Rigged Gearbox?

[skid20]

This may be a stupid question (hopefully not).

I've got a yamaha 125 dirtbike engine that has a damaged cylinder wall. What I'm wondering is if I can take the gearbox (transmission) and adapt it to my Gx200 clone?

Has anyone ever tried this or saw someone try this?

I'm really uneducated when it comes to how a yamaha transmission/clutch set up work. But I was thinking maybe I could remove the cylinder portion of the engine and make some sort of cover for the side left exposed, and use just the gearbox but I'm not even shure if it is a semi-auto gearbox or if I have to disengage power from the engine to switch gears or what.
Any Ideas?

 

[Rotore]

i think the gearbox and engine are all one piece on that engine dude

 

[skid20]

i think the gearbox and engine are all one piece on that engine dude

yes they are all one piece. But the fact still remains that the crankshaft in the engine has to drive the gearbox, if the crank shaft, cylinder, rod and piston are cut from the engine and sealed, then you are left with just a gearbox. My question is if it is possible to use that gearbox as a separate unit from my engine connected by a chain or clutch system of the sort.

 

[theo]

It will work. You will have to figure out the sprockets for the clone and to the engine trans to get the final ratio in high gear. The bike clutch should also work with the engine.

theo

 

[EagleTalons]

I thought about doing this with a 110 broken trike engine.

 

[Kaptain Krunch]

Just rebuild the engine, shouldnt be more than 150 for bore+piston+rings.

 

[skid20]

Just rebuild the engine, shouldnt be more than 150 for bore+piston+rings.

I Have a problem with yamaha engines. no offense to anyone but I think that there to jappy looking for my liking... dont get me wrong I'm shure their great engines but when it comes down to it a honda gx200 looks like a lawnmower engine still unlike the massive and ugly cooling fins on this yamaha. Plus it would be a unique setup. If you have the same stuff as the next guy you are just another LEGO man..... catch my drift? LOL!

 

[Raywelder]

You could unbolt the cylinder jugs or whatever they are called lol.
and bolt a plate over all the holes, take out the rods and pistons. Then I would think that you could run a chain the crank on the clone to the crank of the motorcycle engine.

 

[crazycart]

http://www.youtube.com/watch?v=rLEKnB6VxSk

Its possible. But a lot of work for how useless it will be. It will be a gutless pig. Rebuild the yami

 

[skid20]

You could unbolt the cylinder jugs or whatever they are called lol.
and bolt a plate over all the holes, take out the rods and pistons. Then I would think that you could run a chain the crank on the clone to the crank of the motorcycle engine.

yeah! I was just kinda thinking the same thing about the plate and make a gasket, and oil fill for it in the plate (2 stroke), but I think I might try to get a strait shaft to replace the crankshaft though.. I think there may be a balance issue if the crankshaft is turning without the rod/piston connected, it may wobble like hell and break something!

I'm not really good with dirtbike shifting never really had an interset in having one.... I still have to figure out the process of going through the gears! I've rode an atv, all you had to do was let off the gas and shift, but I dont know if this one requires a clutch linkage or not.
If some knows I wouldn't mind some good ole priceless knowledge!

 

[skid20]

v=rLEKnB6VxSk[/url]

Its possible. But a lot of work for how useless it will be. It will be a gutless pig. Rebuild the yami

ha! that one on the video looks horrid! They should of stipped it down.

One engine should turn a shaft just as good as the other right?
Do you think there may be a torque or RPM issue? I don't know... I'm gonna try it I guess it can't hurt. If my clone don't work well with the clutch thats on the yamaha maybe I could try to use the TAV I got with it and see what happens. LOL!

I'm not putting it back on a dirtbike, I may put it on my mini chopper, I just designed the frame real low profile and around a honda gx160/200. I have plenty of room behind the engine to mount up a multi-speed tranny. The Yamaha engine is a 2 stroke and sound is also important. I don't want it to sound like a big chainsaw.

 

[Raywelder]

yeah! I was just kinda thinking the same thing about the plate and make a gasket, and oil fill for it in the plate (2 stroke), but I think I might try to get a strait shaft to replace the crankshaft though.. I think there may be a balance issue if the crankshaft is turning without the rod/piston connected, it may wobble like hell and break something!

I'm not really good with dirtbike shifting never really had an interset in having one.... I still have to figure out the process of going through the gears! I've rode an atv, all you had to do was let off the gas and shift, but I dont know if this one requires a clutch linkage or not.
If some knows I wouldn't mind some good ole priceless knowledge!

I wouldnt bother with trying to replace the crankshaft with a straight one, It is extra rotational mass, But crankshafts should be balanced. I mean, it would be a little bit better for ya if it was straight, I just think it would be too much trouble for ya.



I dont think it would be useless like it was said above. Its all in how you gear it from your engine to the gearbox.

Sounds like it would be pretty cool.

And why would you put 2 stroke oil in the crank case?

 

[skid20]

And why would you put 2 stroke oil in the crank case?

not 2 cycle oil, probably gear oil that is if the gear box is not a separate chamber from the crank case. I haven't tore it open yet. I don't know much about em. If the gears were originally lubricated with the 2 cycle oil then I figure they'd probably need some sort of oil. lol

 

[Raywelder]

not 2 cycle oil, probably gear oil that is if the gear box is not a separate chamber from the crank case. I haven't tore it open yet. I don't know much about em. If the gears were originally lubricated with the 2 cycle oil then I figure they'd probably need some sort of oil. lol

I think the crankcase and whatever contains the gears is all one thing.
So you would probably just use regular motor oil.
* I think, *

 

[Raywelder]

Either way, You will find out eventually.

 

[Kaptain Krunch]

The crankcase and transmission are two different chambers on a 2 stroke, so just put some 2 stroke oil in the crankcase and gear oil in tranny.

For the record, i dont care how un-original it is, a bike engine will be 50x better than a clone.

 

[crazycart]

In 2 stroke dirtbike engines, the crankcase does not share the same oil as the tranny gears do. Tranny needs either wet clutch oil or 4 stroke oil. I agree with krunchy on this one.

 

[Raywelder]

The crankcase and transmission are two different chambers on a 2 stroke, so just put some 2 stroke oil in the crankcase and gear oil in tranny.

For the record, i dont care how un-original it is, a bike engine will be 50x better than a clone.

Probably, But I wouldnt want to spend the money to rebuild it either.

I think hes wanting to do it for the cool factor, lol.

In 2 stroke dirtbike engines, the crankcase does not share the same oil as the tranny gears do. Tranny needs either wet clutch oil or 4 stroke oil. I agree with krunchy on this one.

Ohhh. I didnt know whether that one would be the same are not, I knew that some were though.

 

[skid20]

For the record, i dont care how un-original it is, a bike engine will be 50x better than a clone.

So if you were to take an engine of the same HP RPM and all that jazz as the engine that was originally connected to a transmission, one is better than the other why? I know it's made for that tranny but whats the difference if it's geared the same?

I just figured I could gain more top end after my engine mods are done.

 

[Kaptain Krunch]

So if you were to take an engine of the same HP RPM and all that jazz as the engine that was originally connected to a transmission, one is better than the other why? I know it's made for that tranny but whats the difference if it's geared the same?

I just figured I could gain more top end after my engine mods are done.

Your yamaha 125 (assuming its a yz125 two stroke) will make at least 20hp, your clone makes 6.5, the yamaha will wind out past 8k, the clone, governed at 3,600, you can ungovern it but then the risk of throwing a rod or the dippers is fairly high. The clone is splash lube, air cooled, yamaha is liquid cooled (assuming its newer than early 80's), 2 stroke so no crank case oil. If you want me to keep going i can, theres no competition.

Now if they were rated at the same hp, and redlined at the same RPM then that would be ok, but would still take up more room.