I need some help/advice

[BigTzzy]

I have a 150cc Tank Urban Racer.

I am having some issues with the variator/clutch.

Let me first tell you what I have installed on my scooter.

1. A KOSO performance variator with 10g rollers. (The stock rollers were 13g)
2. Red clutch springs w/red torque spring. (ebay)
3. Uni foam filter with velocity stack.
4. Stock muffler was "hollowed out" some by prior owner.
5. Racing CDI
6. Performance Coil and wire and NGK iridium plug.
7. 130 main jet and bigger pilot jet (I forget the number)
8. Kevlar drive belt.

Here is the issue I'm having.

Before I installed the new variator and clutch springs and belt, when I would accelerate from a stop the clutch would engage just above 2000 rpm on the tach.
After installing the new variator and clutch springs and belt, from a stop the clutch is engaging just above idle or about 1800rpm on the tach.

It was my understanding that lower weight rollers and the red springs should allow the engine to rev high rpm before the clutch engaged. Please correct me if I'm wrong.

Also, I have never been able to get my scooter to rev above 5500 rpm with a load on it. On the center stand it will rev to 8000 rpm without any problems.

My performance goals for my scooter was to make it accelerate faster off the line. I am not too concerned with top speed anything above 50 mph is fine with me as most of my riding is in the small town that I live in.

P.S. The "load" that my scooter has to move is my 290lb behind. :)

[blueboy5000]

That's too much main jet. Switch to a #110 to #115.

[BigTzzy]

That's too much main jet. Switch to a #110 to #115.



The 130 main jet is the one recommended below 2500' above sea level. I'm at 1400'.
The filter/velocity stack kit came with a 125 jet for above 2500' above sea level.

But I'm not sure how a main jet being too big would effect the tranny issues I'm having.

Why do you think the 130 is too big?

[rks]

Your lighter rollers and stiffer springs should have done exactly what you wanted them to. Are you sure a roller or two didn't get turned over while installing the variator onto the shaft?

Don't see how your 150 would run at all with a main jet that size. OEM size is 105...after intake side modifications, 110 is most recommended size....intake and exhaust mods, and most folks use a 115

My 400 cc ATV, has a 33mm Mikuni Carb...with a 112.5 Mikuni main jet. That size Mikuni jet is equivalent to a 127.5 CVK jet.....So you have a larger jet feeding your 150 cc scooter, than I have in a 400 cc Yamaha...

[BigTzzy]

Thank you rks for the response.

Maybe I should try a smaller main jet.
I went with the size the seller of the intake/velocity stack advised.

This is the the intake I have on my scooter. (https://www.buggypartsnw.com/index.php/gy6-air-performance-upgrade-level-1.html)

I guess I'll take the tranny apart again and make sure the rollers are installed correctly.

[Maddog]

I would suggest concentrating on ONE aspect of power delivery at a time.
Get the carb tuned first.
Experiment with lighter rollers and heavier springs to achieve a desired launch.
Then fine tune things for top speed. Or find someone with your scooter who's your size who has done the research. That guys worth his weight in gold!

[blueboy5000]

Tzzy, the size of your main jet determines your CFM (cubic foot per minute) rating, since your bike is not a very large big-bore kitted bike, it should run ideally with a #110 or #115 as they provide just about the optimum amount of CFM. #130 is very large and is definitely too rich.

Your intake does not determine how much fuel you use, but rather how much torque you will get from you 'low-end' acceleration', and do to the fact that your bike is 150cc 4-stroke, those gains will be nominal to unnoticeable. That intake performs best with a BBK and a nitro-methane set up like is found on drag-racing scooters.

[blueboy5000]

Try the smaller main jet. My Brother is a 375lbs and rides a Vento-style, we run a 115 on his.