Just installed Duromax 440 in my G2, idle creep problem

[fernando651]

Hi guys,

Firstly, thank you for this awesome resource, I used the handy cvt belt length calculator to order my belt.

I finally got to the point of starting my new engine today, and found out that I either have a clutch problem or a belt size problem- because the cart abruptly slams into gear.

I thought I'd save a few bucks with the chinese 780 clutch from ebay.. Maybe that was my mistake.

It appears to engage slightly when at idle. I adjusted the idle speed on that carb to its lowest setting ,which helped a little. But you can clearly see that the clutch closes in about 1/2" when at idle. Which causes the driven pulley to spin, is that normal? Is it a bad clutch?

Or is it possible my belt is too small? if it's too small, how do I figure out which size to get? I'd hate to buy and return 5 belts to figure it out.

Thanks in advance for any help!

-Fernando

[fernando651]

oh, also- its a lifted yamaha G2, i would like the engine to be on all the time, not like a normal golf cart where it turns on when you press the gas.. maybe thats my issue?

I'd love to post a pic of my engine setup but the site wont allow it.

[TheNewGuy]

I believe you need one more post to be allowed to post pics.

[fernando651]

Thanks yes, is believe i need to be 7 days old to post links...

I did some more digging and found that i can replace my clutch springs: beltpalace . co m/comet302292a .ht ml maybe this will do the trick.

[slonomo]

What rpm is the engine running when idling? Need a tachometer for that.

Most stock clones out of the box will idle easily at 1500-2000rpm, but it might take some fiddling and tuning to get it down near 1000-1200 rpm. You have to remember that these engines are designed to run pressure washers, generators, tractors, log splitters....they want to run at 3600 rpm with the built in governor, that's how they are designed. The carbs were never designed to idle at 1000 - 1200 rpm. They "can" idle that low with some work. There are carbs and parts available to help make that happen.

A genuine 780 for a 4 stroke will typically engage at around 1600-1800 rpm. I'm betting your rpm is way high, which will make the cart "creep".

Also, a good belt will have about 1.5"-2" of deflection when installed. You want it to be tight, but not so much that there is no give. When your cart is not running, push down on the drive belt. How much does it move down?

[fernando651]

Thank you for the response Slonomo. I did a bunch more research and got in touch with Jim from beltpalace.com, he has been very helpful. I figured out my engine RPM is 1700, that's the slowest I can get it using the plastic Philips screw on the carb.

I decided to swap the springs out of my Chinese clutch. The ones in there were yellow. I put some purple ones in and it fixed the issue, the clutch no longer engages at idle. I also figure out my weights are 104g (including rocker assembly/rollers/weights.

Sadly, the belt still grabs anyway. Maybe my belt is too big or small.

Here's a nice spring engagement/rpm chart:
http://forums.bajasae.net/forum/uplo...SAECatalog.pdf page 8.

The belt I'm using: Carlisle - MAX1060M3 - Ultimax Max Drive Belt, 1 3/16in. x 43 1/2in.

My dimensions:
Center to center is 12"
Driver pulley is 7-7/16"
Driver pulley with belt wrapped around is 2.61"
Driven pulley is 8-15/16"

Engine has a 1" bore. Driver pulley has 1.37" hub. Think I have the wrong belt?

CVT belt length calculator

[raydhd]

A really easy fix to the idle problem is to use a genuine Honda carb with an adjustable idle circuit from ARCracing part # DJ-3225 and nip off the limiter cap and add an adjustable main jet from either ECcarbs or NRracing. You then have a VERY EASY to tune carb that bolts right in and can be adjusted for a 1000 or so RPM idle and can also be dialed in for a lot more power. It will end up looking like the carb on the bottom left unit in my carbs,carbs,carbs in my carbs,carbs,carbs thread which I bumped for you.

[fernando651]

Thanks Raydhd, happy to see those are only $55 or so. And this will bolt right up to my duromax 440 huh? Dang that means im gonna have to play with my linkage setup again. i will keep this in mind.

so you think a lower rpm will allow the belt to slip? when you guys idle, your driven gear doesnt move right?

[raydhd]

That carb should fit right in with your present linkage. I use a key start so any time I am stopped the clutch is spinning but not the belt. I am using the green springs on my 780R clutch. My idle is just under 1100 RPMS.

[slonomo]

Agree. These clutches are designed to engage at around 1800 rpm so yours is right there, it's trying to engage. Your idle speed needs to be down near 1000-1200 rpm to work correctly. These engines in stock form were never designed to do that so you'll have to either modify the current carb or use a different one that will idle.

How did you determine what rpm your engine is idling at?

Also, drive belts need to have about 2" of deflection. If they are too tight they will grab the sheaves as they are spinning at idle.