Tire Size & Torque

EatBeef

I'm new to modded carts, not new to modded car, truck, ATV or fabrication. I have a 1989 Yamaha gas cart I'm wanting to lift to use for hunting, trail running, etc. nothing extreme. I plan to build my own lift, extending the front and possibly the rear to keep the center of gravity lower while still gaining lift for ground clearance. The cart is missing the back half of the body so I'm not worried about wheel well size or location. The cart runs well and I plan to add a heavy duty clutch spring as I've read here. My question is tire size. What is the tallest tire I can run before effecting performance of a stock engine? Thanks in advance for any input.

BGW

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EatBeef

22"s??? 23"s??? 25"s???

lockman1

Welcome to BGW Beef!

Common law is... as the tire size get's larger, the less torque you'll have.
I'm not very familiar with Yami's, or what engine yours has, (2 cycle/4 cycle, cc's, etc...)
so, It's a guess on just how much torque loss there might be!

One thing... you may not be concerned about tire size on the back with no rear body,
but, if you still have the front cowl on, that may limit your tire size depending on the amount of lift on the front!

slonomo

Most of us with stock engines run 22" and 23" without much trouble. Anything larger will require more HP/Torque to make up for the loss. Just driving around on mostly flat and mild inclines won't make much diff, but hills will. Modified clutch sheaves, belt, spring will help. More power might be in order either way for your personal taste.

1moretoy

EB...if you are building your own lift just make it tall enough you don't have to worry about the tires rubbing but decide what size tires you want first. What model is your 89'? I know mine has a plastic body and it is very light. So if your's is plastic and you can find another rear section put it on. it will not add but about 3-5 lbs.

EatBeef

Thanks for the replies. I was thinking 22's, 23's wouldn't cause to much power lose, but it's good to have an educated opinion. I put the cart on blocks to fake a lift then pulled the 24" front wheels/tires off our ATV and set them in the wheel wells. It looked unbalanced and top heavy to me which is why i was thinking of stretching it 5"-6" in the rear. If I had decided to go with 24" or taller tires I would increase the wheel wells and extent the rear out instead of adding more lift. Right now I have the front drawn up moving the A-arms forward 3" and down 4" which should cover anything 25" or under. It will also have adjustability designed in so I can easily raise it later if needed. I haven't decided what to do with the rear yet. I would like to add adjustable shocks in front and back instead of relocating the original ones. Any idea on weight ranges to look for or specific shock others have used?

EatBeef

Got started on the lift today. Tore most of the front end down, replaced the kingpin bushings and began some mods. I don't like how most lifts I've seen add a tall spacer to keep the tie rods level so I figured I'd move the steering gearbox down a couple inches to accomplish the same end. Had to cut up the original mount and add a doubler plate behind it to support the gearbox. The steering wheel will now be a little lower but that is fine for me. Hope to get more done tomorrow as next week and weekend are already full.

1moretoy

EB, mine is also an 89' with an 8" lift. How are you going to fab your lift in the rear? Mine has blocks in the rear which was done by the previous owner to keep the engine level.

EatBeef

1moretoy since I'm only raising it 4-5 inches I'll likely just relocate the stock spring over shocks. Possibly adding an airbag to adjust ride when I have weight/people on the back. I would like to use adjustable spring over shocks, front and rear, like FOX podiums. I'm not sure what spring rates to look for and I'm afraid they would by cost prohibited. I'm cheap! I still haven't totally poo poo'd the idea of extending the rear which could change my mind. Carts with rear facing seats remind me of riding in the back of a school bus,,, they just look really bouncey. Extending the rear would move the wheels and shocks out under the person and I think improve the ride.
I looked at your photo album, that's one heck of a setup! Is the chain driven gearbox a doubler or hollowed out to be a bearing carrier?

1moretoy

Keep us posted on your outcome. We like lots of pix too. My tranny is all stock except the sprocket vs. a belt driven clutch.