First motorized bicycle build - awesome experience!

To start off, let me say that before I got into the motorized bicycle hobby I knew nothing about mechanics and engines. I didn’t even know what the difference between a 2 stroke engine and 4 stroke engine was and what a clutch, sprocket, carburetor, crankshaft, and ignition coil were. The poor quality on these Chinagirl engines actually makes them perfect for learning; they force you to fix the issues they have and in doing so learn about engines! Hopefully I’m a little more skilled now.

This bicycle is a Trex Navigator 2.0 that was sitting unused in my garage for a couple years. I went out with a couple times this summer when the weather was nice but quickly found out that pedaling a bike is pretty boring. So, I went on eBay and ordered a motorized bicycle kit and after installing it, almost crashed into a tree at 20mph because the kill switch stopped working and the clutch wouldn’t disengage. The pictures of the bike below are the result of about two months of work.

Top speed - 33 MPH flats, 39 MPH achieved downhill. No engine porting or carb tuning

Upgrade List (completed)
Aftermarket throttle
Front Basket
Speedometer
USB Power Bank
Sparks plug (NGK Iridium B6HIX)
iPhone mount
Unrestricted muffler (sounds like motorcycle and improved torque + acceleration. I didn’t want expansion chabecause it would be crazy loud)
Dual pull brake lever
Better quality fuel line
Rubber mounting
LED Rear light
LED Headlight (custom 3D printed mount to fit basket)
Tachometer
38T sprocket
Aftermarket brake pads
Aftermarket clutch lever
Aftermarket clutch pads

 

[CrazyDan]

You choose a nice bike to build on. So many first time builds have just a coaster brake and no suspension fork. You can put a muffler on an expansion chamber to quiet it down. You'll improve fuel economy with one if tuned properly since it pushes unburnt fuel back into the cylinder. Glad you didn't list a boost bottle as a future upgrade lol, damn snake oil.

 

[Vikingimike01]

It doesnt actually improve fuel economy. You just get more power for the same *amount of fuel.

 

[RB55]

You choose a nice bike to build on. So many first time builds have just a coaster brake and no suspension fork. You can put a muffler on an expansion chamber to quiet it down. You'll improve fuel economy with one if tuned properly since it pushes unburnt fuel back into the cylinder. Glad you didn't list a boost bottle as a future upgrade lol, damn snake oil.

I actually already did all the upgrades I listed . Agree with you that boost bottle is gimmick, without valves it physically can’t do anything. One day I’ll put a good quality expansion chamber on it with an unrestrictive muffler...

 

[Frogslayer]

What made you decide to replace your clutch pads? Just curious.

 

[CrazyDan]

It doesnt actually improve fuel economy. You just get more power for the same *amount of fuel.

Normally when you toss on an expansion chamber it runs too rich and you have to lean it out some. Running a smaller jet means you are using less fuel lol.

 

[Vikingimike01]

For me, didn't have to put a smaller jet. And it was not running rich before. It was running a tad lean. It runs OK now. Maybe it's the wonders of a REAL expansion chamber for REAL motorcycles?

 

[CrazyDan]

For me, didn't have to put a smaller jet. And it was not running rich before. It was running a tad lean. It runs OK now. Maybe it's the wonders of a REAL expansion chamber for REAL motorcycles?

So if it was lean before you should have been running a larger jet and getting less fuel economy. Then when you put your expansion chamber on it would have richened it up and you would have jetted down to where you are now, increasing fuel economy. Understand now?

 

[Vikingimike01]

I was just fine with how it ran. I just kept 80# jet. Worked wonders.

 

[RB55]

What made you decide to replace your clutch pads? Just curious.

Stock ones wore out real fast and started slipping, making me have to continually tighten the clutch since I ride this about 15 miles basically every day. Aftermarket ones were actually included with the clutch lever I ordered on eBay so I said heck why not try them out