Operating Temperature on the Cool side

I thought my bike was running far too cool and I wanted the thermostat replaced. My mechanic tells me no way, do not waste the cash on replacing the thermostat.

The bike is covered and stored now but when I was last riding it was 50-60°F. I do as the manual instructs and warm it up. In the summer it takes the recommended 30 seconds for the temp indicator to light up (100°F minimum). At the cooler temps it takes a little longer. So I figured, high idle it and warm it up to the same, 100°F, and it may take a full minute to get there. Then I begin riding. The temperature climbs extraordinarily slowly while doing 25-35 mph. After a couple miles I pull over, let it idle until I see 150°F. I then take off again to 35 mph. The temp drops 149,148,147,146...

In my mind it should not drop at all at this low a temperature because it is far below the thermostat's operation (175-180°F?). My mechanic is telling me these bikes always cool when moving, that is the way it is.

FYI the bike is running engine ice.

I do not see a steady 170° until 40-50 minutes into the ride. It does reach a point where the temp maintains a higher minimum say 170+ and will not go back down to 150.

I have read conflicting remarks. One poster has a VTEC and stated he could never use the VTEC because it won't kick in at 150°. However I don't know, maybe the 6th gen is designed to run hotter.

This is a 6th gen. He describes exactly what I have going on, but again, perhaps that bike heats up more reliably:
http://vfrworld.com/forums/showthread.php/29432-Thermostat-Replacement-6th-Gen-VFR800-VTEC

I have seen other posts about 3rd & 4th generation bikes that act exactly like my bike acts.

Cadbury64 wrote to touch the radiator and it should not warm up at all at first. However, I am on painkillers and am not so sensitive to temperatures, so I may not be able to tell slight differences. I could get an infrared thermometer I suppose if data is required.

I get around 32 mpg. My PCV map is somewhat richer than stock in the upper throttle range. Also I have -1 teeth in the front sprocket. I also do 80/20 local/freeway. So my low gas mileage very well may be an indicator of my setup and habits and not help us decipher this issue.

What do you experience in cold temperatures? Does this bike not heat up linearly? Or is my thermostat stuck open and require replacement? My biggest worry is condensation if the bike is spending too much time running cool.

 

my 99 drops down into the 170's during cool weather. sounds like your thermostat is staying open. Does your fan cycle on and off when sitting in traffic? Keep in mind engines run more efficiently the hotter they get (to a point obviously before damage occurs)

 

After say 1.5 hour ride in 50°F weather, it may or may not reach 220 just as I am idling and maneuvering back into the garage. I can confirm that during the summer, the high temperature coincides with everyone else here, it hits 220°F and the fan kicks on appropriately. So yes, during hot weather I witness the high temperature and fan cycling works just like most others here feedback.

 

My bike warms up to operating temp in a few minutes, really fast in 25-35 mph traffic as you described even in cold weather. I definitely think it may be your thermostat, and unfortunately there's no other way to be sure than to pull it. Speculating is a waste of time. Pull your thermostat, check it's operation in a pot of hot water (drop in a thermometer to measure temps) I did a ride at interstate speeds the other day in 50 degree weather. Temps was around 177 on average.

 

If your thermostat is operating correctly you can check it while starting from cold on the centrestand. It should stay closed until it reaches the set-point to open, which means coolant will stay in the block/pump until warm, then the now-hot coolant will be released to the radiator as the thermostat opens. With your hand on the radiator, it should stay stone cold for a few minutes, but then quickly get uncomfortably hot over a few seconds. If the radiator slowly rises in temp as soon as the engine is started, your thermostat is jammed open.

My bike hits operating temperature (77-78C) within a mile or two of riding in all temperatures.

 

If it does turn out to be the thermostat.... perhaps it's time to find a new mechanic.

 

A cool running VFR??? What's next, you have 80,000 miles on your original R/R?

I'm sure you'll get it sorted, Knight. Good luck.

 

My 6th gen would run very cool in cold weather as well, until I changed the thermostat. Now no matter the temperature (down to like -5C at least) it warms up to VTEC temp in about 2-3km of below 70kph riding. I don't let it warm up in the driveway appreciably, just enough to put on my helmet and gloves. Before I replaced my obviously busted thermostat, in cold or wet weather the bike would often never get to VTEC temp.

 

In cold weather (below 40F.) i put a strip of tape over my oil cooler, and that's the only way my '86 will get up to proper temperature.

 

It's your thermostat. What you describe happened to my 5th gen. In cold whether in would never warm up. I replaced the thermostat and now it's fine.

 

Very interesting, mine as of now since I'm not riding, but do take it out, fire it off. Takes about 5 minutes to reach 175-80 in 40 degree weather not riding it. I start off with the choke some what fast idle at 2k that I set, it would go higher, I just don't see the need, then set it back down to idle. takes about like I said 5 minutes at idle to reach 180. then I just do a few blips, put it in gear ride it back in to the stable where it came, all is good. When I was out and about back when, seems so long ago though, stays around the 170s in this cooler weather, yes it gets to 200 fairly easy in stop and go, saw 198 the last time out in down town traffic. I think I'm good, but I'm going to do that warm it up and watch the temps vs keeping a hand on the radiator to see how this plays out. after reading Jims post, I'm not even close to looking forward to that fix. Knock on wood here.

 

Ok, so this thread brought up a couple questions, I figured best at the least look into it a bit. this morning I rolled the bike out fired it off as usual 45 out side, full choke, let it spool up to 3K it would go higher, I bring it back, then after a few seconds bring it back down around 2k for a minute, then off choke to an idle. Took 5 minutes to get to 165 indicated, 10 minutes it was at 175. It was at the 165 mark I touched the radiators they were luke warm nothing I couldn't leave my fingers on. At 12 minutes it indicated 183, again reached down to touch the radiators MMM yea they are very warm almost hot, now this was at the top of the radiator. At the 15 minute mark it was still at 183, this was all at idle.
Now while at it I threw on my voltage meter had a before starting 12.8v, cranking it dropped to 9.2v, fired right off then went to 13.9v. Here's the funny part. while watching the temps and when I brought it back to idle the voltage went up to 14.4v. when I gave it a bit of rpms say to 3 k it went down to 12.6 if I blip the throttle to 5k I saw a moment where it dropped to 10.v yet when idling it was 14.5, weird, think I'll get a RR and do this again.

 

my 2006 runs cold in anything below 55F. While running down the interstate it will drop into the 140 - 150 F range. It has done that since new. Even both the mechanics I talk to (both old school Honda certified) told me not to worry about it. It takes the temperature of the water in the second radiator, before going back through the engine. Or at the top of the second radiator, can't remember what they said. Nothing to worry about. Overheating is much worse than overcooling. VTEC still engaged even down at that temp after warming up once.