Not much speed after new 420 and clutch - TXT on 28s

tommywilder

Finally going to break down and ask for help. Specifically because this weekend is the local golf cart mud races. I am desperate to do better than normal this year.

Current situation: Just pulled my GX390 after some noise and found too much side play in the rod bearing. Replaced with a Predator 420 Hemi and Comet 780. Only mods to engine are cone air filter and exhaust (tractor muffler.) After getting the engine in, I did try a couple other jets - 41 and 42, but pulled the plug afterwards and it was completely covered in soot. (This is after riding only about 1/2 mile to test for speed, mind you.) Never had one foul that quick before.

EZ-GO TXT (95, I think?) on 28" Super Swampers and a LOT of homemade lift.

I am seeing 25mph. What can I do to get that number up and keep (or gain) some torque in a quick fashion? I only have 3 days to get this thing ready.

Thanks!

BGW

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superpro56

How old is your belt and how wide is it? Do you have a main jet adjuster installed?

tommywilder

Unfortunately I don't have a jet adjuster, but I do have a bunch of jets (small and large) and hobby bits. Thinking I'll try going a little leaner this evening and see how it does.

Belt is getting aged. Any idea what a Gates or other locally-available belt part number would be for stock size?

What kind of speed should I see with the setup that I have, as in, how much am I actually missing?

superpro56

Definitely sounds rich, work with what you have for the upcoming event. For the future, get one of these

https://www.eccarburetors.com/169F-4...rb_p_1212.html

Assuming 12 to 1 ratio rear end and 4000 rpms, it works out to 27mph. You can check it out here and plug in different numbers as far as RPM or axle ratio to see how it may impact your final speed.

http://www.buggiesgonewild.com/speed-calculator.php

Not much help on the belt, the 780 is compatible with either a 1-1/4 or 1-3/16 width belt.

Shepard

Have you removed the governor? You should be able to get up to 41-4200 rpm safely. Make sure you have some type of tachometer.

tommywilder

I have not removed the governor on this one. Not brave enough until after this weekend. Haha My GX390 that this replaced was degoverned. Appreciate the info on the adjustable jet and that calculator. I'll need to figure out what my ratio is this evening.