Heat......Need Help!

[newbluest]

Ok...I've asked before but I'm just not sure I'm outlining this.....

1. My engine heat has never been this bad, but now it all of a sudden spiked.

2. It all started with rough engine idle.....it would bog down and drop below the 1000 RPM level.

3. I adjusted the idle and then the heat spiked.

4. Even though the heat feels as if the plastic is going to melt, the temp bars never change from the middle.


So my questions are:

1. What could be causing this?
2. Could there be a significant problem and the temp gauge isnt showing it?
3. Can the temp gauge ever be wrong?
4. Assuming that this is NOT the usual too hot issue, but something seriously wrong, could it be the coolant pump has failed?
5. I'm lost and need help.....any thoughts?

 

[mjhenne]

Maybe it is just me but it seems my 2007 got MUCH warmer the last 1000 miles or so (about 11,500 miles now) to the point where it seems to be as hot at 75~80 degrees as it used to be at 85~90 degrees and now at temps above 85 it is not nice at all where before, as long as I was moving, the heat was noticable but not a problem.

Along with this is a slight drop in idle and the bike seems to be running a bit more vibey and harsh.

My plan is to not worry overly about this since cool weather is on the horizon and some rainy weekend this fall I'll strip the plastic, sync the throttle bodies (or should I call them starter valves?), adjust the counterbalancers (not a heat solution) and wrap the headers. I'm confident my bike just needs some tlc and kind comments whispered into its mirror housings. The header wrap wouldn't be necessary if the perceived heat returns to normal but perception being what it is I'm sure I'll be overly sensitive to heat now. Maybe the wrap will either reduce the heat a bit or convince me it did.

For the coolant questions - you get 3 bars all the time? Assuming that you have no bars on cold start and warm up to 3 bars I'd think that your cooling system is OK. Another thing to look for is how often/when your fan runs since if you are overheating and have a faulty temp guage and if whatever sensor that turns on the fan is a different sensor than the one for the guage I'd think your fan would run a lot of the time. Mine runs no more than it ever did.

 

[Mellow]

Some more specifics? What year bike? How many miles?

Any chance, since it seems to be running differently, that the throttle bodies need to be synced? I've heard of this helping for some.

 

[mjhenne]

Can the ECU accurately adjust for the reduced air flow from a dirty air filter? In a carbed bike I'd think that would cause a bit of a rich condition but if the ECU overcompensates and leans out the mix (even more lean than designed) could that up combustion temps, drop the idle? I'd think that would increase fuel mileage. Spark plugs need replaced (but how that'd make more heat I don't know)?

I've seen this mentioned before - do all the routine maintenance before deciding there is another sort of a problem. If your bike is new/low miles though you may have another sort of a problem.

Would dirty gas that left deposits in the injectors cause symptoms like this? I think I'll run some Seafoam through mine.

 

[CrashTestDanny]

The tank on my '05 started getting very hot this summer. At first I thought it might be because I was riding without the tank bag and therefore gathering more solar radiation. However, since then I have experienced the problem on every ride over 100 miles and it has been so bad as to give me 2nd degree burns on my inner thighs through heavy jeans. I currently think that during the service right before the first time I experienced this, the heat shield on the bottom of the tank was damaged, removed, maladjusted, or otherwise tampered with. My plan is to take it all apart when the weather gets too cold or the bike gets too hot to ride and fix the heat shield and maybe install extra shielding and a temperature probe or three.

 

[wjbertrand]

The rough running might be a sign of a misfire or other combustion problem. A misfire on an FI bike will result in more unburned HC in the exhaust stream than normal. The PAIR system adds fresh air to the exhaust stream in an attempt to continue buring this off in the headers and farther down stream the catalyst cleans up still more. If there's too much unburned fuel getting into the exhaust system the PAIR and Catalyst systems will be working overtime to burn the excess and that will create a lot of extra heat. I've seen catalyst equipped cage exhaust systems glowing bright red due to a misfire and excess raw fuel entering the exhaust stream.

 

[Blrfl]

3. Can the temp gauge ever be wrong?

The jury is still out on whether or not what you see on the gauge is a linear representation of the coolant temperature. My completely untested and unproven suspicion is that it takes a considerably larger change in temperature to light the fourth bar than it does the third.

--Mark

 

[newbluest]

Mellow and all,


1. I'm at 14K miles
2. Air filter doesn't look TOO bad
3. Idle started acting up with no real correlation to anything
4. Bars start on the temp gauge at zero and work their way up to three bars as usual.
5. No big change in fuel economy. Haven't reset it, but in my riding around I get about 37-40.
6. The heat seems to be emanating from the headers and radiating upwards.
7. Oil level is good. I had it a smidge above the middle, and it hasn't change much.
8. Ran some techron through to clear the idle problem. Could that cause a heat spike?

Any thoughts to plugs? Can the throttle bodies cause that much unburned gas?

My big question is this:

IS THIS SAFE TO RIDE? CAN I DAMAGE MY BIKE?!?!?

 

[mjhenne]

Mellow and all,
IS THIS SAFE TO RIDE? CAN I DAMAGE MY BIKE?!?!?

Almost plastic melting hot? Mine seems a good bit hotter than when it was new but not anywhere near that hot. If I mine was so hot that I was concerned that damage might occur I'd be pulling the plastic, doing a tb sync, new air filter, new plugs (at least pull them to check color), oil change asap. If after doing this if the bike still caused me concern that damage would occur I'd take it to a good Honda tech (wonder if the coolant temp sender can be tested?).

I've not heard of engine heat damaging an ST1300 but I'm fairly new to them so don't put much stock in my opinion.

Edit - if the engine can run lean and be hot or if the engine can run rich enough that the cats are are way hot would the lean or rich or poor combustion condition be enough to affect plug color? My last bike liked new plugs every 6,000 miles or so. Didn't need them but new plugs made throttle response clearly snappier even though the old plugs were of good color, proper gap and little electrode wear.

Anyway - a check of plug color (and I'd check all 4 in case there might be one injector wacky) might be a good idea. On 3rd thought - that is one thing I'm definately going to check on mine. Would a loose spark plug affect the way an engine runs with out making enough noise to be heard?