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r1chard06

Re 1990s to 2001 gas gas trials 250

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Having a few issues can anyone help the wording has been messed with to bypass thermostat anyone have a wording diagram as fan only spins on full throttle also we’re can I get replacmant parts as it boiling over after 10 mins use had new head gasket new pipes new radiator pump seems ok so unsure what to check next

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I'll have a look for a wiring diagram for your 1993 250. It is difficult to diagnose without actually seeing the bike in real life, can you ask a knowledgable trials friend to look it over? The fan itself can be tested with a car/bike 12vDC battery directly across the contacts. Sometimes the fan motors fail and can occasionally turn over albeit rather slowly. If the thermoswitch has been bypassed, then the fan should be on all the time. You say the bike has a new head gasket, there are 2 O rings there, the inner one must be viton, not the usual nitrile O ring as these will not last in this application. What was replaced in the water pump? A shaft and a seal would be required. Although not a known problem for this model bike, there could be a crack in the O ring grooves in the cylinder head which could cause your over pressure problem. Are you sure the water pump is actually rotating? The drive to this pump is by a plastic gear which is very easy to break if not aligned properly when re-assembling the clutch case, if this plastic gear is broken then the pump will not be turning. Bye, Peter B.

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The head gasket I got were standard not vitron we’re would I acquire one of these the pump rotates wen you kick bike over haven’t tried fully running

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Check the fan is blowing a bit like a hair dryer, with a battery hooked up to it. A standard nitrile O ring would last a short time before the heat of combustion would find a way past. Have you tried Gas Gas UK or one of the GG dealers over your way, maybe the Splatshop. Give them your model, year and cc and ask for the head O ring seals. While the head is off, have a really good look for a possible hairline crack in the O ring grooves. Bye, Peter B.

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Whenever I order head gaskets the keep sending some what don’t fit there too thin and sit lower than channel also on vids I’ve seen they go on head mine goes on barrel

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