Need More Top End??????????

[ZMUD]

My 66cc build in my signature has me stumped. Last year I was able to hit 50mph on 9.1 gears. This year I did the ZX and 8.44 to get some more top end and I got 2 more mph. I've tried everything from weights to springs and either the weights are to light and the motor is scream'n and going no where or to heavy and takes awhile to get up to 52mph@8800rpm.I have read other's doing 58-60mph on a 66cc. What am I missing? Do I need a bigger carb? Bigger BBK?

[Trafficjamz]

The ZX does not give you extra top end speed.

Go back to the S trans for top speed.

[Trafficjamz]

what size is your belt?

[bakaracer]

My 66cc build in my signature has me stumped. Last year I was able to hit 50mph on 9.1 gears. This year I did the ZX and 8.44 to get some more top end and I got 2 more mph. I've tried everything from weights to springs and either the weights are to light and the motor is scream'n and going no where or to heavy and takes awhile to get up to 52mph@8800rpm.I have read other's doing 58-60mph on a 66cc. What am I missing? Do I need a bigger carb? Bigger BBK?

if your maxing out at 8800rpms with the setup you have now, thats your issue. with the v8 pipe you should be seeing more in the 9500 rpm range. even a stock pipe will rev higher than 8800rpms. what cht temps are you seeing at wot?

[ZMUD]

Belt is 654x18x30 and I tried the 8.44 without the ZX and the bike hated it.

[bakaracer]

i suspect that 118 main jet is whats causing it. thats a really huge jet for the stock carb

[ZMUD]

I don't have a temp gauge just a tach. But I dont think it has much rpm left IMO. I am running no oil pump and plug is perfect.

[bakaracer]

I don't have a temp gauge just a tach. But I dont think it has much rpm left IMO. I am running no oil pump and plug is perfect.

i got way more to go. the v8 can rev all the way to 10300rpm. if your running that size jet and theplug looks good then you must have a leak somewhere letting air in. because thats a really big jet. that size jet is whats used in a 24mm carb. stock is 14mm

[Trafficjamz]

Did you change the pulley boss when you did the zx swap?

Mark the variator and make sure the belt is being pushed out all the way.

[bakaracer]

Did you change the pulley boss when you did the zx swap?

Mark the variator and make sure the belt is being pushed out all the way.

if he didnt and is still using the s boss his lowend would suck not the topend. plus his rpm is kind of low at 8800rpm if thats what the rpm is maxing out at.

[Trafficjamz]

Did you change the pulley boss when you did the zx swap?

Mark the variator and make sure the belt is being pushed out all the way.

if he didnt and is still using the s boss his lowend would suck not the topend. plus his rpm is kind of low at 8800rpm if thats what the rpm is maxing out at.

Very true

that 118 jet is probably way to rich

and the scooter just does not have enuff power to push to the higher RPM's

[ZMUD]

Did you change the pulley boss when you did the zx swap?

Mark the variator and make sure the belt is being pushed out all the way.

I did the complete ZX from VT. Boss,face,rear pulley and clutch.

Did you change the pulley boss when you did the zx swap?

Mark the variator and make sure the belt is being pushed out all the way.

if he didnt and is still using the s boss his lowend would suck not the topend. plus his rpm is kind of low at 8800rpm if thats what the rpm is maxing out at.

Very true

that 118 jet is probably way to rich

and the scooter just does not have enuff power to push to the higher RPM's

I run amsoil interceptor so I think thats why I'm jetted so high.

So how many R's can I get out of the 66?

[ZMUD]

O...and Tjamz thanks for that crankshaft you sent me. it worked perfect!

[bakaracer]

that belt height looks good. that oil your using is not the cause for the larger jet. sounds like a leak somewhere thats causing you to up jet so big. what exhaust gasket are you using? also what head are you using? if its the stock one then that the issue right there. to high a compression ratio to the fuel your using.

[ZMUD]

that belt height looks good. that oil your using is not the cause for the larger jet. sounds like a leak somewhere thats causing you to up jet so big. what exhaust gasket are you using? also what head are you using? if its the stock one then that the issue right there. to high a compression ratio to the fuel your using.

I figured the oil because "guen84" was having heat issues last year and when he switched oil that all went away.So we figured the oil wasn't for bigger builds but good enough for my 66.


The exhaust gasket is the one that came with the v8,And yes it is the stock head. This is the 66cc bbk from daywot and it didnt come with a head.