Belt question

Icecreamman · Post by **Icecreamman** » Tue Sep 18, 2012 7:27 am

Would a belt stretch enough overnight to lose 30 mph if a bike had just been revived from a 4 year sit?

Robbie · Post by **Robbie** » Tue Sep 18, 2012 11:10 am

Doubtful.

I'd be more inclined to look at the variator......it might have travelled back and forth across the shaft as designed but in so doing, dislodged enouph trash on the shaft to stick it in the low RPM position.

Best guess.....good luck,

Rob

Post by **ericalm** » Tue Sep 18, 2012 5:36 pm

Overnight from a 4-year sit?

What's been done to the scoot and what's happened since? Your first issues will likely be the carburetor, possibly fuel lines, stale/bad gas…

Icecreamman · Post by **Icecreamman** » Thu Sep 20, 2012 6:37 am

Changed the gas and cleaned the carb, that got it going

Changed the plug, oil and filter after an overnight sit, that got it going slow

Changed the rollers to sliders, slight improvement but there IS some slack in the bottom of the belt with it running, cover off

I imagine a certain amount of that's natural but the only other thing I've got to go on at the moment is a possible air bubble in the fuel filter

thatvwbusguy · Post by **thatvwbusguy** » Thu Sep 20, 2012 12:53 pm

It is highly unlikely that the belt would stretch at all while the scooter was stored. The poly cords embeded in the structure of the belt are very resistant to stretching.

There needs to be some slack on the belt for the variator to function properly at idle. Since your cover is off, you can check to see how high your belt is riding on the front pulley using the sharpie method I describe in this post topic23382.html.

Worst case scenario, you could just try a new belt to eliminate belt stretch as a possible factor. If the belt proves to be fine, you will have a known good spare when you need to change your belt due to reaching the wear limit.

There could be some oil or debris from storage on the pulleys allowing the belt to slip. A quick wipedown with some acetone or brake cleaner might be worth a shot.

BootScootin'FireFighter · Fri Sep 21, 2012 5:35 pm

thatvwbusguy wrote:There could be some oil or debris from storage on the pulleys allowing the belt to slip. A quick wipedown with some acetone or brake cleaner might be worth a shot.

Question... what are you wiping down, the inside smooth surface of the variator? I noticed lately that when rolling off from a stop that it sounds like the belt is slipping. It vibrates and rumbles for a quick second, sometimes it chirps, like the tires screeching. But again, only for a quick second. I took out the Gates belt that I was using when I first noticed it, it was size 743x20x30. The belt I replaced it with was a fairly used PGO belt, same as stock, 743x20x28. That's when I noticed that there was a difference of 2 in the last number. It felt like the problem was resolved with that, assuming the Gates was slipping because it was the wrong dimensions. However, it started to happen again with the PGO belt, so I ruled that out. It only happens when rolling out of a stop until the belt catches, from what it sounds and feels like.

Icecreamman · Post by **Icecreamman** » Sat Sep 22, 2012 1:07 am

Brake cleaner

Could the auto choke be sticking?

I've kinda noticed there's no big difference between warm and cold idle lately, but that could be tuning

thatvwbusguy · Post by **thatvwbusguy** » Sat Sep 22, 2012 5:53 am

Wiping down the inner faces of the variator and clutch pulleys where the belt makes contact will ensure that there is no dirt, oil, dust etc. effecting the friction of the belt. It's a long shot, but it is worth checking out.

The OEM belt spec is 743x20x30. No idea why the other belt would work better.

hal888 · Post by **hal888** » Wed Nov 07, 2012 8:21 pm

BootScootin'FireFighter wrote: I noticed lately that when rolling off from a stop that it sounds like the belt is slipping. It vibrates and rumbles for a quick second, sometimes it chirps, like the tires screeching. But again, only for a quick second. I took out the Gates belt that I was using when I first noticed it, it was size 743x20x30. The belt I replaced it with was a fairly used PGO belt, same as stock, 743x20x28. That's when I noticed that there was a difference of 2 in the last number..

Same thing just happened to me. After 7,500 miles on the original belt, I thought I would change. But I ordered the 743x20x30 instead of the stock 743x20x28 by mistake. I changed the belt last weekend, but almost immediately, I could feel the new belt slipping when I reached 15-25 mph. I had to really give it gas to get moving out of this range, and my overall gas mileage dropped 10 miles per gallon. I switched back to the original belt last night, and today the problem seems to be gone.

BuddyRaton · Post by **BuddyRaton** » Wed Nov 07, 2012 9:06 pm

Icecreamman wrote:Brake cleaner

Could the auto choke be sticking?

I've kinda noticed there's no big difference between warm and cold idle lately, but that could be tuning

Brake cleaner is uber nasty stuff and doesn't play well with some materials. If cleaning I would go with the acetone as suggested above.

Tocsik · Post by **Tocsik** » Thu Nov 08, 2012 2:15 pm

Icecreamman wrote:Changed the gas and cleaned the carb, that got it going

Changed the plug, oil and filter after an overnight sit, that got it going slow

Changed the rollers to sliders, slight improvement but there IS some slack in the bottom of the belt with it running, cover off

I imagine a certain amount of that's natural but the only other thing I've got to go on at the moment is a possible air bubble in the fuel filter

Long shot but since you changed the plug and noticed the problem after an "overnight sit", I wonder if the plug isn't tightened all way down. That could cause a compression leak. Don't want to over tighten, though, and strip out those threads so be careful.

az_slynch · Post by **az_slynch** » Thu Nov 08, 2012 5:58 pm

Tocsik wrote: Long shot but since you changed the plug and noticed the problem after an "overnight sit", I wonder if the plug isn't tightened all way down. That could cause a compression leak. Don't want to over tighten, though, and strip out those threads so be careful.

Just to add to this, if you have a new plug, thread it in by hand and spin it on down until it seats. Once seated, slip a plug wrench over it and torque the plug no more than 1/4 turn; this will crush the sealing washer. Any more twist than that and you're risking stripping the threads in the cylinder head.

Tocsik · Post by **Tocsik** » Thu Nov 08, 2012 6:11 pm

az_slynch wrote:
Tocsik wrote: Long shot but since you changed the plug and noticed the problem after an "overnight sit", I wonder if the plug isn't tightened all way down. That could cause a compression leak. Don't want to over tighten, though, and strip out those threads so be careful.
Just to add to this, if you have a new plug, thread it in by hand and spin it on down until it seats. Once seated, slip a plug wrench over it and torque the plug no more than 1/4 turn; this will crush the sealing washer. Any more twist than that and you're risking stripping the threads in the cylinder head.

Much better stated than mine.

PeteH · Post by **PeteH** » Thu Nov 08, 2012 8:22 pm

Yeah, the NGK plug box has a little diagram - almost a half turn for a new plug, only about 1/8 turn if re-seating an existing plug & washer.

az_slynch · Post by **az_slynch** » Fri Nov 09, 2012 12:53 am

PeteH wrote:Yeah, the NGK plug box has a little diagram - almost a half turn for a new plug, only about 1/8 turn if re-seating an existing plug & washer.

Good info! Heck, I've been dissin' those boxes by just checking the part code on the flap before tossing them. Who know they were so informative (other than you, dude)?

PeteH · Post by **PeteH** » Fri Nov 09, 2012 4:04 am

Well, that's useful if you're swapping or checking the plug on the road, when my torque wrench is home in the tool bag.

bgwss · Post by **bgwss** » Fri Nov 09, 2012 12:23 pm

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But I ordered the 743x20x30 instead of the stock 743x20x28 by mistake.

I have been told by Buggy Parts NW it does not matter between these two belts. I have run the 743x20x30 and not noticed a difference. I recently bought one off Amazon and it was noticeably thinner than other belts I have gotten. I got because it was cheaper. Thoughts?

thatvwbusguy · Post by **thatvwbusguy** » Fri Nov 09, 2012 12:48 pm

When you say thinner, do you mean thinner in width, or thinner in thickness? Also, how much is "noticeably"?

Width would most likely be a bigger issue than thickness, since it would have more impact on how high the belt rides in the pulleys. Replacement intervals are typically determined by measuring belt width.

What brand was the belt from amazon so others can avoid buying a similar non-spec part?

bgwss · Post by **bgwss** » Fri Nov 09, 2012 6:15 pm

It was "Jaguar Power Sports Gates Powerlink Standard CVT Drive Belt 743-20-30" when I put up next to the other belt it is not as thick and more pliable. Since I invested in it I am going to use but will be checking it. It was cheap and looks to be cheaply made. Also you look at Scooterworks and they list 743-20-30 not 743-20-28 as the belt for Buddy 150. Anyway live and learn.

Tocsik · Post by **Tocsik** » Fri Nov 09, 2012 7:16 pm

I could be wrong about some of this so anyone please feel free to correct me. But this is what I remember from past reading on MB, Buggypartsnw and a couple other places:

I think the third number in the belt designation is the angle.
The Dr. Pulley variator actually has a 28 degree drive face where the stock PGO is 30 degrees.
Using either a 30 degree or 28 degree belt is OK.
A belt will have a break-in period as it conforms to the drive and pulley faces (both front and rear).

DanielPerrin · Post by **DanielPerrin** » Sat Nov 10, 2012 3:08 am

bgwss wrote:It was "Jaguar Power Sports Gates Powerlink Standard CVT Drive Belt 743-20-30" when I put up next to the other belt it is not as thick and more pliable. Since I invested in it I am going to use but will be checking it. It was cheap and looks to be cheaply made.

I have been known to go with something that I invested in, but I've learned that it's worth paying a little more to get a better quality part to help avoid needing to do an involved repair more than once.

jrsjr · Post by **jrsjr** » Sat Nov 10, 2012 4:47 pm

For anybody else who wonders what happened with the OP's scooter, it turned out that he had a carb problem. In this thread he discovered that the diaphragm (what he refers to as the "membrane") was not seated properly.

So there.

rick71454 · Post by **rick71454** » Thu Jan 17, 2013 10:28 pm

Hello BuddyLand:

I notice at the top end speed, my scooter does this funny thing where it speedwise slightly spudders, skips, and or hesitates. I do not hear the engine do this, but it has to do with continuous forward motion.

I relplace my 11.5g roller with with heavierr ones from the Prima roller weight package of various sizes.

I am thinking it is the drive belt slipping ever so slightly at the highest speeds when the roller weights have push the drive belt to the most outside ranges of the driver pulley.

Is it time to replace the drive belt that has over 11,000 miles on it?
Or Maybe too heavy of roller weights pushed the drive belt to far out on the driver pulley?

What do you all think about this?

Rick71454

thatvwbusguy · Post by **thatvwbusguy** » Thu Jan 17, 2013 10:40 pm

With over 10,000 miles on it, I would definitely replace the belt as a matter of preventative maintenance. There should be a belt width spec in the manual if you want to check the wear limits.

Dooglas · Post by **Dooglas** » Thu Jan 17, 2013 11:42 pm

thatvwbusguy wrote:With over 10,000 miles on it, I would definitely replace the belt as a matter of preventative maintenance.

Absolutely agree. Having a belt break within the CVT while riding is not a pretty thing!

rick71454 · Post by **rick71454** » Thu Jan 17, 2013 11:49 pm

Hello Buddyland:

When a drive belts gets more miles on it, such as 10,000 miles, and it is time to get it replaced....... is the drive belt stretched out, thinner in width, or the structure of it breaking down?

Sounds picky I know, but anyone got the answer?

Thanks
Rick71454

az_slynch · Post by **az_slynch** » Fri Jan 18, 2013 12:11 am

THe belt wears along the sides where it rides against the pulleys. As the sides wear, it gets thinner. A thinner belt cannot ride as high in the font pulley or as low in the rear pulley. So, a worn belt cannot achieve the tallest drive ratio of the CVT system and a loss of top speed will occur.

rick71454 · Post by **rick71454** » Fri Feb 01, 2013 11:15 pm

Hello Buddyland:

The Buddy 125, which I have one, uses drive belt size 743X20X30.
The 20 means width of belt in millimeters.
The recommendation is to change drive belts around 10,000 miles.

Anyone got any idea how much in width the drive belt has worn down to after about 10,000? I mean does it get shaved down to like 18MM or what?

Rick71454

tiii · Post by **tiii** » Mon May 25, 2015 7:49 pm

resurrecting this;

the replace measurement I've heard in forum is less than 19mm

however, there's also the recommendation that at 6,000-8,000 miles, the belt should be replaced as a safe operation concern (so regardless of overall dimensions, replace it or risk it breaking while you're out on a ride).

DanielPerrin · Post by **DanielPerrin** » Tue May 26, 2015 5:02 am

The posts from thatvwbusguy and rick71454 said 10,000 miles. You are right that the thinking is to replace the belt before it breaks while riding. It's a lot better to replace in your shop when it's convenient for you, than to be stranded somewhere and forced to deal with a inconvenient change.

A new belt is also cheap enough that you can avoid the trouble of a roadside break, and changing more often (like every 8,000 miles) doesn't seem to me like it's a huge hardship. "A stitch in time saves nine", and all that.

jrsjr · Post by **jrsjr** » Wed May 27, 2015 12:47 am

Not to mention that a belt breakage can cause the rear wheel to lock up. It's not common, but once in a while we hear about it happening that a broken belt gets tangled up in the rear drive pulley and causes the rear wheel to stop turning suddenly.

It's just not a good idea and it doesn't save you any money or anything to push your belt life. I mean, one way or another, you're going to have to change it. Why not choose to do it at a safe and convenient time?

Icecreamman · Post by **Icecreamman** » Tue Oct 15, 2019 7:10 pm

â€˜â€˜Twas the diaphragm.

k1dude · Post by **k1dude** » Wed Oct 16, 2019 3:33 am

Holy necro!

ucandoit · Post by **ucandoit** » Wed Oct 16, 2019 1:24 pm

Just to chime in. The stock belt on my Buddy 125 was 743x20x28. That is also what the dealer told me was stock and what I bought to replace my belt for the first time at 10,000 miles. The "old" belt looked to be in very good condition. Identical to the new one. I measured the width which was within specs. I saw so cracking, fraying, etc. I replaced it anyway since I had a new one. I'm not saying that you can go forever on a belt. I'm saying that it is probably wise to check the belt from time to time and look at it's condition.

JettaKnight · Post by **JettaKnight** » Wed Oct 16, 2019 5:58 pm

Comes back seven years later to explain what the real problem was!

babblefish · Post by **babblefish** » Sun Oct 20, 2019 7:55 pm

JettaKnight wrote:Comes back seven years later to explain what the real problem was!

Better late than never...