March 6, 201412 yr HI, been having some cooling problems on my old rev3 put a hole in the rad but as I was not far of finishing carried on. Big mistake. Now when hot the coolant projects it's self out of the rad cap. Got the head off and replace with new head gasket and run the bike and still the same.... Found the head is our of shape, so has anybody ever skimmed the head and if so how much was removed, or will it pink it's head off and run hot. Thanks Seth.
March 6, 201412 yr I has and can be done but thats as far as I know. Sorry. Read about it hear and there and I seem to remember that the head gasket thickness needs to be increased to compensate for the skimming. I read about it when I was on enduro bikes, not sure if it relates to trials bikes. Also, when I messed around with scalemoto/pocketbikes, guys used to skim the head to boost compression.
March 6, 201412 yr If you are not certain that the head is out of shape, replace the radiator cap (they are preasure rated). Had the exact same issue on a pocket bike and a new radiator cap solved the issue.
March 6, 201412 yr Probably better off buying a new head. If it has rubber o rings you cant replace the metal lost by skimming the head with more gaskets. I ran an air cooled yam with out a head gasket to increase compression but it just pinked. Gasket was only 1mm but made quite a difference.
March 6, 201412 yr It's not that common for a watercooled engine to warp the head without seizing up other stuff. Usually it's pretty clear you have to stop before it reaches the point of warping the head. Is the head leaking fluid? Did you fix the radiator? Cooling systems work by being pressurized. Under pressure the boiling point of water goes up. That's why a pin hole in the cooling system can cause a boilover. The system never pressurizes properly so the boiling point of the water stays low and when it reaches the boiling temperature the water undergoes a phase change turning to water vapor and causing a rapid and dramatic rise in the system pressure which opens the safety in the cap. I'm inclined to think you still have a small leak somewhere. Then again I could just be full of hot water.
March 7, 201412 yr Check the pump is still working, if you holed the rad that's where the bits will be. TLTEL
March 7, 201412 yr So you stated you found the head was out of shape! Using feeler gauge on a flat surface or a straight edge you can measure this. Sometimes you may place the part into an oven at around 375-400F for a couple hours, then let cool normally which will normalize the metal. Takes out warpage. Then if it is within a thou or two, skim it on flat glass with 400 wet/dry paper till within .001 in. and should be good to go with near no change in performance or clearances. Just saying, good luck! Edited March 7, 201412 yr by copemech
March 7, 201412 yr You can skim the head on a lathe. To avoid an increase in compression, base gasket thickness can be increased. Beta sells them in different thicknesses.
March 7, 201412 yr Author The wife is out tonight so think I will try the head in the oven first. Sorry for not putting in the water pump is turning ok. The bike will pressurize at low temperatures if you touch the bottom of the radiator is still cold.
March 7, 201412 yr You can skim the head on a lathe. To avoid an increase in compression, base gasket thickness can be increased. Beta sells them in different thicknesses. True you could do that but the port timing would then be out of sync.
March 7, 201412 yr True you could do that but the port timing would then be out of sync. True! but you're probably talking less than 0.5mm so not enough to notice on an "old rev3", I have played around with base gaskets, we are not talking race engines here! TLTEL
March 23, 201412 yr Author Just to up date the forum. Head been in the oven. New gasket and still the same. Put the head in my dad's lathe and found was out so new gasket and try again.. still the same starting to think it's not the head... The top of the rad is red hot but the lower of the rad cold.. but have had the water pump cover off and the pump turns and the pipes are on the corresponding outlets. May be it's circulation.. As I did fit new aluminum clutch cover ..
March 23, 201412 yr Author Afte all that found this in the water pump cover. Only found by removing the pipes and starting the bike and found the water wouldn't move up or down the pipes.. at last sorted Seth29..
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