CVT Honda GXH50 + CVT Some questions

Alekor, Do You Know That The Honda 50cc Needs Adapter To Bolt To Cvt? Makes It Wider Also. The Titan Bolts Up And Less Money. Just Trying To Help. Is It Hard For You To Get Parts, Motors, Cvt And Other Parts?? Ron
 
Alekor, Do You Know That The Honda 50cc Needs Adapter To Bolt To Cvt? Makes It Wider Also. The Titan Bolts Up And Less Money. Just Trying To Help. Is It Hard For You To Get Parts, Motors, Cvt And Other Parts?? Ron

That that the adapter I is necessary I know. While precisely has not decided what to choose - original Honda GXH 50 or its Chinese clone. Smaller capacity at a clone and a twisting moment confuses.

To receive spare parts and engines for me it is not difficult - we have firms intermediaries which forward the goods from American the Internet of shops in Russia. It costs additional money, but expands possibilities on construction of motor-bicycles. In America spare parts much more. And frequently with delivery the goods cost cheaper than if to buy from us (for example Honda GXH 50 at us costs 533$ - and if to buy in America - nearby 400$ with delivery).
 
Have you verified that the gearbox on the CVT is 3.75:1 ?
And, when the CVT is at low RPM, that the total reduction is 8.25 to 1?
this makes the CVT speed range = 2.2 (8.25/3.75=2.2)

If so, using 20" tires, with 11T to 48T, the overall gear ratio is 3.75 * 48/11, or 16.4, and the resulting top end speed is about 27.3 MPH at 7500 RPM.

Carrying the rest of the calculations out, the upper breakpoint is therefore 17.1 MPH at 4700 RPM, the lower breakpoint is 7.8 MPH at 4700 RPM, and the first point is 5.0 MPH at 3000 RPM
 
There Is Additional Gear Reduction On The Back Side Of The Cvt. Ron
 

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There Is Additional Gear Reduction On The Back Side Of The Cvt. Ron
Yup. The gearbox is accounted for in the calculations.

The steps involved in calculating the gearing and speeds for your bike are as follows:
  1. Calculate the max RPM gearing/speed.
  2. Using the same gearing as in step 1, calculate the speed at Max Torque RPM.
  3. Apply the CVT Belt reduction ratio, to calculate the maximum torque speed.
  4. Using the clutch pull-in RPM, calculate the pull-in speed, using the gear ratio from step 3

The one, final bit of tuning you may need to do is to adjust the CVT sheave weights. These weights move outwards as the RPM increases, and this pushes the drive pulley sheaves closer together, which increases the drive pulley diameter.

The ideal RPM for this to occur is just about at the max torque RPM, or, maybe just a little lower. (This is the 'flat' portion of the RPM/Speed charts above) If you need to shift the flat portion up, you increase the weights; if you need to shift it down, reduce the weights.

Remember though, this step should be the LAST one you take. The gearing needs to be correct first, else you may never be able to get the most out of your CVT. Also remember that adding a CVT will reduce the total amount of power to the rear wheel by 10-15%. The trade-off is that you should be able to get faster acceleration, and better hill-climbing ability, but, this may be come the expense of maximum top-end speed.
 
Have you verified that the gearbox on the CVT is 3.75:1 ?

Yes.

this makes the CVT speed range = 2.2 (8.25/3.75=2.2)

If so, using 20" tires, with 11T to 48T, the overall gear ratio is 3.75 * 48/11, or 16.4, and the resulting top end speed is about 27.3 MPH at 7500 RPM.

Carrying the rest of the calculations out, the upper breakpoint is therefore 17.1 MPH at 4700 RPM, the lower breakpoint is 7.8 MPH at 4700 RPM, and the first point is 5.0 MPH at 3000 RPM

Thank you. As I understood it is optimum to set cruising speed on the upper breakpoint at 4700 RPM ?
 
Lou, Just For The Heck Of It, What Is My Starting Ratio - 26 " Wheel, 54 Tooth On Wheel, 11 Tooth On Cvt?? I Figured About 29 To 32:1 Starting Ratio. But I Aso Think There Is To Much Slack In The Belt. (CAUSE`S IT TO LOSE SOME STARTING RATIO) BUT IT STARTS OUT NICE (ON TAKE OFF. LOL) NO OVER REVING OF MOTOR. MY BROTHER CLOCKED ME WITH CAR FOR QUITE A DISTANCE = 25 MPH. MY THROTTLE IS NOT FULLY OPEN. THAT FITS YOUR TOP SPEED FOR ALEKOR, OUR RUSSIAN FRIEND. Ron
 
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Which version of the CVT is it, Ron? (Ref the CVT FAQ) (there are two 'flavors' of pocket bike CVT commonly available - each has a different gearbox gear ratio...)

What engine are you using? The pocket bike moter in the photo above? They can wind out to 8000 RPM.

Assuming the newer, type 'B' CVT, you would have a top end gear ratio of about 15.6:1, which, IF the motor has enough power, (and max RPMs) could push you to nearly 40 MPH. However, if you don't have enough engine power for this, the CVT belt drive never really reaches the high end, and you lose some of the CVT speed range. (plus, your belt will probably wear faster.) It's very important that you don't try to push a CVT based system to this point. A 50CC honda may be fine with this ratio, but I doubt that a 35CC Honda/R-S has the 'oomph' to make this work.

At a first guess, the newer CVTs used with a Honda or R/S 35cc, or the Mitsubishi TLE 33/43, shouldn't be geared past 30-32 MPH at their max rpm.

Since they can reach 8000 RPM, you're talking about a 68 tooth rear sprocket, if no jackshaft is used. The older CVT type, with it's 4:1 gearbox, should be fine with a 54 tooth sprocket, though.

When you accelerate, your RPMs should rise fairly quickly to a plateau, then run at roughly the same RPM while the bike continues to speed up. Finally, when the belt drive has achieved a 1:1 ratio (the drive pulley is fully 'expanded') the RPMs will start to rise again, as the bike continues to speed up. If you never get to the point where the RPMs start to increase again, the gearing is definitely too low a ratio.
 
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