New top end

[Nickt919]

When working on older style 66cc engines you will have trouble finding a cylinder with the correct port timing unless you find some really old stock, I've got three different cylinders I've checked the timing on using my 38mm stroke, all would need a lot of port work just to match the original cylinder.

That there is the problem with just getting a new piston and cylinder. There's high and low hole pistons....different strokes, 38/40...different rod lengths...all working on cylinders with different porting. The chances of it all lining up are slim unless the parts all come from an identical engine.

It may be easier to take TheWizzerds recommendation and link for a whole new engine. The link is for a 100cc engine for $112. Just a new top end is probably 60% of that cost. With a new engine everything is fresh and new.

 

[TheWizzerd]

That there is the problem with just getting a new piston and cylinder. There's high and low hole pistons....different strokes, 38/40...different rod lengths...all working on cylinders with different porting. The chances of it all lining up are slim unless the parts all come from an identical engine.

It may be easier to take TheWizzerds recommendation and link for a whole new engine. The link is for a 100cc engine for $112. Just a new top end is probably 60% of that cost. With a new engine everything is fresh and new.

That "100cc" engine is iron sleeve also, so you wont have to worry about plating issues. They have their own potential issues, but mildly tuned and not used in a racing capacity those problems shouldnt surface.

 

[Dserna]

@TheWizzerd that BoFeng carb is a 19 mm?

 

[TheWizzerd]

@TheWizzerd that BoFeng carb is a 19 mm?

19mm mount. So will fit the stock 19mm intake.

 

[Dserna]

19mm mount. So will fit the stock 19mm intake.

The throttle valve opening is 14mm?

 

[TheWizzerd]

The throttle valve opening is 14mm?

17mm venturi