As noted in another thread, I've been de-restricting my son's LT-A50. I've extensively researched the topic and have performed the following:

* Remove intake restrictor
* Remove exhaust restrictor
* Confirm throttle slide completely clears throttle body at WOT
* Change main jet from #55 to #70
* Drill four 1/2 inch holes in airbox cap, effectively increasing potential airflow by ~5X
* Remove muffler end cap (but leave spark arrestor/insert installed and unchanged)
* Switch to BPR5HS spark plug
* Drain el-cheapo 2-stroke oil and switch to AMSOil Interceptor all-synthetic

Results:

* Significantly increased low-end acceleration
* Better power delivery through entire throttle range
* Increased engine noise, especially from intake

Today we measured his top speed. It's the same as before the restrictions were removed, about 17-18 MPH on a level paved surface. It has TONS more power - while it has always been able to climb surprisingly steep hills now it will climb ridiculous grades approaching 45 degrees. But that doesn't seem to translate to top end speed.

I don't want him to have much more speed, actually, but I want to understand WHY the top end seems limited. I expected to have to tighten down the throttle limiting screw on the handlebars but after riding with him both my wife and I agree we're going to leave it wide open. 17-18 MPH is fine when one of us is in front and the other is behind, which is how we always ride to keep him safe.

Just wondering why the top end isn't benefitting from all the de-restricting. Thanks!

 

where did u get the #70 jet from ?

 

Isn't there a clutch spacer in the primary on those little zuki's? All the motor in the world won't make it go faster if there's not enough gearing. Maybe I'm thinking of the LT-50, rather than the LT-A50, though I don't know what the difference is on the two models.