stock pilot or 27.5?? If stock pilot your air screw is too far out. Try 1/2 turn. May need to play with clip position on needle. ALWAYS start fat and work your way down. If stock needle i would think in the middle would work but we have had some that had to go lean (clip to top).

[2bzy2p]

i agree id say it isnt your main but more your needle,,and if your cruzing around low rpms in 6th then pin it its going to take awhile to get back up to speed.

[FASTOYS]

I would say keep it in the 4th clip down for now, try the 1/2 turn out and see if it will work. You may be fine with what you have .

Yes we stock ALL jets!!!

[Fre530d]

I would say keep it in the 4th clip down for now, try the 1/2 turn out and see if it will work. You may be fine with what you have .

Yes we stock ALL jets!!!

 

 

Hey Jeff

 

I have 27.5 pilot jets