Best Carbs for GX390

STSClays.com · 03-13-2013, 01:07 AM

Can you give me your experiences with this engine and its carb? Which carb is best suited for the Golf Cart crowd?

Can you post specs of whatever carb (jetting) you are running and how you like them. Also please list your mods too!

Thanks,

Joe

geoffw · 03-13-2013, 12:19 PM

It really depends what you will be doing with the engine. A stock cam engine using the stock starter/gen will be fine with a stock carb. The only time you need to upgrade is when building the engine for considerably more horsepower.

Likewise, if you ditch the starter/gen and decide to use an electric start engine and let it start and idle like a car would...you will benefit from a good CV carb or any carb with an accelerator pump to cure the off-idle stumble.

On my built GX440 Clone, I use this carb:

http://www.ebay.com/itm/New-Suzuki-L...85f303&vxp=mtr

However, my engine makes 35+hp and sees over 7000rpms.

Call for more details and ill steer you in the right direction.

-Geoff

STSClays.com · 03-13-2013, 01:11 PM

I wont be making that much HP. I honestly just want a carb that will make the engine crisp with no stumbling. I will not have the starter generator on there as I am converting an electric cart to gas using the GX390 engine.

Joe

geoffw · 03-13-2013, 01:20 PM

Joe,

It sounds like a re-jetted stock carb will suit your needs perfectly! The carbs are tuned very lean from the factory to comply with emissions regulations, keep fuel consumption down and because the engines themselves are designed to run at a stable rpm.

-Geoff

STSClays.com · 03-13-2013, 01:45 PM

I tend to agree but I've noticed they only have the one brass jet and a black plastic jet for the pilot circuitry. What sizes would you recommend and what do you do with the Plastic jet?

geoffw · 03-13-2013, 01:54 PM

We drill them out and tune them based on the owners setup and location. Depending on your local climate and the mods you have done, you can drill them out with micro drill bits until you get the desired results.

If you plan on removing the governor and installing some HD springs, you can safely take the engine to 5500-6000 but you might want to richen up the main jet a good bit more.

STSClays.com · 03-13-2013, 02:45 PM

What do you typically drill the pilot just up to in size? That will be the fun one to deal with as it has to be super small to start with!

sassycat · 03-13-2013, 03:11 PM

i use the lil pocket pens with a bunch of drill bits in it..like for cleaning torch tips but these are the drill bits..very cheap and many size bits in there,and you use the "pen"thing to dril the holes by hand very slow..

i just finished my 13hp gx390 and its in the cart and running,3 linked with panhard bar,custom cradle..still have to do the throttle cable and make a intake to be running around tho..
would love to no what jet i can use and wht to do to safely get the rpm,s you mentioned?
i been reading to not take the stock motors past 3800 or somthing like that..
i can already tell the gx390 works the clutches much faster and seems like im gonna like it for what it is..hope you do the same

geoffw · 03-13-2013, 03:18 PM

My contact info is in my signature....Ill be glad to help you both out!

Im very friendly and I love to talk, typing gets old though :)

sassycat · 03-13-2013, 05:20 PM

thanks

very nice of you..when i get to playing with it more i may just do that,and order some parts possibly

03-13-2013, 01:07 AM	#1
STSClays.com Getting Wild Join Date: Mar 2013 Posts: 77	Best Carbs for GX390 Can you give me your experiences with this engine and its carb? Which carb is best suited for the Golf Cart crowd? Can you post specs of whatever carb (jetting) you are running and how you like them. Also please list your mods too! Thanks, Joe
STSClays.com Getting Wild Join Date: Mar 2013 Posts: 77

03-13-2013, 12:19 PM	#2
geoffw Gone Wild Join Date: Jun 2012 Location: Las Vegas, NV Posts: 961	Re: Best Carbs for GX390 It really depends what you will be doing with the engine. A stock cam engine using the stock starter/gen will be fine with a stock carb. The only time you need to upgrade is when building the engine for considerably more horsepower. Likewise, if you ditch the starter/gen and decide to use an electric start engine and let it start and idle like a car would...you will benefit from a good CV carb or any carb with an accelerator pump to cure the off-idle stumble. On my built GX440 Clone, I use this carb: http://www.ebay.com/itm/New-Suzuki-L...85f303&vxp=mtr However, my engine makes 35+hp and sees over 7000rpms. Call for more details and ill steer you in the right direction. -Geoff

03-13-2013, 01:11 PM	#3
STSClays.com Getting Wild Join Date: Mar 2013 Posts: 77	Re: Best Carbs for GX390 I wont be making that much HP. I honestly just want a carb that will make the engine crisp with no stumbling. I will not have the starter generator on there as I am converting an electric cart to gas using the GX390 engine. Joe
STSClays.com Getting Wild Join Date: Mar 2013 Posts: 77

03-13-2013, 01:20 PM	#4
geoffw Gone Wild Join Date: Jun 2012 Location: Las Vegas, NV Posts: 961	Re: Best Carbs for GX390 Joe, It sounds like a re-jetted stock carb will suit your needs perfectly! The carbs are tuned very lean from the factory to comply with emissions regulations, keep fuel consumption down and because the engines themselves are designed to run at a stable rpm. -Geoff

03-13-2013, 01:45 PM	#5
STSClays.com Getting Wild Join Date: Mar 2013 Posts: 77	Re: Best Carbs for GX390 I tend to agree but I've noticed they only have the one brass jet and a black plastic jet for the pilot circuitry. What sizes would you recommend and what do you do with the Plastic jet?
STSClays.com Getting Wild Join Date: Mar 2013 Posts: 77

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03-13-2013, 01:54 PM	#6
geoffw Gone Wild Join Date: Jun 2012 Location: Las Vegas, NV Posts: 961	Re: Best Carbs for GX390 We drill them out and tune them based on the owners setup and location. Depending on your local climate and the mods you have done, you can drill them out with micro drill bits until you get the desired results. If you plan on removing the governor and installing some HD springs, you can safely take the engine to 5500-6000 but you might want to richen up the main jet a good bit more.

03-13-2013, 02:45 PM	#7
STSClays.com Getting Wild Join Date: Mar 2013 Posts: 77	Re: Best Carbs for GX390 What do you typically drill the pilot just up to in size? That will be the fun one to deal with as it has to be super small to start with!
STSClays.com Getting Wild Join Date: Mar 2013 Posts: 77

03-13-2013, 03:11 PM	#8
sassycat Gone Wild Join Date: Sep 2012 Location: bikini state Posts: 2,715	Re: Best Carbs for GX390 i use the lil pocket pens with a bunch of drill bits in it..like for cleaning torch tips but these are the drill bits..very cheap and many size bits in there,and you use the "pen"thing to dril the holes by hand very slow.. i just finished my 13hp gx390 and its in the cart and running,3 linked with panhard bar,custom cradle..still have to do the throttle cable and make a intake to be running around tho.. would love to no what jet i can use and wht to do to safely get the rpm,s you mentioned? i been reading to not take the stock motors past 3800 or somthing like that.. i can already tell the gx390 works the clutches much faster and seems like im gonna like it for what it is..hope you do the same

03-13-2013, 03:18 PM	#9
geoffw Gone Wild Join Date: Jun 2012 Location: Las Vegas, NV Posts: 961	Re: Best Carbs for GX390 My contact info is in my signature....Ill be glad to help you both out! Im very friendly and I love to talk, typing gets old though :)

03-13-2013, 05:20 PM	#10
sassycat Gone Wild Join Date: Sep 2012 Location: bikini state Posts: 2,715	Re: Best Carbs for GX390 thanks very nice of you..when i get to playing with it more i may just do that,and order some parts possibly

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