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

If it bogs on WOT after the engine is warm then your jetting is incorrect. General rule of thumb is:

0 to 1/4 throttle is the air/fuel screw
1/4 to 3/4 throttle is the needle
3/4 to WOT is the main jet

lean it out with jetting and/or go richer on the mix (1:32) for torque.
 
Last edited:
lean it out with jetting and/or go richer on the mix (1:32) for torque.

They want really rich fuel for the break in, 17:1. I think I went a touch too rich, the 1 gallon can wasn't exactly full so I ended up diluting it after and throwing a little untreated fuel in the gas tank on top of the overly rich mix. Yea, "science".

Overall it's running way better than when I started. I've got the choke figured out and had it, well not 'flying', but moving briskly up the hill today at WOT (is WFO just the redneck term?) for a moment and it was happier.

If the rain lets up I'm going to change my parking lot plan and instead of going to a school where I'm sure the po po would show up, I'll go to the office. I know it's parking lot is empty and our campus cops will bug me before the real ones (and either say "cool!" or just tell me to go away).
 
Work parking lot speed test complete... and the results are:

upload_2020-5-31_21-38-30.png

Flat ground, 149 pound rider, no wind. The wife watched the video (reluctantly) and asked why I wasn't hunching down to reduce drag. Low speed high drag.

Anyway, it survived a bunch of zipping around on pavement. I brought it home and torqued down the head bolts, exhaust bolts and intake bolts all which were no longer totally snug. Again, no torque spec but I think I'm done torquing things, eventually those compressed oatmeal bolts are going to snap.
 
Still running, been taking on laps around the neighborhood every day it's been nice out. Chain seems to have settled down, getting the hang of when you can gas it and when it's just going to get unhappy and bog down, etc.

I tried doing some trail riding around the pond, that was a disaster. It won't run slow enough not to die when you're climbing rough stuff; it was easier to just shut the motor off and pedal.

The 8 year old in me is still thrilled every time I ride it.

Talking to dad today, I told him they made some 80cc 'upgrade' kits and was wondering what it would take to pull the engine apart and install one. I feel another project coming on....
 
Still running, been taking on laps around the neighborhood every day it's been nice out. Chain seems to have settled down, getting the hang of when you can gas it and when it's just going to get unhappy and bog down, etc.

I tried doing some trail riding around the pond, that was a disaster. It won't run slow enough not to die when you're climbing rough stuff; it was easier to just shut the motor off and pedal.

The 8 year old in me is still thrilled every time I ride it.

Talking to dad today, I told him they made some 80cc 'upgrade' kits and was wondering what it would take to pull the engine apart and install one. I feel another project coming on....
:eek:

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.
 
My prediction is you will shortly get tired of dking around with this thing...ask me how I know. Go buy an actual bike or go with an electric kit.

I'm sure at some point it will lose it's appeal. However, I do have a real bike and when I jump on it for a ride I'm shocked at how fast and smooth it is.
 
I'm going back to my original assessment of the 80cc kits or "more power". It's got enough, I've scared myself a few times now and I'm not just running around being dumb. Well not as much.

What it needs is either more torque, or even simpler just a re-gearing. Right now when you get it up "on pipe" and it's screaming it goes fast enough, but with solid engine mounts it's vibrating everything so bad you can't even sit down or hold on to the bars. Nothing is broken or loose, it's just buzzing like a Chinese 2-stroke with it's neck being wrung and really not fun to ride like that. With some lower gearing giving it more low end grunt or mid-range "go slightly faster please" motivation it would be more fun / easier to ride casually.

The saving grace is if it starts to lug you can just pedal your way over things / faster and eventually the motor catches up. Geared like it is you can't just treat it like a motorcycle all the time when puttering around.

I did tinker with the chain tensioner a bit, took out some of the slack that's developed as things settle in. I used to get 10-12k miles out of a chain on my KLR650, somehow this one isn't likely to last. Maybe the engine just explodes so you don't have to worry about the chain, or that 3rd tank of fuel...
 
Back
Top Bottom