I have a bennchee bighorn 500 the motor looks identical to a Yamaha rhino 450 I'm wanting to turn bigger tires does anyone have any advice?

 

Google sheave shims or primary shims. Then google fixed plate mod to get back the top end you will loose with the shims. On a Yamaha 450 you can shim up to 1.5mm with out belt rubbing. Only way you will know is get shims and install. Then see how much clearance the belt has to the cover. They were a few that would machine the primary sheaves for more bottom end without effecting the top end. Seems most all are nearly impossible to get up with now. You could pull your primaries and take them to a good machine shop and pay them to machine say 1mm to nothing across 3/4 of the face of the primary also.

 

Ok thanks cause I've gotta do something I have problems turning my stock 25 in tires in the thick mud

 

Are you okay with the factory top speed or never use it? If never use it all you would need would be the shims. Very easy install, though you do need an impact to loosen the primary pulley nut. You can see U tube for videos on installing shims and removing/installing drive pulleys.

 

Did a little searching. The Bennche is made by the same manufacture as Hisun. So that may help you. Typically anything that would fit the Hisun UV with the 471cc engine should work for yours. On the California Carb Board they list the Bennche as only having 14.5 kws of power, that translates to around 19.5 hp. Have no clue as to why they are rated so low on horsepower. That is part of your problem. I still think CVT mods will give you the very most bang for the buck! You could also try lightening the roller weights in the CVT. They typically have a nylon or some other material outer shell with a metal ring cylinder of weight. Try a socket or something the size of the cylinder that will fit inside the outer shell. Tap the cylinder weight out. You would need scales that read in grams to weigh them, see your local drug dealer, just kidding, or anyone you know that reloads ammo. Use an 1/8" drill bit and drill through both sides about half way of the little cylinder weight and reweigh. For a Grizzly that removes one gram of weight, don't know if it is the same for yours. I would look to reduce weight by 2 grams each. What this does is requires slightly higher rpm before the CVT engages, hence increasing torque! You will typically turn slightly more rpm for any given speed. The shims and lightening the weights will not cost you but time mostly, maybe $8-10 for a set of shims.

 

Ok thanks for the info I'll try that and as for the top speed I really don't use it maybe every once and awhile but I would sacrifice some speed for some torque. Any other pointers like brands of belt or anything for more torque?

 

Not on the belt. If you open up your cvt to lighten your rollers message or post up your shaft inside diameter and your boss outside diameter (collar between the two primary sheaves). That will be the inside and outside diameter of the shims. Pretty sure you should be safe with 1.5mm thickness. I have a full set coming for my wife's Grizzly. I can compare there size to your dimensions. To check if 1.5 mm is okay installed and if you want to know 2mm will fit you jack up the rear, start it up and leave the cover off. Rev it up, you want to make sure the belt doesn't rise high enough to touch the cover. I think the shims and a couple of grams off each roller will be what you are looking for.

 

Ok thanks for all the great info I'm going to try it all.

 

I have the shims in my wife's Grizzly 450 now (1.5mm). Waiting for the fixed plate to come from the welders and I should have it back together today! Bent the outside edges in 1.5mm too so the top speed will not change, hopefully. Not tht she even knows what it is! I do though!! If I like it the Kymco will be next!!

 

The Grizzly accelerates better now with the shims in. It lost 1 mph off the top, 54 mph now, 55 mph pre shim and fixed plate mod. In the Grizzly I have a total of $28.50 for the shims and having the fixed plate cuts welded up. On pavement it only gained a little faster acceleration to 60 kph, 6.325 seconds fastest time pre-shim, 6.28 after shimming. In my gravel driveway, it's 175 yards long, pre-shim best was 7.470 seconds to 60 kph. After shimming my best time is 7.110 seconds. So I consider it well worth the little time and money I have invested. It does seem to accelerate harder out the hole but I don't know if the fixed plate is slowing down the upper midrange. Over 50 mph it took for ever to hit 54 mph. Wished I had a way to measure 0-30 or even 45 kph. I used a GPS app on my phone that has trap times for 0-60 and 0-100. I can change them to kph which works better for our quads a we might never see 60 mph, I just can't go lower than 60 kph on the app. which is 37.28 mph.