Questions? Looking for parts? Parts for sale? or just for a chat,

The WD Motorcycle forum

WD Motorcycle forum
Start a New Topic 
WM20 primary chain tension problem, need help!

My 720cc WM20 will not maintain its primary chain tension setting. The gearbox moves back under load, over-tightening the primary chain and making gear change nearly impossible. This happened yesterday on an easy 8 mile ride, despite vigorously tightening the gearbox mount bolts and setting the right-side adjuster to maintain tension on the rear mount bolt. I have the thick, radial-grooved washers under the left-side nuts.

Possible causes include slippery powder-coated gearbox mounting plates that are always oily, or excessive slop in the gearbox case holes through which the mount bolts pass. I do not recall having loose mount holes in the gearbox when I installed it years ago. The bike has a total of 303 miles since assembly 5 years ago. That's a long story in itself.

With multiple mods I've detailed here over the years it pulls strongly and easily reached 70mph last week before backing off. But a B33 will certainly outperform that with the same gearbox adjustment parts

Next step is to pull the primary chaincase, strip the powder coat from the gearbox plates and bang on serrations, perhaps install a second, left-sided tensioner, and check the gearbox case for ovality.

Desperately seeking an easier fix.

Jeff in Rhode Island

email (option):

Re: WM20 primary chain tension problem, need help!

Try nordlock rings jeff...they grab into the metal and also lock the whole assembly...the best in the world in my opinion.

Re: WM20 primary chain tension problem, need help!

Thank you, Roy. I've ordered them!

email (option):

Re: WM20 primary chain tension problem, need help!

Succes with them

Nieuwe pagina 1