Chinese CVT belt quality ?

[scooterfan]

I'm at 27,000 km. Does it need to be changed?

It will be interesting to know what the thickness of your belt is at the moment. I did not take measurements when I took the belt off recently, but there was no indication that the belt was slapping against the bottom of the cover, and the belt still looked in perfect condition.
I don’t bother to worry about the manufacturer’s recommendations - I think belt wear depends on riding habits, speed, heat, distances travelled at a time, weight of the rider, and the way the scooter gets used in general.
I.e. - if the scooter only get used for commuting on short distances only, and the rider is not racing - the belt might last longer.

[TBR125]

Maybe high speed and excessive heat can cause such problems ?
What was the miles on the belt, and has it often been used at such high speed for long distances on the road ?
To my understanding the ratios on your pulleys are slightly different ?

P.S. I think at 71m/H the engine RPM’s will be very high, the engine and pulley heat might be quite higher, and the belt will work much harder - specially during a longer trip ?

Absolutely correct, heat cycle frequency and intensity is the definition of the life span of a rubber/nylon V belt(assuming linear break strength is not exceeded). Mine only lasted 12,000km as I do run the belt hotter than usual even with additional ram cooling. I increased the ratio of the variator which puts the rpm at only 7400 for 70mph. Overdrive gear so to speak.

The nylon reinforcement bands maintain most strength over their lives. The belt dies when the rubber becomes stiff from heating and age and then breaks off the nylon strands. I am not a proponent of Kevlar belts primarily for the fact that in my case belts disintegrate before wearing to spec minimum width.

[scooterfan]

Absolutely correct, heat cycle frequency and intensity is the definition of the life span of a rubber/nylon V belt(assuming linear break strength is not exceeded). Mine only lasted 12,000km as I do run the belt hotter than usual even with additional ram cooling. I increased the ratio of the variator which puts the rpm at only 7400 for 70mph. Overdrive gear so to speak.

The nylon reinforcement bands maintain most strength over their lives. The belt dies when the rubber becomes stiff from heating and age and then breaks off the nylon strands. I am not a proponent of Kevlar belts primarily for the fact that in my case belts disintegrate before wearing to spec minimum width.

I often wonder about another possibility to reduce heat at the inside of the CVT  “box”.

The CVT cover has an air / dust outlet at the center (bottom) of the cover. If you have a close look at the bottom of the CVT cover while it is still in place, you will see that the whole setup is facing at an angle (downwards) to the rear of the scooter.
Right or wrong, I believe that angle is restricting hot air being forced out of the box while  the scooter gets ride at speed. I think air flow from the front (outside around the box) actually prevents hot air and dust from coming out of the box - it might actually force hot air and dust back into the box. Just as a result of the angle of the cover.
The box also has a smaller air outlet at the rear of the box, but I think air coming around the box is actually restricting hot air and dust coming out at the center of the box.

I am actually thinking of installing a bracket just in front of the outlet at the center - just to deflect air around the box a bit better when I’m riding at speed. I am quite convinced an additional bracket could actually cause a vacuum at the bottom outlet, and help to get rid of more hot air and dust out of the box.

[jeeves]

Well your tipe of comments are what I was actually looking for. I am quite technical minded, and always like comments from people with personal experience.
 I am a member of several motorcycle and other groups, and I often see comments from people who do brand bashing while they actually try to push brands of their own liking, therefore my “attitude” - I always like to learn from facts.

If I may ask:

1. I assume the belt which “exploded” was on an Agility (lightweight scooter) ?
2. What brand was the belt which exploded ?
3. How many miles on the belt at the time when it exploded ?
4. At what speed did the belt explode ?
5. Did you often cover long distances under hot conditions with the belt which exploded ?
6. Did you get a feeling, or experience any warning indications that something was wrong with the drive-train before the belt exploded ?
7. Did you do regular maintenance on the CVT system before the belt exploded ?

Sorry about all the questions - I would really appreciate some answers.

1. Yes, it was on my Agility City 125

2. It was a no name Chinese belt. This was a while back, before I started maintaining the scoot myself.

3.The belt had about 7200km when it exploded.

4.I was doing about 70km/h, going uphill.

5.My commute to work and back is a bit over 40km. It  was summertime, but, as I remember,  it wasn't terribly hot at the time.

6. Didn't feel anything different before it happened.

7. It was the first belt change after the OEM belt, and the scoot had around 15000km at the time. The rollers and belt were changed, and the machanic (a friend of mine) said everything looked ok.

P.S.
Also found in the "log book" on my phone that I had a Dynaflex  belt that lost a tooth after 9000km and looked pretty bad.

Sent from my Redmi 4 using Tapatalk

[TBR125]

I often wonder about another possibility to reduce heat at the inside of the CVT  “box”.

The CVT cover has an air / dust outlet at the center (bottom) of the cover. If you have a close look at the bottom of the CVT cover while it is still in place, you will see that the whole setup is facing at an angle (downwards) to the rear of the scooter.
Right or wrong, I believe that angle is restricting hot air being forced out of the box while  the scooter gets ride at speed. I think air flow from the front (outside around the box) actually prevents hot air and dust from coming out of the box - it might actually force hot air and dust back into the box. Just as a result of the angle of the cover.
The box also has a smaller air outlet at the rear of the box, but I think air coming around the box is actually restricting hot air and dust coming out at the center of the box.

I am actually thinking of installing a bracket just in front of the outlet at the center - just to deflect air around the box a bit better when I’m riding at speed. I am quite convinced an additional bracket could actually cause a vacuum at the bottom outlet, and help to get rid of more hot air and dust out of the box.

I have had the cover off for a few days while changing drive train parts. The clutch bell and variator pulley has run approximately 15-20 degrees cooler. I would use a cover with a cut out around the pulleys except that grass would get caught when driving through the fields. Maybe heat sink fins could help.

[scooterfan]

1. Yes, it was on my Agility City 125

2. It was a no name Chinese belt. This was a while back, before I started maintaining the scoot myself.

3.The belt had about 7200km when it exploded.

4.I was doing about 70km/h, going uphill.

5.My commute to work and back is a bit over 40km. It  was summertime, but, as I remember,  it wasn't terribly hot at the time.

6. Didn't feel anything different before it happened.

7. It was the first belt change after the OEM belt, and the scoot had around 15000km at the time. The rollers and belt were changed, and the machanic (a friend of mine) said everything looked ok.

P.S.
Also found in the "log book" on my phone that I had a Dynaflex  belt that lost a tooth after 9000km and looked pretty bad.

Sent from my Redmi 4 using Tapatalk

Thanks for the feedback. The information is a bit discouraging but on a positive note - I mainly use the Agility on short 14 km return trips or shorter. I hardly ever go faster than 90 km/h. Most of the time I do not exceed 80 km/h. I often ride uphill for about 400 meters though. I do regular inspection of belt condition as well.

The Chinese belt that I might buy has name - “Universal Parts”. I Googled the name, but could not find any comments about quality.
I also contacted the local Sym agency for a possible belt, but they asked for a Kymco part number which I did’t have when I visited them. If they are able to supply a genuine Sym belt at a better price than Kymco I might go for a Sym belt.

Thanks again for the information.

[scooterfan]

I'm at 27,000 km. Does it need to be changed?

Are you sure this is the original belt on your scooter ?
If so, it would be interesting to know what the belt width is at the moment. I do not know what the minimum belt width requirements according Kymco is suppose to be.
It would be interesting to compare.

[Viper254]

The original belt in my Like 200 was replaced at 19,000 miles. I fitted an aftermarket replacement and that went PING 800 miles later. I put the original belt back in and it was still going strong when I sold it 

[Neil955i]

The original belt in my Like 200 was replaced at 19,000 miles. I fitted an aftermarket replacement and that went PING 800 miles later. I put the original belt back in and it was still going strong when I sold it 

There's a lesson there for us all I think!

[Vision]

Are you sure this is the original belt on your scooter ?
If so, it would be interesting to know what the belt width is at the moment. I do not know what the minimum belt width requirements according Kymco is suppose to be.
It would be interesting to compare.

If you have instructions/video I'll do it.

[TBR125]

Pull the 2 12?mm airbox bolts to expose the hidden cvt cover bolt. Remove all 9? 8mm cvt cover bolts and slide the cover off the 2 dowel pins. You may need to lightly tap with a rubber mallet or carefully pry with a gasket scraper to remove the cover for the first time. The belt is right there and the width can be measured with it on the bike.

[Stig / Major Tom]

I often wonder about another possibility to reduce heat at the inside of the CVT  “box”.

The CVT cover has an air / dust outlet at the center (bottom) of the cover. If you have a close look at the bottom of the CVT cover while it is still in place, you will see that the whole setup is facing at an angle (downwards) to the rear of the scooter.
Right or wrong, I believe that angle is restricting hot air being forced out of the box while  the scooter gets ride at speed. I think air flow from the front (outside around the box) actually prevents hot air and dust from coming out of the box - it might actually force hot air and dust back into the box. Just as a result of the angle of the cover.
The box also has a smaller air outlet at the rear of the box, but I think air coming around the box is actually restricting hot air and dust coming out at the center of the box.

I am actually thinking of installing a bracket just in front of the outlet at the center - just to deflect air around the box a bit better when I’m riding at speed. I am quite convinced an additional bracket could actually cause a vacuum at the bottom outlet, and help to get rid of more hot air and dust out of the box.

A CVT cools itself by air drawn in  through the forward rubber tube (positioned in a clean air space within the bodywork) by the action of the spinning variator fan blades, and this heated air is  forced out through the two vents in the belt cover of our Kymcos. The forward motion of the scooter through the air helps to suck the air from the vents.(just an assumption - science to support that probably exists)

Some scooters have additional air intake openings directly over the variator fan. Some of these intake vents directly over the variator  have filters to catch debris (usually grass like stuff) , some do not.
But all seem to rely on the forced=air action of the variator fan to move the air along to the exit vents for internal cooling.

If you do not ride in rain, or through farm fields - you might explore the various 'open CVT covers' for the ultimate in cooling.

Sorry, I know you prefer proof rather than opinions.
I can't offer anymore proof than that Kymco has made millions of scooters - and have a pretty good handle on the science of CVTs.
If I saw a white paper exposing that Kymco Inc. purposely builds extra heat into their scooters to increase their belt sales  - then I'd get on board with a need for 'correcting' the way Kymco vents their belt covers.

Stig

[scooterfan]

A CVT cools itself by air drawn in  through the forward rubber tube (positioned in a clean air space within the bodywork) by the action of the spinning variator fan blades, and this heated air is  forced out through the two vents in the belt cover of our Kymcos. The forward motion of the scooter through the air helps to suck the air from the vents.(just an assumption - science to support that probably exists)

Some scooters have additional air intake openings directly over the variator fan. Some of these intake vents directly over the variator  have filters to catch debris (usually grass like stuff) , some do not.
But all seem to rely on the forced=air action of the variator fan to move the air along to the exit vents for internal cooling.

If you do not ride in rain, or through farm fields - you might explore the various 'open CVT covers' for the ultimate in cooling.

Sorry, I know you prefer proof rather than opinions.
I can't offer anymore proof than that Kymco has made millions of scooters - and have a pretty good handle on the science of CVTs.
If I saw a white paper exposing that Kymco Inc. purposely builds extra heat into their scooters to increase their belt sales  - then I'd get on board with a need for 'correcting' the way Kymco vents their belt covers.

Stig

I actually see it this way - if the Agility CVT cooling system was such a “perfect” design, why would other manufacturers have add-ons like additional air intake openings directly over the variator fan ? Surely they would not bother to have such additional add-ons if it it does not make any diffidence in cooling CVT components on their scooters ?
That is just one example. I am quite sure such an add-on would improve cooling on the Agility CVT components as well.

Other manufacturers of more expensive scooters like Yamaha, Vespa, Suzuki, Piagio, etc. have other add-ons which Kymco models don’t have - add-ons like engine oil filters, rear disc brakes, cooling fins on bigger oil sumps, ABS brakes, etc. etc.
Again - if the Agilty was such a perfect design, why did other manufacturers bother to have such designs on their scooters ?

The Agilty’s are obviously a very good design - but I do not think for one second it is a “perfect” design. If it was so “perfect” , I think other manufacturers of high quility scooters would never bother to install add-ons which actually make their scooters more expensive.
Again - the Agility’s are a good design and it is good quality. I am not bashing the Agility’s at all -  but I think we got what we paid for. Other high quality similar sized, or even smaller scooters have add-ons which could easily make a positive difference on the Agility.




 

[Stig / Major Tom]

Well stated.
We'll have to agree to disagree.
Ride safe.

Stig

[TBR125]

If you want more than the stock bike was designed to give then the design is insufficient. From what I have found, even with high load driving, the belt and sheaves remain within the safe material temp range. Also, much of the heat in the cvt housing is drawn from the engine. The aluminum draws the heat from the crankcase down toward the rear axle bolt.

I have been fairly pleased with Kymco's designs except for their drag type variator. If a 115mm variator pulley is used, then the sheaves must close sufficiently to allow the belt to use the full face. With a stock variator the new 20mm belt only uses 94mm of the 115mm face. I can shift the range by removing face material but that is like using the top 3 gears on a six speed. If anyone knows of a wide range variator please let me know. I don't have time to make one.