Its taken a while but I'm finally ready to start jetting my 500 and I'm just wondering what coolant temperature I should be looking for. I remember my engine builder saying that he would expect my engine to have problems if it exceeded 60 degrees celcius (from memory) after he cut the head profile but I've read of other 500s on here reaching ~90 degrees celcius...
My 1987 engine is running an AAEN expansion chamber, 88.5mm bore, 11.2:1 compression ratio, 1.72mm squish clearance, 98 RON octane (New Zealand), 196 degrees of exhaust duration, Keihin 40mm PWK, stock reed cage and an oversize YFZ450 radiator.
Does anyone know what temperature range that I should hope for for an engine built similarly to mine?
I have a Hall motor with Hall pipe and run 60 deg. while moving and upwards of 90 when idle.
60 deg c is 140 deg F. It is difficult for most off road engines to never exceed 140 deg F., especially when the engines make a lot of power and are ridden hard. 60 C will be difficult not to exceed it you live in a warm climate. If all of your riding is done 10 C or below, 60 C max coolant temps may be achievable.
Your build sounds very conservative and should not have any heat related problems if you keep the coolant temperature below 60 C. but using coolant temp as a guide for jetting your carburetor will probably get you into trouble.
11.2 :1 is a very low compression ratio. A 1.7mm squish clearance is too wide and will keep the squish band from doing what it is designed to do. You will need the 98 Octane fuel with this type of head design even though the compression ratio is low.
Make sure the weld at the junction of the stinger and tail cone does not have any weld boogers inside of it. (many of the Aaen pipes have problems at the junction). The boogers inside of the stinger at the junction can cause over restriction and lead to heat related piston failures.