Help with 4stroke engine coupled with a 2002 Ezgo Dana Spicer transaxle

[CCGC2004]

I recently bought a 2002 Ezgo TXT conversion (elect to gas). The engine is a GY6 161QMK with CVT and FNR, driving the Dana transaxle via a jackshaft. The cart has a top end speed of roughly 25mph overland with my son and I onboard. I bought the cart as a project for the family and put a flip rear seat on it, seatbelts, tuned it up, changed all fluids, and called the wife and kids to hop on for a ride, figuring that if the engine was strong enough to go 25mph it could surely get the family down the neighborhood street. Huge red-face moment as the cart would not move with 4 passengers (roughly 500lbs total weight) and I heard an awful grind. So...I researched gear ratios and began looking into this and other possible causes and noted the gear ratios the builder of the cart used are horrible for my situation...all meant for top end and no torque. When built, a small sprocket on the jackshaft was likely used due to the confined space the jackshaft is in). I need more torque to first get the family moving and then maintain a nice cruising speed...and understand this will shave off top end speed which is fine. In doing this I want to be able to still use the Ezgo Dana transaxle set up with existing brakes (avoiding the jackshaft if possible) vs running a solid live axle. My thought is to turn the transaxle around so that the engine output shaft and the transaxle input shaft are both on the same side of the cart (facing towards the passenger side). With this I could, with the right sized sprockets, drive the transaxle directly from the engine output shaft. Has anyone successfully done this before?? Could really use some help figuring it out...or getting a better idea to run with. Thanks all in advance!

[CCGC2004]

Here is a graphic depiction of what I have and the options I am exploring...

[slonomo]

Wow, I'm not really sure what I can do to help you, it looks like you have it figured out. I'm not super familiar with the gy6, except I know it's a 150cc single cylinder engine with about 8 hp. I'm guessing the torque is about the same, maybe 10-12 lb ft. That engine is designed to be used in go karts that weigh less than a golf cart, and mostly for carrying 2 kids.

Let's do the math.

Go kart weight 500 lbs
Kids weight 300 lbs
Total weight = 800
Power to weight ratio = 100:1

Golf cart weight = 700 lbs
Adults (4) weight = 500 lbs
Total weight = 1200 lbs
Power to weight ratio = 150:1

You are trying to overcome a serious power to weight ratio deficit. Not sure that powerplant is up to the task. But, if you want to try, here are my thoughts.

Ideally you'd want equal sprockets on each side so that is effectively a 1:1 ratio. That way your CVT will use the factory go kart gearing, which will be similar to a golf cart drive ratio. I would go small, using two 12T gears, since you have one already. You'll need to change the chain, but that's not a big deal if you have the tool for it. You can start there and see how she does, I'm betting it will be a night and day difference in acceleration and torque.

[CCGC2004]

Thanks for the feedback! This particular GY6 is a 170cc set up so maybe has a little more power to turn into torque. I have already tuned the varistor and clutch for more torque (10g sliders in the varistor and 1500rpm clutch springs). This helped some, but not enough to overcome the gear ratios in the current set up. So...do you think I can flip the transaxle and avoid the jackshaft, or should I keep the jackshaft and go 1:1 from the engine to the jackshaft and 1:1 from the jackshaft to the transaxle? Thanks again...really appreciate it!

[CCGC2004]

Sorry about spell check..."variator"!

[slonomo]

I would not flip the transaxle at any costs. Changing the gearing to 1:1 ratio should be fairly simple, no?

[CCGC2004]

Agree on less work...just figured if I could go straight from the engine to the transaxle it would make the whole set up "simple". That said, I am going to go with the 1:1 from the engine to the jackshaft. Assume I should also go 1:1 from the jackshaft to the transaxle? I will hopefully get to this in the next 7 days and will update the thread with the results! Thank you for the assistance!

[slonomo]

Originally Posted by CCGC2004

Agree on less work...just figured if I could go straight from the engine to the transaxle it would make the whole set up "simple". That said, I am going to go with the 1:1 from the engine to the jackshaft. Assume I should also go 1:1 from the jackshaft to the transaxle? I will hopefully get to this in the next 7 days and will update the thread with the results! Thank you for the assistance!

Yes, basically you want the crankshaft rpm to match the input rpm of the primary clutch. That will effectively give you "the same" speed as if the clutch was run directly to the engine. You can still always play with the input side gears and adjust the gearing from there, once you know how the cart reacts. I think it's going to work much much better.

[CCGC2004]

Rgr all...I am optimistic

[CCGC2004]

Ok...so much for optimism I guess. So here is where I am at. I ended up with a 19 tooth output sprocket driving a 24 tooth on the jackshaft (couldn't do a matched tooth as planned). The chain has considerable slack even though by online calculators and manual measurements and fitting it is the correct length (cannot take another link out or it will not fit on the sprockets and have no way to move the engine or jackshaft to take up the slack). From the jackshaft I have a 3.5" pulley driving another 3.5" pulley on the transaxle. I am experiencing, from the way it feels, what I would think is either the v-belt slipping, or the transaxle gears slipping, or the hubs slipping. There is no grinding feeling or noise. I can get the cart to move in forward and reverse but it is jerky and the engine is getting to high rpm's to get things going. I am perplexed by this as I did not have this issue with the previous set up (just had no low end torque). Any ideas??

Don't hate on the belt tensioner...it looks bad but worked on the original set up :)