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Old 05-23-2011, 08:37 PM
M0t0rHead M0t0rHead is offline
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Default Conversion from Belt to Chain Drive? HELP!

Ok, i had earlier purchased a Go-Kart to rebuild for a school project. It was running great until a few weeks ago, when the belt started slipping at the driven sprocket. I live very far from the track, so I often rip around my streets, BUT THE AREA HAS MANY STEEP HILLS. the belt was fairly new when i bought the kart, and now i can bend the teeth with my finger. i am not sure whether there wasnt enough belt tension, or it just wore excessvly cuz of the hills. Now even if i toe the throttle, the belt slips. im afraid this will happen again, and am thinking about converting the kart to chain drive. is this the best way to go? and how much work would it be?

PS: im using an adjustable engine mount, but i cant tighten the belt further due to seat/sprocket clearance. Also, adjusting gear ratio to reduce slippage wouldnt be an option, as the motor is governed and i dont want to lose valued top speed.
5.5HP honda clone
2:1 Reduction Unit
Optibelt Omega Belt
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Old 05-23-2011, 08:44 PM
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Pics might help a bit.

The conversion is doable, but is going to cost you a few bucks. Now, before you say, "but new belts will cost a lot over time", (and you ARE right), I really think we oughta examine the cause of the failure.

So.. Let's see some pics and get some measurements! You never know- you may be better off with a chain, you may have to regear while you're doing the conversion.
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Old 05-23-2011, 09:07 PM
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a clutch wont be a permanent fix either. they also wear out over time. however you can maintain a clutch, for example lubricate the bushing regularly like you should. you cant do that to a belt..........

also with a clutch, youll increase speed as you increase throttle. the engine has to idle in order for you to stop.

on a belt tensioner you dont need a throttle. you can keep it wide open the whole time and just engage or disengage the belt whenever you need.


when properly used, good quality belts can last a VERY long time. i have seen old rusty tractors completely falling apart, like 50 years old, still original belts.


may want to consider a torque converter if you got the cash. it will outperform a centrifugal clutch.
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Old 05-24-2011, 08:38 PM
M0t0rHead M0t0rHead is offline
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ok, here r some pictures of the Kart during the rebuild in January.
sorry, thunder, i think u misunderstood, i am using a 2:1 reduction unit right now. its basically a wet clutch (centrifugal) that honda sells w/ their motors.
and the belt model is an "optibelt OMEGA 960 8M" so: 960mm belt length, and 8mm tooth spacing?
there is also an OMEGA HP/KARTPOWER belt which is supossed to be tougher, but idk if its worth the extra bucks. but first as u said, toystory, we gotta determine the cause of failure...
also, if u were to stick with belt drive, could i get a shorter belt and slid the adjustable engine mounts back?
1. http://i1204.photobucket.com/albums/...irthday072.jpg
2. http://i1204.photobucket.com/albums/...irthday093.jpg
3. http://i1204.photobucket.com/albums/...irthday092.jpg
4. http://i1204.photobucket.com/albums/...irthday095.jpg
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Old 05-31-2011, 08:09 PM
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Interesting... To convert that to chaindrive and still have the same ratio-
Measure the diameter of the drive pulley
Measure the diameter of the driven pulley
Divide driven diameter by drive diameter (ie 8/2=4)
Select a new centrifugal clutch. Now suppose it has 10 teeth on it.
Multiply clutch teeth by the number found in the above calculation (4) to determine axle sprocket tooth count. ie- 10x4=40.
Purchase 40 tooth axle sprocket.

For the record, I have no experience with cogged belt drives. The principles are there, but I don't know what you can expect for stretch. Do make sure the engine or axle are bolted down firmly and unable to shift...
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Old 05-31-2011, 09:14 PM
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alright, that should work. also, i can swap the driven pulley, i dont need a whole new clutch. my axle bearings have a bit of play, but those arent of much concern for now, right? Thanks for your help
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Old 06-01-2011, 05:12 AM
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I don't know how much play a "bit" is, but you might want to consider remedying that. Could cause the chain to come off...
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Old 06-01-2011, 06:32 AM
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That belt drive looks like it should be fine, as long as it has almost no play. How much would a slightly shorter belt cost? If it isnt that much i would consider trying it.
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Old 08-09-2011, 01:15 PM
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i checked the optibelt website and if im correct the belt lengths change in 20mm increments. So do you think i should go down from the current 960mm to a 940? Or further to a 920mm? The pics above show the (little) seat/cog clearance, if any.
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Old 08-09-2011, 01:19 PM
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cuz i kno that belts stretch out slightly with use. And i dont wanna run into the same problem again of not being able to slide the engine forward, as its already moved forward as far as it can go.
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Old 08-09-2011, 02:19 PM
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Both of my race karts have motor mounts just like yours, they both have about 4 inches of forward/back adjustment. Try adjusting your motor mount all the way back first, then use a tape measure to learn how short of a belt you could use.
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Old 09-24-2011, 03:16 PM
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Toothed belts are positive drive devices cannot withstand any slipage. The very first time it loosened up and slipped probably ruined the belt is seconds. Buy a slightly shorter belt and adjust it regularly. These type of belts are far superior to chain drive when applied properly. They are quieter cleaner and can withstand higher linear speeds than chain. The downside is the sprockets are heavier.
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