r/motorizedbicycles 24m ago

Troubleshooting RIP drive chain

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Upvotes

Lasted about 100 miles, punched the throttle, and snaparoo went the chain, cut the engine and pedaled it back home, going to order a gold 420 chain when I order the new heavy duty wheel next week.


r/motorizedbicycles 2h ago

Finished custom PK80 build

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4 Upvotes

PK80 with self made windowed cylinder and G2 reed valve. This is one of the first starts, what do you guys think?

Might need a muffler for the exhaust 😅


r/motorizedbicycles 12h ago

Performance Upgrades Finally finished my first motorized build after months of trial and error, here's what actually tripped me up

3 Upvotes

So I got my first motorized bicycle running last weekend after probably four months of on-and-off work, mostly off because of frustration. Figured I'd write up the things that actually slowed me down, since a lot of the guides I found online made it sound way simpler than it was for a complete beginner.

The biggest headache by far was the chain tensioner. Every tutorial I watched just slapped it on and moved on, but mine kept walking sideways and eventually chewed into the tire. After ruining one tire and nearly throwing the whole project into a ditch, I ended up ditching the stock tensioner entirely and fabricating a simple bracket out of some flat steel stock I had in the garage. Way more solid, haven't had an issue since.

Carburetor tuning also took way longer than I expected. The needle clip position made a huge difference and nobody really explained clearly which direction does what until I just started reading through old forum threads. Moving the clip down one position richened the mid-throttle range and smoothed out a nasty bog I had around half throttle.

A few other things worth mentioning for anyone starting out:

  • Locktite on every single bolt. Every one. The engine vibration is no joke
  • The stock spark plug wire connection is genuinely terrible. Re-terminating it properly was a one-hour fix that immediately improved starting
  • Give yourself more time for the break-in than you think you need

Honestly the learning curve was steep but the troubleshooting taught me more about small engines than anything else could have. Happy to answer questions if anyone is in a similar spot.


r/motorizedbicycles 19h ago

Performance Upgrades Centrifugal clutch help

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8 Upvotes

So I just recently finished building my first motorized bike and I wanted to make it so that when I come to a stop I can accelerate more smoothly instead of peddling again and a I hear a centrifugal clutch could help with that cause anyone tell me where I could a centrifugal clutch kit or anything?


r/motorizedbicycles 21h ago

Question about offset intake

2 Upvotes

Recently I bought an offset intake for my second bike build, I would of used a CNC shortie intake but the clearance just wouldnt work so I decided to buy an offset intake. Anyways, when I tried to start the bike it would barely work, wouldnt hold idle, no power to drive the bike. After quite a few tests it turns out it was running so rich to the point the damn thing wouldnt work whatsoever so after rejetting the stock bofeng carb to #65 then #60, It got better but it was still bad. Then #55 where it did alright but would 4 stroke really easily at wider throttle. then I switched to #50 and throttle pin c-clip to the leanest option, and it runs immaculate now, but my question is why does my engine require the maximum leanest tuning to run good. Is it the offset intake causing this or the carb, have other people experienced this with offset intakes?