Slowly but surely . . .

This project is taking a while (cash flow).

 

[Randall]

Did you consider just making a jackshaft instead of moving the engine? Thats what I did since I didn't want to offset the weight of the engine too much (my engine+converter combo is like 70lbs and didn't want it hanging off the side).

As a bonus it also gives you more fine tuning for gearing adjustments, and allows you to run a more powerful jackshaft brake. Was quick and cheap to make, welded it right to the back of the reinforced seat post along both sides and through that middle slot. Excuse the messy welds, its a cheap 110v flux core that I made some improvements to but its still not as good as my sears stick welder...I don't have a 220 outlet for the big one in my new place yet.
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Sorry, lots of questions: What size washers did you use and I am assuming there are bearings inside the washers? What size bearings?
Sprocket sizes?

 

[FNTPuck]

Another thing about your design is that you can move the sprockets to get better alignment since it has a keyway. Is this correct?

Correct, sprocket can be moved in or out exactly as much as needed. My engine is very wide so I would need crazy sprocket spacers and a way offset motor to line up directly with the output sprocket. With this, I can just move then where I need and tighten the set screws.

Sorry, lots of questions: What size washers did you use and I am assuming there are bearings inside the washers? What size bearings?
Sprocket sizes?

I purchased the axle, sprockets, bearing hangers(they are basically thick washers that are flat on the bottom), and bearings as a kit from a gokart shop for like $45 or something. I made the back plate that they are welded to from a heavy duty 1/4" thick Winch plate, and purchased the lock collars from Amazon. Total cost for everything installed was only around $65.

If I had to do it again, I would do it all the same but also purchase better bearings since these ones are kind of cheap. I'm sure its fine for a low RPM 4stroke but I wouldn't run them on anything thats going to see 8-10k rpm or something. After I am done with all the initial testing, when I tear the bike down to paint I will install better quality jackshaft bearings (I only pressed the bearings in with red loctite since I plan on replacing them soon) Fit was decent with a slightly tapered bearing case with thick lip on one side, but a bit too loose IMO for a good press fit. I recommend using proper bearing installation grade loctite and throwing nice bearings in there.

Note that for a brake, while jackshaft brakes are very powerful due to higher mechanical advantage, I would still install a wheel mounted rear brake as well since if your chain brakes, the jackshaft brake will do an awesome job at stopping your converter output from spinning but thats it lol. I plan on doing a dirtbike foot brake setup for the rear as a backup brake.

Some more pics for ya in case you give it a try:

 

[Randall]

Correct, sprocket can be moved in or out exactly as much as needed. My engine is very wide so I would need crazy sprocket spacers and a way offset motor to line up directly with the output sprocket. With this, I can just move then where I need and tighten the set screws.



I purchased the axle, sprockets, bearing hangers(they are basically thick washers that are flat on the bottom), and bearings as a kit from a gokart shop for like $45 or something. I made the back plate that they are welded to from a heavy duty 1/4" thick Winch plate, and purchased the lock collars from Amazon. Total cost for everything installed was only around $65.

If I had to do it again, I would do it all the same but also purchase better bearings since these ones are kind of cheap. I'm sure its fine for a low RPM 4stroke but I wouldn't run them on anything thats going to see 8-10k rpm or something. After I am done with all the initial testing, when I tear the bike down to paint I will install better quality jackshaft bearings (I only pressed the bearings in with red loctite since I plan on replacing them soon) Fit was decent with a slightly tapered bearing case with thick lip on one side, but a bit too loose IMO for a good press fit. I recommend using proper bearing installation grade loctite and throwing nice bearings in there.

Note that for a brake, while jackshaft brakes are very powerful due to higher mechanical advantage, I would still install a wheel mounted rear brake as well since if your chain brakes, the jackshaft brake will do an awesome job at stopping your converter output from spinning but thats it lol. I plan on doing a dirtbike foot brake setup for the rear as a backup brake.

Some more pics for ya in case you give it a try:
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Awesome, thank you for this!!!

Yeah, I think I'm definitely going to go this route. I won't have to rotate the exhaust either, I like it where it is (lol).
Picture attached of my design for the block:
(going to grind the two flat spots and maybe even double up on the washers on each side and a gusset also on each side.
Also going to grind a slot for the seat tube to fit in (more welding surface).

 

[FNTPuck]

Awesome, thank you for this!!!

Yeah, I think I'm definitely going to go this route. I won't have to rotate the exhaust either, I like it where it is (lol).
Picture attached of my design for the block:
(going to grind the two flat spots and maybe even double up on the washers on each side and a gusset also on each side.
Also going to grind a slot for the seat tube to fit in (more welding surface).

Nice! I welded it to the seatpost along the seams and through the center hole, then also welded gussets to the post. My seatpost is reinforced with a thick walled steel tube stuck inside, welded to the seatpost using 4 straight through holes spaced across the seatpost before installing it(8 rosettes total) then two diagonal into the bottom bracket to tie it to the bottom of the bike as well.

Oh, for the gearing the jackshaft axle came with 10t and 14t sprockets. I run them "backwards" with the 10t taking the power and the 14 going to the rear sprocket for more top end since my motor has very high TQ and can handle pulling the higher gearing. For a 212, I'd probably stick with the normal order of 10t CVT>14tjackshaft input>10tjackshaft output>rear sprocket. Still good for ~55mph with a 36t from a bone stock 3600rpm goverend 212, and if you pull the gov and throw a carb+pipe and spin it to 5k it will be ~75mph assuming its making ~10hp.

 

[Randall]

Nice! I welded it to the seatpost along the seams and through the center hole, then also welded gussets to the post. My seatpost is reinforced with a thick walled steel tube stuck inside, welded to the seatpost using 4 straight through holes spaced across the seatpost before installing it(8 rosettes total) then two diagonal into the bottom bracket to tie it to the bottom of the bike as well.

Oh, for the gearing the jackshaft axle came with 10t and 14t sprockets. I run them "backwards" with the 10t taking the power and the 14 going to the rear sprocket for more top end since my motor has very high TQ and can handle pulling the higher gearing. For a 212, I'd probably stick with the normal order of 10t CVT>14tjackshaft input>10tjackshaft output>rear sprocket. Still good for ~55mph with a 36t from a bone stock 3600rpm goverend 212, and if you pull the gov and throw a carb+pipe and spin it to 5k it will be ~75mph assuming its making ~10hp.

Awesome thank you for the info. Will keep you posted on the progress.

Definitely thinking also about a Stage 3 or 4 kit from gopowersports and deleting the gov and oil shutoff.
Going to be registering this and tagging it (license and all the rigamaroll)

 

[Randall]

Short video of the sound of this beast:



The rattling you are hearing is the front CVT pulley. It was loose and almost lost it. It is tightened down now.

 

[FNTPuck]

Short video of the sound of this beast:



The rattling you are hearing is the front CVT pulley. It was loose and almost lost it. It is tightened down now.

Badass! I'm hoping to have a roller in the next few days finally...

 

[Randall]

Badass! I'm hoping to have a roller in the next few days finally...

Right on! Can't wait to see it.

 

[Randall]

So I got the front light mounted. Not sure I like the mounting. I might change it in the future.

 

[Randall]

Also going to have to cut the fork tube cups off and redo them. (wrong size: face palm)