52cc Stage 2 CAG CVT powered X-Games Motobike

[16v4nrbrgr]

After taking a look at how the clutch and CVT have been working, I might not go ahead and mod anything yet.

The steel 3 shoe clutch hasn't broken into the drum yet, so any mods will change once it does. I also don't look forward to taking the shoes out to drill them in a press, so if I need to do it, once would be nice. I think from what I have read about the three shoe steel clutch, its more worthwhile to get the aluminum one rather than drill it full of holes. The weight of the steel shoes is actually an advantage under overgearing or overloading, the aluminum may generate too much heat and burn out quickly.

The CVT looks as if it might need to engage early just to keep from spinning away power, at least with a stock belt. It isn't under any tension without centrifugal force, which is good news for the rest of the drivetrain, it definitely must slip some off idle.

The transfer case in the CVT leaks gear oil, and I'm monitoring it on the counter, if it just oozes I'll use red moly CV grease. The first oil change showed it didn't puke everything, but there was also break-in crap, maybe oil for one more shakedown before grease.

I think once the clutch breaks in (it fortunately shows no signs of overheating) with the 41t, it will be much better.

Keeping everything I stock that I can is the plan, when you need to replace parts its nice when they are cheap AND convenient.

 

[16v4nrbrgr]

I'm waiting for the 1st gear, so I figured I'd mess with the fairings. I have a couple stock windshields too but I figured I'd make a tall one.

The goal is to bridge the top to the bottom with aluminum sheet and maybe some struts to hold it all.

I could paint them black, red, fake CF, or a combo, but I think the Honda graphics gotta go, they're out of place.

 

[16v4nrbrgr]

Maybe this will work, the motor's starter and trans are wide, and I'd like the scoop to direct air over them.

 

[16v4nrbrgr]

For now I'm going to keep the Honda graphics and leave the bottom fairings for a later project. The big 41t sprocket is on there now, should be interesting.

 

[lowracer]

16V,
Love to see a video of this bike rolling down the road!
-Low-

 

[16v4nrbrgr]

Maybe once riding it becomes routine, I'm just happy to have it all together right now, I'll add some pics in the sunlight today. Hoping for the best with the new gearing.

I wish Honda sold bikes like this here for the street, its a hopped up CBF Stunner 125.

Not too shabby for less than 1/4 of the cost, and I can put it in the back seat of my car.

 

[16v4nrbrgr]

The issues on todays ride so far, the throttle cable adjuster on the carb vibed loose and raised the idle, loctited and siliconed. The head bolts either loosened up or this is one of those engines you gotta re-tighten the head bolts a couple times when new, took care of that. I also put a o-ring inside the plastic carb sheath for the intake. I also tightened up the derailleur cable once again, because it runs well in 1st gear, but didn't like to downshift back into it. Hopefully that improves, as I'm liking the gearing anyways.

 

[16v4nrbrgr]

Just got back from another ride, and the bike is behaving pretty well. I got it going 32 mph, and it has a couple thousand revs to go if I can tune the CVT and clutch to extract them. I should look into some fiber reeds for the intake as well. It doesn't want to downshift into the 41t so I gotta figure out how to make the chain want to make the big step. I think its gonna need some buttonhead screws as ramps to make the chain want to skip into the big step from the 43 to the 41t. I can run it stuck in 41t but that seems like a waste of all the effort. I'm gonna see what the MTBers did about this problem.

 

[16v4nrbrgr]

Looks like possibly putting buttonhead screws through the big cog to help the shift transition from the next higher gear might work. Kinda like on a chainring on the cranks, there are ramps, bumps, or pins to help make the big steps between gears work. I had to add some screws like this to the 3 speed cranks on my MTB a couple years ago, maybe I can figure out the right placement from that bike, which is a 3x9 speed.

 

[16v4nrbrgr]

Drilled through the sprocket at 20 and 21 teeth apart to put some screws in as ramps. I hope it works when its all spinning fast later today.

 

[Pluto]

That is one awesome build!

Looks as good or better than that little Honda.

Amazing...

 

[16v4nrbrgr]

Thanks Pluto, I hope to make it work as good as it looks lol!

Today I took a couple rides to see if it'll shift into the lowest cog. It wants to, but the countersunk screws I put on don't protrude enough, so I'm gonna step it up to buttonheads and see if it'll shift with those. I got it to downshift once with the wheel in the air so I think I may be onto something.

I now gotta switch the transfer case over to grease from 75/90 oil, it runs out too quickly past the seals and makes the belt slip. I think the gears should be broken in enough that the grease won't fill up with crap now.

It also has a low rpm misfire without load, which I think is related to either the reeds or the stock spark plug wire, I'll put a better plug wire on and there will be fiberglass and cf reeds coming in the mail from the UK. You can get them off ebay from the US but I ordered a kit for minimotos with a fiberglass reed in a cage, a gasket, and a spare carbon reed to try out maybe once its all broken in, since they are typically stiff and aimed for the top end.

I'm thinking about doing the cvt mod where you remove one of the four weights to make it shift later, I might as well do it all at once.

 

[16v4nrbrgr]

repost error

 

[16v4nrbrgr]

Got my plate in! The taillight is a convenient thing to attach it to.

Here's the CF reed in a cage with a shaved down stop. The top is shaved down to clear the crank since I have the reeds and intake flipped for a level carb. The other side is sanded back and the ends ground off by about 3/16" to allow more flow.

I also used a strap wrench (thanks Maniac) to take apart the cvt and pull out 3 variator weights of the 6 in there. If I need something in between I'm gonna need to lighten the existing weights, which are plastic rollers with metal rings encased inside. I could also get a gram scale and order some rollers for scooters in different weights, hope this cheap mod works, lol.

I changed the trans oil to red synth moly grease, and also put buttonheads in the rear cog in place of the csunk screws to hopefully make it downshift.

Tomorrow I'm gonna try it out, when all the threadlocker and sealant is dry.

 

[16v4nrbrgr]

I looked up 16x13 variator rollers at Treatland's website and there's a ton of them!

https://www.treatland.tv/SearchResults.asp?Search=rollers+16+x+13

I hope using the 3 weights will work well and I don't need to swap them out, but I guess its best to use 6 rollers of half weight eventually, to distribute the load and the wear evenly.

Today I'm gonna test the shifting, the CVT variator mod, the transfer case grease, and the CF reeds. I'll be happy with the same top speed if it fills in the powerband, which I think the CVT mod should achieve.

I also ordered a cherry for the top, I actually need it because the stock plastic cap is a leaking POS, lol.

 

[16v4nrbrgr]

The mods definitely improved how the bike takes off! It gets into the powerband as well, really transformed the bike! Its really loud when it gets on the pipe, lol!

I got it going 37 mph before heading back because I think the head bolts need something serious to stay tight, lol. The CF reeds give it great compression, I might need to get a bigger pullstart handle because my old arthritic hands slip off when they're sweaty.

I think the cvt roller mod was definitely worth it, I might get the scooter rollers if I find they're inconsistent.

I can't get it to downshift into 1st consistently, that's something that has been a constant bother. I can see the wear marks where some ramps would help out shifting so I might have to take a file to the sprocket or something.

 

[16v4nrbrgr]

So in the pursuit of tight head bolts, I took out the hardened washers and put split lockwashers in their place, along with lots of red loctite on the bolts. I also found that the alloy pullstarter housing touches the HP head fins, which could cause funky stuff to happen when its hot, so I sanded the flange that covered the left head bolts back so it doesn't touch, and I can check all four bolts since she's been testy.

 

[Intrepid Wheelwoman]

I'm really amazed at what these pocket bike engines are capable of. A local supplier is selling them at $NZ95.00 at the moment and I'm sorely tempted.

 

[16v4nrbrgr]

They're very peaky! The major drawback is that when its pulling hard on the pipe its very loud. I'm considering trying a plug in one of my muffler outlets to gain some midrange and maybe make it quiet down more. Geared to go 30 max it could have some very strong torque if its anything like my other piston ported pocket bike motor.

I don't have huge expectations but I think I at least have the head bolts staying tight now. I know the motor would love it if I lightened the clutch, put stiffer springs on, or a different performance clutch, but as of now it picks up at a power level that won't bust the freewheel, and the weak point in the system is belt slip. If I can ever afford the new 42 tooth SRAM XXO cassette and a derailleur for it, then I can get rid of the cvt and use the geared drive for possible gains.

Thank you for your kind words, I've been quite surprised at how nice this rides. At first it was just kind of a folly idea that I shelved because it really isn't a practical bike lol.

 

[16v4nrbrgr]

OK, so I had to helicoil a couple engine mount bolt holes on the right side cuz they buzzed out. It's holding tight now fortunately. The head bolts keep loosening up, and the carb tuning is weird because my mixture looks fine but my motor cut out on a long staight, and it had a fouled plug when I got back. I think the main jet can foul the plug when I whomp on throttle at high speed. Its still kinda four stroking unless I twist throttle so nicely and ramp up the fuel then its nice and clean and vibe free. I plugged one of the exhaust outlets with a silicone cork, and I'm thinking that maybe the bike doesn't like the backpressure, it sure does at lower speeds, but maybe its a restriciton at high speed. The idea was to give it some backpressure and keep more fuel in the motor since the outlets together are too much.

I picked up some connector bolts typically used to put together futons and the like, I might try and use them as stretch head bolts. I specifically selected them because they have large flatheads with a lot of surface area to grip and a reduced shank diameter, so maybe they'll stretch instead of loosening up? It's worth a try anyways.

I think this bike has a ton of potential for racing if the engine can be sorted out to be reliable under some prolonged whupping. I don't think I'll try and use it for a daily rider since it's either the engine or the derailleur taking turns giving me grief, lol! It shifts ok now so that's cool, you just gotta blip the power on downshifts to persuade it.