jetting tips 35mm A.S. - DEK needle

[dynofox]

I've got an '86 TRX 250r that has a 35mm pwk a.s. installed and I'm trying to fine tune the jetting. My current set up is 155 main, DEK needle on clip position 1, 42 pilot, air screw at 2.5 turns out. My quad has the complete stock air box including the snorkel and non-drilled lid. The motor is pretty stock, 170lbs of compression, has a boyesen rad valve, fmf fatty and turner fat boy silencer. I run 91 octane fuel mixed with amsoil interceptor at 32:1. The quad seems to run pretty well but I think there is more to be had, I'm thinking there has to be a better option for the needle than the DEK. Should I give the needle from my stock 34mm pj a try? It will foul a plug once in awhile when being trail ridden with my family, my brothers '85 quad racer never fouls plugs on these same rides. I trail ride in central upstate NY with an elevation of around 1000ft. I know not many people use the 35mm A.S. but any tips on jetting specs would be great.

[dynofox]

Anyone?

[8686]

Are you dead set on leaving the airbox lid on? If not, take the lid off (just leave the snorkle on for now) and take it for a spin. What spark plug are you using? Gap?

[dynofox]

Some of the trails I ride there are wet spots, I'm not sure how well it would do with the lid off. I know the air box set up on these quads is very restrictive but unless I want to open my air cleaner up to all the elements I'm somewhat stuck. I'm running a K&N with a prefilter btw. I use br8es gapped at .20. Once I know its done fouling plugs I plan to switch to br8eix. Figure dial it in on $1 plugs versus $5 plugs. It doesn't foul that many plugs, maybe one every few rides and this is normally when riding slow with my family (1st - 2nd gear low rpm riding).

[regg187]

If you don't want the lid off at least put a few holes in it, it will only let water in if that goes under water, which my guess not many r's go seat deep in water. forget the prefilter unless your duning it in the sand. that is what it is mainly for. that should help you flow more air more air = more air & fuel mix= more power 0r volumetric efficency as it's called. I have a 3 x5 hole in the top of my airbox lid that is covered with screen to keep the chunks out, and have ridden in the surf in Mexico with no drowning problems.

that should make a noticeable increase for you!
pre filters restrict air flow by 5% or more according to K&N

[dynofox]

I've got a uni filter as well, maybe I'll toss that back in without a prefilter and modify one of the air box lids I have and do some more testing.

[regg187]

K&N will flow more than the uni, uni with a prefilter = restriction use the K&N with no prefilter for best results:)

[dynofox]

While digging through my box of jets I found a CGM needle and tossed it in. This is leaner than the DEK needle across the board, will give it a try and see how it goes. :)