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Exhaust "popping"
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Posted by: Stryker1513

I have a FMF 4.1 slip-on, JD jet kit with set up with how they recomend, 180 main, 45 pilot, red needle, and an r&d power bowl. And my exhaust pops really loud when i let off from WOT. Any reasons/Solution?

Posted by: patrickj75

maybe a bigger pilot. whats your fuel screw at?

Posted by: Stryker1513

2 turn out

Posted by: patrickj75

on my Honda with a pipe i ran 180 main, 50 pilot and about 1-1/2 turns out. i'm at about 950 for elevation.

Posted by: mcracer

I'm running 4.1 w/ mega bomb using 48 pilot and 175 main 2 turns out and no popping at all.

Posted by: atvrider23054

you have an exhausst leak like me take it back to the dealer

Posted by: inthewoods10

Ktm notourious for exhaust leaks, look at all your exhaust joints, if you have black soot you've got a leak, biggest problem is at the head, i used rtv hi temp gasket seal works for a while but will eventually blow out, when it starts back firing again on decel i just re apply more sealant, solved the issue for me!

Posted by: tapper torney

I've got the exact same problem (leaking at the header) . Annoys the hell out of me, especially since i have rarely seen this problem on the bikes. silicone is only temporary as you say !!!!!!

Posted by: bajaracer21

Heres what a guy did to fix the leakage.

http://i224.photobucket.com/albums/dd127/blue450yo/dum/28j8f1v.jpg

Posted by: thump4863

quote:
Originally posted by bajaracer21
Heres what a guy did to fix the leakage.

http://i224.photobucket.com/albums/dd127/blue450yo/dum/28j8f1v.jpg

I would not weld like he did - that can cause major issues down the road.

Posted by: OutlawBill

If it is leaking at the weld why would re welding hurt as long as you due not warp it. Has any one tried JB Weld.

Posted by: thump4863

quote:
Originally posted by OutlawBill
If it is leaking at the weld why would re welding hurt as long as you due not warp it. Has any one tried JB Weld.

What he did was not reweld. There is a plate that mounts to the motor and the pipe just fits on this. He welded the plate to the pipe making it rigid when its made to flex.

Posted by: OutlawBill

looks like he weld the exhaust flange that bolt to the head and the exhaust pipe fit in too and held on by the springs. If tis is the point that is leaking there either the gasket has failed or there are holes in the flange. Checking out J-B weld will not work only goo too 500 degrees F but PERMATEX® Hi Temp. Metal Repair Compound should work good too 2000 degrees F

Posted by: Boytjie

Hi Guys... my 525XC started to leak whilst XC riding in the desert (70min from car), noted the bike lost power. As soon as I stopped, found the bike boiling (6 hours on the clock - thus brand new)

Found the exhaust leaked, hot exhaust gasses blowing onto water cooling hoses. After drama getting it back home, send quad to KTM. They done an exhaust weld, I am still waiting for KTM (Austria) letter stating that they approved it. I am concerned that the flexed exhaust is now ridgid with the original header bolts (quite small) - this might caused later on due to ridgitdity the header bolts to break... worse transfer the stress now somewhere else (the head itself, might lead to cracking)

Comment are welcomed...
Cheers,
Boytjie