new clone tuning

Younggun

for anyone who hasn't followed my build I have a 2002 ezgo workhorse that I installed a new clone engine in from vegas carts.

When I purchased the cart the motor was on borrowed time and eventually failed. I chose the clone option primarily due to cost effectiveness and practicality down the road. Seems the parts for this motor are much more reasonable than ezgo parts for the robin not to mention you are going from 11 hp to nearly 20hp which I would think could certainly be beneficial hauling a load of mulch or a group of guys to deer stands.

BGW

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Younggun

On to the tuning process, my motor is in stock epa form minus the governor I removed, the extended header pipe, and the open element air filter.

I am running the comet 780 clutch, also from vegas carts.

my reasoning for the near stock configuration is this, I am not looking for a hot rod just a good hard pulling reliable workhorse.

Initial start up and test run was less than favorable, it topped out around 23 which is plenty fast for me and my use but seemed to have no low end power.
I took BigJohn's advice, since he just did this same swap in his cart, and tightened the belt significantly from where I had it. This made a world of difference in low end and still seems to be topping out around 23 mph on gps. I also noticed it was hard to start without the choke so assuming it is lean with the new open filter and lots more airflow, I removed the carb and used a torch tip cleaning set to reem the main jet out about two steps. I also used Fab1 filter oil and oiled the filter up well. This seemed to help with start ups and it doesn't seem to have the backfire issue on deceleration that a lot of guys on here talk about.

Younggun

well still not convinced I have the belt tension and clutches set up just right, I decided to pull the driven clutch. I wanted to inspect and clean the ramp buttons and spring in this clutch since the original drive clutch already had to be replaced.

Bingo!! once I opened the driven clutch up I found the ramp buttons were so far gone that the cam helix was actually sliding on the allen head bolts that hold the buttons in place since there was nothing left of the buttons! The ramps on the helix were in bad shape as well due to this so today I replaced the helix with a 28 degree one(my original was a 36) and installed new ramp buttons. I threw it all back together tonight and took it for a spin and it has a ton more low end power now.

Younggun

Just got off the phone with Geoff at Vegas carts and went over a few more tuning questions, he clarified for me these motors are sold in EPA form to meet regulations for retail sale. They usually provide a set of HD valve springs and an advanced timing key with these motors when they are shipped. Mine didn't have these so he is sending them out today at no charge, he said the reason they recommend installing them is because with the governor removed the factory springs are not capable of handling the higher rpm's the motor will now turn a without floating. In my situation where I am not looking for top speed but rather low end torque, I could go either way. He did still suggest that I put the advanced timing key in since it significantly helps the torque curve in this motor. Exhaust wise it's like anything else, you want top speed you need to get exhaust out fast so less restriction means more rpm's which in turn gives you more speed, in my application I chose the more restrictive but quieter stock muffler since top speed is not my goal and it will make very little difference in low end performance.

Warlordsix

Okay, this is good info. I am a minor fanatic about clutch tuning. For me, I cannot look myself in a mirror if I'm wasting the performance of a perfectly good motor with mismatched clutching/gearing.

Ernie

slonomo

Now we're cooking! Glad to see that you are getting to the bottom of this. If you look at Bigjohn's setup, he has a much larger muffler. You won't gain much at low rpm, but in the midrange is where this engine shines, and a more open exhaust will help you here. Also, the timing key, yes that will help. And the upgraded carb Geoff sells will give you better response, and you can use a more open air filter and jet the carb. This WILL give you more mid range performance, which I think you will appreciate. Those mods, the same ones Bigjohn did, will make that engine sing! Changing the valve springs will give you more rpm. Right now with the stock weaker springs, at aroung 4000 rpm your valves will start to float. This is bad for power. With the larger springs the valves will seat properly at the higher rpm. You don't need to run this at 5500 to get power, 4000-5000 is the sweet spot, lots of power here. Beyond that, yeah, cam, porting, carb, rod, pushrods, etc will give you big power. But you should be happy with just a jet, air filter, and larger muffler.

Obviously you have addressed the clutch issue. With the new clutch, a tight belt....you should be able to pull any hill you can throw at it!

natew121

tips , got a gx390 runs 35 with me by myself. with the steel rear seat/flip bed on the back.
as suggested air filter +exhaust ,
^rejet after you can buy a jets or drill the stock one(how i did mine was go to harbor freight they have a drill bit set with some really small bits , find which ever one fits the stock jet hole and move up one at a time and use plug readings until you reach a somewhat rich not lean mixture.)
hd springs + advanced timing key.

head milled .50-.100 by it self will have the biggest " thrown in your seat feel".
0r
if you dont want to get the head milled you could get a thinner head gasket which vegas or parsonsracing , or nr-racing has. will increase compression a tad bit slightly bumping up the power

a thing to remember with each mod that will "increase horsepower" .will increase the air flow which you will need to increase the fuel(rejet)

sho305

I hit 37gps with mine on 22s, still with stock carb and block is all stock inside just no governor. Head cut/ported, 4 deg key, robertson made header, car muffler and airbox, vegas HD springs and 1.3 rockers. This is a 420 clone from home depot online, before Vegas was into engines, its a Lifan.

I built another clone before mine its all stock except for the exhaust and airbox which are similar to mine. It runs about 31 gps, or about the same as the stock G9 engine did....mostly because it runs the same rpm. It gets to speed much faster, much more power, took forever for the G9 to get to 30gps (is max it would do on flat road). Think it does around 5400 rpm floating the valves I am sure, mine revs higher with the springs. Really we don't hit the road much so top speed is not a big factor. 37mph on it is a little hairy and I had worked on aligning the front end before that. There you can ride roads but 25mph speed limit. In fact I have only run it that fast a few times mostly just to gps it. Both clones I hogged out the main and little bit on the idle jet too, if you touch the airbox or exhaust you will have to.

Younggun

well just a quick update here, I have been crazy busy between pumping and trying to get everything ready for our trip to talladega next week. I haven't messed with the cart this week other than a few rides to the woods or around the yard. I am waiting on a new throttle cable, due here anytime now, to fix the sticking issue due to burrs near the end of the cable. I am hoping to pick up an index drill bit set tomorrow while I am in the neighborhood of harbor freight, that should help me finish dialing the carb in. I am still waiting on some valve springs and timing key from Geoff as well, with any luck this stuff should all fall into place next week sometime so i can wrap this project up.

Anybody had any luck running an automotive resonator or muffler on their cart? was thinking I may give that a try and see if I could still keep the noise level down a bit while increasing flow.

bigjohn141

I used a Walker muffler # 22769 from oreilly's which I found searching through the big block muffler thread. Its not a cheap muffler but is actually pretty dang quiet. I cant say its as quiet as a factory ezgo setup but its on that level. I have took the cart on the golf course a few times and driven right past the course manager without a word.

Yes I wrapped it in header tape to try and keep the temp down since it does get warm under there.

Oh and one other tip, get the spark plug hole air hose adapter to air the cylinder up to replace the springs if you dont want to remove the head. I did mine in a few minutes without an issue.

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