is my engine builder right?

[exrider008]

i just brought my engine to island racing and they r putting a wiseco 406 piston in. i have a HMF full exhaust and a K&N filter. i called them today and asked them what i should do for jetting and they told me only to go 2 on the main which would be a 150 but that sounds WAY to lean. but i trust these guys alot cuz they do GREAT work but this just dont sound right.

[GPracer2500]

Two sizes up from stock is a 152.

148
150
152
etc.

With a pipe, filter, and 406 I think you'd be higher than 152--but it depends on your elevation, temps, etc. They probably meant 2 sizes up to account for the extra displacement. So if you were running a 155 before that would be a 160.

[exrider008]

i allredy got the jet and my dealer gave me a 150 when i asked for 2 up on the main. i know that stock is 148 so 148+2 is 150 not 152:confused:

[GPracer2500]

When people talk about sizes they are refering to the next size up. The sizes go like this:

148
150
152
155
158
160
etc.

Going from a 148 to a 160 is 5 sizes not 12.

[exrider008]

o ok. so dose that sound close to the right jetting to start with cuz to me it sounds WAY to lean.
thanks

[GPracer2500]

The pipe and filter where allready on there, right? Like I said, the builder probably meant 2 sizes up from whatever the correct jetting is for your old piston and the pipe/filter, NOT two sizes up from stock.

ETA: two sizes up from a stock bore to a 406 sounds about right [shrug].

[exrider008]

ya it had the pipe and filter were on it but it had a stock jet in 148:confused: and ran great:confused: :confused: so i gess im just going to go and get a 152.
Thanks for all the help!!

[Glamis400ex]

I had a stock motor with K&N, no lid, full exhaust and mine ran great at 158. That seems lean to me. My 416 was at 165.

[2004exrider]

ya, thats gonna be pretty lean. I'd suggest starting around 160, 165. that should be a good starting point.

Jimmy