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Discussion Starter #1
There's not many KTMs out there that don't have an exhaust leak at the header causing poping when you back off & giving a slight lag at take off.
My bike is of the poping variety.
Here's what I did to fix the problem.

Look closly at the alignment of your headers to the flange. See mine here are slightly closer at the top than the bottom.



When you look closly at how the header is supposed to seal you will find a very small tapper in the pipe that is suposed to fit up to the taper on the manifold. There is absolutly no room for error. The allignment must be perfect.
Have a look at the amount of soot in these headers where the exhaust has been by passing. Notice the small clean spot on the bottom. This is the only spot that the header has made contact with the flange.



This is what it has to allign with.



With the flange removed you can see how much the exhaust has been leaking.



Look at the fall out around the flange. This bike only has 17 hours on it.



After spending a couple of hours trying to work out the best way to make it seal I came up with a couple of ideas.
1. Try & bend the header to get the alignment spot on.
Decided that that was near impossible to get it exact.
2. Fill the void with exhaust cement.
There is too much clearance between the header & the flange. It would just blow out, something I learnt from others on this forum that have tried that.
3. Weld the bloody thing on to fully seal it.
After studying it for another hour I couldn't find any reason that it could not be a solid mount on the engine.
Having a tig welder handy I did just that.
The only thing I had to change was the centre bolt on the manifold.
I used a M6 x 16 cap head socket screw so I could use an allen key to tighten it up.



All back together agian. The alignment is perfect & guess what, no poping.
I only put the springs back on because it looked odd without them.

 

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There's not many KTMs out there that don't have an exhaust leak at the header causing poping when you back off & giving a slight lag at take off.
My bike is of the poping variety.
Here's what I did to fix the problem.

Look closly at the alignment of your headers to the flange. See mine here are slightly closer at the top than the bottom.



When you look closly at how the header is supposed to seal you will find a very small tapper in the pipe that is suposed to fit up to the taper on the manifold. There is absolutly no room for error. The allignment must be perfect.
Have a look at the amount of soot in these headers where the exhaust has been by passing. Notice the small clean spot on the bottom. This is the only spot that the header has made contact with the flange.



This is what it has to allign with.



With the flange removed you can see how much the exhaust has been leaking.



Look at the fall out around the flange. This bike only has 17 hours on it.



After spending a couple of hours trying to work out the best way to make it seal I came up with a couple of ideas.
1. Try & bend the header to get the alignment spot on.
Decided that that was near impossible to get it exact.
2. Fill the void with exhaust cement.
There is too much clearance between the header & the flange. It would just blow out, something I learnt from others on this forum that have tried that.
3. Weld the bloody thing on to fully seal it.
After studying it for another hour I couldn't find any reason that it could not be a solid mount on the engine.
Having a tig welder handy I did just that.
The only thing I had to change was the centre bolt on the manifold.
I used a M6 x 16 cap head socket screw so I could use an allen key to tighten it up.



All back together agian. The alignment is perfect & guess what, no poping.
I only put the springs back on because it looked odd without them.

MY mechanic did the same thing to mine!! Awsome!!
 

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Great advice!! now i have my weekend project...thanks.
 

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Thanks for the advice. I just checked the area around my manifold and found carbon too. I'm wondering if shorter springs will work? The stock springs don't appear to have much tension on them. I'm thinking more tension may seal the header against the manifold.
 

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i just took some heat tape that i use to powdercoat with and i wraped it around the flange off the head an slammed the head pipe to it and have been riding it for over a week with no leak no pop
 

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Does exhaust joint sealant tape work on headpipes by any chance? I'm referring to the kind that melts together to make a seal once it heats up, I know it works on mid-pipes but the temps are alot lower than the exhaust coming straight out of the engine. Is the copper type sealant what everyone has used that blows out?
 

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i think that it is good to weld one or two spots before you take the header of, that way you get the alingment right, than taki it off and weld the rest. I am wondering if there is more chance that the header would brake around the manifold after you weld it????
 

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Discussion Starter #10
Mine is still good. No cracks at all.

I welded it off the bike because I was being lazy & didn't want to disconnect my electrics.
Just tacked it up & re checked the alignment on the bike before I fully welded it.

I looked at it for a while before welding it & decided with the motor being a solid mount to the frame & the header having a rubber mount on the frame above the right hand foot peg i couldn't see any major issues.
 

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Mine is still good. No cracks at all.

I welded it off the bike because I was being lazy & didn't want to disconnect my electrics.
Just tacked it up & re checked the alignment on the bike before I fully welded it.

I looked at it for a while before welding it & decided with the motor being a solid mount to the frame & the header having a rubber mount on the frame above the right hand foot peg i couldn't see any major issues.

ok that´s good, i will do the same, i was thinking of taking it to the dealer but it seems to me there is no permanent fix for it there so this sounds good to me, i will fix it this week when i have my fmf speed slip-on

Thank you
 

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Here's a bigger question. With having such an air leak on the header, is there a high chance to suck in cold air and pop the piston? Or it just the popping is so annoying you want to fix it? I would think that if its a known fact that this leak could cause premature piston failure that ktm needs to step up and fix this issue.

After looking over the pictures again it looks like the problem is the weld on the header. If you look at the picture of the header before he welded it that there is a rust ring on the weld. It looks like the pipe can't properly seat on the header. Maybe if part of the weld was ground off to get a better fit or if it was just re welded all the way around and then ground to a nice tapper to make a good fit. I'll bet there be an aftermarket header soon that will fix the problem with a bolt on solution
-Voodoo
 

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I had the same type of leak on my KTM 525/ predator hybrid as the new KTM quads seems to have.

I found that a good application of high temp copper sealer has worked super for over a year now. The trick is to put it on and let it cure fully before starting the bike. I let mine cure for 3 or 4 days before starting it simply because I got involved in a few thing s around the house and forgot about it. A good 24 to 36 hours drying time should be enough though.

I use the same technique when installing exhaust systems on my sleds, put on a good bead of high temp sealer and let her sit for a day or so, and presto good to go for the season.

IMO, that weld job is gonna cuase the header to crack sooner or later and when it does it's gonna take out the header. You might not think this is possible but the frame on the quad flexs way more than you might think it does and when it flexs you need to have some give in the exhaust, by welding it solid you took this flex point away!

Again, just my opinion.
 

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if we saw really little white smoke where the line connects to the exhaust, could there be a leak over there and be responsible for the popping (I can't say if it keeps popping, I only ran it 20 min, it popped like 3 times)
 

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actually just started the engine 5 min ago to show the ATV to my cousin, and on deceleration, it popped twice.....
Should I try to get High temp silicone and just apply it at every connection to check if there s a leak?
If I take the exhaust line and exhaust to check for paths like the pic above, will it show as much as the pic knowing that the atv only ran 30 min?
 

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Be careful what you add there hish, the popping is because its sucking little air there. If you add silicone, there is a chance of sucking the silicone into the motor. Might try the copper sealer that was suggested a few replies up from here. Jetting will help you out a lot and if your like me that will be enough. If your really worried about it then weld it up like Lost Down Under did. I think he should be giving updates after he's ran it that way for a bit and let us know if he got any cracks. I'd wait few more weeks.
-Voodoo
 

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Discussion Starter #17
It's been 6 weeks now since I welded it up.
Just went right over the header again & found no problems.
The bike gets ridden at least once a week. The next couple of weeks are going to be a bit harder on it with both Saturday & Sunday rides on.
Riding is MX, dune work & also trail work.
I will keep you guys posted every couple of weeks.
 

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It's been 6 weeks now since I welded it up.
Just went right over the header again & found no problems.
The bike gets ridden at least once a week. The next couple of weeks are going to be a bit harder on it with both Saturday & Sunday rides on.
Riding is MX, dune work & also trail work.
I will keep you guys posted every couple of weeks.

Hi Guys,

My quad is only 6 hours old when the exhaust leak deteriorate to the extent that the hot exhaust gasses escaping heated the cooling hose so much that the engine overheated... KTM welded the exhaust as shown before. I am quite concern that this might caused stress fractures elsewhere at a later date. I have ask KTM to officially reply that it is endorsed by them... still awaiting the endorsment.

Regards
Boytjie
 

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Discussion Starter #20
Just an update for those that have asked.
My header is still good. No cracks or stress marks after welding it up. It has been a while now & all is good.

On another note, had a mate put a full akrapovic system on and had the same issue.
I had nothing to weld the titanium with so we cut 5mm off the end of the header pipes where they go onto the flange on the motor.
Put it back together with no sealer.
That was 2 weeks ago & there is still no poping on back off.
Looks as though this fix has worked as well and there's no welding involved.
 
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