Post by oldchopperguy on Jun 14, 2013 14:41:58 GMT -5
Well, "Lil' Bubba" is back on the road after two months of wrenching...
What began as a simple tire valve-stem replacement morphed into a total "fix" of everything that can "go Chinese" after 5 riding seasons. Whew! When I learn something from experience, I like to pass it on to others... And after getting my 150 engine running PURR... FECT from idle to 9,200 rpm... Oh YEAH... PERFECT! I turned my attention to tweaking and fine-tuning my variator.
My variator is a Prodigy, which came with 12, 13 and 14-gram rollers. I think however, my experience would be pertinent to a stock variator too.
I started out "middle-of-the-road" with the 13-gram rollers. Those FINALLY gave me the elusive "honest-55 mph" top speed, at a modest 6,700 rpm. However, in city riding, acceleration was sluggish and general riding was lugging the engine.
The 13-gram rollers were SLIGHTLY too heavy.
So, I swapped them for the 12-gram rollers. Zero-to-30 mph was downright FAST. But... Top-speed was now 45 mph at a screaming 9,000+ rpm.
The 12-gram rollers were WAY too light.
I know... it sounds like Goldylocks and the 3 bears' porridge... LOL! In normal daily riding, neither the 12's or 13's ever let the engine run in the "sweet-spot" of 6K to 8K rpm.
So I split the difference and installed three 12-gram, and three 13-gram rollers. (I don't really like the idea of mixing weights, but it seemed like the only way to get "12.5-grams") And they were already on-hand...
BINGO! Acceleration is very good zero-to-35 for in-city. Top-speed did unfortunately drop to 52 mph, but can be maintained uphill, and in moderate wind, so I guess I can live with that. I know some riders' 150's will do 60+, but 50-53 mph is pretty much the realistic "norm" from what I can tell from my own experience, and that of others.
The entire feel of the scoot's performance is now as "right-on-the-spot" as I can imagine it to be. Hard acceleration runs the tach quickly to 7,500 rpm and it stays right there until 50 mph, where it climbs to 8,000 for that last 2 or 3 mph.
Gentle throttle application from a dead start gives strong acceleration at a steady 6,500 to 7,000 rpm, and at 40 mph I can back off on the gas and still climb to an easy-cruise at 50 mph. Easy on the engine, and easy on gas-mileage.
For the first time in 5 seasons, I can REALLY control the performance by actually WORKING the variator. NOT running WOT and hoping for the best. THIS I'm sure, is how a CVT tranny REALLY should be working. THIS is how Vespa and Kymco 150's I've ridden feel. On hills, or into the wind, the speed now remains steady, with the engine changing rpm slightly to compensate, as the CVT tranny does its job. It has made a MAJOR improvement in the enjoyment of everyday riding.
My engine WAS stock, except for a Mikuni factory-style carb (added because the stock carb was just plain BAD), a UNI-sock filter and a "blue" CDI and Bando coil, with an iridium plug.
During my working on this, I replaced the exhaust system (totally rotted...) with a home-made 1-inch inside-diameter header and a 50cc GY6 rear section. I doubt the actual muffler makes much difference, but the 1-inch header REALLY woke up the engine.
The point I want to emphasize is that the weights in your variator seem to make an INCREDIBLE difference in your scoot's performance. AND, just ONE GRAM can go from too-light, to too-heavy.
After this, I'd recommend riders pay attention to tweaking their variators, as much as tuning their engines.
As a side-note, I weigh 235 lb, and my clutch is original-stock, and for me, is perfect as-is. Engages hard and smooth at 2,800 rpm and gives great engine-braking from speed. My drive belt is the original, a Gates Powerlink with 5 seasons and 3,500 miles on it. It's still in excellent condition, with virtually no residue in the CVT cover.
Last change I made also, was to cut the CVT cover, exposing the clutch-bell. The clutch runs nice and cool.
Hope this "report" may be of some help to others, at least as a starting-point for their own scoot mods.
Ride safe!
Leo (done wrenching for now) in Texas
PS: I'll get some pix of the scoot to update my "show us your ride" section when I get it cleaned up again... The exhaust and CVT cover changed "Lil' Bubba's" appearance quite a bit.
What began as a simple tire valve-stem replacement morphed into a total "fix" of everything that can "go Chinese" after 5 riding seasons. Whew! When I learn something from experience, I like to pass it on to others... And after getting my 150 engine running PURR... FECT from idle to 9,200 rpm... Oh YEAH... PERFECT! I turned my attention to tweaking and fine-tuning my variator.
My variator is a Prodigy, which came with 12, 13 and 14-gram rollers. I think however, my experience would be pertinent to a stock variator too.
I started out "middle-of-the-road" with the 13-gram rollers. Those FINALLY gave me the elusive "honest-55 mph" top speed, at a modest 6,700 rpm. However, in city riding, acceleration was sluggish and general riding was lugging the engine.
The 13-gram rollers were SLIGHTLY too heavy.
So, I swapped them for the 12-gram rollers. Zero-to-30 mph was downright FAST. But... Top-speed was now 45 mph at a screaming 9,000+ rpm.
The 12-gram rollers were WAY too light.
I know... it sounds like Goldylocks and the 3 bears' porridge... LOL! In normal daily riding, neither the 12's or 13's ever let the engine run in the "sweet-spot" of 6K to 8K rpm.
So I split the difference and installed three 12-gram, and three 13-gram rollers. (I don't really like the idea of mixing weights, but it seemed like the only way to get "12.5-grams") And they were already on-hand...
BINGO! Acceleration is very good zero-to-35 for in-city. Top-speed did unfortunately drop to 52 mph, but can be maintained uphill, and in moderate wind, so I guess I can live with that. I know some riders' 150's will do 60+, but 50-53 mph is pretty much the realistic "norm" from what I can tell from my own experience, and that of others.
The entire feel of the scoot's performance is now as "right-on-the-spot" as I can imagine it to be. Hard acceleration runs the tach quickly to 7,500 rpm and it stays right there until 50 mph, where it climbs to 8,000 for that last 2 or 3 mph.
Gentle throttle application from a dead start gives strong acceleration at a steady 6,500 to 7,000 rpm, and at 40 mph I can back off on the gas and still climb to an easy-cruise at 50 mph. Easy on the engine, and easy on gas-mileage.
For the first time in 5 seasons, I can REALLY control the performance by actually WORKING the variator. NOT running WOT and hoping for the best. THIS I'm sure, is how a CVT tranny REALLY should be working. THIS is how Vespa and Kymco 150's I've ridden feel. On hills, or into the wind, the speed now remains steady, with the engine changing rpm slightly to compensate, as the CVT tranny does its job. It has made a MAJOR improvement in the enjoyment of everyday riding.
My engine WAS stock, except for a Mikuni factory-style carb (added because the stock carb was just plain BAD), a UNI-sock filter and a "blue" CDI and Bando coil, with an iridium plug.
During my working on this, I replaced the exhaust system (totally rotted...) with a home-made 1-inch inside-diameter header and a 50cc GY6 rear section. I doubt the actual muffler makes much difference, but the 1-inch header REALLY woke up the engine.
The point I want to emphasize is that the weights in your variator seem to make an INCREDIBLE difference in your scoot's performance. AND, just ONE GRAM can go from too-light, to too-heavy.
After this, I'd recommend riders pay attention to tweaking their variators, as much as tuning their engines.
As a side-note, I weigh 235 lb, and my clutch is original-stock, and for me, is perfect as-is. Engages hard and smooth at 2,800 rpm and gives great engine-braking from speed. My drive belt is the original, a Gates Powerlink with 5 seasons and 3,500 miles on it. It's still in excellent condition, with virtually no residue in the CVT cover.
Last change I made also, was to cut the CVT cover, exposing the clutch-bell. The clutch runs nice and cool.
Hope this "report" may be of some help to others, at least as a starting-point for their own scoot mods.
Ride safe!
Leo (done wrenching for now) in Texas
PS: I'll get some pix of the scoot to update my "show us your ride" section when I get it cleaned up again... The exhaust and CVT cover changed "Lil' Bubba's" appearance quite a bit.
