ThePsuedoMonkey
XS400 Addict
I know that the engine should be hot to the touch, as it is air-cooled, but this is different. All last year it ran quite well and somewhere in the comfortable temperature range (under say 80C by best guess) even on the longest rides on the hottest days. On really cold days, I would be able to grab the upper cylinder to warm up my (gloved) hands, and this heat was never unbearable.
This year, it seemed to run quite a bit hotter. Measuring with my thermocouple, it seemed to be at least 90C on the cooling fins, and around 80C or so at the crankcase. This is very different from before, so I am convinced that something is wrong, as there is no reason for the crankcase to be that hot. I knew that one of my floats was sticking, probably letting fuel into the oil, so I serviced the carbs and changed the oil. This does not seem to have affected the temperature.
The only thing that I can think of that would still make it run hot is a lean condition (or maybe fuel still in the oil pathways). All last year I was using 45mm pods about 3" past where the stock airboxes would have been, under original jetting (135 main, 42.5 pilot). During the carb service, I installed a 140 main and 47.5 pilot and put on 54mm EMGO pods. The lack of power at top end tells me (I assume) that this is lean, so I have a pair of 145 and 150 mains on order, as well as a set of the "bench tested" pods from MikesXS.
My question in all of this, is if the lean condition is the culprit in the overheating engine. Should I be thinking about another rebuild to look at bearings and rings and such?
This year, it seemed to run quite a bit hotter. Measuring with my thermocouple, it seemed to be at least 90C on the cooling fins, and around 80C or so at the crankcase. This is very different from before, so I am convinced that something is wrong, as there is no reason for the crankcase to be that hot. I knew that one of my floats was sticking, probably letting fuel into the oil, so I serviced the carbs and changed the oil. This does not seem to have affected the temperature.
The only thing that I can think of that would still make it run hot is a lean condition (or maybe fuel still in the oil pathways). All last year I was using 45mm pods about 3" past where the stock airboxes would have been, under original jetting (135 main, 42.5 pilot). During the carb service, I installed a 140 main and 47.5 pilot and put on 54mm EMGO pods. The lack of power at top end tells me (I assume) that this is lean, so I have a pair of 145 and 150 mains on order, as well as a set of the "bench tested" pods from MikesXS.
My question in all of this, is if the lean condition is the culprit in the overheating engine. Should I be thinking about another rebuild to look at bearings and rings and such?