G1 performance

[frankr2994]

ya well i recently got an old g1 that is a pile of crap. got the body ripped off of it and basically throwing it away. anyways i took off the carb and replaced it with a factory yamaha blaster carb i had laying around.bypassed the oil injection and mixed up some gas with 50:1 amsoil. also my factory blaster iginition coil with a spark plug for a blaster ( different thread depth and heat range than what was in it.) my first question is how has anyone adapted the throttle cable for the blaster carb. i have my stock cable off the blaster but its not long enough to do anything with. before i spend alot of time making linkages under the cart has anyone came up with something simple? i will also be putting on a stock blaster pipe. no questions there i can make that work. i want to mill the head on the engine as well. without CCing the head to determine my compression ratio and how much to mill does anyone have a good number of thousandths to mill off? and the last question is ignition timing. with the whole reverse deal can i advance the timing. haven't tore into that part of it yet but if it just uses 1 pickup and its set a 0 i guess there is nothing i can do. or has someone added a second pickup for reverse so the timing can be advance.

so questions are throttle cable, milling the head, and timing.
and by the way i have drove it around just sitting on the gas tank and working the carb with my hand and it already feels like it has double the power it had when i started. my goal would have it strong enough where i could powerslide it a little bit.

[slonomo]

so questions are

throttle cable
*Probably going to have to rig it up. The blaster carb is a gravity fed type that most dirt bikes and motorcycles use. The G1 uses a fuel pump so it might flood the carb out, so watch that.

milling the head
*You can do that and it will raise compression a bit, but not much, probably not enough to make any real power. These engines are made for low power and longevity since they were in golf carts. You'll never make any real power with the stock cylinder and piston because the porting is really what limits the power curve and output.

timing
*You can advance the timing by rotating the timing plate counter clockwise. The adjustment screw holes for the timing plate only allow you to rotate it so far and the amount of adjustment won't yield much power but might enhance the throttle feel in forward. In reverse the engine will run worse, but still should work ok.

my goal would have it strong enough where i could powerslide it a little bit.
That will likely happen on gravel only if it's tuned right, good belt and clutches, and the original 18" tires. This engine is very limited in how much power it will make so don't expect too much as far as horsepower. Even with good compression, bigger carb, bigger expansion chamber exhaust, this engine will top out at 12-13 hp. if you are lucky. The real way to get more power is to convert it to a Enticer 250 or Bravo 250 snowmobile engine. You can retain the electronics so you'll have reverse. You'll double the horsepower with stock tuning, right around 18-20 hp, and up to 30 hp tuned.

[frankr2994]

it will make as much hp as i want it to make. just might take more work. its a 2 stroke and a motor that i am somewhat familiar with. i used to drag race a yamaha blaster those had bad porting and were very weak stock and i made it fly. so ok rig the carb. oh and i have been driving it. the fuel pump does not overpower it. i don't have a fuel gauge on it but i'm thinking a little pulse pump like that is just a little bit of flow at about 1/2 psi. but how much can i mill the head? oh and if i am not satisfied with how it runs when i'm done i don't really have an issue with taking the jug off and porting it out. i just know that all i'm going to really pickup is topend so its not getting ported unless i'm not happy.

[slonomo]

Sounds like you have a good plan then.

As far as milling the head, I don't know how much to tell you, you could do the old playdough trick. take the head off, put a small layer of playdough on the piston, replace the head and cycle the engine by hand one turn. Remove the head and inspect the playdough to see where it contacts. Add some more playdough in the low spots and cycle it over again. Once you have the entire compression area filled with dough, you then can measure how much clearance you have/how much of a dome you have. That will let you know how far is too far when milling.

The compression on this cart is ultra low and the ports are tiny and positioned in the cylinder for low rpm power only. This cylinder design will never make real "fun" power. It will get better as you tweak it, but it will be limited.

In contrast the Blaster ports are bigger and are positioned in the cylinder for much higher rpm power. The Blaster also used an expansion chamber exhaust and 26mm carb to give it 16-18 hp in stock form. With carb, pipe, and piston it could make 22-25 hp. The Blaster engine was actually derived from a water cooled dirt bike design and they plugged the water jackets to make it air cooled. It's a high revving race engine that was de-tuned.

As long as you aren't expecting Blaster-like performance increases then you'll be doing ok. A few extra horses and good throttle response is definitely possible.

[slonomo]

You might enjoy these threads, I did....

http://www.buggiesgonewild.com/big-b...lockin-g1.html

http://www.buggiesgonewild.com/big-b...-250-swap.html

This is the best way to get real performance from a G1 cart. It looks and runs like factory. I'm in the process of doing an Enticer 250 top end swap on mine. Will have a write up very soon.

[pachanga90]

One of the primary power-killers is still the timing,both ignition and port-timing.Yes you can change both,but advancing timing will decrease ability to run in reverse.The newer sleds that run in reverse for reverse-gear,have ignitions-systems that will adjust timing as necessary.Other than that,see how far you can push it before it pops!

[slonomo]

Originally Posted by pachanga90

One of the primary power-killers is still the timing,both ignition and port-timing.Yes you can change both,but advancing timing will decrease ability to run in reverse.The newer sleds that run in reverse for reverse-gear,have ignitions-systems that will adjust timing as necessary.Other than that,see how far you can push it before it pops!

Ditto

[sho305]

I had one with a decked head, I think I only took 030 off it. Problem is they are iirc 6:1 compression and if you port the exhaust higher less than that. You mill the head and get into the squish band pretty quick so you need to cut the cylinder for big compression and its hardly worth it might as well go to the 250 parts/engine. I did advance the timing it was doggy in reverse after that. Long time ago I think I opened up the holes in the plate to rotate it more. I cut the exhuast port roughly 1mm higher if that. I worked on the clutches, the stock G1 clutch with a spring in it. This cart would spin all over on grass or gravel/dirt, and would spin the tire on pavement too. It did at least 30mph but before the times of gps back then. It was all stock on the outside. I may have done more to it was always messing with it.