Info on Performance and low end

[agilebda]

Good Day and Happy New Yr. to all.

I've been working on a friends GTI300 for a few hours. His bike don't seem to have the low end "giddy up" and go. Not as zippy as my GTI anyway. He's had the bike for 7 years now. We have changed the rollers, belt, and scuffed the back pads a little (all new OEM stuff) and the low end still seems to lag. Top end is fine at 145 km/hr speed. Just takes a good stretch of real estate to achieve that.
My only other thought to this is that the variator is old and worn and probably needs replacing. Perhaps the angle of the variator is now different due to excessive hours and usage which in turn affects performance? There seems to be a little belt slippage in the low to mid range as well. What are your thoughts? Oh......before i forget, I have not changed the rear torque spring either.

[Stig / Major Tom]

 I might not be thinking about this from the correct direction.....but, wouldn't worn pulleys lead to better acceleration and lower top speed?....rather than the reverse?
Maybe the scoot is, at 7yrs of age, down a bit on HP?
Stig

[agilebda]

I don't know at all. Thank God for this forum where I learn new things every day. Yes maybe lacking HP. Do you think it's due for a rebuild of some sort? Piston rings? Valve clearances?
Do you think it can be fuel issue? Weak pump? Weak injectors?

[scooterfan]

Maybe you should just do a compression test on the engine to eliminate the possibility of a worn engine. It might make sense to do valve clearance adjustments before the compression test.

[de dee]

  When you changed the rollers were they Dr. pulley sliders ., they made a big change on my downtown, higher revs on take off and 155 Kmh. at top end ,  if you are changing the variator pulleys would you try Malossi variator , I would love to see what they are like. on a kymco gt.,  I am ordering one for my yager 200 and my Piaggio 350 b v  best price at scooter partsco. com, 

[agilebda]

  When you changed the rollers were they Dr. pulley sliders ., they made a big change on my downtown, higher revs on take off and 155 Kmh. at top end ,  if you are changing the variator pulleys would you try Malossi variator , I would love to see what they are like. on a kymco gt.,  I am ordering one for my yager 200 and my Piaggio 350 b v  best price at scooter partsco. com,

I've always wanted to try the malossi variator. Had one on my scoot but definately needed a performance exhaust to compliment the malossi variator. Wayyyyy too much low end revving. I have a Zard Exhaust on that way, just might try a polini or Dr Pulley variator system. I've tried the Dr pulley sliders and didn't see too much difference at all. Just my opinion.

[agilebda]

Maybe you should just do a compression test on the engine to eliminate the possibility of a worn engine. It might make sense to do valve clearance adjustments before the compression test.

Just might do that. Thanks alot. Look what I found today. Ground wire touchinh exhaust and was melted showing exposed wire.....yikes!

https://drive.google.com/file/d/1DO5f5iBzuW7vCk9PmVUKLlk66UIJiEIG/view?usp=drivesdk

[Viper254]

I think we're going a bit overboard on compression tests and all that. Try dropping the variator roller weights by 1g or 2g and I suspect you'll get the "ZIP" back.

[agilebda]

Actually dropped rollers by 1 gr and the torque seemed to smooth out like it don't exist.

The low end zip and response still puzzles me. I've come to the conclusion that it may be a crappy belt. He purchased from ebay taiwan for 90 bucks. Came in a OEM package and everything.

My last would be to replace the split ground wire and see what happens. Other than that i'm thinking fuel filter on the fuel pump. Do you know if they sell the filter seperate instead of buying the entire pump?

[agilebda]

So I came home and told the wife I have some performance enhancers....she was all excited!!! Til I told her for the scoot, and her face expressions changed! HAHA
 Bike got it low end zip back. Installed the 15g Dr Pulley sliders and she runs sweet. He purchased some crappy non OEM rollers from ebay and never done the performance any justice. Now the mid range has good RPM and take off is smooth and sweet. Better than the OEM in my opinion.

Thanks

[Stig / Major Tom]

Actually dropped rollers by 1 gr and the torque seemed to smooth out like it don't exist.

The low end zip and response still puzzles me. I've come to the conclusion that it may be a crappy belt. He purchased from ebay taiwan for 90 bucks. Came in a OEM package and everything.

My last would be to replace the split ground wire and see what happens. Other than that i'm thinking fuel filter on the fuel pump. Do you know if they sell the filter seperate instead of buying the entire pump?

Filter is on the pump.....don't think you can buy the filter separately. Probably can find one on ebay that fits and does the same job.
Stig