Yamaha G9 Clone Build

Lawn Dart · 08-31-2011, 02:35 PM

Hey guys fairly new to the forums here but no stranger to working on small engines or racing or fabrication period.

My cart i just picked up for free last week from my cousin. After doing some research and looking at photos it turns out to be a Yamaha G9 with some missing parts. The plan is to use a predator 420cc engine that i will be picking up early next week sometime. I am still looking and wanting to buy a primary clutch, starter/generator, motor mount for G9. But i might just drop the idle down and use the electric start. The reason i am going with this engine is the warranty. I can blow it up or if anything goes wrong it will have the no hassle 2 yr warranty.

Here is what i am working with. Any suggestions/questions/comments are welcome.

The plan is pressure wash it and strip it down for a nice coat of lime green "lawn boy" paint. Then some different wheels on it also. But that might be a little bit. The tires are 23x12 dirt devils all the way around. I have been wanting to do a golf cart engine swap for a while now and i am finally getting the chance.

Dlcain · 08-31-2011, 03:18 PM

Awsome! Looking forward to see how the build progresses.

G1-G9 · 08-31-2011, 05:28 PM

do you have two different carts? a green one, and a black one? i have a g9 that i plan on putting that engine in. im going to make it so that it starts up with my starter generator and charges with it also. where are you located?

Lawn Dart · 09-01-2011, 07:35 AM

Quote:

Originally Posted by G1-G9

do you have two different carts? a green one, and a black one? i have a g9 that i plan on putting that engine in. im going to make it so that it starts up with my starter generator and charges with it also. where are you located?

No its the same cart. I would like to do that also but here is the run down on the cart. I got it for free from my cousin and his daughter blew it up about 2 years ago. He took the engine and all to the machine shop and the guy just put it off to the side. I am having him look for it and see if he can find it. It has all the stock stuff starter/generator and motor mount, stock clutch. I really hope he can locate it cause it would save me a lot of money off the bat with this swap. I live about 20 mins from downtown louisville, ky on the indiana side.

This swap looks rather simple and straight forward from what i have seen from others. I plan on moving the predator ignition into the body of the cart where the factory ignition is. This cart is also lifted so i don't think i will have issues with clearance. I am going to route the exhaust towards the bottom of the cart i believe and then i have a cone intake from one of my racing lawnmowers that i will put on the carb. And i am thinking of using the stock fuel pump and pulling a vacuum source from the engine. Whats the best spot? Tapping the OHV valve cover and using that?

sho305 · 09-01-2011, 10:43 AM

Here is the clone I did, there are other threads on them.
http://www.buggiesgonewild.com/gas-y...-thread-3.html

The basic problems are you have the airbox/carb close to the rear shock so you have to cut the crank short to get the adapter close to the block. Even if you take the recoil off the carb is close. The clone with the airbox above is easier to use can put a hose off that to a remote air cleaner. The one with the side airbox off the front of carb is a real pain to deal with and the element is just foam not good for a dusty cart. I had to fab a pvc pipe into it and make a flat cover since it hit the shock. You can buy the other box on ebay to move the air intake above the carb.

I laid bars and welded them on top of the stock engine mounts, dropped the front down to level it as you can see in that link. I used stock belts, set it up stock distance to clutch, etc. The new clone I think is the predator iirc not sure about it but the old clone has a mag ignition, which is coil on the flywheel that requires no power. You can't remove it, it only grounds to kill it like a lawnmower engine typically has except some like old kohlers that had an auto style coil and points. I used a relay to ground it when power was off, and it runs just like a stock cart you can't tell except the exhaust sound. Power is about double but it runs about the same top speed both with no governors. It gets up to speed way faster and climbs way better, seems to work fine with the stock clutch but this does have a cut secondary sheave.

I use the carb spacer for fuel pump it overflowed the carb had to put a return line on it. Some have better luck using a smaller B&S or Mikuni pump for a gokart and they don't overflow the float like the yami pump that is larger. Some say the rocker cover works but it is venting for engine and outside the valve in there, it really needs to be under that cover. I'm going to try to tap a hole under it for mine I'd rather not use the intake. Also going to deck my head and advance the timing, etc. See if I can get a little more rpm. You can mod these a lot but it will cost you. The 420cc is just a bored and stroked 390 13hp, they call it 16hp, the manual says 15hp. It does seem to have a lot of torque though it takes off and sets you back in the seat. It spins like crazy if you try to pull something, I even got it to burn a donut taking off dead stop on a dirt drive. At high speed the power just goes away and it will not rev more than a stock G9 with no governor. This one only has the car airbox and car muffler, but no mods to engine at all aside from governor removal. Still has the electric start though it stopped working for some reason, but he never uses it.

You can leave all the stock wiring in the cart, all you will have left hanging is the plugs for the coil, ignitor, and pickup. Use the white/red hot wire from the coil plug to run a relay that grounds the ignition out on the clone to kill it unless it sees power from the cart wire. Otherwise you have no way to turn it off should the throttle get stuck. You can turn the idle off temp to kill it but its not really safe. I starts faster if the idle is set to idle just faster than the compression release blows off at.

Lawn Dart · 09-01-2011, 11:19 AM

Quote:

Originally Posted by sho305

Here is the clone I did, there are other threads on them.
http://www.buggiesgonewild.com/gas-y...-thread-3.html

The basic problems are you have the airbox/carb close to the rear shock so you have to cut the crank short to get the adapter close to the block. Even if you take the recoil off the carb is close. The clone with the airbox above is easier to use can put a hose off that to a remote air cleaner. The one with the side airbox off the front of carb is a real pain to deal with and the element is just foam not good for a dusty cart. I had to fab a pvc pipe into it and make a flat cover since it hit the shock. You can buy the other box on ebay to move the air intake above the carb.

I laid bars and welded them on top of the stock engine mounts, dropped the front down to level it as you can see in that link. I used stock belts, set it up stock distance to clutch, etc. The new clone I think is the predator iirc not sure about it but the old clone has a mag ignition, which is coil on the flywheel that requires no power. You can't remove it, it only grounds to kill it like a lawnmower engine typically has except some like old kohlers that had an auto style coil and points. I used a relay to ground it when power was off, and it runs just like a stock cart you can't tell except the exhaust sound. Power is about double but it runs about the same top speed both with no governors. It gets up to speed way faster and climbs way better, seems to work fine with the stock clutch but this does have a cut secondary sheave.

I use the carb spacer for fuel pump it overflowed the carb had to put a return line on it. Some have better luck using a smaller B&S or Mikuni pump for a gokart and they don't overflow the float like the yami pump that is larger. Some say the rocker cover works but it is venting for engine and outside the valve in there, it really needs to be under that cover. I'm going to try to tap a hole under it for mine I'd rather not use the intake. Also going to deck my head and advance the timing, etc. See if I can get a little more rpm. You can mod these a lot but it will cost you. The 420cc is just a bored and stroked 390 13hp, they call it 16hp, the manual says 15hp. It does seem to have a lot of torque though it takes off and sets you back in the seat. It spins like crazy if you try to pull something, I even got it to burn a donut taking off dead stop on a dirt drive. At high speed the power just goes away and it will not rev more than a stock G9 with no governor. This one only has the car airbox and car muffler, but no mods to engine at all aside from governor removal. Still has the electric start though it stopped working for some reason, but he never uses it.

You can leave all the stock wiring in the cart, all you will have left hanging is the plugs for the coil, ignitor, and pickup. Use the white/red hot wire from the coil plug to run a relay that grounds the ignition out on the clone to kill it unless it sees power from the cart wire. Otherwise you have no way to turn it off should the throttle get stuck. You can turn the idle off temp to kill it but its not really safe. I starts faster if the idle is set to idle just faster than the compression release blows off at.

Awesome thanks for the info. But i know these clutches are very similar to a CVT clutch that was on the Kawasaki prairies that i used to run/race. We would machine the primary clutch facing where the belt resides to get more top speed out of them. I haven't seen anyone on the forum mention that to date. I know my quad would run about 70mph and with the machine work it would run about 15mph faster. It was dangerous going that fast though lol

sho305 · 09-01-2011, 01:32 PM

Depends on what you did, the face can wear and it can be made true again with machining. You can cut them so they go closer together and give more top gear ratio for more speed long as the belt does not come out of the top. Sometimes they slip and machining can get you more belt grip. With carts it is not as useful because you have much less HP to operate with, they never slip. While clutch work can help for sure, it is not the same as an engine with a higher rpm powerband and more power. It can help to cut the inside of the secondary to push the belt up and give a lower bottom gear for climbing and towing, but that cut is where they touch not where the belt goes. Top speed higher gear would help, but up there the engine is out of breath anyway unless you have a built lawn engine with a cam, or ATV engine, etc. so not sure it will give you much. Most people here don't mess with them that much but some in the big block section do.

Lawn Dart · 09-01-2011, 02:45 PM

Quote:

Originally Posted by sho305

Depends on what you did, the face can wear and it can be made true again with machining. You can cut them so they go closer together and give more top gear ratio for more speed long as the belt does not come out of the top. Sometimes they slip and machining can get you more belt grip. With carts it is not as useful because you have much less HP to operate with, they never slip. While clutch work can help for sure, it is not the same as an engine with a higher rpm powerband and more power. It can help to cut the inside of the secondary to push the belt up and give a lower bottom gear for climbing and towing, but that cut is where they touch not where the belt goes. Top speed higher gear would help, but up there the engine is out of breath anyway unless you have a built lawn engine with a cam, or ATV engine, etc. so not sure it will give you much. Most people here don't mess with them that much but some in the big block section do.

Makes sense for most. I would imagine if you are going to go fast with a kart you would ditch the stock rear-end anyways and just use a live axle with disc brakes and a sprocket/chain setup. I know on our racing lawnmowers we ditch them and use a Peerless 700 gearbox with a 1 1/4 Chrome Moly axle with cassettes and disc brakes. Pretty much racing cart parts. But i don't think it would last to long in a heavy golf cart without bending.

Black Thunder · 09-01-2011, 04:16 PM

That looks like my Black Thunder! (before you painted it green)

G1-G9 · 09-01-2011, 06:14 PM

man sho you do alot of typing. nice work also and thanks for all the info you give.

08-31-2011, 02:35 PM	#1
Lawn Dart Not Yet Wild Join Date: Jul 2011 Location: Louisville, KY Posts: 74	Yamaha G9 Clone Build Hey guys fairly new to the forums here but no stranger to working on small engines or racing or fabrication period. My cart i just picked up for free last week from my cousin. After doing some research and looking at photos it turns out to be a Yamaha G9 with some missing parts. The plan is to use a predator 420cc engine that i will be picking up early next week sometime. I am still looking and wanting to buy a primary clutch, starter/generator, motor mount for G9. But i might just drop the idle down and use the electric start. The reason i am going with this engine is the warranty. I can blow it up or if anything goes wrong it will have the no hassle 2 yr warranty. Here is what i am working with. Any suggestions/questions/comments are welcome. The plan is pressure wash it and strip it down for a nice coat of lime green "lawn boy" paint. Then some different wheels on it also. But that might be a little bit. The tires are 23x12 dirt devils all the way around. I have been wanting to do a golf cart engine swap for a while now and i am finally getting the chance.

08-31-2011, 03:18 PM	#2
Dlcain Gone Completely Insane Join Date: Apr 2011 Location: Ocala, Florida Posts: 400	Re: Yamaha G9 Clone Build Awsome! Looking forward to see how the build progresses.

08-31-2011, 05:28 PM	#3
G1-G9 LIFE IS TAKING FOREVER Join Date: Apr 2010 Location: DANSVILLE NY Posts: 5,327	Re: Yamaha G9 Clone Build do you have two different carts? a green one, and a black one? i have a g9 that i plan on putting that engine in. im going to make it so that it starts up with my starter generator and charges with it also. where are you located?

09-01-2011, 10:43 AM	#5
sho305 Vegas modded 420 Join Date: Jun 2009 Location: West MI Posts: 15,443	Re: Yamaha G9 Clone Build Here is the clone I did, there are other threads on them. http://www.buggiesgonewild.com/gas-y...-thread-3.html The basic problems are you have the airbox/carb close to the rear shock so you have to cut the crank short to get the adapter close to the block. Even if you take the recoil off the carb is close. The clone with the airbox above is easier to use can put a hose off that to a remote air cleaner. The one with the side airbox off the front of carb is a real pain to deal with and the element is just foam not good for a dusty cart. I had to fab a pvc pipe into it and make a flat cover since it hit the shock. You can buy the other box on ebay to move the air intake above the carb. I laid bars and welded them on top of the stock engine mounts, dropped the front down to level it as you can see in that link. I used stock belts, set it up stock distance to clutch, etc. The new clone I think is the predator iirc not sure about it but the old clone has a mag ignition, which is coil on the flywheel that requires no power. You can't remove it, it only grounds to kill it like a lawnmower engine typically has except some like old kohlers that had an auto style coil and points. I used a relay to ground it when power was off, and it runs just like a stock cart you can't tell except the exhaust sound. Power is about double but it runs about the same top speed both with no governors. It gets up to speed way faster and climbs way better, seems to work fine with the stock clutch but this does have a cut secondary sheave. I use the carb spacer for fuel pump it overflowed the carb had to put a return line on it. Some have better luck using a smaller B&S or Mikuni pump for a gokart and they don't overflow the float like the yami pump that is larger. Some say the rocker cover works but it is venting for engine and outside the valve in there, it really needs to be under that cover. I'm going to try to tap a hole under it for mine I'd rather not use the intake. Also going to deck my head and advance the timing, etc. See if I can get a little more rpm. You can mod these a lot but it will cost you. The 420cc is just a bored and stroked 390 13hp, they call it 16hp, the manual says 15hp. It does seem to have a lot of torque though it takes off and sets you back in the seat. It spins like crazy if you try to pull something, I even got it to burn a donut taking off dead stop on a dirt drive. At high speed the power just goes away and it will not rev more than a stock G9 with no governor. This one only has the car airbox and car muffler, but no mods to engine at all aside from governor removal. Still has the electric start though it stopped working for some reason, but he never uses it. You can leave all the stock wiring in the cart, all you will have left hanging is the plugs for the coil, ignitor, and pickup. Use the white/red hot wire from the coil plug to run a relay that grounds the ignition out on the clone to kill it unless it sees power from the cart wire. Otherwise you have no way to turn it off should the throttle get stuck. You can turn the idle off temp to kill it but its not really safe. I starts faster if the idle is set to idle just faster than the compression release blows off at.

09-01-2011, 01:32 PM	#7
sho305 Vegas modded 420 Join Date: Jun 2009 Location: West MI Posts: 15,443	Re: Yamaha G9 Clone Build Depends on what you did, the face can wear and it can be made true again with machining. You can cut them so they go closer together and give more top gear ratio for more speed long as the belt does not come out of the top. Sometimes they slip and machining can get you more belt grip. With carts it is not as useful because you have much less HP to operate with, they never slip. While clutch work can help for sure, it is not the same as an engine with a higher rpm powerband and more power. It can help to cut the inside of the secondary to push the belt up and give a lower bottom gear for climbing and towing, but that cut is where they touch not where the belt goes. Top speed higher gear would help, but up there the engine is out of breath anyway unless you have a built lawn engine with a cam, or ATV engine, etc. so not sure it will give you much. Most people here don't mess with them that much but some in the big block section do.

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09-01-2011, 04:16 PM	#9
Black Thunder Not Yet Wild Join Date: May 2011 Posts: 59	Re: Yamaha G9 Clone Build That looks like my Black Thunder! (before you painted it green)
Black Thunder Not Yet Wild Join Date: May 2011 Posts: 59

09-01-2011, 06:14 PM	#10
G1-G9 LIFE IS TAKING FOREVER Join Date: Apr 2010 Location: DANSVILLE NY Posts: 5,327	Re: Yamaha G9 Clone Build man sho you do alot of typing. nice work also and thanks for all the info you give.

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