Divorced Gearbox 4 speed Manual

[karl]

Had this mosquito fogger 125cc china engine cracked open for over a year.

Finally dids it.

Removed all the unnecessary junk, torched /cut off the rod, blocked off holes , ect. Patched a crack with good ol marine tex.

Ground the rivets off the flywheel, extracted the hub, and found an inch 1/16 weld on hub that fit tight.

Got a matching 16t #40 sprocket to drive it.

Cut down the weld on hub to clear the timing cover, and it seems we got a winner, tight and true.

Clamp and burn it together, and ready for a direct drive from a flathead briggs or other engine.

The original wet clutch is still used, so now go kart or mini bike with a 4 -speed manual trans.

It's even holding oil!

 

[JTSpeedDemon]

Ohhhh the JEALOUSY!!
Maybe there is something good about those Chinese hunks of junk!

 

[karl]

Ohhhh the JEALOUSY!!
Maybe there is something good about those Chinese hunks of junk!

Ill trade for your new/old fancy kart

Totally, finally getting used for something good

 

[mckutzy]

This is really good work...
I definitely like this project...
Having the jug being a bolt on and all other parts relatively compact enough...
This could be a bolt-on to a top mount for a clone...


I wonder if it'll work with the automatic transmission variants though??? ...
Either way... Something to do with these China quad/bike engines...
Very much like this...

 

[vpd66]

Nice work. Make sure the direction of the input (crankshaft) shaft turns the same direction as the output shaft. If that makes sense? LOL

 

[karl]

This is really good work...
I definitely like this project...
Having the jug being a bolt on and all other parts relatively compact enough...
This could be a bolt-on to a top mount for a clone...

Thanks, no room, that is where the turbo goes!
All depends on what I find to implement this on...

I wonder if it'll work with the automatic transmission variants though??? ...
Either way... Something to do with these China quad/bike engines...
Very much like this...

Im sure it could work, but may need to overdrive the input, to match the slower speed of a utility engine.
Less to think about with the standard. And digging some paddle shifters.

Nice work. Make sure the direction of the input (crankshaft) shaft turns the same direction as the output shaft. If that makes sense? LOL

Good advise, may produce undesired traits . Yes both input and output shaft turn the same direction. Thanks for the interest.

 

[karl]

This could be a bolt-on to a top mount for a clone...

?

 

[Karts of Kaos]

perfect.

 

[mckutzy]

Hehehe... I love it...
Does the kick still work to start the engine???
I have one of those loncin atv motors...
It's an auto without a gear selector...
I'm going to look into this and see if I can giver a go with this style of conversion, but keep a look out for a manual engine.

 

[chimmike]

Man I'd love to put this on a modified predator 212 and our go-kart hahaha

 

[Budget GoKart]

so the 190cc ish 4 speeds can go 70ish so i wonder what a kholer twin would do to the transmission lol

 

[karl]

so the 190cc ish 4 speeds can go 70ish so i wonder what a kholer twin would do to the transmission lol

Id say she'll be right for the Ton. If the clutch holds. LOL.

Hehehe... I love it...
Does the kick still work to start the engine???

I gutted the kickstart stuff, and put the blank shaft back in. Im sure it could be used, might be a lil difficult to kick.

An auto would be interesting.

 

[jamyers]

Interesting! I wonder if the crank and counterweights are going to be ok without the rod/piston, or if it'll shake itself (and you) to pieces... ???

 

[karl]

Interesting! I wonder if the crank and counterweights are going to be ok without the rod/piston, or if it'll shake itself (and you) to pieces... ???

Good observation. With a 1600rpm rated drill flat out, you can hold the gearbox down with one hand, with light force.
Yes you can feel the imbalance. I shall be turning it at half speed or less, the OG motor probably reached 9k.
It would have been wise to weigh the rotating assembly, and take some mass off the counter weights, to crudely compensate.

Learning experience, I can always take it back apart.

 

[vpd66]

Instead of removing weight off the counter weights why not just build a "bob weight" like they do when they balance a crankshaft. They weigh the big end and small end of the rod, the piston, pin, and rings and come up with a weight that attaches to the crank journal to simulate the rotating weight. If I were to do it I'd just machine a straight shaft to replace the crankshaft.

 

[karl]

Instead of removing weight off the counter weights why not just build a "bob weight" like they do when they balance a crankshaft. They weigh the big end and small end of the rod, the piston, pin, and rings and come up with a weight that attaches to the crank journal to simulate the rotating weight. If I were to do it I'd just machine a straight shaft to replace the crankshaft.

I like the idea! I only have caveman tools, chop box and a welder, but that would be ideal to replace the crank.

The problem with adding weight is the crank is tightly shrouded, so the bob weight would need to be slim, it could be done.

Also I could probally carefully drill the crank through the cylinder hole, pack it up and use a shop vac. Clean out the vac, and weight the shavings LOL.

Another issue is I used an acetylene torch to cut off the rod, and threw it in the scrap barrels at work.
How much did it weigh? Fun stuff.

 

[jamyers]

I'm with you on the caveman tools - but with a little staring at it and thinking, you can do a lot with a chop saw, a welder, and a big rock.

Ideally you could replace the crank with a shaft, but that's most likely going to take some machining, unless you can find a piece of shafting that's just the right diameter. Worth a look, though...

If you can't find one, I'd take the crank out, put the (I'm assuming ball or roller) bearings on it, and set the bearings on some v-blocks (could be cut out of 2x4's even).
With clean ball bearings, it should spin freely, so that the heavy side (which is going to be the counterweight side at first) will go to the bottom.

I think I'd start by removing as much counterweight as I could. Looking at the crank, it's got a lot of mass all the way around, I'll bet you could get it to balance just by removing from the heavy side. If not, then see how many lead fishing weights it takes to balance. That'll give you an idea how much mass you'll need to add for balance, then you can think about either welding or bolting it in.

 

[karl]

If you can't find one, I'd take the crank out, put the (I'm assuming ball or roller) bearings on it, and set the bearings on some v-blocks (could be cut out of 2x4's even).
With clean ball bearings, it should spin freely, so that the heavy side (which is going to be the counterweight side at first) will go to the bottom.

Thanks for the advise, I think ill tear it down again and do so.

Ill let yall know how it goes.

I was supposed to install my new toy tonight, but after arriving today found the control panel got bashed and cracked all around.
And a crack in one of the voltmeters. So we shall see how that goes tomorrow. Can't email pics to customer support, no direct address.

 

[vpd66]

How about taking the crank out and pressing it apart, cutting counter weights down has far has you can, throw away the crankpin that the rod mounted to and center drill each end of the crank and weld in a crank connection pin? You are still using the original crank just modifying it. It could be done without machine tools.

 

[karl]

How about taking the crank out and pressing it apart, cutting counter weights down has far has you can, throw away the crankpin that the rod mounted to and center drill each end of the crank and weld in a crank connection pin? You are still using the original crank just modifying it. It could be done without machine tools.

Close enough, torched off the counterweights, problem solved, absolutely mint ! Just need to throw it back together , and send it!

Tractor/ trac bike getting mad upgrades, 4 slappable gears! Fat tires! Braaap!