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QUOTE(John B @ Oct 20 2007, 05:48 PM) <{POST_SNAPBACK}>
At a trial this afternoon, and arrived at the first section (right next to the car park). Coolant was coming out of the overflow (I have the overflow pipe cable tied to the frame, directed at the exhaust). Didn't think a great deal - rode to the second section, and it was the same, and the third and so on. Not constantly coming out, but regularly. Finished the first lap and topped the water up - there wasn't a great deal had gone out. Second lap - exactly the same - regular overflow of coolant - and (couldnt figure this out) - the fan was constantly on.......After the second lap, decided to retire - Im not a quitter, but engine preservation was top of my list!
Had a brief look - took the rad cap off, started the bike up and coolant was circulating. No gunge in the oil, so water pump seal presumed to be ok.
However, regarding the rad cap, you can blow through it from the rad side, with no restriction (it is restricted, - but mainly due to the fact you are blowing through a 5mm bore pipe !)
Surely the rad cap should be sealed, and open under water pressure when water is boiling ? Thinking about it, after last weeks trial, when I was washing the bike, noticed the overflow tube was detatched from the rad cap. Snapped it back into place and never thought anything about it ? - Is this linked or a coincidence?
Summary ......
I think it's the rad cap which is not letting the water get to pressure, and allowing it to come out of the overflow pipe. Is the fact the rad is not getting to preddure the reason why the fan is constantly on ?
Help would be appreciated !
cheers
John.
hi there john, having assumed that when the cylinder head was removed it was checked for visable signs of cracks or disortion? If you are confident that this was not the problem having realised that after all this work you still have the problem (after all this is process of elemination). with coolant you have to look at where the coolant passes, first the rad then the pump then through the crankcases then through the cylinder wall then through the cylinder head then back to the rad. sounds easy but then think of where pressure maybe forced in. two strokes need crankcase pressure to run.not saying this is entering from crankcases but maybe from crankcase to cylinder joint (base gasket). really in my opinion i would have the cylinder head pressure checked and milled or skimmed as i have seen so many people doing work they didnt have to, while the cylinder head is off check the cylinder too it may be worth changing the base gasket while it is in bits but my suspicion is with the cylinder head being cracked or more than likely warped. thanks for reading. steve.