More Speed after 72cc install? 2015 Super8 4T

[AylmerFreerider]

Hey all trying to figure out why I can't get a solid 70-75 km/h out of my 2015 Super8 4T.  I seem stuck at 65km/h

I have done the following

72cc BBK
Polini Hi-Speed Variator w/ 6.5 weights
1000RPM Contra Spring (was a 750 stock) - Looking to go to the 2000 RPM spring with the new power from the 72cc BBK
Technigas Silent exhaust installed.
derestricted CDi (removed purple wire)

[eamartin]

What is your carburetor set-up?

[tortoise]

Big bore kits offer more torque for hills and headwinds, but the drive pulley ratio remains the same relative to crankshaft revolutions . . unless rear gears are changed.

Unbalanced rotational dynamics also enhance the odds of crankshaft and connecting rod bearing failure.  Pretty much a lose/lose situation!

For others researching . . initially select a scooter model with an engine size suitable for your speed expectations, and keep it stock!

[AylmerFreerider]

What is your carburetor set-up?

I upped the main jet to a 92 from an 82 (10% ish for the BBK)

[AylmerFreerider]

Big bore kits offer more torque for hills and headwinds, but the drive pulley ratio remains the same relative to crankshaft revolutions . . unless rear gears are changed.

Unbalanced rotational dynamics also enhance the odds of crankshaft and connecting rod bearing failure.  Pretty much a lose/lose situation!

For others researching . . initially select a scooter model with an engine size suitable for your speed expectations, and keep it stock!

I have read many different things and most say that the bottom of the motor is pretty much the same from 50cc-125cc.

I wasn't looking for great speed gains 5-10km/h  I am not looking at turning my scooter into a hotrod just a safe rod.

[eamartin]

I have done the following

72cc BBK
Polini Hi-Speed Variator w/ 6.5 weights
1000RPM Contra Spring (was a 750 stock) - Looking to go to the 2000 RPM spring with the new power from the 72cc BBK
Technigas Silent exhaust installed.
derestricted CDi (removed purple wire)

What is your air filter set-up?

[eamartin]

Also,  what was your top speed on level ground before any modifications?

[AylmerFreerider]

Also,  what was your top speed on level ground before any modifications?

Air filter is the same (mechanic said he expanded the opening only)

My top speed before was 65km/h on the flat

[eamartin]

allHey  trying to figure out why I can't get a solid 70-75 km/h out of my 2015 Super8 4T.  I seem  stuckat 65k

You don't seem to have improved your top speed at all.  Is that correct?  Did you do upgrades incrementally or all at one time?  Oh...did you ever install the smooth boss bushing?

[AylmerFreerider]

You don't seem to have improved your top speed at all.  Is that correct?  Did you do upgrades incrementally or all at one time?  Oh...did you ever install the smooth boss bushing?

I did things incrementally.  First the smooth boss then the a larger jet (80-82).  These both came with the scooter when I purchased it.
Then I upgraded the exhaust and installed the Polini Hi-Speed variator. 

Got to 65km/h then I went the BBK route for more power/ a little extra speed.  I didn't have the expectation of doing 90km/h. I just want a steady 70km/h whcih was only 5 extra km/h

[eamartin]

Doing the mods incrementally,  did any of them NOT improve performance?

[Stig / Major Tom]

….initially select a scooter model with an engine size suitable for your speed expectations, and keep it stock!

Amen.

Stig

[Tromper]

Pretty much with the other folks on this one.  A 50cc 4 stroke's only gonna take ya so far.

If 50cc is your passion for whatever reason I'd be looking for a 2 stroke before doing more with this one.

If not then look into something with a bit bigger motor.
You can tweak 'em all ya want, in the end There's no replacement for displacement.

[AylmerFreerider]

Amen.

Stig

Issue is license.  I can use my regular drivers license with this.  No need for a special license I would need for anything listed at bigger than 50cc

[AylmerFreerider]

Pretty much with the other folks on this one.  A 50cc 4 stroke's only gonna take ya so far.

If 50cc is your passion for whatever reason I'd be looking for a 2 stroke before doing more with this one.

If not then look into something with a bit bigger motor.
You can tweak 'em all ya want, in the end There's no replacement for displacement.

\

Figured out the issue.  Needs a secondary gear upgrade.  Seems that with the 4T the limit them 65km/h
With the BBK the power is now there for the for a 10% upgrade.

Now to find the secondary gear