All about Mini Bike (Coleman Ct200u) and Go Kart Gearing Explained Part 2

[@markbenson3021]

I seen similar website on calculating and it was done at 3600 I didn't take in consideration of the screw being backed out.... Thank you sir u are the man

[@sidewayzmike]

I want to make my coleman safe to run WOT, when I let a friend or two ride it. Just wanna keep the valvetrain safe from float, etc. WOT on flat asphalt, I experience a slight bit of valve float, so I feather the throttle and keep the situation safe as I can. But, if someone unfamiliar, they might screw my motor up. Ideally, I am thinking I should increase top speed a little, sacrificing some of the "downstairs grunt".. this, in turn might be just enough to soak up the horsepower my bike makes (stock) and keeping the valvetrain in the safe zone. Im thinking bump the rear sprocket down from 50t to say a 44t? Maybe playing around with the front gears is less ideal, for my theory? Or, drop the 10t clutch, in favor of a 12t or 14t clutch? I want to keep the oem jackshaft setup intact for this season. Not looking to go down torque converter road at this point of ownership, maybe in a year or so..

[@sidewayzmike]

Btw, I think I got an old ct200u, my vin production date show letter E, might have a 2014 on my hands. The bolt on the clutch, accepts 10mm socket, so I prolly run 16mm setup crank, not the 3/4 or 19mm

[@TheVintageEngineer]

@@sidewayzmike if you have a 2014 you have a 3/4” crankshaft. What all do you have done? I’m already getting that you have removed the Governor. Maybe the simplest solution would be putting the throttle stop screw back in for other riders.

[@sidewayzmike]

The governor is still installed, with me adding a zip tie inside of the spring attached to the governor arm. Runs really well, and the throttle sweep is nice and linear. My throttle plate/linkage is probably old style, because I never cut any welds or required any bending of tabs. I basically ran the screw out far enough to no longer be effective, and added loctite, so it doesn't vibrate into the stratosphere lol.

[@TheVintageEngineer]

@@sidewayzmike if that’s the case just cut the zip tie off when others ride it and add it back when you get on.

[@sidewayzmike]

I have had the itch to pull the clutch, and finally get to measuring my output shaft. I left the micrometer in my toolbox at work Friday. So, if I dig into it on this nice Sunday, im resorting to measurements with only metric and standard wrenches! Would prefer to have my mic on hand. Its anybody guess, if the previous owner shelled out for a replacement engine since 2014! I contacted hisun, coleman, and even coleman Facebook messenger, and even a direct email to [e-mail] about running engine # against frame vins, but I get ZERO RESPONSES!

[@Miklalo]

Can you show us a update of what your mini bike looks like now when you have free time for 2019?

[@TheVintageEngineer]

Mik lalo check out my brake replacement video. I don’t think I’ve changed anything since then

[@Miklalo]

Anthony Shelton i seen your break video awesome work on that video 👏🏾👏🏾👏🏾👏🏾

[@MrThegabbster]

Hi bud a GX 340 with 11Hp. On a Doodle bug with 12 T clutch and 75 T. Rear is that good drag racing tork

[@Strict30]

Would an 14/75 be good for faster top end . I have mod2 cam 22pound springs that should be enough power to get it going right?

[@TheVintageEngineer]

On a Coleman? You running clutch and jackshaft, torque converter, or straight chain from clutch to rear sprocket?

[@Strict30]

@@TheVintageEngineer clutch on db30

[@TheVintageEngineer]

I’ve seen a few guys run straight chain on those. I’m thinking you will be ok for a fast street bike. It will take it a little time to get up to speed since it’s geared taller.

[@javierpagan364]

So if I put a 15t instead of a 20t I'll lose torque but gain speed?

[@TheVintageEngineer]

Javier Pagan talking about the sprocket on the jackshaft that they clutch is linked to? If so then yes it will give more speed with less torque. Be careful as the factory jackshaft is an uncommon 16mm. You either need to find 16mm bore sprockets, bore a 5/8 bore sprocket to 16mm, or replace the bearings with 6203 5/8 bore bearings and replace the jackshaft with a more common 5/8 one.

[@javierpagan364]

@@TheVintageEngineer i already have the sprocket but I was asking before I go to the machine shop. Thanks for the info. I only ride street so I don't mind losing too much torque. Thanks for the info

[@TheVintageEngineer]

Javier Pagan go to app.kartcalc.net/#justCalc you can input your specs and it will show you the difference as well. You should get about 33-34 mph with the new sprocket at the 4600 governed rpm limit

[@javierpagan364]

That's what I'm looking for thanks for the info. 35 its my goal

[@jacobsebastien3910]

Nice Video bro' 👍👍

[@Miklalo]

What is your current sprocket that you use for your mini bike? I was thinking about taking off the jackshaft an running a straight chain is that better for more speed i weight about 160 pounds.

[@TheVintageEngineer]

Mik lalo I run a torque converter with an 8 tooth front sprocket and a 72 tooth rear.

[@Miklalo]

Anthony Shelton what’s your top speed now?

[@TheVintageEngineer]

Mik lalo mid 30s, was at 42 before gearing so low.

[@markbenson3021]

Hey I noticed you math was at 4600rpms..... I thought it was calculated at 3600rpms?please let me know if I'm incorrect

[@TheVintageEngineer]

Mark Benson should be calculated at 4600 RPMs. If the throttle biasing screw is backed out all the way on a most 200cc-ish motors the max RPM before the governor kicks in is about 4600. That answer your question?

[@sidewayzmike]

How about adding the zip tie on the governor spring? Valve float average rpm, on a stock 196cc coleman?