QuestionHi, I need advise on my 85 VT 700 running on the hot side going down the road. It has the proper coolant in it. I have tested the thermostat out of the bike. The temp guage, temp sensor and cooling fan all seem to be operating properly. I have run the bike several times with the radiator cap off to get any air out and to ensure a full system. I don't know what to do next. Is it possible that a bike can run on the hot side with too much carb cleaner in the fuel?
AnswerOkay... first the bike is 24 years old. If coolant wasn't changed on a regular basis, you could have electrolysis issues inside the cooling system or the radiator is plugged up/restricted. Did you have the radiator cleaned?
There is usually a bleed nut/screw on the top of the engine (thermostat housing) to help get the remaining air out of the system. Even though the cap may appear to be at the highest point, there are places to trap air lower down.
I wouldn't trust a used thermostat, even if it seems to test okay outside of the system. If it has been replaced in the last year or so, fine.
If you are leaning out the motor with excessive amounts of fuel additives, it could cause it to run warmer, but really only under high speeds/loads. Make sure that the carbs are clean and synchronized properly, otherwise you can have one cylinder dragging the other one along, which causes heating issues.
Have the engine pressure checked to see if you aren't losing coolant due to a head gasket failure/leak.
Bill Silver
