84 VF1000F no power at any time, and quite hot above 85 outside temp

So my 84 VF1000F seems to run really hot. I put a new thermostat in that matches the stock spec. And I cleaned out my system with a coolant flush. But it still runs really hot, as in the gauge goes almost all the way to H most of the time.

The fans do kick in when the temp gauge gets very hot.

I'm wondering if the temp sensor on the top radiator is not registering properly. And what can I use to check the temp of the fluid? I do have a laser temp gauge.

What is a replacement for the upper radiator sensor temperature?


And what to check for low power? New air filter is installed, and runs same with and without fuel pump installed. My SV650 dusts the VF.


Thanks!

 

The sensor for the temp gauge is mounted in the thermostat housing, the sensor on the top rad is for controlling the fans.

My VF1000F only runs hot when I'm stuck in slow summer traffic, the stock thermostat is 82C or 180F, I tried to find a cooler one (170F) but haven't been able to find one that fits. My stock fan sensor turns the fans on at 110C or 230F (way too hot), I found an aftermarket one that is designed to turn the fans on at 91C or 196F, I still have to test it before I install it.

I don't have the part number handy, I'll have to look it up for you.

 

for the temp issue, backflush your cooling system, then verify that your water pump is actually pushing coolant, if its not it'll run pretty hot.

the low power issue I'd chalk up to several possibilities, poorly adjusted valves, carbs out of synch and possibly dirty carbs, also check plugs too. and put the fuel pump in. from experience, these things DO make differences. but you're also expecting a 25+ year old machine to be powerful on par with a 10 year old design which was designed to make more power from less displacement.

 

Did you verify that the fuel pump actually works? My 83 750 will not run worth a damn without the pump. If your pump is not working and or you run without a pump, you may be running real lean. That would create the heat your talking about and the low power output.

You can put in a small micro switch for the fans to turn on manually anytime you'd like. Works great for traffic/town situations and adjusting carbs. Motor stays 180-190 ish.

 

That's doubtful. If your bike doesn't work with gravity feed then I would say something is wrong with it, all of 700/750's have run fine without a pump. If his bike runs without the pump it will be fine, the fuel in the carbs is not under pressure so gravity feed cannot induce a lean condition that way.

I'd check to see if you are getting bubbling in the coolant overflow bottle. If so you have a blown headgasket. That would explain both the overheating and the low power. It's quick and easy to check so worth the effort just to verify. It's rare but can happen. If that's ok then I would check that your water pump impeller is still good. Again, rare but possible.

Good luck!

 

Well, I dug in and found two of the vacuum diaphragms are torn. So, it's now running like a badly tuned v-twin?

 

New diaphragms ordered from NRP. Easy to install on existing slides. What a difference! The bike revs easily to redline, serious power now!

Running cooler now. I looked at the water pump, and that turned out ok. I took both radiators off, cleaned out the bugs stuck in them, and the top radiator, in particular, had a lot of sediment at the bottom of it. I then flushed quite a few rounds of water through the system. Almost looked as if there was "mud" in the system. Running way cooler now.

Thanks for the suggestions!