so... those 50cc bicycle engine kits....

Jayne

Just here for the memes
Charter Member
Supporting Member
Multi-Factor Enabled
Joined
Dec 16, 2016
Messages
8,028
Location
Unincorporated Wake County
Rating - 100%
34   0   0
6 months ago I got the notion to get some sort of moped, scooter or whatever to replicate my childhood memories of riding around on the back of my great uncle's Honda Trail 50. I looked at those, zuma scooters, the honda ruckus, and some other stuff including those 50cc (and 80cc) motors you stuff into a bike to make your own moped. ultimately I got nothing.

Last week, I was once again thinking about it, then took the plunge and ordered one of the $108 50cc kits off amazon. It showed up yesterday, and after spending most the day tinkering, I ended up with this:

crazy_bike_motor_1.jpg

My 1993 DB Ascent is now sporting 50cc of Chinese crap. The only real trouble getting it installed was the rear motor mount. The instructions say "go to the hardware store and buy longer threaded rods so you can mount it correctly". Thanks China.

Those 'rods' are M8-1.0, so not exactly standard (M8-1.25 stuff is everywhere). I found 2 bolts and since they weren't fully threaded had to make some ghetto spacers I won't share pictures of out of old nuts and washers, but it worked.

I wants 1:17 fuel for 'break in' for 500km. That's a LONG break in for something that can't go all that fast. I mixed up some 'almost 1:17', dumped some in the tank, started pedalling down the driveway and popped the clutch... damn thing fired right up.

In about 150' the chain popped off the sprocket so I had to go back and tweak with the tensioner a bit, but after that I ended up riding around for about 15 minutes before stopping to let it cool down. It says not to ride more than 30 min at a time during break in.

So it's impractical, kinda noisy and slow and you're basically running around with a chainsaw strapped to your bike, but it's really stupidly fun.

I need to heat the exhaust pipe up and as the manual says "make it flexy" so I can bend it parallel with the frame so the mount will work correctly, but otherwise I think it's good to go. Not sure where, but it will go.

Oh, and maybe figure out how to mount the rear of the chain guard that doesn't involve a zip tie. The manual says "use good zip tie!".
 
An ounce of image is worth a pound of performance.
s-l640.jpg
 
I've watched a bunch of YouTube vids on these things and some of them got pretty good results. I know the ones with more displacement (not a motor guy so I may be wrong) will send that bike fast enough to be pretty lethal if you come off.
 
Ok, I’ve been in purge mode recently and have given tons of stuff away around the house. All the bikes the kids have outgrown are now gone but I’ve held on to some even though they are not ridden. I now have a project for my sons old Cannondale which used to be my old bike.
 
I want an e-bike for many of the same reasons, but I can’t imagine that I would use it enough to justify the cost.


Good on you for finding a good fun per dollar option!
 
Does it have any grunt going uphill ? Or only useful on a flat road ?

Minor grunt, haven't had to pedal to assist it going up the road by the house but I can see on some larger hills it would run out of steam.

Did a 'speed test' today, got it up to 16.9 mph according to the GPS tracker. Woo!

It's breaking in though, I'm noticing it's smoothing out and actually responds to throttle inputs a little. It's still sorta low/medium/high settings rather than fine throttle control but at least you can crank it full open and it won't die. Won't go very fast, but won't die.

Each little round trip is 1.7 miles according to the GPS track, so I've got over 9 miles on it so far. :)
 
Last edited:
Minor grunt, haven't had to pedal to assist it going up the road by the house but I can see on some larger hills it would run out of steam.

Did a 'speed test' today, got it up to 16.9 mph according to the GPS tracker. Woo!

It's breaking in though, I'm noticing it's smoothing out and actually responds to throttle inputs a little. It's still sorta low/medium/high settings rather than fine throttle control but at least you can crank it full open and it won't die. Won't go very fast, but won't die.

Each little round trip is 1.7 miles according to the GPS track, so I've got over 9 miles on it so far. :)
Only 300 miles left to break her in!!!
Do you think the 80cc would be a better option? Wonder how quiet you could make it? I would not want it to draw attention while puttering around.
 
I thought I posted in this thread last night but don’t see my post. I did break open a bottle of Woodford yesterday so who knows. I’ve been purging around the house recently and have given several bikes away. I kept my sons bike that he doesn’t ride anymore which was one of my old Cannondales. This looks like a fun project so I ordered one of the kits. Hopefully be here soon so we can play around with it.
 
Do your bicycle gears still work or is it just a one speed now?
Im no engineer, but looking at the pic... It looks like the bike gears will work when pedaling, but the engine only has one big gear for when using throttle.
 
Do your bicycle gears still work or is it just a one speed now?

The bike gears and pedaling are separate from the engine. When you pull the clutch in (and it has a lock feature to keep it disengaged without having to hold it) it's just like the regular bike and everything works the same.
 
I thought I posted in this thread last night but don’t see my post.

My thread double posted, so it's probably in the other copy.

You might want to source some M8-1.0 threaded rods ahead of time so you can skip the "go to the hardware store" step in the instructions:

IMG_7613.JPG

Then again, the kits all seem to be slightly different, so who knows what yours will have.
 
Do you think the 80cc would be a better option? Wonder how quiet you could make it? I would not want it to draw attention while puttering around.

Define "better". I went the 50cc route because it was the cheapest option, and I honestly didn't think it was going to work so I wanted to minimize my cost of failure... and now that I'm riding around on it.... this thing is plenty fast for the ill handling no suspension bike it's bolted to. 80cc would be faster, and the added torque would be handy on hills... but it's totally not street legal or anything so how far could you possibly go? If you had tons of off-road area to play in, even one of those little 50cc kids dirt bikes would kick this things butt with their suspension and variable gear ratios and such.

If I want to go fast, I'll just use the actual motorcycle in the garage. If I want to annoy the wife and dust the yard for mosquitos at the same time... then 50cc is enough.
 
I thought I posted in this thread last night but don’t see my post. I did break open a bottle of Woodford yesterday so who knows. I’ve been purging around the house recently and have given several bikes away. I kept my sons bike that he doesn’t ride anymore which was one of my old Cannondales. This looks like a fun project so I ordered one of the kits. Hopefully be here soon so we can play around with it.
I saw your post last night... weird.

Sent from my Pixel 2 using Tapatalk
 
So it's impractical, kinda noisy and slow and you're basically running around with a chainsaw strapped to your bike.

How about one of those form 1 Chinese fuel filters minus the form one?
 
Co worker has couple bikes he added these to and he really likes them for small foot print and weight packing in his camper since he goes to daytona races every year and uses them going back and forth to track.
 
I saw your post last night... weird.

Sent from my Pixel 2 using Tapatalk
@
I thought I posted in this thread last night but don’t see my post. I did break open a bottle of Woodford yesterday so who knows. I’ve been purging around the house recently and have given several bikes away. I kept my sons bike that he doesn’t ride anymore which was one of my old Cannondales. This looks like a fun project so I ordered one of the kits. Hopefully be here soon so we can play around with it.

There were 2 threads. It looks like @Jayne created two threads 3 minutes apart for the same thing. I mean, same dang first post.
https://www.carolinafirearmsforum.com/index.php?threads/so-those-50cc-bicycle-engine-kits.62657/
So, yeah, you posted in 'this' thread...but not 'THIS' thread
 
There were 2 threads. It looks like @Jayne created two threads 3 minutes apart for the same thing. I mean, same dang first post.

When I posted it didn't work, it just hung there. I just let it sit there while I did something else and it timed out. Then I hit "post" again, and it worked immediately. But it also looks like it worked the first time, just didn't tell me about it (or the browser).
 
I'm afraid of heating up the exhaust pipe and bending it to run parallel to the frame as the manual suggests, so the pipe was just hanging off in space only supported by the two bolts in the manifold. Since the provided bracket was nothing more than a 1/2" (at best) piece of strapping, I grabbed a longer piece of 1" from the barn and made a highly custom exhaust mount:

IMG_7633.JPG

I re-used existing holes in the strap which is why it's a litlte wonky but it was easier on my drill bits to not have to go through the strap twice for each hole. If it stays put over a few test runs I'll pull it and paint it black to match (I have high temp black paint).

It looks nasty, but it's actually pretty solid.

Also did something the manual would never mention, used some wire loom, electrical tape and zip ties to actually secure off the electrical bits such that they are. The "mostly covered" connectors were probably not long for the world as shipped by the manufacturer.

IMG_7634.JPG

Made a couple more test runs as well, actually ran out of gas on one of them. The 3 position petcock isn't just a cosmetic item, there is actually a reserve setting that works. Glad I didn't have to actually pedal my way back to the house in defeat, that would have been embarrassing.
 
Last edited:
~23 pounds. The package was just over 24 and everything in it is on the bike. Ah, plus fuel, so maybe 25.

My entire bicycle only weighs 18 pounds! I'd hate to have to pedal that up a hill if it runs out of gas. On the other hand, I bet it rolls downhill pretty good.
 
I've done enough laps of the neighborhood now that I've gone from the neighbors smiling and waving to shaken heads and disapproving looks. The engine is clearly breaking in, it's got more, well I hate to say "torque" because we're talking minuscule numbers here but it feels like more. You can go from 1/4 to 3/4 throttle and actually feel it go faster. If you just hit WOT it sorta grunts and stumbles, but backing just off a bit from there it actually moves.

The idle adjust screw is very twichy, but I have it now where it will idle when you pull the clutch in vs. just race to some crazy RPM. Well most of the time anyway. Sometimes it still runs away a bit.

I'm half (or more) tempted to toss it in the back of the truck and find a school parking lot and see how fast I can go on flat paved ground. I mean, they're not using the schools now anyway, so some Bonneville testing would be a viable use of that resource.
 
I've done enough laps of the neighborhood now that I've gone from the neighbors smiling and waving to shaken heads and disapproving looks. The engine is clearly breaking in, it's got more, well I hate to say "torque" because we're talking minuscule numbers here but it feels like more. You can go from 1/4 to 3/4 throttle and actually feel it go faster. If you just hit WOT it sorta grunts and stumbles, but backing just off a bit from there it actually moves.

The idle adjust screw is very twichy, but I have it now where it will idle when you pull the clutch in vs. just race to some crazy RPM. Well most of the time anyway. Sometimes it still runs away a bit.

I'm half (or more) tempted to toss it in the back of the truck and find a school parking lot and see how fast I can go on flat paved ground. I mean, they're not using the schools now anyway, so some Bonneville testing would be a viable use of that resource.
The main Wake Tech campus on 401 south of Raleigh has plenty of space, and the entire MSF course tracks painted in the outermost lot. That's where they run the courses locally.
 
I saw one rigged up on a kids scooter........that thing would probably do 20+ mph.
 
The main Wake Tech campus on 401 south of Raleigh has plenty of space, and the entire MSF course tracks painted in the outermost lot. That's where they run the courses locally.

Ah good idea. Lines and stuff to test my skill against.
 
One must add a a turbo before doing speed test, You clearly have not spent enough money on this project yet!
 
Back
Top Bottom