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Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc.


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Old 07-30-2012, 07:05 AM
swazi_matt swazi_matt is online now
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Default Exhaust Rattle

How long do the o-rings at the exhaust-engine connection normally last, mine seem to last a few rides and then the exhaust starts to rattle, especially as the idles drop (eg if i rev and then pull in the clutch)

I am using 44x3.0 viton o-rings, so i doubt they are melting and the last time i fitted the pipe i spent a long time making sure that it was fitting square (rattle got really bad this weekend when i banged the pipe on a rock, so i know it is not square anymore!)


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Old 07-30-2012, 07:16 AM
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us ktm green orings from a 05 ktm200exc only ones that lasts
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Old 07-30-2012, 07:28 AM
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They didn't last well on my 300. It vibed as you described. Always on decel.

I custom lower isolator mount. Nice big thick piece of rubber and a sturdy bolt. Much better than the tiny stock one which was flogged out. I also put new springs on which helped. And.. My last trick. Be generous with the high temp silicone. I give the inner lip of the pipe a nice big smear all the way around before pushing the pipe on. I'm 90% certain the lower mount was the issue though. Allowed the pipe to rotate a bit and cause vibes. Now it actually holds the pipe while absorbing the vibes.
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Old 07-30-2012, 08:34 AM
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Custom mount? Couple pics please.
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Old 07-30-2012, 09:35 AM
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No pics at the moment, but a quick description. Basically I used a upper pipe mount that had broke. Used the rubber from that. Drilled a whole through the middle, slid a bolt through and used that as the isolator for the lower pipe. I'll get pics in the next few days. Its nothing flash. Just a bit beefier
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Old 07-30-2012, 01:48 PM
swazi_matt swazi_matt is online now
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Thanks Jake. My lower mount is almost nonexistent, will have to see what I can find to replace it
Have also been thinking about using some gungum on the inside lip of the pipe
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Old 07-30-2012, 03:26 PM
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If you put a bolt THROUGH the rubber and attached it to each side then effectively you have no isolation. What should work good is the old type of cylindrical isolator(same as I used to mount my shrouds) between each side, and a spacer of the same length to bring the mounting surface of the pipe tab back to position. No drawing, but can you visualize that?

I had a pipe last so long that the surfaces of the flange actually wore out where the orings seated, so it was always loose and leaked after a few rides with fresh orings. You can source orings just SLIGHTLY bigger for a tighter fit. Eric K has done this, do a search, I'll have to try it myself.
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Old 07-30-2012, 04:41 PM
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Correcto.

I had purchased a on as you describe to use but the threads on each side were too large to fit my purpose and I wasn't able to source a smaller one or interested in drilling out the pipe. It was a 5 minute fix for me as the old one had disintergrated.

The setup I have isn't technically floating and more of a fixed sturdy solution, however it still allows some movement of the pipe when required. End of the day overall vibes reduced, and the horrible noise on decel has stopped. It used to kick in in half a ride.

My pipe had actually started to wear a groove into the spigot plate before doing this from continually moving under engine load.
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Old 07-31-2012, 03:11 PM
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I think the faultiness in design begins with having only 2 exhaust springs.
Anyone weld another set of loops and add another spring?

I sacked out 2 lower hangers, and broke 2 upper hangers in the first 10 hours of riding. I had to fab a beefier upper hanger to keep things from shaking apart.

New O-rings only make a difference for the first ride. After they take the slightest set, things are loose again.
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Old 08-01-2012, 06:45 AM
swazi_matt swazi_matt is online now
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picked up a small isolater for a car from an exhaust shop, slightly thicker than the GG one, but if i bend the tangs on exhaust it should fit nicely
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