porting a 750 sx motor

tokarzl · 03-03-2010, 03:21 PM

I have a 92 750sx I would like to put a larger carb on it and port the motor out, i would also like to get a new impeller im looking for a whole lot more of low end punch

i would like to stay with a single carb
anyone do this type of setup before any specs or carb setups you have worked with

PLD · 03-03-2010, 09:22 PM

I ran the stock single carb on my setup even after the porting and it ran fine. But going to the bigger 44mm + carb made a HUGE difference. I personally am running a 50mm as of now but I have a full bolt on 750. It is all going to depend on the rest of your setup.

tokarzl · 03-04-2010, 12:58 PM

i have timing advance 23 cc high compression head i run 93 octane gas pjs dry pipe and i belive its a 38mm carb

PLD · 03-05-2010, 12:00 AM

23cc head on pump gas and advance? what psi is that?

Honestly I would give Art a call at JetWorks and tell him your plans and what you want. He is a very nice guy and this is from what I hear, have read, and talking to him over the phone.

tokarzl · 03-05-2010, 02:58 PM

185 psi

River Rat · 03-05-2010, 05:58 PM

23cc on a 750 is way too much compression for 93 octane. I think your compression gauge is reading a bit low. 26cc will be 185 / 190 ish range and that is as low as you want to go on a 750 motor without having a professional engine builder set the proper squish. You should be running more octane than 93.

As far as advanced timing get a msd enhancer and retard module. PM (MCN6) he has set up a couple motors for me for exactly what I wanted to do.

PLD · 03-06-2010, 10:19 PM

Perhaps you already have some porting done already? Have any pictures of the cylinders and know your deck height and such?

tokarzl · 03-07-2010, 03:05 PM

no i do not i am in the process of pulling the motor i will do some investigating to find out, but yeah the compression gage read 185 psi both cylinders and the guy who had it before told me to run 93 with klotz at 50:1

mcn6 · 03-07-2010, 04:21 PM

23cc domes on on 93 octane pump fuel??? Normally you would be near 100 octane CCR's with that set-up... Is it possible you were given innacurate information regarding dome volume or that you are using thicker than OEM gaskets or something?

tokarzl · 03-08-2010, 10:35 AM

i called the guy yesterday and said they where 23cc domes its an r&d head that was milled if im looking to port would that cause me to use higher octane gas also??