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Workshop => Carburetor, Intake, and Exhaust => Topic started by: arens330r on November 05, 2013, 06:25:10 PM

Title: 40.5 carb for alky
Post by: arens330r on November 05, 2013, 06:25:10 PM: ok well i have plans for a 370 on alky with a lectron, but for now i have a 330. can i get away with a power jet and fuel pump on the 40.5 to feed the 330 untill the 370 is built?
Title: 40.5 carb for alky
Post by: udontknowme on November 05, 2013, 09:57:36 PM: why not just get the lectron now. dont quote me but i think you would have to drill out the dump tube. plus your needle valve is probly for gravity. but really i think gravity feed from a guzzler might be good although ive never tried it. 3/8npt in with 5/16 out dumps some serious fuel
Title: 40.5 carb for alky
Post by: arens330r on November 05, 2013, 10:00:49 PM: yeah from what im hearing gravity feed on a 330 will be ok. i just dont know if a carb for a 370 will be to much for a 330
Title: 40.5 carb for alky
Post by: udontknowme on November 05, 2013, 10:44:55 PM: maybe it will be ok but its better if someone that tried it can chime in and say. although i never heard of anyone not drilling the dump or running a PJ
Title: 40.5 carb for alky
Post by: arens330r on November 06, 2013, 05:17:45 PM: what is the dump tube?
Title: 40.5 carb for alky
Post by: Jerry Hall on November 07, 2013, 12:31:52 AM: Quote from: arens330r;16796
what is the dump tube?

The dump tube is the needle jet.
Title: 40.5 carb for alky
Post by: udontknowme on November 07, 2013, 02:24:41 AM: you can try with no PJ and small dump but blame carlos if the piston burns down :biggrin-new:
Title: 40.5 carb for alky
Post by: Jerry Hall on November 07, 2013, 10:39:50 AM: A 40.5 carb is not enough for a serious running 330 or a middle of the road 370.

I prefer to use Mikuni carbs for alcohol because they have 3 more tuning circuits than the PE, PJ or PWK series of Keihins carbs. The Mikuni carbs are designed so that the needle jet can be changed to various sizes, the float valve seat can be changed for different fuel pressures and flow rates and they have an adjustable air correction circuit.

My experience has shown that the additional circuits in the Mikuni carbs gives an experience tuner the ability to get a more precise tune than on Keihin carbs that were designed for the two strokes.

I do not understand why Keihin does not offer these additional circuits for two strokes but offers these additional circuits for the off road four strokes as well as the carbs they make for the street type engines. All of the after market Keihin needles for the PE, PJ, or PWK series of carbs are single taper needles. The reality is most engines need needles with at least two tapers and sometimes three. I think that Keihin must have assumed that there are not any seasoned tuners in the off road world and thought it would complicate things or add more confusion for us dirt goons.
Title: 40.5 carb for alky
Post by: big330 on November 07, 2013, 03:48:31 PM: yeah I have a 40.5 on alky with the dump tube & main & pilot drilled out by a local builder with pump. been running it on my 370 esr for 3 years with no damage, runs like a scolded animal. youd be dialed in on a 330.
Title: 40.5 carb for alky
Post by: arens330r on November 07, 2013, 05:33:01 PM: i think i like the idea of the pj all the alky micro sprint guys run there on 270's there has go to be a reason for that!