Hi again, temperature issue

Hi folks, I've been away for a bit (it turns out Swiss winters AREN'T very good for riding....)

Finally got the transmission roughness sorted, with a new chain and sprocket set. I also moved down south, near Montreux (on the Lake Geneva shoreline), and I rode the VF500 down yesterday, 350km (220 miles). I managed to pick the coldest say of April, after a week of temps in the 20s *C, it went down to near freezing.

Now with that in mind, the temp gauge barely lifted off cold, and my consumption was terrible. I'm thinking that maybe the thermostat is knackered (stuck open), so the engine isn't getting to a proper working temperature. What say you? Is it an easy fix? I changed the oil and coolant before doing the trip.

Other than the temperature, she didn't miss a beat and I had a very pleasant ride down.

 

Yep that sounds about right. If it's the 500 then the thermostat is easy to get at, a sharp tap with a piece of wood is always worth a try. If that don't cure it, then open & replace.

 

If it was a long journey and the thermostat was stuck open I'd still expect the engine to warm up to normal operating temperature. It will take longer but it will get there eventually. Your fan isn't on all the time is it?

 

I haven't checked the fan, but on a run today - warmer weather, and slower roads - the needle still didn't get up to the middle, and was swinging around quite a lot. The faster I went, the colder the engine.

 

You'd know if the fan was stuck on. It would be on all the time as soon as you turn on the ignition. It's noisy. I suspect your gauge is bust. VF500s run pretty hot so its inconcievable to me that on a long run the bike isn't getting up to temperature.
If after a long fast run you then let it idle for a while, does the temperature then climb quite quickly?

 

If you were talking about last Sunday, it was not much warmer on the other side of Lake Geneva where we reached the dizzying high of 4C starting out with ominous grey cloud then drizzle. But at least my VFR was warm and toasty within 10 minutes.

It definitely sounds like the thermostat is stuck open. The guys at Moto Passion in Vevey should be able to sort this out if you don't want to fix it yourself, and will give you time to take something else for a test ride. Just watch out for the cameras....


SkiMad

 

He did 200 miles. Why would an stuck open thermostat cause the engine to run cold after that kind of mileage? Even if it was subzero I'd expect the engine to get to normal temp after 20-30 miles, especially a VF500, unless he was riding very timidly. However I could be very wrong.
Maybe the new coolant is super efficent. :wink:

 

Skimad, I actually live in Bouveret, five minutes from the French border on the south side of the lake - and yes, it was cold! Thanks for the tip on the mechanic shop.

It wasn't a timid ride (although that depends on your definition...). 120km/h (75mph) most of the way, revs around 6.5-7k. I think it's the thermostat, and all the heat is dumping through the radiator - hence the faster I go, the colder it is. Temp rises quite quickly when stationary. I'll take a look this weekend.

 

OK. It does sound like your gauge is working. Where did the gauge setttle for the bulk of your 220 mile journey and was it different to before? I still find it hard to get my head around the fact the the thermostat does anything on a long run at speed.

 

If you are in Le Bouveret then Kick Moto in Anthy Les Bains is probably a lot nearer, and I know their workshop staff are brilliant. If you visit them, make sure you head upstairs and checkout the amazing display of historic motorbikes. Its a very pleasant run alongside the lake, and once you fight through the traffic in Evian, the Thonon by Pass is good for a quick blast - just remember the camera right at the end by the Carrefour overbridge.

I think that makes four VFRWorld forum members now located around the bords du lac. Anyway I hope you get the bike sorted soon, and maybe see you at the annual Burn Mountain Festival in July - which is hosted by SAMVA my local moto club.



As you can see your VF will fit in nicely.




Skimad

 

Hi everyone. First post for me. You may want to try flushing the cooling system and refilling with fresh coolant and Water Wetter. My VFR was running cold as well and I had read about this fix on another forum.

 

I have thought about this and I think I am wrong and the original responses are correct. It almost certainly is your thermostat sticking open. What is interesting is that I think my bike may be afficted also as my bike is very cold blooded and poor on fuel. All symptoms consistent with a stuck open thermostat. I am going to stick a thermocouple to the hose coming out of the top of the thermostat housing and another to one of the hoses going into the bottom of the housing. From a cold start the bottom hose(s) should get warm quickly as this is the coolant circulating in the engine block. If the top hose gets warm at the same rate it means the thermostat is stuck open. The top hose is the one that feeds the radiator.

I have a spare thermostat and I checked it in a cup of boiling water. It starts to open at about 85degC.

 

Either the temp sensor is bad or the thermostat is stuck full open...OR both. (I'm going with the thermostat) If it is the temp sensor...be careful you may want to soak the threads on the temp sensor with some type of penetrating oil. I snapped one off last summer. Didn't take much effort to do that. Fortunately I was able to drill it out without damaging the threads in the housing.
120kmh is not timid.
Jeff

 

Hold on - that's a very sneaky intro - Welcome to the Madhouse Panhead!

If you don't want heaps of ragging we expect you to post up photos of your ride very soon otstir: either here or better still in the Intro section.

As for the over cooling problem - the bike is over 25 years old, so it makes sense to completely flush out the cooling system. Indeed its possible that crud in the coolant may be the reason why the thermostat is jammed open. Once its cleaned through, it's important to refill with the right amount of a decent antifreeze to prevent corrosion, although water wetter may be overkill for a bike running cold.

SkiMad

 

I'm going to take a look at the weekend. i like the idea of the thermocouple top and bottom of the rad, I'll see what I can find in terms of temperature probes. When I had the sprocket and chain replaced, the workshop said they changed the coolant (and oil), but they probably didn't flush it.

 

Right. Well I did my expt with the thermocouples and boy was I confused at first. Both hoses were pretty much the same temperature. The upper hose feeding the rad was always a couple of degrees hotter than the lower hoses going into the bottom of the stat housing, but they were very similar. I datalogged it but I couldn't really detect the thermostat opening. I was expecting the top hose to be a lot cooler than the the bottom hose until the stat opened and then I would expect them to merge. This isn't what I found. This is because I assumed incorrectly that the stat acts like a valve that diverts coolant into the rad. However looking at the manual, this isn't the case. The stat just acts as a restrictor, reducing the flow, until the coolant gets to 82degC and then the stat starts to open, increasing the flow into the rad. None of this really helps the OP. You are going to have to open the stat housing and pull out the stat to check it. It's very easy, just two bolts. FWIW my stat was fine which is a bummer cos Iwas hoping I could pin my poor mileage on on it.