Hot Exhaust

[Boxerdad]

I need some help with side case melting exhaust. I was on a long day in July at high power settings when I noticed my exhaust had melted a hole in my side case. I have since patched the hole with plastic and a new heat shield, but I took the bike for a 15 mile ride this morning and the bag got hot again....enough to warp my patch as well as the stock plastic. Any reasons you can think of why the exhaust is running so hot?

The bike is my 96 RT with 110K miles. Most recent major maintenance was a new throttle cable about a year ago.

[dan cata]

That's weird. The shield came off from my bike but it does not melt the case.

 

Could it mean that the bike is running too lean? That would make it overheat. Or perhaps you are sitting in traffic too much. Do you get 6 bars at temperature on the dash often?

 

Dan.

[Tobias]

A misfiring engine, or a vacuum leak can cause a catalytic converter to glow red hot. It doesn't take long for the converter to be permanently damaged.

How is the bike running?

How long since a tune up?

With the tupperware off can you see where it's getting hot?

[Danny caddyshack Noonan]

If I recall correctly, I thought a too rich condition and a good cat could go hot due to the exotherm resulting from converting the unburnt fuel downstream. I could have that confused with something else though. I haven't had coffee yet and it's almost lunch time.

 

Lean will always get you a hot exhaust valve and pipe though as well.

[dirtrider]

Afternoon Danny

 

Continually too rich & there is not enough oxygen to allow full burn in the cat & too lean there is too little oxygen for complete burn in the cat. Rich also adds some cooling effect of the fuel as that absorbs heat.

 

That is why the closed loop o2 sensor controlled fueling system is designed to continually go from rich, to lean, to rich, to lean, etc. (you can actually see that is Rogers posted data) The rich fuels the cat then the leaner allows enough oxygen to light off & keep it going.

 

I would imagine the hottest exhaust (at least in the forward part of exhaust) would be to just either side of stoichiometric.

 

Added: Now a cylinder misfire is something else again as that adds LOTS of unfired fuel with proper amount of air at a good ratio to ignite in the cat.

 

[roger 04 rt]

+1 to DRs comments.

 

Highest exhaust temperature is at stoic 14.7:1. Highest cylinder head temperature is slightly rich f stoic (more power being produced).

 

Highest catalytic converter temperature is misfiring engine: raw fuel plus unignited oxygen hits hot catalytic and fuel burns there.

 

What mods if any have you made to your bike?

[Boxerdad]

Well I just looked at the plugs yesterday and they look fine. The valves were within tolerance. I synced the throttle bodies, but they required very little adjustment, they were off very little at idle, but spot on @ 4K.

 

When it happened I had performed several sustained (180 mile) runs at around 90mph or higher from Montana to Iowa, and the ambient temperature was ~100 degrees. I thought maybe the high power settings combined with the high ambient temps caused the issue. But it is still occurring.

 

One last thing is that the muffler has a hole about 1/2" on the inside diameter of the muffler outlet.

 

I've made not performance modifications. She is 110K miles of stock German goodness.

[dirtrider]

-----

 

One last thing is that the muffler has a hole about 1/2" on the inside diameter of the muffler outlet.

 

 

Evening Boxerdad

 

That might be your entire problem. Can you post a picture of that hole so we can see what you have there?

 

[Boxerdad]

Here are the pics of the hole. It is at the bottom of the inside diameter of the muffler opening.

 

[dirtrider]

Evening Boxerdad

 

That hole could be your problem. That hole could be directing a jet of hot exhaust gas up towards the case bottom.

 

You might try finding a piece of thin walled pipe that just fits in the muffler center hole then driving that in with a wooden or rubber mallet, then tacking it in place with some small tac welds.

 

You can even let the pipe stick out the back a couple of inches to get the hot exhaust out back farther.

 

[Boxerdad]

Thanks! I'll get rid of the hole & see how it goes.

[kmac]

Since you have to fix that hole anyway, try knocking out that entire center plate and see if opening up that exhaust exit frees up breathing and it stops, if it is too loud then the fix DR suggested will correct that anyway.

 

Just an outside the box idea.