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2019 KTM Duke 390 w/RapidBike Evo ECU piggyback
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Discussion Starter #1
If you own a Duke that has the exhaust pipe routed above the engine case on the left side you are probably thinking that KTM engineers like their left leg baked to perfection in the summer. I don鈥檛, so I bought this aluminium exhaust pipe protection/heat shield for dirt bikes from China for like $15 with shipping included.
52965

I鈥檓 going to wrap the left side of the exhaust pipe with this all the way to the black muffler box. This thing is quite soft aluminum, thus bendable to the contours of your cat 鈥榥 pipe.
There鈥檙e more colours available, but I think black is neutral enough. This should lessen the infrared radiation (heat) coming off the pipe enough to not pay attention to this problem.
This has been addressed in > 2020 Duke 390 but may still be an issue with the 2021 Adventure as I think they rerouted the pipe for more ground clearance (or will soon).
 

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Be careful, or @Ede might come after you telling you that exhaust shields don't do anything:

 

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Discussion Starter #4 (Edited)
Be careful, or @Ede might come after you telling you that exhaust shields don't do anything:

馃榿
Well, I鈥檓 always in my full riding gear and even in riding jeans that damned pipe feels like someone is holding a heater lamp on full blast near my leg. If that heat shield lessens the heat by 50% I will call it a success.

Some people wrap their pipe with fibreglass wrap. This is a bad idea! I read a lot about it and the professional mechanics say that over time it weakens the pipe metal and holes are formed under the wrap from the bits of condensation between the wrap and pipe. It鈥檚 a big 鈥渘o no鈥 for regular street use and it鈥檚 only used on a racetrack where long term pipe durability is not a problem.
 

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Some people wrap their pipe with fibreglass wrap. This is a bad idea! I read a lot about it and the professional mechanics say that over time it weakens the pipe metal and holes are formed under the wrap from the bits of condensation between the wrap and pipe. It鈥檚 a big 鈥渘o no鈥 for regular street use and it鈥檚 only used on a racetrack where long term pipe durability is not a problem.
Yeah, I measured the temperature of the wrapped exhaust and it was much, much hotter than without it.
 

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2019 KTM Duke 390 w/RapidBike Evo ECU piggyback
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Discussion Starter #6
Here is my attempt to install a dirt bike exhaust heat shield onto my beloved 鈥渃razy horse鈥 as I call my Duke. The installation was painful as the shape of the heat shield didn鈥檛 conform to the super narrow 鈥渢wist鈥 on the lower left frame contact point.
I鈥檒ol have to wait until early March to report on the effectiveness of this. My bike is still uninsured and winterized.
52995
 

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Discussion Starter #8
Y'all's fancy 2020 models have the heat shield already, does it not help?
Mine is 2019 model it has a small heat shield on my picture, but it鈥檚 not enough. In addition, I think the new 2021 Adventure may have this problem as their pipe routed the same way.
 

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Be careful, or @Ede might come after you telling you that exhaust shields don't do anything:

What's your problem?
Take a 300 degree hot pipe and add a heat shield and it's still 300 degree.
The heat has to go somewhere if there should be less heat on a certain part. A fan or wind will make the part cooler. But if the hot air is blown at the leg then that is not the desired effect.

I am happy to listen to anybody who found a solution. But I don't expect any wonder.
 

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So KTM engineers just did a useless modification to the 2019+ models? Why is that heat shield there?

My problem is with the complete disregard not only for physics, but also for engineering prowess of KTM and other manufacturers.

I'll try this again: hot air blows from the radiator, which is around 100 degrees. The hot air from the exhaust doesn't blow, it barely flows upwards. When the bike is moving, either should be felt just very little, if at all.

One type of heat will keep on going no matter the speed, though, and it is the radiative heat. That's what the shields - both the ones installed by KTM themselves and other manufacturers, and the aftermarket ones - are designed to both absorb and deflect reflect back. Since the shield is removed from the source of the heat by some distance, not only it absorbs only a portion of the heat energy, but also receives the vital air flow that cools it much more than the same air cools the exhaust pipe. The rest of the heat energy will be deflected reflected back. Think of it as if you shine a super bright light on a black piece of metal. For sure you'll have most light deflected some reflecting back, even as some is absorbed.

In the end. any piece of flat metal that's slightly removed from the exhaust pipe will both absorb some of the radiative heat (dispersing a portion of it both through convection and its own radiation), and will deflect some reflect some back.

Edit: deflect, not reflect.
 

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Discussion Starter #13
What's your problem?
Take a 300 degree hot pipe and add a heat shield and it's still 300 degree.
The heat has to go somewhere if there should be less heat on a certain part. A fan or wind will make the part cooler. But if the hot air is blown at the leg then that is not the desired effect.

I am happy to listen to anybody who found a solution. But I don't expect any wonder.
We are solving a different issue here. I wasn鈥檛 trying to solve the fan blowing hot air issue. I installed an aluminium 鈥渉eat sink鈥 on the pipe in the same principle of heat dissipation as aluminium CPU heat sinks work in computers. My solution doesn鈥檛 have any heat dissipation fins. This is an experiment. I hope to have an approximately 50% improvement in pure pipe heat dissipation here. I don鈥檛 care about hot air as I don鈥檛 feel it in my riding jeans wich all of us should wear even in the summer.
 

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Discussion Starter #14
I have another idea 馃挕. I think the proper solution for this is a bigger, specially shaped black chain guard with an integrated heat shield that simply covers the hot area.
 

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馃榿
Well, I鈥檓 always in my full riding gear and even in riding jeans that damned pipe feels like someone is holding a heater lamp on full blast near my leg. If that heat shield lessens the heat by 50% I will call it a success.

Some people wrap their pipe with fibreglass wrap. This is a bad idea! I read a lot about it and the professional mechanics say that over time it weakens the pipe metal and holes are formed under the wrap from the bits of condensation between the wrap and pipe. It鈥檚 a big 鈥渘o no鈥 for regular street use and it鈥檚 only used on a racetrack where long term pipe durability is not a problem.
When using aftermarket inox headers and decat pipe, condensation is not an issue.

For stock pipe you can use High Temperature ceramic based coatings that can withstand temperatures up to 1,800藲. And then wrap all that crap with fiberglass fabric tape.

Keeping temperature high helps exhaust flow so increases performance. Also in 2019 and previous models the exhaust runs aside TBI, hot air in the intake is always a bad idea: reduces performance and induces knocking...

53007
 

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Discussion Starter #16
When using aftermarket inox headers and decat pipe, condensation is not an issue.

For stock pipe you can use High Temperature ceramic based coatings that can withstand temperatures up to 1,800藲. And then wrap all that crap with fiberglass fabric tape.

Keeping temperature high helps exhaust flow so increases performance. Also in 2019 and previous models the exhaust runs aside TBI, hot air in the intake is always a bad idea: reduces performance and induces knocking...

View attachment 53007
Yeah ceramic coating seems like a more complex way to fix this.
Why do you need to wrap the coated pipe with a wrap if it鈥檚 already coated?
 

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Discussion Starter #17
Update, my experiment was abandoned as I realized that it鈥檚 not going to work, because the aluminium heat shield is too thick and is rubbing against the frame. During engine operation the pipe must be allowed to vibrate freely without rubbing on the frame, so I took everything off.
Looks like ceramic paint coating is the way to go.
The questions are:
  • Where to get a black or bronze ceramic paint colour?
  • How to apply it on the pipe and muffler below? (Will brush work or it has to be spray painted?
  • How to prepare the surface for this particular paint?
  • What鈥檚 the brand name of the heat shield paint?
  • Where can we order it for a reasonable price?
  • How much does the paint cost?
  • How much will it cost someone else to paint it if needed?
 

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Discussion Starter #19
can't you make a nice shaped cover that fits to the outside of the frame
I was thinking about this approach too, but it had the following drawbacks (look at my picture above and note the white trellis frame which is moving constantly):
  1. The cover needs to cover the area in the lower muffler and foot peg as well as above the trellis frame wich makes the shape and method of mounting of the cover complex.
  2. Style... it鈥檚 very difficult to make such complex cover that would fit with the bike鈥檚 current theme and style and be reliable enough. The point of heat shield was an attempt to keep the style relatively intact.
 
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