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Post by oldchopperguy on Aug 23, 2015 0:17:20 GMT -5
OK, guyz and galz...
I need some advice from anybody who's replaced factory ROLLERS with Dr. Pulley SLIDERS in a Kymco Grandvista, People, or Bet n' Win 250... (same engine/drive-train).
Recently, my area upped the speed-limits all round again, and it's getting harder and harder to keep up safely. Same problem I had with my old Chinese 150. Suddenly my "comfortable cruise" of 65-70 is getting mighty "marginal". I know that no changes to the variator will give me "adequate" highway speed, but just an extra 3-5 mph would be a BIG improvement.
What I need to find out is what weight sliders would be best all-round, with a little emphasis on possibly cruising at 75 mph at less than WOT. The engine HAS the torque, with strong pull from 4K rpm on up, and I think it COULD run fine at 75 mph at 7,000 rpm. Right now, 75 is near WOT and over 8K rpm. I'd lose a little acceleration, but that's OK.
I'm not sure what the weight is on the factory rollers, but the few posts I've seen on the Grandvista seem to recommend 18 or 19 gram SLIDERS. From experience with my old 150, I know weights make a LOT of difference, even one-gram.
I'd really like to hear from anyone who's run sliders in a Grandvista, People or Bet n' Win Kymco 250 to hear how they worked for you.
Many thanks!
Leo in Texas
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Post by trailheadmike on Aug 23, 2015 8:21:40 GMT -5
I found this exchange on a Kymco board that might be useful:
Can you recommend weights. I'm interested in reducing my highway rpms. I run 65 to 70+ mph. I don't care if it reduces the acceleration. Btw, I average 55 mpg - that's with the tallest givi windshield and largest givi trunk / top case (I had to make an adapter out of wood). Stock windshield I got 58 to 60. I find high speed on the highway hurts the most but that is live in San Diego.
-Paul
2005 GV 250 w/ 10K mi.
Paul, after all my testing the Dr. Pulley Slider Weights at 18 grams are the best compromise, and it will drop the rpm to 7000 rpm at 70-75 mph. If you have standard roller weights you will see an improvement. You can go to 20 g Dr. Pulley weights for a bit less rpm "in the middle" but you will loose acceleration. Your gas mileage depends on that big windshield that is a barn door to push, and yes, I loose also mph and mpg when I have it on it in winter.
Eric
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Post by oldchopperguy on Aug 23, 2015 13:59:11 GMT -5
I found this exchange on a Kymco board that might be useful: Can you recommend weights. I'm interested in reducing my highway rpms. I run 65 to 70+ mph. I don't care if it reduces the acceleration. Btw, I average 55 mpg - that's with the tallest givi windshield and largest givi trunk / top case (I had to make an adapter out of wood). Stock windshield I got 58 to 60. I find high speed on the highway hurts the most but that is live in San Diego. -Paul 2005 GV 250 w/ 10K mi. Paul, after all my testing the Dr. Pulley Slider Weights at 18 grams are the best compromise, and it will drop the rpm to 7000 rpm at 70-75 mph. If you have standard roller weights you will see an improvement. You can go to 20 g Dr. Pulley weights for a bit less rpm "in the middle" but you will loose acceleration. Your gas mileage depends on that big windshield that is a barn door to push, and yes, I loose also mph and mpg when I have it on it in winter. Eric
Trailheadmike,
THANKS! That's exactly what I'm looking for. This fellow nailed it...
Just for the record, my old Grandvista also has the largest Givi windshield, but I don't sense much problem pushing it. It is extremely aerodynamic. My particular GV had the drive-gear upped one tooth long ago, and that allows old "Minnie Mouse" to do better than 80 mph on the level, with no wind. However, she's still running slightly too high an rpm (over her "sweet-spot") for comfort, even at 70.
Two seasons of riding the GV, plus a lot of past experience tells me she'll be a lot happier at 70-75 if she's running a thousand rpm LESS than she does today, and, she has the torque to do it. This old design has a LOT of torque, and plenty of acceleration. You can feel the sweet-spot big-time right at 65 mph. Above 70, she begins to struggle slightly, with too-high rpm.
I'm convinced that SLIDERS' ability to FULLY close and FULLY open the variator will, on a 250 or larger, move that sweet-spot up nearly 5 mph without losing much acceleration.
The "250 class" of old, carbureted scooters are just a teensy-bit short of "cruise" speed today. The old mouse will roar up to 65 and cruise there all day. Back in 2005, when the GV was introduced, THAT was plenty of highway speed. NOT anymore... I'm finding 70 mph is absolutely THE SLOWEST one dares to run without risking becoming road-kill. Trying to cruise 65 causes traffic to SCREAM around me in every lane, and the shoulder, along with the "obligatory" cut-you-off and brake" flying beer-bottles, and the bird... LOL! At 70+, the  mph Bubbas and soccer-moms will at least "tolerate" you sharing the road.
As I've often advised others, "there's no replacement for displacement". However, I just LOVE this old Kymco for 98% of my riding and have no desire for a different scoot. When just a few extra mph at a comfortable rpm will make a real difference, I've found roller-weight tweaking CAN do the job. I was AMAZED at how that helped my old Chinese 150! And I never even got to try SLIDERS... A new set went with the old Xingyue when I got the Kymco.
I think I'll try the 18 gram sliders. I may hold off until next season... I have an aversion to messing with something that runs perfectly... LOL! But I'm also wanting to see just how the sliders might work.
Many thanks again,
Leo in Texas
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Post by rockynv on Aug 26, 2015 12:05:21 GMT -5
One thing to watch out for is the height of the sliders to ensure you get the correct range of motion without having the belt rub the case. On the Piaggio design engines the oil sump gasket is in-line with the belt so you need to add an extra washer between the boss and the drive face to keep the belt from rubbing against the gasket and pulling it out.
The Dr. Pulley Sliders made a big difference in how the bike performs since they allow the variator to open a bit widers giving you better take off and then are able to close it up that bit more increasing top end. They made my Aprilia which was already a Silver Bullet a bit more extreme.
Matt at Parts for Scooters keeps a good selection of Dr. Pulley sliders in stock and is a National Distributor with the added big plus of being a really great guy to deal with.
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Post by oldchopperguy on Aug 27, 2015 0:13:15 GMT -5
One thing to watch out for is the height of the sliders to ensure you get the correct range of motion without having the belt rub the case. On the Piaggio design engines the oil sump gasket is in-line with the belt so you need to add an extra washer between the boss and the drive face to keep the belt from rubbing against the gasket and pulling it out. The Dr. Pulley Sliders made a big difference in how the bike performs since they allow the variator to open a bit widers giving you better take off and then are able to close it up that bit more increasing top end. They made my Aprilia which was already a Silver Bullet a bit more extreme. Matt at Parts for Scooters keeps a good selection of Dr. Pulley sliders in stock and is a National Distributor with the added big plus of being a really great guy to deal with. Thanks for the "heads-up", rockynv!
I'll surely watch out for any parts interference.
It may be a while before I can get the sliders. Lots of health issues with the missus, and prescription drugs using up all the Social Security income and more... Cheesh!
As you mention, sliders' rep for fully opening and closing the variator is the reason I want to try them. They surely spread the available engine power over a wider range of rpm. This offers a broader "sweet-spot" "lower low" and a "higher high" range. That adds up to better acceleration, higher top speed and better gas mileage! A win-win combination!
Many years ago, my old "Minnie Mouse" already had the final drive upped one tooth, which accounts for her 75 mpg gas-sipping mileage, and 80+ mph top speed. However, speed comes at too high an rpm for comfort, when trying to cruise 70+.
I don't need to run over 80, I just want to run 70 at a little more sensible rpm.
Based on others' experience (like yours) I think the sliders would be a great upgrade. The stone-age carbureted 250 seems to be a bear for torque (a happy "thumper" but with some real rpm) and seems to me to be able to handle high speeds at a lower rpm. I must admit I truly love the entire Kymco engine, clutch and CVT setup. With 15K miles on the clock, mine is still absolute "perfection" from dead start to WOT. It's just that while WOT provides 80+ mph on the level, it brings even 70 mph at too many rpm for my comfort, even with the one-tooth up-gearing.
I'll surely post results when I can get to it! These old Kymco 250's (Grandvista/Grand Dink, Ben n' Win, People, etc.) seem to have a near "cult following". Now in my second season riding "Minnie Mouse" I can REALLY see why. Very affordable, they truly leave little room for complaints (unless you just can't abide the "Taiwanese hunker-down" seating position)... Trust me, you DO get used to it... They just were designed for a top speed of 70 mph, with a 60-65 cruise... As/per the service manual.
They'll do THAT all day long, bone stock, and do so with the reliability of the family Toyota. But nowadays, at least around here, you need a little closer to newer 300 cc performance. They're not all THAT far away from it either. The new twin-cam, 4-valve fuel-injected 300's top out around mph, with a "comfortable" 75 to 80 mph cruise. Just a little tweaking puts the old 250's close enough to newer performers. And, I'm stuck on that old-school, small-wheel look!
Sincerely,
Leo
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Post by rockynv on Aug 27, 2015 4:50:12 GMT -5
The extra 50cc on the 300cc bikes (some of which are really around 275cc) can sometimes appear to get lost due to its lower rpm and change in torque band so the difference in reality may not be as great as it sounds. Many skip the jump from a 250 (249) and go to a 350 (33X) or 400 instead to get a more meaningful difference.
On the Vespa the 300 was more to be able to tune the bike to meet the new Euro pollution standards while maintaining the performance of the 250 so gains if any are quite small to non-existent.
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Post by spandi on Aug 27, 2015 11:18:03 GMT -5
Funny you should be bring this up now Leo, as I'm installing 19 gram Dr Pulley sliders in the variator. (Even though it's not a Kymco, it's still a 250, I'll have to let you know how it works out.)  |
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Post by oldchopperguy on Aug 27, 2015 14:40:43 GMT -5
Funny you should be bring this up now Leo, as I'm installing 19 gram Dr Pulley sliders in the variator. (Even though it's not a Kymco, it's still a 250, I'll have to let you know how it works out.)
Spandi,
That's GREAT! Please DO keep us posted. There are many 250 riders on the site, and the 250 is fast becoming a "lost" class... 300, 350, 400 cc and larger engines are replacing the venerable 250's across the board.
However, the old-school 2-valve, carbureted 250's are not going away any time soon... They're the "small-block Chevy" of the scooter world, and just TOO good, TOO reliable and TOO affordable to "disappear". And as the newer fuel-injected engines take over, the carbureted oldies get cheaper and cheaper used. I haven't looked lately, but I would imagine China is still producing NEW carbureted 250's for half the price of new 300's, making them sort of the "buy of the century". And, the old workhorse 250 will probably live on for decades in ATV's...
My old Grandvista is pretty heavy at 360 pounds, and I'm no lightweight at 235 pounds. So, the weight of the sliders will be important. I found with my old 150 that one-gram difference could even be too much, and ended up mixing 3-each of two different roller weights for the perfect mix. Hopefully, the extra torque of a 250 should make the weight choice a little less critical. 18, 19 or 20 gram sliders should all be "useable" but ONE choice will still be the best... I'm guessing for heavy riders, and carrying a passenger, 18 gram; for lightweights, 19; and for VERY light riders (and those wanting the LOWEST rpm, BEST gas mileage and don't mind losing acceleration) the 20 gram version.
I'm firmly convinced that roller/slider weights make MUCH more difference than most engine mods with these "twist n' go" scooters. Even if you mod the engine (which is likely to compromise longevity) you STILL must change the CVT setup (beginning with variator weights) to get the most from the engine mods.
I'm looking forward to hearing about your experience. I believe a simple, affordable upgrade in slider-weights might just bring older (and AFFORDABLE) Chinese, Taiwanese, Japanese and other outdated 250 cc scooters up to a more competitive state with newer, more expensive models on the open road. After all, we're not trying to get unrealistic big-block performance... Just squeeze out a scant few extra mph, at a little lower rpm. Hey, it's worth a try! 
Keep us posted (particularly on the type of your scooter) and...
Ride safe!
Leo
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Post by spandi on Aug 27, 2015 22:23:11 GMT -5
Thanks Leo, I will. Right now in addition to the sliders, I'm putting in a stereo system, second battery (with isolator unit) I've got most of the Tupperware off and I'm finally coming to the end of what started out as a few upgrades and ended up a rebuild.   |
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Post by rockynv on Aug 27, 2015 22:41:12 GMT -5
How many slots in the Grand Vista's variator? There are six in the stock Piaggio variator on the Sport City 250 and it takes 21X17_11gr Sliders for my 250 lbs since stock is almost 12 grams so the next lower size is what recommended. The Sport City 250 is rated to carry a bit over 460 lbs and the one gram lighter worked out great for me all around. I believe your Kymco takes six 23X18_20 gr rollers and if that's so then 19 or 20 grams may be perfect for you. Beed Speed Standard Roller Chart |
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Post by oldchopperguy on Aug 29, 2015 13:39:40 GMT -5
How many slots in the Grand Vista's variator? There are six in the stock Piaggio variator on the Sport City 250 and it takes 21X17_11gr Sliders for my 250 lbs since stock is almost 12 grams so the next lower size is what recommended. The Sport City 250 is rated to carry a bit over 460 lbs and the one gram lighter worked out great for me all around. I believe your Kymco takes six 23X18_20 gr rollers and if that's so then 19 or 20 grams may be perfect for you. Beed Speed Standard Roller Chart
Rockynv,
I haven't pulled the variator, but the shop manual (yes, I DID score a genuine Dink shop manual on eBay!) shows the variator/roller setup as six, evenly spaced, and looking much like a Chinese 150 variator.
Your roller chart is great to have! I printed it off... Lots of pages!
If the stock rollers are 20 grams, I'd guess sliders should be the same weight or even a gram heavier. But from others' posts, they seem to prefer 18-19 grams. I think you could hardly go wrong at factory 20-gram roller weight with the more efficient sliders.
Side note: It's widely accepted that the Grand Dink and Grandvista are the same. They ARE similar, but definitely NOT the same. The rear frame, plastics, grab-rails and seat on the Dink kick WAY up (a steeper angle than the muffler) placing the passenger much higher than the rider... Therefore, many of the related parts probably won't interchange. From the side, the Dink and Grandvista have quite different profiles. The Dink looks quite "foreign" to my eye, while the GV looks very "normal/American" as in "Chinese-modern"... LOL!
The Dink also uses numerous different assembly "doodads" in the front, including the windshield and headlight setup. Instructions in the Dink manual don't always relate to the Grandvista. I think the GV was designed to look just a little more "Western" in appearance, for America and Canada, and uses a few short-cuts to reduce production costs, while still retaining  % of the "home-turf" Taiwan parts. For Canada, I believe it was to be called the "Grand View" or something similar. It never did make it to Canada as far as I can see.
It's interesting that the shop manual is labeled "Overseas" since it's in English, and meant for "Overseas" shops, outside of Taiwan... The English is a LOT better than Chinese manuals, but still leaves a lot to be desired...
Thanks again for the roller chart! It may be next season, but when I can get to the sliders, I'll surely post the results!
Ride safe,
Leo
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Post by rockynv on Aug 30, 2015 13:32:48 GMT -5
Leo,
Hope things clear up for you soon. I am not that far behind you and do understand having to put projects on hold because as Don Ameci put it "Things Change". I finally got what I wanted to do last November done last week and this week I may be able to get a project I wanted to do in April finally in the works. Right now I may just try to get a ride in before the Tropical Storm gets any closer.
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mph Bubbas and soccer-moms will at least "tolerate" you sharing the road.
% of the "home-turf" Taiwan parts. For Canada, I believe it was to be called the "Grand View" or something similar. It never did make it to Canada as far as I can see.