52cc Stage 2 CAG CVT powered X-Games Motobike

[16v4nrbrgr]

WOWZA! It freakin' rips now! I changed the 72 jet down to a 68 because it was awfully smoky at around 55F air temp, might try to get a 70 or go to the 72 to ride in the cold. The chain clearance is working great and the derailleur is working in the low gears consistently with the straighter chainline.

There are a couple loose ends I gotta figure out, like a loose connection inside the epoxy for the tacho, when I flex the plastic case I can see it connecting intermittently. I might just ante up the $40 for another one if it keeps it up, I mounted it on some washers to keep the mounting plate from flexing the case, will see if it works next time.

I put a couple black screws at the fronts of the rear number plates to keep the tangs from popping out, the screws on the opposite side don't prevent that. I also had to tighten the **** out of the left mirror with some more blue loctite, the inner split clamp in the bars likes to vibrate loose, and it started migrating out of the end.

The bike now has plenty of power to keep accelerating off from 30+ mph, I did a short run to check the head bolts and they torqued fine, so I marked them with some paint to keep an eye on them. The acceleration from a stop is pretty good, it helps a little to push off from a stop and at 10 feet it gets into the powerband and zings. This bike would make a killer racer, I hope I can figure out how to do an event this year because it would be competitive with the suped up bikes in the mid-class. Of course it doesn't have pedals, so I'm prolly DQ'd before the gates!

 

[16v4nrbrgr]

Mopeds oftentimes don't have pedals, especially around the SF Bay area, where 2-wheeled transportation is encouraged to cut down the traffic congestion. Racing mopeds usually get rid of the pedals since they can take off from a stop with sufficient power, and you don';t have to worry about touching down a pedal and losing traction in a turn or missing the pedal and breaking your ankle.

Moped,

moped,

moped,

moped,

 

[16v4nrbrgr]

and finally, moped.

Pedals on the best mopeds are vestegial devices that are shed at high speed, like a lizard's tail when booking it from party pooper predators.

 

[Dan]

"WOWZA! It freakin' rips now!" LOL, cool 16v.

"I marked them with some paint to keep an eye on them" Gonna try that.

Really is a beautiful build with some incredible attention to detail. Purty work.

 

[16v4nrbrgr]

Thanks Dan, couldn't have done it without the knowledge and inspiration from motorbicycling.com members!

 

[16v4nrbrgr]

Since the other bikes are pretty much squared away, I decided to take the motobike out for some Sunday, Sunday, Sunday! lol

It was about 65 degrees and sunny this afternoon, and got progressively colder through the day, last run 30 minutes ago it was about 55F in the shade, lots of cold mist in the air.

The first run I did, it was four stroking at high engine speed and fouling the plug, fortunately not too bad so I was able to take it easy and avoid WOT and get the bike home. The plug confirmed it was on the rich side, along with smoky azz exhaust, so I took the 68 jet out and put in a 66.

The second run I did, was awesome, but not without problems. Now it really rips to the top end and has a lot better torque through the powerband. I got going about 35 and must've missed a shift or something, and came to a stop and when I tried starting again, it felt as if the CVT belt was slipping, the bike wanted to go but didn't have enough torque to get anywhere and revved freely. I though, "Oh crap, now I gotta mess with the variator or get a Kevlar belt or something..."

Since I had to walk her back, at least I thought anyways, I stopped for a rare picture. I usually don't do this because I feel like a d-bag taking pictures of my belongings in public, lol.

I walked the bike home, not bad since its so extremely light, I can just hold it from the tail and guide it along. I opened up the CVT to find everything was okay, cleaned some minor oil mist out, and rotated it to see if the rear wheel was getting traction. It wasn't, so I thought, uh oh.

Turns out when I downshifted prematurely and abruptly at speed out on the road, it just kicked the chain off the 11t motor sprocket, and it was sliding nicely on a step machined into the sprocket, glad that step is there, since it didn't wear the chain or the sprocket with my stupidity trying to rev it up to get the belt to grip, I thought maybe it was oiled up or something before.

So I put the CVT cover back on, put the chain back on the sprocket teeth where they belong, and had a perfect rip around the neighborhood before it got too cold, I don't want to press my luck with the jetting and ping this motor since I had issues with the top end previously. I think I'm getting close to a good tune that I can trust on longer rides, and I just gotta remember not to downshift into first when I'm going really fast, because I think the chain inertia around the tiny sprocket at those speeds is too much, and it wants to jump off, fortunately to a smooth and safe location, instead of Gnarville.

 

[16v4nrbrgr]

I put the 68 jet back in it today, for flat ground ripping the 66 pulls to the top end better, but it makes a sharp noise when under load up hills that is disconcerting. I checked it out and it looks good inside, so I think the 66 is just for racing purposes only, to raise the redline it'll pull. With the 68 it has better midrange torque and the top end is smoother and sounds happier for daily around town stuff, although about a thousand rpm lower and less snappy. This carburetor is kinda lacking in the tuning department, on jet is all you got to play with, I guess I could figure out a way to make the transition holes tunable with a hollow bolt made into a jet for that cavity, maybe later.

I'd like to try a regular X1 mid-bike gear reduction box on it instead of the CVT too, I think the regular gear reduction would allow for another couple thousand revs out of the engine, and there's more power up there as well. This little engine flows a lot of air!

 

[16v4nrbrgr]

I'm pretty happy with the bike now, did a half-assed high speed run today and got it to go 39 mph, I'm sure I can break 40 if I max it out in first and then shift through the next couple of gears with enough breathing pause to let the belt shift down the variator and gain more gearing advantage, the cassette is pretty close ratio so it might zing up to another couple mph.

I think I'd like to tune the carb to lean out the low speed circuit a bit, it takes some careful twisting of the throttle to avoid getting too rich too early, I think if the low speed circuit is leaner it will rip up into the powerband better and have more low end torque. I found this good writeup on the tuning tricks for the Dellorto SHA and its clones like the Runtong, aka RT.
http://www.mopedarmy.com/wiki/Dellorto_SHA

I'm going to probably try tapering the bottom of the slide little by little until it pulls more crisply, it's okay right now but when it warms up and the effective mixture in the cylinder gets richer it four strokes a bit.

My friend who's also got a moped addiction gave me a 14mm Dellorto SHA to play with, I already swapped over the aluminum float bowl which solved all of the leaking issues I had from the plastic one deflecting and leaking around the edges not clamped down by the two screws, I also don't have to worry about the float bowl being an unpredictable vacuum leak! I might also use the slide from that carb for tuning and various parts as needed, since its a 14mm and my RT carb is a 15mm, and the top end pull is quite nice already. This carb is so simple inside, with few moving parts, so there isn't much to screw up in the cloning process.

 

[16v4nrbrgr]

Wow! Simply filing the bottom of the slide back about 10 degrees like the picture really cleaned up the low end acceleration! I think I'm going to keep it this way even through I think I could lean out the part throttle circuit a bit more, since I'll prolly switch to a leaner jet in the summer and want to make sure I don't go too far in the other direction.

I'm really impressed with this bike now, it rides very nicely and I can upshift into 3rd or more at high speed, and it shifts the variator into low since it slows down the pulley, and adds low end grunt in the higher gears.I ran around the neighborhood a couple times to try out the slide mod, maybe I'll try a top speed run on another day. I gotta keep it low key, keep seeing more and more old folks from the neighborhood walking around since the weather has been nice, and I don't want them ganging up against me and the other guys in the neighborhood that ride mopeds, lol!

 

[g_rashid]

Nice build. I own one (MotoX frame 'donated to me by my son) and would like to go with the possibility of adding a AV& / AV10 Motobecane or a Peugeot 103 engine to the frame then go from there.

 

[g_rashid]

What's the approx cost of this build?

 

[16v4nrbrgr]

It cost a reasonable amount, not too much for what I've got out of it. If you're planning to build one it's apples and oranges unless you clone what I've done, and I don't add up the receipts because I don't want to know, lol.

 

[g_rashid]

cool. I've also considered the pa50 engine or going 4 stroke xr50 engine.

I wont go cvt, too costly. My onl opposition to the av7/av10/103 engine is the space needed and the space for the engine moving at variation.

'Motoped' is interesting too, I just ran across their site.

 

[16v4nrbrgr]

I'd be careful with how you mount the engine to the frame since its aluminum, especially if you use a torquey four stroke pit bike engine. I chose to make the bolt-on subframe to avoid compromising the frame with any welding which needs to be of matched alloy and heat treated afterward, which can compromise the whole frame if done incorrectly. I like the motoped too, but I estimate mine cost roughly half of a completed one of those costs, weighs half as much, and I can't use mopeds on trails so a lot of its benefits wouldn't be really worth it to me where I live. If you can use dirtbikes on trails, it would be a good option for a street legal dirtbike and there are large displacement pit bike motors with a lot of power.

 

[g_rashid]

Sounds nice, thanks for the tips. I spoke of the xr50 as an option, I prefer 2 stroke. The frame appears to be the same metal as the Honda Hobbit and the Motobecane as I took a look at the welds and bare metal. I more than likely will cut the frame and make mounting brackets to accommodate the AV series engine. I may not have the engine with a variator because of clearance issues. I can get the bike at 45mph+ easily.

 

[16v4nrbrgr]

Sounds good, you should start a thread and log your progress on the build.

I don't want to spoil your ambitions for 45+ mph, but that engine makes about half the horsepower of a Stage 2 Cag, so if you keep the pedals for a takeoff speed of about 10 mph, I would expect that you'll get about 35 mph tops out of it.

 

[g_rashid]

I'm not sure if you know about the Motobecane av7 av10 / Peugeot 103 engines very much. with the most subtle of mods these engines hit 45 easily.

http://www.youtube.com/watch?v=5fXcFBCQc44

Thanks for the advice

 

[16v4nrbrgr]

It's a nice engine for sure, I have a neighbor with a couple Peugeot mopeds with a similar engine and they are fast. The problem is that it is single variated, meaning that the CVT does not take up the slack on the driven end of the belt drive, so the motor has to be able to rotate in order to keep the driven belt at constant tension, which would be a complex mounting method to devise and fit on a home built bike.

It's also kinda expensive to modify a Motobecane/Peugeot engine, and to achieve similar results to an almost stock stage 2 Cag engine with an X2 CVT, you would need to spend a couple hundred dollars on top of the $300 for the engine in order to achieve the same horsepower, meaning that it would cost over quadruple what a pocket bike engine and gearbox would cost, plus all the mounting and tuning complications. It can be done for sure, but I would consider buying a running Peugeot moped and tricking it out before attempting a project like that.

The linked video is very neat indeed, but you have to ask yourself whether you want to ride a mini dirtbike at those speeds head-first, laying down on the seat with special lowered handlebars and leg supports required to ride in the most unnatural and uncomfortable riding position in order to cut down your drag enough to go that fast. Not to mention how extremely dangerous riding laying down head first is, and its horrible for bike control because you have little influence over the front-rear weight transfer, only good for going fast in a straight line. I'd consider that guy in the video borderline suicidal trying that type of stuff on the highway, lol!

So far I haven't even tried maxing my bike out since its still breaking in, and it takes off from a stop without pedals at an acceleration rate similar to a car, and pulls strongly in a short distance, achieving 40 mph sitting upright in a natural and comfortable riding stance. I haven't even done a run yet where I tried crouching behind the fairing throughout the acceleration run, and so far have only needed to shift to 3rd gear on the derailleur. Shifting up has a nice benefit when coupled with a CVT in that it causes the CVT to "downshift" to the smaller diameter part of the variator cones which aides acceleration torque, and then the CVT can upshift gradually as clutch bell speed increases, and thus allows a higher top speed when maxed out at the largest diameter before another upshift.

You should start a build thread of your own posting your thoughts and showing the progress of your build and folks here will be more than glad to offer any advice that you ask of them. I think it would be interesting to see how somebody else approaches a build on this same frame. Honestly, I don't think it's necessary or tactful to post up pics of your stripped frame in my thread without an idea yet of what you're going to do, and then start giving me advice and questioning what I know about a 2.5HP french moped engine, I know enough to know I'm not all that interested, ahem. To see another approach you should check out Flattie42's build over at Pocketbike Planet forum, he's building something completely different than mine, and changing a lot of the stock frame components and geometry to suit his own tastes.
http://www.pocketbikeplanet.com/showthread.php?p=581541#post581541
If you become a member you can see the pics in the threads.

It took me a ton of money and hundreds of hours of research and work to get from:

to:

And I hope that you don't take your own build lightly, since it takes a lot of conscious effort to make an aluminum framed motorized bicycle safe to ride. I can't stress enough the importance of understanding how aluminum fatigue and heat treatment works before picking up the first cutting tool or laying a bead of weld.

 

[16v4nrbrgr]

Today I went for a rip and got 41 mph, but I'm jetted kinda rich for the recent summer weather, and I was wearing baggy pants and a t-shirt. I think if I wore some more aerodynamic clothes and jetted it richer to suit the unseasonably warm weather there's a couple more MPH in it.

My friend's heavily modded 5 Star General with a Peugeot mounted up, with a cylinder kit, performance variator, 19mm Carburetor, and racing expansion chamber was very fast, it's got quite a bit of torque and can go 45+, I was impressed!

 

[g_rashid]

whoa guy,

no ffense whatsoever. I wasn't trying to hijack your thread at all, by no means. No need to get all in your feelings about your build. It's very nice, I just thought I'd post some ideas to get some insight, geez.

I wasnt quite sure that it would be an emotional experience for you.

1. I have an AV7 waiting to be bolted up on the frame, alreadty "tricked" out, thanks.

2- I posted the video of the guy riding the mobylette just t oshow you the speed capability of a AV7/10 , 103 Engine, since you had doubts. Who really rides as such on a normal basis? SMH, shame on you.

3. I saw pocketbikeplanet. been there as a member for some years now. but thanks. And again, it's not thta serious, they are just bikes... breathe man, breate.

I'm not here to make enemies.

Once again, nice build. I have no time for the negativity or arrogance .
Thanks and .