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Post by oldchopperguy on May 24, 2014 2:23:51 GMT -5
Today was the first time I had opportunity to take an extended ride on the freeway, since replacing the tires on my '07 Kymco Grandvista 250 with P-rated tires. I never pushed the J-rated tires it came with for safety reasons... So, I REALLY wrung old "Minnie Mouse" out on a 40-mile run, and re-discovered a phenomenon I first experienced to a lesser extent, with my old Chinese 150...
I found the old 150 would go to about 54 mph if I simply opened the throttle and let her rip until she'd go no faster. HOWEVER... If then, I'd slightly close the throttle, she'd drop several thousand rpm with little loss of speed. Then, open the throttle again and she'd go another 3 or 4 mph, to around 56 to 57 mph. You could then back off and run 55 at a lower rpm. There is more to these CVT trannies than we may realize! I'm finding they may well have just a bit of "overdrive" in their itsy-bitsy DNA!
My Kymco 250 speedo is right at 5 mph "optimistic" at highway-speed, so I can just subtract 5 from "indicated" for my real speed... So today, the traffic was pretty "frisky" and with proper tires, I decided to see just what Minnie would REALLY do top-end, and just how fast she'd REALLY comfortably cruise. I went to WOT up the entrance ramp, and onto the freeway, where she topped out at an indicated 81 mph (which is about an actual 76 mph) at just over 8,000 rpm.
I then backed off the throttle a little, and sure enough, the revs dropped to around 6,500 with only a few mph loss of speed. I then re-opened the throttle, and the speedo climbed to an indicated  mph (actual speed about  mph!). THAT is a full 18 mph faster than the manual gives for top speed on the Grandvista!
Now I backed off the throttle a little, she dropped down to just over 6,500 rpm and cruised at an indicated 75 (actual 70...) at only 6,500 rpm! With PLENTY of throttle left!
The Kymco 250 exhibited EXACTLY the same phenomenon as the Xingyue 150, but in-proportion to the larger engine!
I've found that with these CVT trannies, acceleration, AND city gas-mileage can also be GREATLY improved with throttle control, rather than just going wide-open. These transmissions CAN be worked to get the most from them, and the bigger the engine displacement, the easier and more dramatic the "workability" becomes.
I'm now firmly convinced that individual scooters have individual "quirks" based on engine-size, weight, gearing, clutch-engagement rpm and roller/slider weight and style. CVT's ARE actual, real transmissions. While they don't have separate gears, they go through the whole gamut of rpm-to-speed performance issues as if they were clutch-n-gears setups with 4 or 5 speeds.
With the small 9hp 150, there was not enough horsepower, or torque to make the "feel" for controlling the tranny "obvious". It could be done, but it took "finesse".
With the little 19hp 250, There's JUST enough of a useable power band to truly "work" the CVT to your best advantage... Top-speed, top CRUISING-speed, climbing steep hills, etc. can absolutely be controlled to a GREAT extent through skillful throttle manipulation.
So... It's my personal opinion that WOT is NOT necessarily the top-speed of a given scooter (certainly NOT Minnie Mouse at least...). And, it pays big dividends in performance and gas-mileage to really master that twist-grip! Anyone else experiencing this "advanced" controlling of the CVT transmission please chime in! I think we could all fall more in love with our small, and moderately-powered rides if we had better, and more sophisticated control over the transmissions!
Leo (cruisin' faster, burnin' less gas, and lovin' the lil' mouse more than ever) in Texas!
PS: While on my all-out top-speed experiment, a Mustang convertible rolled up next to me, the driver sort of giving me that "Cheesh, how does that little scooter go so fast" look... LOL! (Minnie DOES look VERY much like a Chinese 150 on the road...).
Trying to carry on a conversation at highway speed from vehicle to vehicle is quite a job, but I yelled over to him "Hey bro, how FAST ya' goin'?" He peeped at his speedo and shouted "almost  !" Which to my happy surprise, verified my mph estimate! My back-off and speed-up "technique" was DEFINITELY giving me some SERIOUS extra top-end, AND cruising-speed... GOTTA love THAT!!!
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Post by ng5y on May 24, 2014 2:41:10 GMT -5
Interesting, will have to experiment some time on a long flat spot.
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Post by SylvreKat on May 24, 2014 8:37:19 GMT -5
I'll just take your word on that technique working for my scoot.  My question for you, Leo, does Mrs Leo know how fast you took Minnie?  Cause I know, if I ever do get up the gumption to try for Peej's top end, I'm sure not telling my Mama how fast I went!!! >'Kat  |
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Post by spandi on May 24, 2014 9:10:08 GMT -5
WOW Leo! miles per hour! (did you end up in 1955?)  |
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Post by tvnacman on May 24, 2014 11:21:12 GMT -5
I have noticed this a while back on my 150cc if I roll back about 1/8 to 1/4 it seems to go a little more speed , but you have to wait for it and it will climb . It seems to be the same way in the old cryslers if you walk it up slowly without down shifting you get up in the high speeds . I did not study the difference , but I do feel a big difference .
John
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Post by oldchopperguy on May 24, 2014 12:57:04 GMT -5
I'll just take your word on that technique working for my scoot. My question for you, Leo, does Mrs Leo know how fast you took Minnie? Cause I know, if I ever do get up the gumption to try for Peej's top end, I'm sure not telling my Mama how fast I went!!! >'Kat
Yeah, mama knows... She's actually relieved to know Minnie will at least keep up with the slower traffic... LOL! She was always concerned I'd get rear-ended on the 150 because it wouldn't keep up. They drive SO doggone fast around here that it's a LOT safer to have a little speed if you need it. Local traffic around here is like entering a WWI dogfight... Being an old-school biker, I find myself more relaxed and enjoying the trip on 2 wheels than on 4... I never get really relaxed driving a car, but on a bike I can truly kick back and enjoy the ride. And even more so on "the mouse" because she is actually more "user-friendly" with better handling than my last old Harley Electra-Glide... Better brakes, faster acceleration, only slightly slower top-speed, better lights... MUCH better windshield... and NO shifting! But just as solid on the road... Getting old I guess... LOL! I'll bet Peej will hit well over 70... And with those big wheels, and solid Italian quality, you would enjoy the freeway romp just like you would on a Ducati Monster! Ride it like ya' stole it!Leo |
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Post by oldchopperguy on May 24, 2014 13:01:29 GMT -5
WOW Leo! miles per hour! (did you end up in 1955?) In all honesty, I was surprised to find the mouse would go THAT fast. Those 12" wheels are turning up a serious rpm at 80+... The amount of increase available through playing with the throttle though was amazing. Ride safe! Leo |
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Post by oldchopperguy on May 24, 2014 13:14:35 GMT -5
I have noticed this a while back on my 150cc if I roll back about 1/8 to 1/4 it seems to go a little more speed , but you have to wait for it and it will climb . It seems to be the same way in the old cryslers if you walk it up slowly without down shifting you get up in the high speeds . I did not study the difference , but I do feel a big difference . John
Tvnacman,
Yup! The phenomenon DOES exist! However, I may have discovered just WHY "the mouse" seems to exhibit it more so than I expected. Update note: I visited my dealer today, and spoke with him about the scooter seeming to have considerably more speed than the approx. 70 mph top-speed the manual shows.
Thinking back, he recalled thinking the original owner, using the scooter primarily for road-touring, and had him install higher final gears many years back. Being slightly "over-geared" would absolutely accentuate the phenomenon, with the engine reaching its "sweet-spot" at near top speed. Backing off on the throttle allows the variator to close just a little, and when accelerating again, the engine then has the torque available from higher rpm to take advantage of the slightly higher gearing... Truly like a mild overdrive. That would also explain why the mouse gives such amazing gas mileage (over 80 mpg in town). While my low-end acceleration is plenty good, I have noticed my low-speed rpm being very mild and "sedate". All that would indicate a higher-than-stock gearing. Starting up from a dead stop, the initial rpm are quite low. Hard throttle doesn't bring on that "snarl" until hitting over 30 mph. Then she comes on like gangbusters! Definite signs of tall gears. I'm no drag-racer, so like it!
You never know just what you'll discover in a used ride!
The throttle-manipulation phenomenon is definitely there though, even with bone-stock rides.
Good observation!
Leo
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Post by spandi on May 24, 2014 15:23:34 GMT -5
Hey Leo, if you can, find out which taller gears he put in for his customer. (an extra 10 mph on the freeway is a good thing!)
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Post by alleyoop on May 24, 2014 15:54:03 GMT -5
Spandi, figure on this, For every 1 tooth up and 1 tooth down on the gearing you can expect to gain 3-4 miles per hour on your top speed. So realistic going 2 up and 2 down you can expect about 6-8 mph, but also depends on your motor and how strong it is.
Also remember guys backing off the throttle a little once your at Speed at WOT and it gains a little more speed that is telling you , it is a LITTLE LEAN at WOT and you may want to slap in the next bigger main jet.
Alleyoop
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Post by wheelbender6 on May 24, 2014 16:44:19 GMT -5
That's great info, oldchopperguy. I had noticed that my top speed seemed to vary from day to day, regardless of wind and slope. The scoot seemed faster when I rode in traffic and had to work the throttle a lot. I will have to give the "Passing gear" throttle technique a shot.
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Post by spandi on May 24, 2014 17:45:18 GMT -5
Spandi, figure on this, For every 1 tooth up and 1 tooth down on the gearing you can expect to gain 3-4 miles per hour on your top speed. So realistic going 2 up and 2 down you can expect about 6-8 mph, but also depends on your motor and how strong it is. Also remember guys backing off the throttle a little once your at Speed at WOT and it gains a little more speed that is telling you , it is a LITTLE LEAN at WOT and you may want to slap in the next bigger main jet. Alleyoop Thanks OOP! |
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Post by alleyoop on May 24, 2014 20:05:50 GMT -5
If you understand what doing this is really doing when you let off the throttle a little and then open it up again you will know why it MAY speed up and it has nothing to do with the gearing it has to do with the variator turning faster due to a little more rpms. Remember the Belt is at the highest point in the Variator when it reachs around 40mph and after that it all depends on your RPMS to turn it faster. Also not all will gain any speed doing this it depends if its a little lean at that point, if its a little rich side or right on it will not do a thing.
Alleyoop
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Post by oldchopperguy on May 25, 2014 0:31:06 GMT -5
I do understand what Alleyoop is describing. Apparently, my variator is not fully closed until a higher speed than is common. For example, I get my best acceleration by simply goosing the throttle for a few seconds (like 2/3 throttle) and as soon as the initial takeoff gets going, I close down to less than half-throttle. I can gain around 8 mph-per-second all the way to about 65 mph. THAT is FASTER than my Honda Accord!!! From there on up, I can plainly feel the variator "working" with little change in rpm.
For whatever reason, my variator is quite active at most any speed, doing more for performance than increasing rpm seems to do. As far as is known, the variator and clutch are factory-stock. The dealer thought the gears had been replaced with taller ones, but no more than the 2-teeth up and 2-teeth down like Alleyoop mentioned. It was just too long ago and too many other scooters serviced over 7 years for him to be absolutely sure. Please remember, this IS an 8-model-year-old scooter... Ancient history to the dealer.
However, this working of the variator seems to be fully "intentional" and no fluke. (I found the same phenomenon with the little Kymco People 200 I used as a loaner). By decelerating a little and rolling on the throttle, you could absolutely feel the change in gearing while the engine maintained a narrow rpm range. And that was a 160 air-cooled GY-6.
I had the dealer run a full diagnostic on mine when I bought it, and the mixture was spot-on at all rpm, the valves were checked and adjusted and the compression was checked and found to be correct. My engine is very strong, possibly because it was broken in hard, and its 14K miles were mostly near-full-throttle on the freeway.
I know very little about the liquid-cooled 250 engines, so I can only relate the phenomenon the best I can... But this scooter exhibits a LOT of variator action at a WIDE variety of speeds. I'm getting more and more accustomed to it, and am finding I have control almost in the ballpark of a clutch n' gears setup.
I think some of these CVT trannies are far more "active" than others, and more controllable than we may have thought. Especially those used by Kymco... Just my experience, but it seems others have noticed it too, with various scooter brands, models and sizes.
The spark-plug on mine is not accessible without removing the seat-pan and some plastics, so a proper "plug-chop" while riding is just not practical. Because of this, I was particular about the dealer running a full diagnostic on the engine. It IS nice to have access to a customer-friendly Kymco dealer with all the electronic diagnostic "bells and whistles"... LOL!
At any rate, it's a VERY interesting performance study, and one seldom even mentioned. If I can learn more, I'll post what I find out.
Ride safe,
Leo
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Post by alleyoop on May 25, 2014 16:20:14 GMT -5
Yep that is how the variators work, like I said the belts climb the highest at around 40mph and you can easly verify that, then once the intial weight is rolling the rpms start to climb and the speed starts to increase. But again I will say it is not because the belt has climbed any higher it is because now the weight is moving forward and the motor does not need so much power to keep the already moving object. That is why the RPMS climb it is less of a load on the motor and it gets to pump out the rpms now. Then once the speed you want to cruise out is reached you can back off the throttle and it will hold the speed there at much lower rpms. Same with my trike I start off and the rpms climb right around 7200 and as I reach say 50mph I can back off the throttle and I am now running 5100-5200 rpms and cruising at that speed, at 60 it will cruise at 6100--6200. Same with a car you hit the pedal to get to the speed you want then you can back off the pedal and your rpms will drop and cruise at that speed. It takes more power to move a dead weight but once you get the weight moving forward all that power is not needed.
I have experimented with my cvt so much I used to only put the 4 center bolts on because I would take it off so much. Then I used to run it without the cover on I got tired of taking even the 4 center bolts off and on. I have tried different gram roller weights different gram sliders, different variators, clutchs, springs, longer belt even cut down a boss. But I always marked my variator to see what was happening to see what the belt was doing at different rpms and where it was climbing or not climbing on the pulley face with what I had in there.
Alleyoop
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mph (actual speed about 
mph!). THAT is a full 18 mph faster than the manual gives for top speed on the Grandvista!
!" Which to my happy surprise, verified my 
..BAD TO THE BONE..
