[BillyDoc]

Hi Guys,

This is a great forum for new owners! Info is everything. Thanks for doing it.

I just bought a new (to me) 1999 Vulcan 750 that was in need of some Tender Loving Care. So far, so good . . . but I don't understand the cooling behavior. If I let it sit and warm up, the temperature comes up to the left side of the little thermometer symbol and the thermostat seems to open and it stays there. The fan comes on too. But if I ride it the temperature stays cold, barely coming up to half way between the first two marks, or if it is warm out maybe a sixteenth of an inch past the second mark. How much the temperature comes up seems to be directly related to the outside air temperature and my driving, not the thermostat. I thought maybe the thermostat was sticking open so I flushed the system and changed the thermostat . . . but this didn't make any difference! Of course, running cold all the time seems to effect the gas mileage (only about 35 mpg) and fouls the plugs.

So, is this normal? Does this thing air-cool so much that the thermostat just doesn't ever open?

Thanks for your thoughts!

BillyDoc

 

[Ironman]

Hi Guys,

This is a great forum for new owners! Info is everything. Thanks for doing it.

I just bought a new (to me) 1999 Vulcan 750 that was in need of some Tender Loving Care. So far, so good . . . but I don't understand the cooling behavior. If I let it sit and warm up, the temperature comes up to the left side of the little thermometer symbol and the thermostat seems to open and it stays there. The fan comes on too. But if I ride it the temperature stays cold, barely coming up to half way between the first two marks, or if it is warm out maybe a sixteenth of an inch past the second mark. How much the temperature comes up seems to be directly related to the outside air temperature and my driving, not the thermostat. I thought maybe the thermostat was sticking open so I flushed the system and changed the thermostat . . . but this didn't make any difference! Of course, running cold all the time seems to effect the gas mileage (only about 35 mpg) and fouls the plugs.

So, is this normal? Does this thing air-cool so much that the thermostat just doesn't ever open?

Thanks for your thoughts!

BillyDoc

What kind of outside temperatures are you experincing right now? Are you down south in the 70's and 80's or up north in the 40's and 50's? The thermometer on my bike, an '04, always ends up about the middle after it warms up, hot or cold. When it's like 75 or above, the fan usually pops on for a few seconds after I shut it down. I wonder if your thermometer might be defective. The fouled plugs could be from running too rich rather than too cold. Did you remember to vent the air out of the system using the bleed valve? It seems leaving air in the system usually results in overheating, not underheating, but I just thought I'd mention it.

 

[BillyDoc]

Thanks for the info Ironman, I thought something wasn't right. The temperature right now is about 70 (I'm on the Gulf Coast) and I just rode the bike about 15 miles. The temperature gauge came up about 1/8" past the second mark on the guage, and never got any higher. In the morning, when it's been about 60 degrees it doesn't come quite up to the second mark.

I didn't have a service manual until yesterday, and when I read it I noticed that it said to make sure and place the thermostat in with the bleeder hole "up," so I just took the cover off and checked. It was at about 2:00, so I re-oriented it "up." Although I don't see how this is going to help much, if at all. The thermostat was closed, as it should be, and this is a new one. I have been bleeding the thermostat housing, saw that here!

Also, in looking at this problem I came across Gypsi's web site and noticed that she puts a board in front of her radiator to partially cover it when it's cold . . . which made me think that this cold-blooded business was normal! But now with your info I think maybe I still have a problem.

The temperature guage could be bad, but it seems to work exactly right when I just sit and let it idle until the temp comes up. It comes up to just the left edge of the thermometer symbol (the water at the bottom of the symbol, actually) and locks there, just like the thermostat just opened up and it is now up to temperature. The fan comes on too, so it could be that the thermostat has been open for a while and I'm seeing the cooling from the fan. Better check that guage, I think.

I don't see how the water can go through the radiator without going through the thermostat, so you shouldn't need to cover the radiator at all if it's cold. The thermostat should be closed!

Also, I think you're right about the fuel mixture being rich. I did put in new KN filters, and that helped a lot! Now I'm getting 41 mpg, but I think it should be a lot better since that is at mostly 50 mph or so and not hot rodding (much). I've ordered a colortune plug and a vacuum gauge which should show up in a week or so to do a tune up. The temperature thing is what is worrying me though. I'm going to see if I can figure out the thermometer and check it now . . . and also check the sparks on all four leads. (I did put in new plugs.)

Since Gypsi seems to be having a similar problem, how are other bikes doing? Like mine, or like Ironman's?

Bill