I REALLY need more power and speed

[Sheriff John]

I got a motor-bicycle and home built it. I haven't ever rode it because of the low power, instead i use my goped. I LOVE riding it and id dont want to sell it, but i just NEED to up the anti.

 

[Skarrd]

how much power are you looking to get?

 

[Sheriff John]

as much as i can. 80cc motor

 

[Skarrd]

well one thing you can do to free up some power is to pop the intake pipe off, rotate the piston to top dead center, and check if the skirt is still covering the port, use a fine tipped shapie to mark where it still is, then take the cylinder off and cut out said area of piston.

also an expansion chamber, correct oil mix and carb tuning help alot!


remember, 24:1 1st gallon, 32:1 there after.

 

[Sheriff John]

so i cut the piston with a dremel? And do i do this to the entire part or the skirt that is showing?

 

[Skarrd]

so i cut the piston with a dremel? And do i do this to the entire part or the skirt that is showing?

just the part that you can see covering the port. search on the forms, theres several threads talking about it.

here's a good spot to start looking High Performance Bicycle Engine Tips - Motorized Bicycle: Engine Kit Forum

 

[bairdco]

if you really are a sheriff in san diego,VC Section 23135 states that it's illegal to modify a motorized bicycle to go over 30mph.


(sorry, couldn't resist...)

 

[spad4me]

Post pictures if possible.
You will not get a goped quality engine from a china girl kit.
The best you will get is a goped type performance with a shift kit. And engine mods, plus a tuned pipe.
Sick Bike Parts LLC - Performance parts for your motorized bicycle

Count on spending more than the china girl kit cost.

I use a gp460 with a scooterguy mount. A 5 to 1 reduction transmission feeding the sick bike parts front crank setup.
40 to one in first all the way to no more oomph left in the 460 in seventh gear.


The Chinese engines do not measure cc displacement as you or I would. An 80 cc is a 66 cc.
I recently bought a 40 cc engine that turns out to be a 24 cc.
Good price but I wont buy from them again.

 

[Sheriff John]

Ok, so I decided to do two things.

1. The piston skirt mod
2. I want toopen the exhaust port. How much do I do it?

If I do both of these, what will I gain in performance?

 

[scotto-]

You should get a little bit more, but nothing that'll blow your socks off. Add a tuned pipe and it'll help a lot more.

 

[Skarrd]

really though, if you want serious power... get a morini. you'll end up spending the same on hop up parts for the china girl (and replacement parts)



kinda wished i had gone that route now, lol.