CT200U - Increase Top Speed? 60 Tooth Rear Sprocket?

#1
I've got a stock CT200U. I clocked it at around 21-22 mph this weekend. I'd like to get it up to 28-30mph with the easiest mods possible. I am not as interested in increasing low end torque as much but I also don't want to exchange a ton of it for top speed. I also don't want to remove the governor, as I'd prefer to keep the engines RPMs safe to extend longevity.

Any ideas on how to increase my top speed by 8mph? Will a 60 tooth rear sprocket give me a speed increase? I saw a video on Red Beard's garage where he added a 60 tooth rear sprocket and claimed it gave him more torque and more top speed. But he also had the high performance engine mods done to the bike as well.
 
#3
I've got a stock CT200U. I clocked it at around 21-22 mph this weekend. I'd like to get it up to 28-30mph with the easiest mods possible. I am not as interested in increasing low end torque as much but I also don't want to exchange a ton of it for top speed. I also don't want to remove the governor, as I'd prefer to keep the engines RPMs safe to extend longevity.

Any ideas on how to increase my top speed by 8mph? Will a 60 tooth rear sprocket give me a speed increase? I saw a video on Red Beard's garage where he added a 60 tooth rear sprocket and claimed it gave him more torque and more top speed. But he also had the high performance engine mods done to the bike as well.
I think you missed that he had a Torque Converter. With a clutch, there is no way to gain both torque AND speed by changing gears. It is all a trade-off.

Now I will add that a torque converter swap is pretty easy with the OMB kit and it will give gains on bottom AND top end, but it is much more expensive than simply changing a sprocket.
 
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Bonanza Bryan

Well-Known Member
#4
I would spend the money and get a 30 series tav along with a stage 1 performance kit with 18lb valve springs that will get you to where you want to be and your bike will ride much better with the tav
 
#5
I’ve been debating getting the torque converter but I don’t know a lot about them. I primarily ride this bike out in the desert near Joshua Tree down in SoCal. So it’s very sandy and some of the dry lake beds I ride on are dusty and have a fine, talc like powder. Since a TAV is belt driven, would this be an issue in that type of environment? Just wondering if I’d end up with the TAV belt constantly slipping on me.
 
#7
I’ve been debating getting the torque converter but I don’t know a lot about them. I primarily ride this bike out in the desert near Joshua Tree down in SoCal. So it’s very sandy and some of the dry lake beds I ride on are dusty and have a fine, talc like powder. Since a TAV is belt driven, would this be an issue in that type of environment? Just wondering if I’d end up with the TAV belt constantly slipping on me.
I would worry more about sand getting into the garter weights and driver hub than on the belt. But still, with a cover and some good maintenance you'll be fine. If you can afford it, get the TAV.
 
#8
I wouild also say a tav is best..your riding area seem air filter clogging will be a big issue i reccomend a old sock over filter ..something you can shake out to protect filter..there are many vids on YouTube to put a tav on..iv'e done it but some people have a different opinon on how... You need to see what size the crankshaft because newer ct200 has 16mm older 3/4" to get right tav..good luck
 
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#9
My bike is hitting abut 30+ right now. The governor is bypassed. It is limiting my RPMs to a little over 5K at the moment. I have a billet rod, GX160 aluminum flywheel and 22LB springs and a few other mods. I cut some coils out of the return spring to get the extra RPM but you need the rod and flywheel if you do this. If your just looking for a little speed I would do the rod, GX160 flywheel, GX140 valve springs and throw in a 31 jet to slightly richen up the fuel mixture just a little cuz the carbs are slightly lean usually as they are. I would run the GX140 springs over the normal 18s cuz there just a little lighter and are just insurance cuz you will be running the motor to the limit of the stock springs. You cant run any more than stock lift with the 140 springs and would only run them with a stock cam but will have the least amount of wear on the cam out of any stiffer spring you could get.

Your best bang for the buck would be a torque converter but you need to raise motor and some times cut the cross bar that holds the chain guard. There is a 38 tooth sprocket on the market but it would sacrifice your bottom end torque and would not run it unless you had a torque converter or were only running on pavement. While you have the motor apart I would recommend putting a flat top piston in the motor. I like to do this to stock motors when I pull them apart. Its only $10 and an easy mod. If you motor is not new though I would also get rings and hone the cylinder when you install it. I have used the old rings just fine but I recommend doing it the right way lol.

The rod is around $60 the flywheel is around $40 springs about $8 to $10 and a gasket kit $10. It will not effect how the bike feels and will add your top speed your after. If you do plan on later fully removing the governor I would swap to 18# springs over the GX140s. I have 22LB springs in my motor cuz I am installing ratio rockers. The 18s and GX140s cant handle them. But unless your running ratio rockers or a high lift or the cam recommends them there over kill.

I know you don't want to remove the governor but getting the above parts and bypassing the governor will give you the performance your after, allow it to live with the extra RPMs and set you up for future mods if you decide in the future. With all this said though the torque converter is your best bang for buck and will add low end power and more top speed than the above mods.
 
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#10
Agree with most of the comments above. Sand absolutely sucks down torque. Eats it for breakfast. I wouldn't waste my time and money on a sprocket change for the sole purpose of gaining top end. You WILL lose torque to gain top speed.

A quality torque converter is going to make this a much better bike, and exactly what you need for desert riding.

Sand does a lot less damage to a TC than it does to a chain. The guys who off road a lot on two wheels are removing their chains and soaking them in solvent after every ride to remove the grit stuck to the lubricant.

Sand also kills the bushing on centrifugal clutches. Quickly.

If I was going to chose between engine modifications or adding a TC, I'd go with the TC. You can upgrade the engine later.
 
#13
[MENTION=50915]2SlickNick[/MENTION] did on one of his builds. Again, it's just a clutch so you'll have that trade-off of torque for top speed. Go for the TAV2.
 
#14
Robotfist, If you have a 3/4" crankshaft, this kit will do fine for 1/4 the price. You might have to use some 1" spacers under your engine depending on what frame you have. The draw back to this cheap kit is really only the belt. The belt supplied could wear quickly. A Comet brand or Bando brand belt will alleviate that concern and still save you 1/2 the money over the other kits (also made in China).
The cheap kit is $50 with Free Shipping.
To get more torque AND more speed from your current set up, you probably will have to install a smaller rear sprocket than you have. Just installing a torque converter with current rear sprocket most likely won't increase top speed but will give massive low end torque, meaning wheelies. You can still have low end grunt and gain top speed by using a smaller rear sprocket. I would shoot for 4:1 or 4.5:1 gearing from your chain set up. You asked about a 60 tooth sprocket... What is your current rear sprocket? Do you have #35 chain or the bigger 40/41 chain? If I had to guess... I'd say you already have the bigger 40/41 chain on your minibike.

Please keep us posted on what you do and on your results.

Danford1
https://www.ebay.com/itm/COMET-TORQ...m=112293196079&_trksid=p2047675.c100010.m2109
 
#15
More info...
If you want a simple and super strong way to raise the engine, get this solid piece of aluminum. It is 1" thick and 4" x 7" long.
$22 with free shipping.
You can also fab something up using 1" square steel, if you have that. It won't be as stiff torsionally (resistant to twisting), but steel tubing will work.

Also, the mounting bolts in some of these cheap kits are metric and the engine has SAE threads. You might have to go to the hardware store and buy 4 bolts. They are 1" long and use a 5/16 Fine thread. I usually just get allen head bolts as they are stronger than grade 5 regular bolts. Check the bolt that holds the clutch to the crank. Sometimes you need to buy one of those for the same reason, metric in kit, SAE on crank. If the bolts don't thread easily BY HAND into the engine or crank, then you need different bolts. Don't force the bolts in if they don't go all the way in easily by hand. A lot of guys make that mistake, you don't have to :)
Good luck.
Danford1

https://www.ebay.com/itm/1-X-4-ALUM...673259?hash=item41ad423bab:g:XlIAAOSwvg9Xb0p3
 
#16
Robotfist, If you have a 3/4" crankshaft, this kit will do fine for 1/4 the price. You might have to use some 1" spacers under your engine depending on what frame you have. The draw back to this cheap kit is really only the belt. The belt supplied could wear quickly. A Comet brand or Bando brand belt will alleviate that concern and still save you 1/2 the money over the other kits (also made in China).
The cheap kit is $50 with Free Shipping.
To get more torque AND more speed from your current set up, you probably will have to install a smaller rear sprocket than you have. Just installing a torque converter with current rear sprocket most likely won't increase top speed but will give massive low end torque, meaning wheelies. You can still have low end grunt and gain top speed by using a smaller rear sprocket. I would shoot for 4:1 or 4.5:1 gearing from your chain set up. You asked about a 60 tooth sprocket... What is your current rear sprocket? Do you have #35 chain or the bigger 40/41 chain? If I had to guess... I'd say you already have the bigger 40/41 chain on your minibike.

Please keep us posted on what you do and on your results.

Danford1
https://www.ebay.com/itm/COMET-TORQ...m=112293196079&_trksid=p2047675.c100010.m2109
The torque converter will add both torque and top speed. The stock jack shaft is a 2:1 ratio and the torque converters low range is 2.7 with a .90 overdrive. I don't think the belt set up gives you the full .90 in overdrive though cuz there is some slip in the belt.

The jack shaft set up uses a 10 tooth on the motor to a 20 tooth and then a 10 tooth to a 50 on the rear. Ends up being 10:1 ratio. The stock chain is 420 chain.
 
#17
I’ve been debating getting the torque converter but I don’t know a lot about them. I primarily ride this bike out in the desert near Joshua Tree down in SoCal. So it’s very sandy and some of the dry lake beds I ride on are dusty and have a fine, talc like powder. Since a TAV is belt driven, would this be an issue in that type of environment? Just wondering if I’d end up with the TAV belt constantly slipping on me.
I live in the Antelope Valley CA (High Desert) and run my CT200U and TAV and it runs great in the desert. Stg 1 and TAV get me 38-40mph. I left rear sprocket stock and dropped to an 8 tooth up front and it is a beast. Torque for days and still approaching 40mph.
 
#18
I love my ct200u and will never part with it..it's my dog..i got extra rims so i can switch big tire to small ones easily and has a tav..it's the one i sneak out on the street..i also got a trailmaster but if i had to own one late model bike the trailmaster mb200 is the way to go coz it's very comfortable off road.
 
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#19
Ldogg29 has the right idea with that 8 tooth. IMO a 9/60 would make for great gearing on the Coleman. Heck, there were a couple guys in the Coleman group who were running the huge 70 tooth sprocket. The idea is higher RPM during the shift into OD and at top speed.
 

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