[Bull Ramus]

This is my '03 999s I bought as a stop gap while I was fixing a few issues on my other bike...been great for two months then this happened, felt slightly rough on the last couple of miles of my ride, when I checked it out there's oil coming out of the belt cover on the vertical cylinder, and fibres! oh no!

So the belt has shredded itself on the inside edge, luckily, its still intact so no valve / piston damage, unluckily there's now oil leaking on the vertical cylinder, its hard to pinpoint the exact area but it looks to be around the exhaust cam pulley is where its coming from.

So I'm happy to replace the belts but I'd like some advice on the oil leak.

any thoughts?

 

[EL Twin]

I'd be expecting to find strands of the belt have worked their way under the lip of the camshaft seal in behind one of the pulleys. That belt doesn't look very old, try to find a specific cause for the belt to stripping the edge like that before you replace it.

 

[tye1138]

I think the immobile roller has unscrewed itself somehow. This caused the two parts of the belt to rub on each other and cause the failure.

Its a pretty common failure point when people don't use locktite on the shaft.

 

[selbitz748]

This Scares me a LOT. Glad the belt didn't break completely. I have a 2000 748 that I have had for 2 years and the previous owner told me he changed the belts recently, but couldn't prove it because he did it himself. I have ordered replacement belts from Motowheels, but they are on backorder.... I just hope they come in and i can replace them for piece of mind before something happens.

 

[Rockit]

Have read about it, but not seen it for real, and am not bothering to remove the cover on mine to check, but visually seems that the belts are very? close together near the rollers. Eccentric roller might have been tightened in the wrong direction. Oil could be from a resultant vibration effect through a seal

 

[Bull Ramus]

ok, yes, this is the major worry at the moment, I'm assuming the installation hasn't been done correctly, the previous owner insisted he'd just changed the belts when I bought it, I checked them myself when I got it home and they did look fairly new and well tensioned, they were aligned correctly and there was no oil inside the covers, so this has gone wrong within the last 500 miles, looking at the rollers now, everything's straight and torqued down and the remainder of the belt on the vertical cylinder is still tensioned the same as on the horizontal cylinder, he's had this bike for 10 years and always changed the belts himself so I'm assuming he knew what he was doing, but it does point to an issue with the installation.

I'm not really familiar with these motors so there could be something obvious that I'm not seeing but I'll check the tensioners to see if he has turned them the wrong way.

 

[Bull Ramus]

There's some play on the mobile tensioner, I can rock it a little bit with my hand, the lock nut is still tight, looking at the underside of the belt it looks like its been cut by the edge of the roller, does that sound likely?

 

[tye1138]

Yep, its the mobile tensioner then. Usually its one of the two rollers which causes that issue from being misaligned.

So I'd pop the roller off and make sure there aren't any debris behind it. Then see if its OK when you put it back on. I'm kinda surprised it was the problem because it needs to be really tight to hold tension and in the first few pix it looked like the roller was in the right position.

 

[1fast750ss]

On top of what Tye said, make sure you pick up new cam belt retainer nuts with the new belts. I've made it a practice to never reuse them.

FYI, not to make a tragedy into opportunity here: I have the ExactFit belts for members at about $90 per pair with the code.

This will get your baby back on the road faster.

Oh, I forgot to also mention. Pull the pulleys off and check the bearings. I've seen this hapen when a bearing starts to go, not saying this is the case, but always an ounce of precaution. Could have been the tensioner nuts being old.

 

[bstar360]

That belt has tracked off so I would be looking at all the belt roller bearings.
As above I replaced the tensioner pulley nuts and washers on my 1098 when I did them.
Washers are of a new design, a wave type.

 

[Bull Ramus]

Ok, I've had the pulleys off, they were both torqued down, to me it feels like they both have some degree of play in them, but the one on the vertical cylinder moves more than the other one, its more like a slight rock although the bearing still feels good, the inside lip has been polished by the edge of the belt.

So the question is is it normal to have any degree of play in the rollers? or should I just replace both of them?

This engine has 20,000 miles on it btw, its had next to no TLC by the looks of it.

 

[tye1138]

They shouldn't have any play. The bearings can get damaged from belt over tightening though.