Triumphrat

grzegorz

I fitted crankcase no return valve ..works like champ

SCbonneville

Also, replace the rotary breather disc (plastic disc with the metal tubing that the seal rides on) at the same time... I would bet dollars to donuts that there is a slight groove worn on the tubing where the seal contacts it...

There is a specific procedure for pre-stretching/sizing the seal using a factory plastic piece. After the clutch cover installation, you should wait 30 min to an hour before firing up the engine to let the seal seat on the tubing.

And yes, I've done the replacement... cured the problem...

Richybow

This one had passed me by but now I've checked my engine number and its in the 180000's. How prevalent is this problem among affected engine numbers, and what's the reason some play up and some don't...the way it was built, a bad batch of o rings, long lay offs drying the seals?

Forchetto

Mileage I suppose. The seal has to stand up to a rotating action and it wears out with use.

PieMan

yeah, mileage and heat build up. My personal 04 Bonnie has got through one every 5,000 miles for the last 15,000 miles, but it does go on the dyno quite often, which can build up heat in the engine.

__________________
Mike (UK)

04 Bonnie Black Special

http://www.triumphtwinpower.com

Richybow

I'm guessing that there are plenty that don't have the problem at all, even after considerable miles...

mikeinva

Some last along time some dont its like any other seal or gasket it bites you when it wants to lol.SC is right any time you replace a seal insect where the seal rides if its worn replace it.If you dont the seal wont last as long.

__________________
Why do I feel young on my bike