Need more RPMs ?

Morgan44 · 01-02-2014, 07:12 PM

I don't think I'm getting the full potential from my old motor. With the governor unhooked, 125 compression, no seal leaks, k and n, barbecued muffler, throttle cable correct, choke cable correct, and super clean carb, it just doesn't seem to wind out. I Hooked a tach up and was getting 3250 and might just bump 3500. I'm not expecting a hot rod, I understand what I have. I just think there is a little left on the table. What about the fuel pump? I've taken it apart and inspected and couldn't see any tears or problems. I've read that with the supply to the carb hose off it should pump a pretty good stream. Well I put it into a jar, it did pretty well, but how good of a stream should it be? Is it possible to explain that? Any other ideas on what to check? Maybe I'm wrong and it's all she's got. From reading other post, it just seems to be falling a little short? Thanks !!

1989Marathon · 01-02-2014, 07:20 PM

The problem isn't the lack of fuel, it's the lack of air/fuel. The stock carbs are pretty small. A 2-stroke is just an air pump. If you can't get the air/fuel in, you can't rev it. You'd be surprised what is possible with a larger carb. A 30mm Mikuni is ideal for your motor. I put a 34mm Mikuni on a G1 215cc and it would rev easily to over 7000rpm. 34mm is a bit too large, and makes tuning very hard to do.

Morgan44 · 01-02-2014, 07:44 PM

And what else would need to happen with the addition of a 30mm carb? Any certain place I would get that carb?

1989Marathon · 01-02-2014, 08:21 PM

You can find a used Mikuni VM30 carb on ebay almost all the time. You will need to make an adapter to connect it to the reed cage, then figure out the jetting. The throttle/choke cables go right to the carb. If you have decent skills, it's pretty easy.

Morgan44 · 01-02-2014, 08:48 PM

I'm pretty handy but I don't have any experience with carb jetting. Any info on that process? What about this?

Amazon.com: Mikuni Round Slide VM Series Carburetor - 30mm VM30-83: Automotive

Morgan44 · 01-02-2014, 09:01 PM

Here is some good info I think on carb jetting. I get it. I just didn't know all the proper language for everything. That's some good reading though. Tell me more about which carb to start with? Is the one in the previous post what you are talking about?
http://www.iwt.com.au/mikunicarb.htm

1989Marathon · 01-02-2014, 09:09 PM

You can go on ebay and get one for 1/2 price.

Morgan44 · 01-02-2014, 09:29 PM

I'm not seeing any. Maybe I don't know what I'm looking at. Would I have to get a jet kit and the carb, or would you be able to tell me what to get exactly? I love to learn and tinker so any help is appreciated!

1989Marathon · 01-02-2014, 09:37 PM

Here's a link to a chinese-made 30mm Mikuni. They seem to work pretty decent. There is a link inside to one that has a cable operated choke, but this one can be set up for a cable.

30mm Mikuni

Morgan44 · 01-02-2014, 09:58 PM

And as far as jets are concerned? Do I need additional jets to change out or will be able to work with what's there? What about the exhaust, any changes there?

01-02-2014, 07:12 PM	#1
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Need more RPMs ? I don't think I'm getting the full potential from my old motor. With the governor unhooked, 125 compression, no seal leaks, k and n, barbecued muffler, throttle cable correct, choke cable correct, and super clean carb, it just doesn't seem to wind out. I Hooked a tach up and was getting 3250 and might just bump 3500. I'm not expecting a hot rod, I understand what I have. I just think there is a little left on the table. What about the fuel pump? I've taken it apart and inspected and couldn't see any tears or problems. I've read that with the supply to the carb hose off it should pump a pretty good stream. Well I put it into a jar, it did pretty well, but how good of a stream should it be? Is it possible to explain that? Any other ideas on what to check? Maybe I'm wrong and it's all she's got. From reading other post, it just seems to be falling a little short? Thanks !!
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

01-02-2014, 07:20 PM	#2
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730	Re: Need more RPMs ? The problem isn't the lack of fuel, it's the lack of air/fuel. The stock carbs are pretty small. A 2-stroke is just an air pump. If you can't get the air/fuel in, you can't rev it. You'd be surprised what is possible with a larger carb. A 30mm Mikuni is ideal for your motor. I put a 34mm Mikuni on a G1 215cc and it would rev easily to over 7000rpm. 34mm is a bit too large, and makes tuning very hard to do.
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730

01-02-2014, 07:44 PM	#3
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Re: Need more RPMs ? And what else would need to happen with the addition of a 30mm carb? Any certain place I would get that carb?
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

01-02-2014, 08:21 PM	#4
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730	Re: Need more RPMs ? You can find a used Mikuni VM30 carb on ebay almost all the time. You will need to make an adapter to connect it to the reed cage, then figure out the jetting. The throttle/choke cables go right to the carb. If you have decent skills, it's pretty easy.
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730

01-02-2014, 08:48 PM	#5
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Re: Need more RPMs ? I'm pretty handy but I don't have any experience with carb jetting. Any info on that process? What about this? Amazon.com: Mikuni Round Slide VM Series Carburetor - 30mm VM30-83: Automotive Amazon.com: Mikuni Round Slide VM Series Carburetor - 30mm VM30-83: Automotive
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

Today
BGW	Sponsored Links __________________ This advertising will not be shown in this way to registered members. Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum

01-02-2014, 09:01 PM	#6
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Re: Need more RPMs ? Here is some good info I think on carb jetting. I get it. I just didn't know all the proper language for everything. That's some good reading though. Tell me more about which carb to start with? Is the one in the previous post what you are talking about? http://www.iwt.com.au/mikunicarb.htm
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

01-02-2014, 09:09 PM	#7
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730	Re: Need more RPMs ? You can go on ebay and get one for 1/2 price.
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730

01-02-2014, 09:29 PM	#8
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Re: Need more RPMs ? I'm not seeing any. Maybe I don't know what I'm looking at. Would I have to get a jet kit and the carb, or would you be able to tell me what to get exactly? I love to learn and tinker so any help is appreciated!
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

01-02-2014, 09:37 PM	#9
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730	Re: Need more RPMs ? Here's a link to a chinese-made 30mm Mikuni. They seem to work pretty decent. There is a link inside to one that has a cable operated choke, but this one can be set up for a cable. 30mm Mikuni
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730

01-02-2014, 09:58 PM	#10
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690	Re: Need more RPMs ? And as far as jets are concerned? Do I need additional jets to change out or will be able to work with what's there? What about the exhaust, any changes there?
Morgan44 Gone Wild Join Date: Oct 2013 Posts: 690

Similar Threads
Thread	Forum
RPMS for 295 robin	Gas EZGO
G2 RPMS need to ask again	Gas Yamaha
RPMs	Gas EZGO
HP and RPMs	Extreme DC!
low rpms only	Gas EZGO