How hot should a waterbox get?

[motobehrens]

RN SJ with stock waterbox. B pipe w/ flow control valve. Pipe is hot to the touch but doesn't sizzle. I do a 50/50 mix of extended wide open riding with low speed playing around. Seems like mine is hotter than it should be. How hot should a waterbox be; cool, warm, hot to touch, too hot to hold hand on, or sizzle?

 

[Matt_E]

The B-pipe chamber should sizzle right by the headpipe.
Your waterbox should not be hot at all.

 

[Waternut]

Waterbox might be warm but that's the most any of mine have been. Sounds a bit like your flow control valve pressure might be set too high or you were idling for a long time prior to feeling it.

 

[kevbo]

Its typical for the waterbox to run hotter than the engine. I would keep it under 160.