My son has a 2002 Suzuki LT-A50 which runs great. However, I'd like to change the drive ratio to run the engine at higher RPM's. This would give him a bit more in the low end, too.

Obviously, my choices are increase the axle gear size or decrease the engine gear size. The engine gear is already pretty small, so I don't really want to go much smaller to keep the chain wear minimized.

The axle gear, unfortunately, is welded to the one-piece rear axle. That brings me to my question: Is there some standard way to "increase" the size of an existing gear? I'm thinking of something like a section of drive chain with gear teeth on one side. You'd wrap it around the existing gear, link it back to itself, and the gear teeth on the outside would now become the chain's contact point. Thus you'd have increased the OD of the gear by the thickness of the "wrap".

Does anything like this exist? Thanks!

 

I'm just stating my opinion here, but I really don't think that it's worth it on a 50cc kids bike.

I say just wait until the kids a little bit older then get a 100-150cc bike.

Just my opinion, sorry if I couldn't help with what you want do to.

 

Years ago there were sprocket halves that could be bolted on over the stock sprocket. Those were applicvation specific and doubt it would work for you. The only way I know of is to remove the axle. Find a bigger sprocket. Machine the 2 sprockets so they fit together and then weld them.

 

A machinist friend had this suggestion: Find an appropriate sprocket (proper number of teeth and spacing, etc.), cut out the center so it's more of a "ring" instead of a disk, slip it over the end of the axle assembly, and screw it to the side of the existing sprocket. It will be slightly misaligned, but if the distance between the two ends of the chain is long enough it won't matter. This is also 100% reversible if desired.

BTW, yes - I think this is worth doing. That little LT-A50 is a GREAT machine. With the throttle restrictor backed off it will pull my 170 pounds up a hill, accelerating the whole way. My 50 pound son rockets around on it just fine. I'm not complaining about its performance one bit... I'd just like to keep the engine running at higher RPM's so it stays cleaner.

 

Taking .020" off the head will yield good all-around power gains. Easier than messing around with sprocket on the axle.

 

<div class="FTQUOTE"><begin quote>Originally posted by: WAATV

A machinist friend had this suggestion: Find an appropriate sprocket (proper number of teeth and spacing, etc.), cut out the center so it's more of a "ring" instead of a disk, slip it over the end of the axle assembly, and screw it to the side of the existing sprocket. It will be slightly misaligned, but if the distance between the two ends of the chain is long enough it won't matter. This is also 100% reversible if desired.</end quote></div>

I would machine the center out so it fits over the stock sprocket and use bolts and large washers to hold/locate it on. (instead of my first idea of welding) No misalignment problems that way.

 

<div class="FTQUOTE"><begin quote>Originally posted by: dwhst9Taking .020" off the head will yield good all-around power gains. Easier than messing around with sprocket on the axle.</end quote></div>

As I said, I'm not seeking increased power. It has plenty. I want to run the engine at higher RPM's for a given speed. That requires a drive ratio change. In the process he'll probably get a bit more low-end torque, which is fine, but I wouldn't do this just for extra torque because it already has plenty.

Don't be fooled! This little Suzuki 50cc engine has PLENTY of power. We still have three of the four restrictors on the machine and my son goes everywhere and does everything. No way am I giving him more power for a long while.

 

If it is a CVT transmission you can put lighter weights on the clutch to increase engine RPM!

 

<div class="FTQUOTE"><begin quote>Originally posted by: ghcoe

If it is a CVT transmission you can put lighter weights on the clutch to increase engine RPM!</end quote></div>

These don't have a CVT. That's what sucks about 'em. The new 4-stroke LT and KFX 50s do though.

I did lighten his clutch weights however. The increased stall helps him get off the line quicker, obviously. BTW, you said you want to turn more RPM so it runs cleaner? Is yours loading up? More RPM on a stock setup will more than likely hurt performance with a stock pipe.

 

i took the easy way, decrease the height of the rear tires. along with gearing there is the mass reduction as well.