Sunday, January 23, 2011



Dear Dr Phil: I own a much-loved Yamaha WR200 two-stroke (gotta love premix!) that is close to mint condition mechanically and to look at. However the engine overheats (boils) in a very short time. Plenty of workshops have checked over the bike but the problem remains. And, yes, the head gasket has been checked and changed many times. Any advice you can offer?
-- Oscar Rex, via

Some years ago a mate of ours named Keith Langely asked me to look at his WR200, which presented with exactly the same symptoms, Oscar. After the normal starting checks (head gasket included!), I started flow-circuiting the cooling system and found the metal T-piece hose attachment under the right-side radiator seemed blocked on one side. The outlet was not straight, so I cut off the bent pipe with a hacksaw – and guess what? Somehow back at the factory the bent pipe had been welded onto the other pipe BEFORE they’d drilled a hole for it! This, of course, was preventing flow from the right radiator. I showed this to Yamaha Motor Australia’s then service department boss, Simon Thomas, and he said: “I’ve never seen that before!” Come to think of it, that was Simon’s response to many of my service questions! Check it out on your bike – you never know.
-- Dr Phil,

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