PROX Timing Chain for YAMAHA TDM 850, TDM 900 1991-2009

The PROX 31.2891 timing chain is designed for YAMAHA TDM 850, TDM 900 from 1991 to 2009. The timing chain drives the camshafts from the crankshaft and keeps the valves in sync with the piston. As it stretches, it throws the valve timing out and pushes the tensioner to the end of its travel.

Specifications

• Brand: PROX
• Manufacturer part number: 31.2891

When to replace it?

• Rattling or chain noise on the timing side, especially at idle.
• Tensioner at the end of its travel.
• Timing marks that no longer line up.

At the intervals in the service manual, and as soon as the tensioner reaches the end of its travel. Check the sprockets and the guides at the same time.

Fitting tips

1. Set the engine at top dead centre on the compression stroke, marks aligned, before removing anything.
2. On most motocross engines the chain is endless, with no master link: replacing it means removing the crankshaft sprocket or a camshaft, as described in the manual.
3. Line the camshafts up with their timing marks again, then put the tensioner back under tension.
4. Turn the engine over two full turns by hand and check the timing again before starting.
5. Refit with a valve cover gasket in good condition.

Why PROX?

Founded in 1975 and based near Amsterdam, ProX specialises in engine and clutch wear parts for off-road bikes. The brand has most of its range made in Japan, by OEM suppliers, for quality on a par with the original parts.

Spare parts and items to plan

• Cam chain tensioner : see the selection
• Valve cover gasket : see the selection
• Valve shims : PROX 29.VSA948 · PROX 29.948
• 2-stroke oil : LIQUI MOLY 1 L 3065 · LIQUI MOLY 1 L 3063

Frequently asked questions

Should I replace the tensioner?
Check it: a worn tensioner, or one at the end of its travel, must be replaced along with the chain.

Compatibility

Check the exact model and year of your bike in the list below before ordering.

Fits:
YAMAHA TDM 850 2001
YAMAHA TDM 850 2000
YAMAHA TDM 850 1999
YAMAHA TDM 850 1998
YAMAHA TDM 850 1997
YAMAHA TDM 850 1996
YAMAHA TDM 850 1995
YAMAHA TDM 850 1994
YAMAHA TDM 850 1993
YAMAHA TDM 850 1992
YAMAHA TDM 850 1991
YAMAHA TDM 900 2009
YAMAHA TDM 900 2008
YAMAHA TDM 900 2007
YAMAHA TDM 900 2006
YAMAHA TDM 900 2005
YAMAHA TDM 900 2004
YAMAHA TDM 900 2003
YAMAHA TDM 900 2002