Post subject: LARGER SPROCKET - PROS/CONS/SOLUTIONS
Posted: Fri Sep 12, 2008 4:43 pm
Buggy Enthusiast
Joined: Sun Oct 28, 2007 6:31 pm Posts: 140 Location: Tempe, AZ
I am considering changing to a larger rear sprocket to gain some hill climbing ability. Searching the forum, I see that I can expect a 4-5 mph loss in top speed if I do this. My question is: if I change to a larger sprocket 37 or 39 teeth) could I regain the top speed if I put on larger diameter rear tires? Seems like things would even out. I ask you guys who have more experience in these matters.
Thanks for any information/opinions you may be able to provide. I love this website. All you guys are awesome. I do not see any inputs from women buggy owners/drivers. Is this a male sport?
later, Alzwel (Frank)
_________________ ALZWEL (Frank) Baja Motor Sports Reaction 150. UNI filter, glass pack muffler, #130 main jet, 1/4 inch gas line, 2000 rpm torque spring, yellow clutch springs, 12 gm sliders, speedometer/odometer, chain and brake rotor skid plate.
Joined: Mon May 19, 2008 11:05 am Posts: 539 Location: Grande Cache, Alberta, Cda
I think the larger sprocket was one of the best mods I made for the money. I didn't lose that much top speed at all changing from 32t to 39t, and lets face it... you're not going 40mph climbing hills anyway. (at least not all the way up!)
I gained back speed when I rejetted, added a new air intake and gutted exhaust. But the lighter rollers (or sliders) and larger sprocket turned my buggy from a slug to a mountain goat. It revved higher with lighter weights, so my top speed was really only 3-4mph slower with the larger sprocket. Not enough to notice the difference in my opinion. It depends on how fast you wanna go I suppose.
I think with the larger tires, you may not have the same torque as with 19's or 20's like some of us have stock, but I strongly suggest the sprocket change anyway. No matter what top end your after... your hill climbing ability will improve from where it is now.
PS... My wife drives too, but doesn't come on BN. That's a good thing. Cuz she'd quickly find out just how many hours I spend on this site. It's for the best really. She'd be just as addicted as the rest of us, and NOTHING would get done.
_________________ 05' Carter Talon GSX 150 2R 39t rear sprocket (32t stock) 9g rollers (~14g stock) NGK Iridium Plug H.O. Bando Coil Dr.P Hit clutch 1500# torque spring 120 main jet @ 5000 ft elevation 42 pilot jet Uni Air Filter w/cover Drilled out stock exhaust
Larger tires decrease torque and increase top end. So yes you could gain speed back but it will throw the speedo out a bit. Speedo counts axle rotations and calculates that to a stock tire size for speed. A larger tire you will travel slightly further per tire rotation. Thus slightly higher top speed although the speedo might not show it.
Joined: Mon Jul 16, 2007 9:14 pm Posts: 2595 Location: west virginia
myself i don't think you can go wrong going with the bigger axle sprocket.after looking that you are already running 24'' tires and a stock 31 or 32 tooth sprocket you are geared pretty high.i know everbodys areas are different but your takeoffs and getting up hills couldn't be that good. mine came with a 31t and 22'' tires that where pretty true in height.even after my cvt mods i needed more and the 39t sprocket hit the spot in my opinion the bigger sprocket will gear you lower to get those big tires turning over, probably get to top speed faster. also it will be doing your clutch a big favor when you hit a hill the cvt is shifting down but the axle gearing and big tires is still keeping the gearing higher on that end putting the clutch in a strain.do you heat your clutch up pretty fast when riding? thats just my thoughts pud
_________________ 2006 sunl 150b Dr. pulley 10 gram sliders,prodigy variator, 1500 torque spring,39 tooth sprocket,2000lb winch, red neck uni filter with K&N precharger, 125 main jet at 1,634 elevation, drilled out exhaust,ngk iridium plug,performance intake
I agree absolutely. You will get to top speed faster for sure it will just reduce what that too speed is because you have to turn more rpm for any given speed.
Joined: Mon May 19, 2008 11:05 am Posts: 539 Location: Grande Cache, Alberta, Cda
After I got my buggy running better, last night I took it to the biggest hill I could find, just to see if I could make it now. And I realized something...
Getting up isn't a problem. Getting BACK DOWN is the problem.
I can chew to the top of anything...as long as the tires will grip.
But coming back down, the hill was so steep my front brakes locked up and the buggy just kept on sliding....
Time for new tires and seatbelts.
_________________ 05' Carter Talon GSX 150 2R 39t rear sprocket (32t stock) 9g rollers (~14g stock) NGK Iridium Plug H.O. Bando Coil Dr.P Hit clutch 1500# torque spring 120 main jet @ 5000 ft elevation 42 pilot jet Uni Air Filter w/cover Drilled out stock exhaust
Joined: Sun Feb 12, 2006 7:20 pm Posts: 1238 Location: S. Glens Falls, NY (Upstate)
If you put a larger sprocket on the axle, then put taller tires on, you are going to loose some of what you gained by putting on the sprocket. If you get back to the same top speed at the same engine rpm you will not have changed your overall top (final) gear ratio. You may find that you lose little or no top speed w/ the sprocket change as your engine will be able to rev higher unless you are already bumping up against a rev limiter. How often do you get to max it out anyway!
_________________ FOR SALE 2003 Jehm Blazer 125cc, Vapor 10 gram rollers, 20x10x8 Razr's, 34 tooth sprocket, 9pk cooler
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