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Antifreeze Leak @ 15,000 RPM
Just an FYI post. On my '06 I've had an intermittent antifreeze leak that only seemed to appear at 15,000 RPM. I could never catch it because it was small and as soon as the antifreeze sprayed out it would flash off on the engine.
However, at times I would see antifreeze heading down to the kick stand. I looked everywhere and could never get it. I figured it might be the head gasket and the engine was slated to come out for overhaul over the winter so I pre-ordered all new hoses and hose clamps - literally every hose on the bike other then the silicon ones I had on.
Well go figure, during post-rebuild testing the damn thing still leaked at 15,000 RPM. This after planing the head and all new hoses and clamps. Anyway, I filled the tank half full and then warmed it up. With the tank up and the engine at 15k I saw something very interesting...
The feed hose to the cold start/fast idle valve would balloon from pressure only at 15,000. Not 14k, literally only at 15k. The stinking thing expands and this is where the leak is coming from. So re I re-tightened and re-positioned the clamps and re-tested. Long and short, they needed to have the living piss tightened out of them in order to address the leak.
What is interesting is that I think it's actually a design flaw. The restriction in the fast idle valve causes the feed line to balloon at high RPM. Anyway, it can be addressed with a re-enforced hose but I thought I would mention it as that stupid leak survived an engine overhaul, all new hoses and clamps etc. When I saw how that line ballooned up at 15k it's clear that every bike with that design will do it. If you're seeing intermittent loss of coolant after beating the bike, that would be the first place to look. My guess is that it would only effect engine up to 2006 as my understanding is that post 2006 they use a IAC for fast idle etc. The line that balloons is the one on the bottom of the valve in the pic. When you look at the valve you can see that it is a 45 degree right turn as the coolant flows through it. At 15k the water pump is spinning like a mad bastard and the pressure increases. When the antifreeze hits that 45 it's a big restriction and that's what causes that lower line to balloon and be prone to leaking. It's quite surprising because when I think of how many times the original hose would have ballooned from 2006 to 2019.....it's amazing it never burst.
06 CBR 600 RR
Last edited by Arjay67; 02-24-2019 at 05:48 PM.