Mmb80 not running good

#41
Using a Comet style backing plate is often times easier than making an actual long jackshaft that goes across the width of the bike. But clearance can be an issue because of the size of the plate.
But don’t forget, if you are not using a driven and driver from the CVT, you could trim quite a bit from the rearward portion of the plate, since instead of a 6 in driven you will be using smaller sprockets.
Don’t forget about a cover, you’ll need that to keep your leg from getting chewed up.

Maybe a predator would be easier in the long run
Can you get a comet backplate without the rest?
Good point where could i get a cover?
 
#42
If you do a google search you can find just the cover, or just the backing plate.
Just make sure it will bolt to your engine.
I have experience with doing this, but not using your particular engine.
If the bolt pattern on your engine is different than mine, it may not bolt up without modification.
 
#43
If you do a google search you can find just the cover, or just the backing plate.
Just make sure it will bolt to your engine.
I have experience with doing this, but not using your particular engine.
If the bolt pattern on your engine is different than mine, it may not bolt up without modification.
What engine did you use?
Do the 79cc predators have the same bolt pattern as the 212s????
 
#46
For 99 bucks on sale, you'd be hard pressed to do wrong by upgrading to 6.5 HP. The goodies available for these Honda GX200 clones just makes it a viable way to go.
I agree. But was just thinking if I could get a jackshaft for around 40 I'd be fine.
What do i need besides a clutch for the 212?
Maybe if I can't get the Jackshaft then I'll just keep this one stock for a couple more years.
 
#47
Not sure. Do you have a decent steel rule? Or at least a good measuring tape?
You can measure the bolt pattern and see if it is compatible.
I have only put backing plates on Briggs and Tecs but if they can bolt up to your engine, they do work.

I agree, kinda feel like there should be a predator in your future.
 

Rapidrob

Well-Known Member
#48
I just don't see how you can get all the parts for 40 bucks. You can get the aluminum mounting plate for 35 bucks shipped. The shaft,bushings,gear, chain (s) will cost you much more.
 
#49
Not sure. Do you have a decent steel rule? Or at least a good measuring tape?
You can measure the bolt pattern and see if it is compatible.
I have only put backing plates on Briggs and Tecs but if they can bolt up to your engine, they do work.

I agree, kinda feel like there should be a predator in your future.
Ok I'll measure. I'm curious as why I shouldn't use the knock off backplate.
Is it just because it's not strong?
 
#51
I agree. But was just thinking if I could get a jackshaft for around 40 I'd be fine.
What do i need besides a clutch for the 212?
Maybe if I can't get the Jackshaft then I'll just keep this one stock for a couple more years.
To me it seems like you are trying to use a jackshaft to use a small engine to do a big job.
Nothing wrong with that. Happens all the time.
But now combine that with limited experience/knowledge and a limited budget (ask me how I know) and high expectations, and then it might just be better to go with the bigger engine.
 
#52
To me it seems like you are trying to use a jackshaft to use a small engine to do a big job.
Nothing wrong with that. Happens all the time.
But now combine that with limited experience/knowledge and a limited budget (ask me how I know) and high expectations, and then it might just be better to go with the bigger engine.
your'e probably right. ill look up some youtube videos on the predator swap.
 

I74

Active Member
#54
Integrating / ''piecing together'' a Jack shaft set up, other than the HRM ''complete kit'' on that bike, is a lot of work,, even for someone with lot's of years experience.
You gott'a know what you are doing.
If you ''really'' want to do a Jackshaft set up, check out ''Hot rod minibikes'' complete kit.
It comes with everything you need, including instructions.
Price with shipping for the kit, is around 134 bucks though.
There is a couple of You tube vids out there, of the kits put on MM-80'S.
The gears that it comes with though , including your 11t clutch & 75t rear sprocket,, puts the gear ratio @ over 9 -1, which I personally think is to steep.
You do have the option to go with a 70t rear sprocket, like the one from Monster scooter parts, for the Doodle bugs.
Then you can keep your 11t clutch,


If you went with a 212, you would need a 3/4 clutch, with at least 12 teeth. I would then get a Max torque SS clutch.

You would also need a bit longer chain.
I would also recommend the 70t sprocket for that combo, to tame it down some out of the hole.

At this point,, the Predator swap, or the jackshaft kit ect.,, would cost you close to the same, as long as you didn't add a 212 adapter mounting plate, & instead,, just drilled new mounting holes in the plate that's on the bike.

You are still going to be looking at some work,, regardless.

I
 
#55
Integrating / ''piecing together'' a Jack shaft set up, other than the HRM ''complete kit'' on that bike, is a lot of work,, even for someone with lot's of years experience.
You gott'a know what you are doing.
If you ''really'' want to do a Jackshaft set up, check out ''Hot rod minibikes'' complete kit.
It comes with everything you need, including instructions.
Price with shipping for the kit, is around 134 bucks though.
There is a couple of You tube vids out there, of the kits put on MM-80'S.
The gears that it comes with though , including your 11t clutch & 75t rear sprocket,, puts the gear ratio @ over 9 -1, which I personally think is to steep.
You do have the option to go with a 70t rear sprocket, like the one from Monster scooter parts, for the Doodle bugs.
Then you can keep your 11t clutch,


If you went with a 212, you would need a 3/4 clutch, with at least 12 teeth. I would then get a Max torque SS clutch.

You would also need a bit longer chain.
I would also recommend the 70t sprocket for that combo, to tame it down some out of the hole.

At this point,, the Predator swap, or the jackshaft kit ect.,, would cost you close to the same, as long as you didn't add a 212 adapter mounting plate, & instead,, just drilled new mounting holes in the plate that's on the bike.

You are still going to be looking at some work,, regardless.

I
Too many decisions.
And again I think ill just keep it stock. Just need to get the carb worked out.
 

I74

Active Member
#56
I would get this carb off of E-bay then,, for 20 bucks & free ship.
It has an adjustable idle mixture screw, brass throttle plate,, brass pilot jet,, & gaskets ect.

That's the one I will eventually end up getting for mine also. s-l640.jpg
 

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