OzVMX Forum
Clubroom => Tech Talk => Topic started by: Barney on August 24, 2011, 07:40:03 pm
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Hi All, I'm new to OZVMX so go easy on me - my son and i have been working on an 84 cr250r readying it for Heaven VMX competition in NSW - after having front forks and rear shock rebuilt our first outing we blew the head gasket. We had already JB welded the water pump case and rebuilt the entire pump unit. have just replaced main engine seal as was dragging oil into the barrel and took bike out for a test and it performed well. Our biggest issue is that it continues to lose coolant - lost around 250ml during ride. Has new radiator cap, hoses and clamps - no coolant in oil (as before) and none in exhaust - bike was putting plenty of power to ground on the 15 minute test ride. Any suggestions as to why it continues to lose coolant and where it may be escaping from??
thanks Barney
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what head gasket did you use could be leaking forcing coolant out through the radator over flow
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Wipe your finger across the overflow pipe when you stop Barney.
Could be a couple of things and that's a good place to start looking.
Cheers Mike
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Thanks for the prompt responses guys - the head gasket we used was from a full gasket set we bought from the US - it is the same material as all the other gaskets just with a steel ring at the head. The one we blew appeared to be a copper gasket??
It does leak coolant from the overflow pipe - we thought this was just the water level and pressure stabilisingf itself?
Hard to determine how much could be leaking our from there whilst riding.
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i have the same bike mine blew one of those metal ones , did you check the head and the top of the barrell to see if they were warped .my head was
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not a dicky radiator cap is it?
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mine had the same problem . Head gasket is wrong ,or put on wrong or head is warped. When you fill up with coolant push the kick starter through its storke a few time and re check the water level.Top it up if needed go for short rid e and if you lost some coolant top up again.It might stabilize other wise check the head and torque it down to spec with a new gasket.
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Again thanks guys. details are - head was warped and we had machined - but not top of barrell which appears OK - new radiator cap (correct Honda version). I have had the head off twice after installing a new gasket and reused the same one - bike actually hadn't been ridden during this time but had been started.
I think I will try and replace the head gasket again - is a copper or standard material gasket best option?
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Cometic brand I think do a top end set with a composite head gasket,Available from Serco i think,May also be available from B&B importers W.A.,they do Winderosa I know,Also Bert Kingston QLD & Birdman Mcycle Accessories do top end kits,Get your local dealer to ring them & ask what type of Gasket is in the kit,Get one :),Also whilst it's apart take off the cylinder & either have the face machined(careful to only take off as little as possible so as not to upset clearances) or do it at home yourself with wet & dry on a piece of glass,You will of course have to remove the studs & dowels,I done the glass trick on my 85 125 cylinder & head which was having the same problem & it worked a treat ;).Gasket kits are also available on U.S. Ebay.