How far should I go?

Banshee1700 · 12-26-2014, 09:50 AM

Prolly this weekend ima go pick up a Yamaha G1 that's been sitting im sure over a decade! Primarily it will be for my wife... BUT, any married men on here knows how that goes. That being said, an after thread surfin this is kinda wat I'm thinkin. I'm wanting around 30mph top end, I plan to make a custom 6" lift to fit 22-10-10 wheels/tires, clutching it to have enough torque to pull the tires fairly easily, an the motor still be reliable. I'm guessing shave the head maybe .030, port cylinder, I'd like to run a single stock banshee carb(28mm), remove governor, change filter n exhaust so it can "breathe" better. But this is my first cart an I ain't sure how much difference each mod produces. I'm all ears/eyes
An jus Tryin ta get some opinions before hand...

1989Marathon · 12-26-2014, 10:33 AM

Quote:

Originally Posted by Banshee1700

I'm wanting around 30mph top end, I plan to make a custom 6" lift to fit 22-10-10 wheels/tires, clutching it to have enough torque to pull the tires fairly easily, an the motor still be reliable. I'm guessing shave the head maybe .030, port cylinder, I'd like to run a single stock banshee carb(28mm), remove governor, change filter n exhaust so it can "breathe" better.

That won't happen with a G1 motor no matter how much you mod it.
Everything else is a good way to go. The stock exhaust is actually pretty good.
Get ahold of Slonomo. He can offer his experience with G1 mods.

TheGDFP · 12-26-2014, 11:35 AM

These guys have trodden most paths, but maybe...

I wonder how thick the stock steel sleeve is? Cubes is king, and a Phazer 485 has the same stroke, 4mm more bore, for piston up-size.

Maybe even a jug swap? Sled stuff may be too radical, easier to remove than add. You can cut the base of the sled jug and allow piston above deck, recess chamber instead of cutting gasket surface.

Vice-versa, Cometic surely has the pattern, and will make base gasket/spacer to raise jug/ports, cut a like amount off top. Maybe aim closer to Blaster port map?

250cc sled head looks to have a much wider quench pad to start with, and smaller chamber.

Reed tip area seems fine, but could use some streamlining. As narrow as the intake port is, and no Boyesen ports, maybe cut the center divider, run single-petal reed and a directional stuffer? Rad-Valve should help.

Banshee1700 · 12-26-2014, 12:54 PM

Marathon, nice ta finally get ta talk with Ya! I read the thread slonomo posted during his build. It was obvious U know Ya way round a G1! But I'v read threads on here where people say stock it would run 15+, gov adjusted 20 Somethin an off close ta 30... I do know how some people tell "tales" bout there stuff too tho! Wen I worked at the yamaha shop had a dude come n as tell me he had a Banshee pipe on his Warrior... I jus smiled n said bet that helped a lot huh;)... Anyhow... So wat am I lookin at realistically with no gov, stock jug, an clutchin for the 22" tires?

1989Marathon · 12-26-2014, 03:40 PM

Quote:

Originally Posted by Banshee1700

So wat am I lookin at realistically with no gov, stock jug, an clutchin for the 22" tires?

You shouldn't have any problem getting 30mph.

Here are two videos. The first is a stock G1 with no belt and no load on it. The second is my modified G1. I ran that cart at 42mph before I chickened out.

http://www.youtube.com/watch?v=ti9Gh9phoiA

http://www.youtube.com/watch?v=QNFBJDzMfUY

smallblock450sl · 12-26-2014, 05:15 PM

I say.....have fun with it!

Banshee1700 · 12-26-2014, 06:13 PM

I love projects like this, jus hope I ain't counting my chickens before they hatch... It
has been sittin up a LONG time so reckon before I do anything much far as mods I
gotta get er runnin decent first. I Preciate all the advice an stuff an ill keep yall posted
an prolly pick ya brains a lot more before it's over. Anyhow, thanks for MAKIN me feel welcome on the site n hope all yall have a safe n happy New Years!

sho305 · 12-26-2014, 08:30 PM

I ran a mostly stock G1 over 30mph, before the times of gps. I had the head decked you can only deck so much and you hit the chamber, more you have to mod the cylinder. Since they have like 6:1 compression it helps. I raised the exhaust port just a hair. I rotated the crank pickup to advance the forward timing. It helped that the cart was fairly new back then. This was stock tires it really screamed on the top end. I did mess with the clutches but forget what I did.

G1 stock has about the same powerband as a 4cycle and should shift around 3500-4K rpm, and has good torque. It will wind way up unlike a 4 stroke. While its based on a 70s sled motor it has reeds unlike the similar 250cc in older yami sleds. Without reeds you loose the bottom end but breathes a lot better on top. You need the sled pipe to get the power (around 25hp), it can be a chore to get it in there with the same length and widths. Lot of people have swapped the bravo or enticer 250 in there using the G1 pickup on the crank. Personally I'd swap to a 300-340 sled motor they were the bomb and the sound of the twin is much like a banshee. Since they would run over 60 in a sled seems like they would have enough power. Reverse could be worked out somehow.

Banshee1700 · 12-26-2014, 08:37 PM

Hmmm, I got quite a few forks n the road as to which way I wanna go with this thing it seems!
I don't really wanna go all out, spending a bunch of money an 6 months R more gettin it up
an ready... But I DO want (wifey) ta have a bad a$$ buggy;)!

1989Marathon · 12-26-2014, 08:46 PM

With a twin cylinder, you will lose reverse.
A G1 motor has very limited torque. It is by design.
The torque curve of a G1 isn't even close to a 4-stroke.

For those of us that have modified a G1 motor, we can tell you that if you are able to achieve the performance you want(which you won't) you will lose drivability. I don't know of any G1 motors that were tweaked more than mine. Although it will outrun almost any cart on a flat surface, it will lose as soon as it comes to an incline.

If you want low-end torque, a 215cc G1 motor won't provide that no matter what you do to it.

Hopefully slonomo will chime in soon.

12-26-2014, 09:50 AM	#1
Banshee1700 Not Yet Wild Join Date: Dec 2014 Posts: 17	How far should I go? Prolly this weekend ima go pick up a Yamaha G1 that's been sitting im sure over a decade! Primarily it will be for my wife... BUT, any married men on here knows how that goes. That being said, an after thread surfin this is kinda wat I'm thinkin. I'm wanting around 30mph top end, I plan to make a custom 6" lift to fit 22-10-10 wheels/tires, clutching it to have enough torque to pull the tires fairly easily, an the motor still be reliable. I'm guessing shave the head maybe .030, port cylinder, I'd like to run a single stock banshee carb(28mm), remove governor, change filter n exhaust so it can "breathe" better. But this is my first cart an I ain't sure how much difference each mod produces. I'm all ears/eyes An jus Tryin ta get some opinions before hand...
Banshee1700 Not Yet Wild Join Date: Dec 2014 Posts: 17

12-26-2014, 11:35 AM	#3
TheGDFP Gone Wild Join Date: Apr 2014 Location: Flint, MI, USA Posts: 656	Re: How far should I go? These guys have trodden most paths, but maybe... I wonder how thick the stock steel sleeve is? Cubes is king, and a Phazer 485 has the same stroke, 4mm more bore, for piston up-size. Maybe even a jug swap? Sled stuff may be too radical, easier to remove than add. You can cut the base of the sled jug and allow piston above deck, recess chamber instead of cutting gasket surface. Vice-versa, Cometic surely has the pattern, and will make base gasket/spacer to raise jug/ports, cut a like amount off top. Maybe aim closer to Blaster port map? 250cc sled head looks to have a much wider quench pad to start with, and smaller chamber. Reed tip area seems fine, but could use some streamlining. As narrow as the intake port is, and no Boyesen ports, maybe cut the center divider, run single-petal reed and a directional stuffer? Rad-Valve should help.

12-26-2014, 12:54 PM	#4
Banshee1700 Not Yet Wild Join Date: Dec 2014 Posts: 17	Re: How far should I go? Marathon, nice ta finally get ta talk with Ya! I read the thread slonomo posted during his build. It was obvious U know Ya way round a G1! But I'v read threads on here where people say stock it would run 15+, gov adjusted 20 Somethin an off close ta 30... I do know how some people tell "tales" bout there stuff too tho! Wen I worked at the yamaha shop had a dude come n as tell me he had a Banshee pipe on his Warrior... I jus smiled n said bet that helped a lot huh;)... Anyhow... So wat am I lookin at realistically with no gov, stock jug, an clutchin for the 22" tires?
Banshee1700 Not Yet Wild Join Date: Dec 2014 Posts: 17

12-26-2014, 05:15 PM	#6
smallblock450sl Sometime's............ Join Date: Oct 2007 Location: Tacoma Washington Posts: 11,874	Re: How far should I go? I say.....have fun with it!

12-26-2014, 06:13 PM	#7
Banshee1700 Not Yet Wild Join Date: Dec 2014 Posts: 17	Re: How far should I go? I love projects like this, jus hope I ain't counting my chickens before they hatch... It has been sittin up a LONG time so reckon before I do anything much far as mods I gotta get er runnin decent first. I Preciate all the advice an stuff an ill keep yall posted an prolly pick ya brains a lot more before it's over. Anyhow, thanks for MAKIN me feel welcome on the site n hope all yall have a safe n happy New Years!
Banshee1700 Not Yet Wild Join Date: Dec 2014 Posts: 17

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12-26-2014, 08:30 PM	#8
sho305 Vegas modded 420 Join Date: Jun 2009 Location: West MI Posts: 15,443	Re: How far should I go? I ran a mostly stock G1 over 30mph, before the times of gps. I had the head decked you can only deck so much and you hit the chamber, more you have to mod the cylinder. Since they have like 6:1 compression it helps. I raised the exhaust port just a hair. I rotated the crank pickup to advance the forward timing. It helped that the cart was fairly new back then. This was stock tires it really screamed on the top end. I did mess with the clutches but forget what I did. G1 stock has about the same powerband as a 4cycle and should shift around 3500-4K rpm, and has good torque. It will wind way up unlike a 4 stroke. While its based on a 70s sled motor it has reeds unlike the similar 250cc in older yami sleds. Without reeds you loose the bottom end but breathes a lot better on top. You need the sled pipe to get the power (around 25hp), it can be a chore to get it in there with the same length and widths. Lot of people have swapped the bravo or enticer 250 in there using the G1 pickup on the crank. Personally I'd swap to a 300-340 sled motor they were the bomb and the sound of the twin is much like a banshee. Since they would run over 60 in a sled seems like they would have enough power. Reverse could be worked out somehow.

12-26-2014, 08:37 PM	#9
Banshee1700 Not Yet Wild Join Date: Dec 2014 Posts: 17	Re: How far should I go? Hmmm, I got quite a few forks n the road as to which way I wanna go with this thing it seems! I don't really wanna go all out, spending a bunch of money an 6 months R more gettin it up an ready... But I DO want (wifey) ta have a bad a$$ buggy;)!
Banshee1700 Not Yet Wild Join Date: Dec 2014 Posts: 17

12-26-2014, 08:46 PM	#10
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730	Re: How far should I go? With a twin cylinder, you will lose reverse. A G1 motor has very limited torque. It is by design. The torque curve of a G1 isn't even close to a 4-stroke. For those of us that have modified a G1 motor, we can tell you that if you are able to achieve the performance you want(which you won't) you will lose drivability. I don't know of any G1 motors that were tweaked more than mine. Although it will outrun almost any cart on a flat surface, it will lose as soon as it comes to an incline. If you want low-end torque, a 215cc G1 motor won't provide that no matter what you do to it. Hopefully slonomo will chime in soon.
1989Marathon Gone Wild Join Date: Oct 2010 Posts: 6,730

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