diving deeper into belt issues part2

[Doowithblue]

From the info I've gathered it seems the least amount of belts have blown by maintaining the stock secondary spring. Perhaps yamaha prefers torsion over side load?

 

[Big_Phil]

I honestly can't see offset being a serious cause to belts blowing as long as you're within spec range.
Has anyone ever given the proper answer as to why the secondary doesn't close back up when sled is on the stand? I've heard theories but nothing really concrete. It's another thing that just bothers the hell outa me. Maybe I have OCD too? Lol.

This is the biggest problem with belt blowing IMO, and also in Yamahas opinion as well. The bigger rollers seem to help, but my testing is a little inconclusive because I ran out of season to test thoroughly.

I spoke with someone higher up at Yamaha, they agreed that the belt isn't staying tensioned properly between the clutches, and the jerking when accelerating is causing belts to snap. He said the new clutch calibration for 2019 should fix this problem, bigger primary rollers, different secondary spring and a different helix. Your dealer should have the part numbers for the updated parts by now.

I can tell you the 8JP belt is not the problem. This video is my brothers viper racing a cat with a 1600cc predator motor with 15o shot of spray. Viper is running an 8jp at over 350 hp. That belt prob has 100 passes or so on it. We haven't changed the belt in 3-4 weekends of racing. The predator sled was running 165-170mph at nbssr this year in 1320 for reference.

 

[Beerman]

As for the bigger rollers - does anyone think the 15.8mm from Thunder would be better than 14.8mm? Any insight into what size Yamaha will use in the 2019's?

 

[ryama]

Hey man hit me up next year if you want to ride I'm in Waterloo

Sounds good.I look forward to meeting up. By the way are you the guy who does shocks in Vista Hills?

 

[Big_Phil]

As for the bigger rollers - does anyone think the 15.8mm from Thunder would be better than 14.8mm? Any insight into what size Yamaha will use in the 2019's?

I believe Yamaha will be using the 15.5mm rollers. The stocks are 14.5mm, so the 14.8mm isn’t much difference. You may want to change your primary spring to something with a softer starting rate, as the larger rollers will increase engagement rpm. I never rode my sled stock so I’m not even sure what the engage at stock.

 

[Doowithblue]

Sounds good.I look forward to meeting up. By the way are you the guy who does shocks in Vista Hills?

Yessir have we met?

 

[ROCKERDAN]

I will say my last trip, all hi speed trails in Qc, I lowered the B/O to 3/3, and ran a bk/red primary(48/120), weights at 77.3g of weight in my DTYA1's. A lighter setup overall then previously run all winter.

I ran it fast, up there.....but not as hard down low(rolled on easier most of the trip) as my home region where its tight and i run it hard corner to corner and belt does not like that at all.

This lighter setup did run really cool.....but I know it wont work well corner to corner around home since just rolling to a stop abit too fast, I could feel the belt hanging down in, and not coming to top unless I really feathered it in to the stop. So corner to corner it would be not back-shifting nearly fast enough, and likely snap if Im not careful with flipper catching it loose.

I know my rollers life is alot easier since I went to a lower pressure setup(less primary spring and less secondary wind) But winter came to an end and never got more time on this setup. I think the gearing plays alot more into things when you are riding tight trails corner to corner with good traction/studding vs higher speed trails where the gearing is less in play as you are running up/over 70mph most the entire day.

I wonder when we will see the first early models, and see if they do actually come with the larger rollers and diff helix.

Dan

 

[STAIN]

but honestly I think as a whole the problem is not as big as a forum can lead to people to believe.

I think this is true with a lot of things..........

 

[Beerman]

IMHO your wasting your time.

Let some air in with a vent, get your offset right, make sure your clutches are in good shape and throw a ultimax belt on it. I personally don't know of one Cat guy having an issue with belts, I'm sure there is some but I've not seen one. I have however seen a lot of SW having issues.

Maybe a little overkill, but Swiss Cheese is one of my favorites.

 

[KnappAttack]

Maybe a little overkill, but Swiss Cheese is one of my favorites.
View attachment 140193

That will work good Art till the first belt blows and wipes it all out. Bring duct tape in the trunk for when that happens.

 

[74Nitro]

From what I have seen on HCS, big tunes are causing problems with the Cat secondary clutches. Either way, on the internet, belt life seems better in the Cat version. I think they took the lessons they learned with their previous turbo sleds and applied them to the 998. Lower gearing and a turbo specific belt are probably making the difference.

I can't help but wonder what the sales figures are for each version though. I put 700 miles on this season and from what I saw on the trails, Sidewinders out number the cat version by 5-6 to 1. I can't help but wonder if there are more reported issues with the SW because there are far more of them out there?

When I was at the Cat dealer in Timmins about 5 weeks ago, he said the Winder outsells the Cat 10-1

 

[Beerman]

That will work good Art till the first belt blows and wipes it all out. Bring duct tape in the trunk for when that happens.

<sigh> yeah, God I hope to get these belt issues behind me. But I have Prevost's clutch guard that wraps all the way around, I think (hope) it'll be ok.

 

[stevewithOCD]

Art, what was the difference for C to C, offset & parallel to your old sled?

 

[Beerman]

We never took an actual measurement of parallel on the ‘17 but Steve said it looked slightly off, but was facing forward, the opposite of what you typically see. The ‘18 is definitely parallel, I measured from both the fixed and moveable sheaves and the difference from the front of the clutch to the rear was consistent.

C-C on the ‘17 was 262.5mm with an offset of 59mm. The ‘18 C-C is about 262 but I need to measure more closely and can do that tonight. Offset is 60mm with no shims. I’ll have to have the primary machined this Summer so I can get the offset lower, but from the looks of it 58mm will be the least I can get. I’m pretty sure you can’t mil more than 2.5mm off the shaft or the moveable will make contact.

 

[XP123]

That will work good Art till the first belt blows and wipes it all out. Bring duct tape in the trunk for when that happens.

Mike you are a riot.