Two "mechanics" later and she's still running hot!

Got my 2007 back from the shop after it overheated a couple of weeks ago. It has been running hot for a few months (basically since it started warming up here in Florida. But I got it up to 260 degrees and the coolant overflowed (I guess that's what happened... there was green fluid coming out of the bottom).

If you haven't figured out, I'm mechanically retarded.

So, anyhow, took it to a second shop (the first one just checked the coolant levels) and, of course, they couldn't duplicate the problem. To be proactive, they made it so the fan turns on with the bike (not when it reaches a certain temp).

Just went for a short ride down I-95, no traffic, 60-90 mph then down some city streets to get home. Again, no traffic but a few stops at the lights. A few miles from the house I hit 248 degrees! WTH?

 

The fan doesn't need to be running all the time as it will be fighting with the natural wind flow at speed. That's a typical band aid repair done by someone who doesn't know (or care) what the real problem is.


Thermostat?

 

T-stat or water pump has failed. replace the Thermostat as they are cheap. If the bike still overheats then look at the water pump. the impeller can be fine when cold but as it warms up the impeller starts to slip on the shaft causing the impeller to stop spinning and will lead to overheating. Also blocked rad(s) can cause this as well so look at them too.

 

I am with MPH
Replace the thermostat or at very least flush the coolant system by the book. Did you try to replace the cap and burf the hose?

 

+1 to both of these.

 

You can do the thermostat yourself, there's an excellent guide on VFRD.

 

Rule out a head gasket leak by firing up the bike with the radiator cap off (FROM COLD). Blip the throttle a bit and see if any bubbles puke up. This may also help in diagnosing the pump, you may see flow or when blipping the throttle see the level pull down temporarily. What has the maintenance been on the cooling system? was someone mixing in tap water with coolant? hopefully a sillicate free coolant has been used. I recently went through the whole overheating deal on one of my CB-1's. new thermostat, water pump inspection etc.. etc.. Turned out to be what looked like calcium or mineral deposits blocking the inlet side of the radiator core. Had it power flushed which helped a great deal, but I'm till going to be in for a new radiator at some point. Might be worth your while to pull the radiator and take a look in the inlet side as that is where most of the accumulation will start. I borrowed a borescope for this.

 

wish I could pick up a cherry CB1. Those were the good old days. Good luck on the original posters problem. :thumbsup:

 

If you can find one in good working order shouldn't go for more than 2k. Problem is for every one in decent shape with factory paint, there's 3 rashed to hell rattle canned some random color. Hasnt received the same kind of cult love like the nt 650. Gear driven cams like the viffer, one of Honda's most durable engines. I've got 2 runners in decent shape, a 3rd for parts and a stockpile of other stuff tank, exhaust, gauge set, crank pistons, cylinders etc..

Oops off topic. Uhh, check that radiator