Hi all, Just had my nrg 172 set up on a dyno, got a lot of things sorted, big problem I have is a power dip at around 45mph. Current set up is: Malossi mhr 172 l/c, Polini variator with 13g pm rollers, Standard crank, Pm55 pipe, Standard clutch, Standard contra spring, standard belt (about 4 months old), Pm secondary gear kit, Standard clutch bell. Yellow polini clutch springs, Set lightened flywheel, Ran at 19.76bhp @ 7998.1rpm with 13.46 ft/lb @ 7672.1rpm I know there's loads of better parts I can get but I've got the isle of wight scooter rally in 3 weeks and just want to sort out this power dip. I'll link a picture of the dyno print out in a bit. Thanks all!
If your riding it to the rally then i'd advise to up-jet it slightly, rolling roads tend to set them up on the lean side.
I have upjetted, its at almost the upper a/f limit. Runs like a dream but there's just a little flat spot at 45mph.
youd imagine its jetting related? as the clutch springs will have done their job after 3-4 seconds and after that the varoator will be in play until it runs out of gearing and then the revs will beging to climb at the last bit maybe ty the stock varoator and see if the flat spot moves? this would suggest its the variator if it doesnt solve it then maybe look into other things, if the scooter is high millage the rear torque pully can have wear on the grooves, this gives an inconsistant curve on the power and can create a flat spot. my old aerox 100cc with 20k on the clocks had this issue and it would hit 50 and then the revs would climb for a few seconds, follwed by a dip in power as the torque pulley got past the wear. its cuased by driving at a set speed for a long time just like flat spots on rollers, if you or the previouse owner drove at around 45 for long periods of time the rear pulley can become worn in that one place and will stick their rather then sliding open smoothly
The rear pulley is dying, bit loose, that might be it... The polini variator works much better than the stock one, did try both.
