I have a vacume in my cooling system, the bike will run for a bit then die, when the rad cap is opened the rushes in.

Any ideas where to start?


If I understand your post right, you stated that when then engine dies, you open the radiator cap and air rushes in. After that you are able to start it??? I don't know how that would get fixed by you opening the radiator cap. I would check to see if you are losing coolant first. If you are losing coolant, you need to find where it is the crankcase(oil), or on the floor. Once you figure that out, then you can go on. Don't know how a vacuum in the coolant would cause a motor to quit running unless it siezed from overheating. I'm no expert, just some of my random thoughts to hopefully give you somewhere to search. Maybe someone else can't get you closer, but I think we will need more info to be of any help. Hopefully your coolant overflow hose didn't get routed to the crankcase vacuum hose on the engine, you might want to check the routing of all of your hoses to make sure someone didn't have the motor apart and connected something wrong.

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