I have a 2T overheating problem. The engine is a Piaggio EXV1M which is a 150cc liquid cooled. standard barrel and 60mm piston. I rebuilt the engine complete inc. bearings, seals, water pump, gaskets, etc - all done proper with correct tourque settings and adjustment. The engine spec is factory stock, Airbox, Mikuni VM20 carb, exhaust all stock standard except for the crank which is PM Tuning 55mm. using 1.5mm base spacer supplied by PM. I am using the standard factory water impeller and auto-lube pump. ick: - which I know is pretty shite but I expect they are OK in this case :blink: The problem is this. scoot warms up at idle OK and radiator feels to have uniform heat - I leave the scoot to run at idle for as long as I like and the temp dial always shows constant heat just under 80c (which is mid-way on the gauge) so its all looking good, no sign of water leaks engine note is constant, seems OK - So then I go for a gentle ride at low RPMs low engine load (flat straight road) and within less than 100meters the engine tone changes and she nips up (rear wheel locks) The engine will restart OK & the temp dial shows OK (80c) but for some reason she is getting too fucin hot. I static pressure test the cooling systems - it's not leaking. - I did the air purge - so I am fairly sure there is no air pocket (radiator heat feels normal) cylinder case feels fkin hot tho. I am wondering if the 55mm crank will cause the overheat ? I have used the 1.5mm base spacer (cyclinder head clearence is OK -) is there something I am missing from the set up? Spark plug used is BR9ES and it looks black and oily (I dont reckon she is going lean) and I don't reckon there is an air leak induction or exhaust. the engine seems happy to restart each time, but if she is going hot it cant be good. :cry: anyon
youve not corrected the kit for the long stroke crank im assuming wich wont help whatsoever, the exhaust port will have a step, this will fold air over back on itshelf trapping the heat and gasses in the barrel, your better off using a stock crank than a long stroke on an uncorrected kit. ive never done this myself so wouldent know if its the cause of the overheating, but i dont think it would be helping. easy things first. thermostat.. you have a small bypass hose on the water system thats in place for idle speed water flow untill the thermostat opens, id guess the thermostat isnt opening fully or theres a kink in a pipe somwherew. if its nether of the above it sounds like the crank is tight thus making the kit work alot harder to do alotm less. give them a try an get back on with the results. it wont harm it never running a thermostat, it just means you have to wait a little longer for it to warm up
The ports have not been corrected - it is a factory stock cylinder. I have been very careful to check all the coolant pipes, they are all OK. Yes, I did check the thermostat operation before rebuild and it was opening fully in boiling water. I have since removed the thermostat from it's housing on the engine but I still get overheats. I reckon you are right, the exhaust gas is folding back in because of the lip (55mm crank) and causing it to get very hot very quickly - the water temp gauge is showing normaly because the coolant doesn't have time to remove the heat fast enough. The way I see it right now, I have to take the engine to a 2 stroke specialist who can correct the ports. I should done that in the first place, :banghead: I got the 55mm crank now I am paying the price for fuckign with shit I don't understand. :blush:
