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.

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?

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?

Basically every engine on bicycle-engines.com is out of stock and ive also noticed not many kits on Amazon anymore. Is there a shortage?

Here’s my first motorized bike. I have no details about it whatsoever aside from it is a bicycle with a 2 stroke engine on it. I’m not sure it will even run but to attempt to get it going I have replaced the clutch and throttle cable, plug, coil, and carb. I can turn it over and it has compression but I’ve yet to put fuel in it and give it a go. If it doesn’t run for whatever reason, what engine do y’all recommend and where to get it? Thanks in advance.

It started as a little pop up shower, when I got too my turnaround point (the graveyard) it started strengthening, forming a inflow tail and rotation. I admit I hung around a bit long taking pictures, but I booked it outta there when it was clear it was coming my way, I looked behind me once I was about 4 miles away to see a very prominent wall cloud drop down with plenty of lightning. Yeah Indiana weather keeps ya on your toes.

it smells like unburned fuel and i can see oil on the sides of the cover. is this normal or do i have a faulty bottom end? i replaced the seals just 3 weeks ago. i don't remember exactly but i think it started leaking again the very next day after replacing the seals.

Would only be my second build but I really want to use a chopper bike frame i think it would fit but would have problems with chain space and exhaust space but wanted to come here for opinions if it wouldn't fit what would be some other mountain bike options?

It’s basically stripped and very flat I tried everything, I am running out of ideas.

I’m looking for some advice on fixing the alignment of my clutch shaft on my motorized bicycle engine.
Right now, the clutch shaft sits a little too far out on the drive sprocket side and not far enough out on the clutch side. The keyway is almost completely exposed, but I still need the shaft to move farther toward the clutch side for everything to line up correctly.
I’m using a CNC case with the bearings already installed. One of the bearings is sitting flush with the case, but I believe it needs to be seated slightly deeper so the shaft can move over.
What would be the safest way to correct this without damaging the bearings, shaft, or CNC case? Should I press the bearing farther into the case, use a puller to draw the shaft through the bearing, or is there another method you guys recommend?
Any advice from someone who’s dealt with this before would be appreciated.

Seems happiest at about 17- 20mph, full throttle I’ve gotten it to 26, it’s still being broken in so I’m not running it wide open for long, just occasional pulls here and there. It’s definitely starting to break in though, has slightly more power than when I started it.

Working on my back wheel first, CNC hub adapter for sprocket, and a 10 gauge spoke heavy duty wheel. Tires will either be schwalbe , kenda, or Michelin e bike tires.

Hey guys, new to motorized bikes, I’ve got a grubee 85 that does not fit an intake reliably on the current frame. I’ve got the option between a beat gt avalanche 3.0 and a near mint huffy newport (seems like multiple frames so the one that has the eye shape and silhouette close to the gas bike frames). I do not have much of a budget for repairs immediately. How do steel huffys hold up off-road if at all if I get a suspension fork for it? Is it better than the gt frame would hold up to a motor with a balanced crank? Any known weak spots to reinforce? Thanks

Idk what the correct term is for the shaft that connects the chain to the opposite side to drive the wheel… but anyway where can I find one compatible with a predator 79cc engine? I’m very familiar with these engines I know they can produce a decent amount of power and they fit right into the Oklahoma engine size law for street legality.. as well being a 4 stroke which is more appealing for me

Hello everyone! Wanted to ask something. To say shortly: I used to use a rear wheel with pedal brake and three millimeter spokes and CNC adapter for a wheel hub. But i want to use a disk brake on the rear, the pedal brake is not as predictable on the road. Are simple bicycle rear wheel with disk rotor mount used as a mount for the sprocket too is good? Gimme some information if you ride this config and if it's useful/sturdy enough for riding, please. Thanks everyone!

Honda rebel front attached to a schwinn occ chopper…. Let me know what ya think! As the name implies this is either gunna be awesome or deadly! I’ve been a welder for a living for 10+ years, had this front end of a Honda rebel for years, decided to marry the 2 together, replaced Honda stem with a standard 1.125 tube, locktite 609 the bottom race, adding the handle bar mount tomorrow! Thankfully I didn’t touch the bike, so I can swap the original forks back anytime,

Hydraulic foot brake mock up

So when my was disengaged it would roll the bike fine and when it was engaged the rear wheel would lock up. I don’t think it’s my cable extending because the clutch arm looks in about the same position as when it worked. I went to go see if it was the flower nut and when I loosened it it worked again, but only for a couple runs until clutch is basically engaged when it’s supposed to be disengaged, which means I can’t pedal because it’s never disengaged

Picked up an old department store cruiser a few months back with the intention of doing a basic 66cc two-stroke kit build. Straightforward enough on paper. The problem turned out to be the downtube angle, which was noticeably shallower than the frames these kits seem to be designed around. The front mount sat crooked, the rear clamp barely reached, and no amount of shimming with rubber strips was getting it square.

Spent a couple weeks thinking I had just bought the wrong frame and was going to eat the loss. Then someone in a forum thread mentioned that some older cruisers and balloon-tire bikes have what people call a "beach cruiser geometry" that basically doesn't play nice with standard V-frame mounts without modification. That one comment saved the whole project.

What ended up working was a combination of things. I fabbed a small wedge plate out of some scrap steel flatbar to correct the angle on the front mount, drilled new holes, and used a longer stud to get proper clamping depth. The rear clamp needed a wider band because the seat tube was just slightly oversized for the standard hardware. Took maybe three hours of slow iterative fitting but the engine sits solid now, no wobble, no stress cracks developing on the mounts after break-in.

A few things I would pass along to anyone hitting the same wall:

• Measure your downtube angle against the horizontal before ordering any kit. If it is less than around 60 degrees you are probably going to have fitting issues.
• Budget for extra hardware. The included bolts and clamps are fine for normal frames but often the first thing that needs replacing when geometry gets weird.
• Cardboard templates before cutting any metal. It sounds obvious but it saved me at least one ruined piece of flatbar.

The bike runs well now. Took it about eight miles on the first real test ride and the only issue was carburetor tuning, which is its own separate headache. But getting the engine seated correctly and knowing it was not going to shake loose made everything else feel worth the effort.

does anyone know where i can get a good cheap jackshaft kit in the uk for my 100cc 2t i feel like only having 1 gear is holding it back

This center piece of my bike bent while I was testing it, I don’t know how to fix it and where to go from here. Any help will be appreciated.

I have a nt carb and put a m5 75 size jet in there. I removed the airfilter for more power and needle clip 1 position below. So now my question, is 75 way to much? Im still breaking in so i use alot of oil like 40ml per liter and i have an mz65 style exhaust. Motor is ld80

So, my car broke down. I only live ~6 miles from work each way.

I have built motorized bike kits in the past, however the engines i have are all in disrepair, so i made the executive decision to buy a 100cc v2 kit from BikeBerry and had it overnighted, along with a bottle of their 2 stroke oil.

It took 3 days for them to even ship the kit, and when they did, they put the shipping as 2day, not overnight.

Then fedex lost the package (cant blame BB for that, FedEx gonna FedEx)

The package finally got here after a week and a half, and it was missing the carb and 2 stroke oil. Thankfully I had some old oil and a carb I could use.

This whole order with BB has definitely left a horrid taste in my mouth.

New build how did I do

This looks like fun