What gearbox is this?

Originally counted 10/29T outside, but looking at pic once I transferred it to computer, might be 9 on the small sprocket.

Gear box is totally silent, sucked to find the only part of the used motor kit I bought that I liked besides the mount I suppose ended up having 3 studs broken in it, but hopefully it's a good box and I can just pull those and re-tap. It's not leaking, the stuff in it, doesn't smell like oil or anything looks like tons of some sort of chain goop.

Before I buy a different engine in the future I'll def measure distances, I do not think this is a gearbox that came with this motor, but maybe. They had different models but they were ususally belt drive and what not. I never could find pics of their gearboxes inside but it outside pic doesnt look what they sell nor any of the scooter model's sprockets, even the "climb" ones dont even have 11T, they have like 14 and what not and a 9T for climb and the scooters max out at like 20mph always with this engine at the top rpm

My bike I must be barely hitting 3,500 rpm at 25

9T sprocket inside driving 29T

29T drives 11T on other side of gearbox

which 11T drives the 44T

So I did that on the gearbox program, I read BBB said in shoutbox leave the other one alone guess it's for jackshafts.

I was thinking I should opt for a 9T on the output, would make 7000rpm be 40~. Not sure if I can get a 9T though I'll have to check it's shaft and what not.

wow so it's not a junk gearbox, awesome!

I'd go higher then 44T on the rear wheel but then the chain will hit 2 pieces of metal (part of the frame, and part of the rear mounts frame)

What about a 9T output?

thanks guys @Ludwig II I may get some more pics of it as I may want to see if a 4 stroker will fit soon, so I'll get cluthc drum pics and will prob clean up the grease in it (spread some back to bottom and top to fling around)

nah I'm not saying the chain inside the gearbox is loose.

with the way I mounted my over rear mount, the output sprocket doesn't quite align with the wheel sprocket cause I have it like an 8th of an inch over to the left (if your behind bike) so I had to flip the sprocket the other way but it's less then an 8th of an inch close to rubbing on the frame.

if I went to a 56T or so w/out a nice roller tensioner setup the chain being tight and straight would rub the frame probably.


if you see the rear mount arm hanging out, now those are mounted, right where it's mounted chain side the chain almost rubs the frame (doesn't, chain is pretty looking, was slightly at first but then I took a metal file and after a few rubs theirs plenty of space) but if I go larger, the frame metal gets closer and closer as you go deeper in the frame.

Engines a 33cc keyang 2 stroke, I want to go to something like a honda 4 stroke 50cc some day, bout to put in new carb gaskets and such in a bit, but with the gunked up carb I was able to cruise 26 no prob, if it goes up to 30~ and cruises steady, I may not change gearing till 4 stroker.

^Whats that mean heh.

Ah i see.

lol so you sort of saying to use a lump hammer to bend the metal away from the chain?

When I put a 4 stroke, I'll def move the motor over enough so I can run larger sprockets and face the teeth in toward the spokes instead of out

MotorBicycleRacing said:

May not be loose now but what are you going to do when it does?

Several builders here have tried adding tensioners of various kinds.

How about rotating the gearbox 90* so it points straight down.
Will that help your clearance?

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Yeah this engine is mounted at an angle. When I do 4 stroke I think this gearbox can mount straight down, if it does that would help the chain clearance to a bit larger, but it is sort of straight down, I need the sprocket more back.

Ludwig II said:

Is there enough clearance to move the engine fractionally sideways and fit a dished sprocket, or will the chain then hit the tyre?

These micro sprockets, 9 tooth etc, horrify me. 12 is about as small as I'd want to go, as below that, the chain is following a rather lumpy path around it and suffering as a result.

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Ah I see.

My chain actually clicks on the 11T sprocket when you roll it back, the derailer schwinn chain I first got worked like crap and a few links would bind, then I went to more of a BMX style chain, bell - mixed it with my other chain that came with this motor and it's been same tension nearly for 30 miles. I want it to stretch a tad more but I think it already did it's stretching (you can squeeze it a tad, it actually is almost perfect, maybe 1/8th inch looser it'd be happy but ok so I will def wait and look into a 50~T sprocket some day.

Also free spinning the motor up prob around 30mph I notice the ghetto sprocket sandwhiching I did seems fine, but the actual hub slightly moves. I don't think my sprocket is wobbling it's the hub cause the axle inside has a slight bend, if you spin the wheel holding the axle you see it bumps on the left side (not the derailer sprocket side).

What damage could result from that? It's a very slight outward, you only can see it when the engines spinning the rear wheel FAST, no binding noises from the chain or anything sounds smooth as butter.