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Discussion Starter · #1 ·
'78 Arctic Cat Jag 340. Motor runs and everything seems fine except the last time went to run it and it seemed to vibrate a lot and then the muffler popped off. I later installed new springs to hold the y-pipe and muffler together but when I give is a lot of throttle you can see the muffler and y-pipe come appart. Now the flanges on them are messed up a little but I think I can straigten them up. What would cause this???? A bad muffler???? How do I find out what's going on??????
 

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I would take a close look at the muffler I am betting you might be plugged up with a mouse nest. Take it off and give it a good shake and see if anything comes out it can be a real pita to get those things cleaned out.
 

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A buddy of mine had mice haul a bunch of corn in one of his. It actually made a clinker in it when the corn burned. He said it was a sucker to get out.
 

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Discussion Starter · #4 ·
Hmm. Maybe I will just cut it in two then weld it back up. I was thinking maybe I had a nest in there because there was one inside the air box that I had to clean out. Just weird that it ran fine just days before
 

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try using compressed air before cutting it.
i set my compressor to 100psi on an 80 jag.
worked perfect.
 

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Discussion Starter · #6 ·
Yes I thought of that too. Just worried about those header bolts! Can't get enough room with out removing it
 

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Discussion Starter · #7 ·
Well I pulled it off, jacked my compressor to 100psi but nothing seemed to happen. Nothing sounds like it's in there and air would come out of the other end. Yes, I blew in both ends but that didn't seem to matter. What else would cause this thing to vibrate fiercely like it is???? It ran fine one day and a few days later it does this.
 

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are you blowing thru can or pipe?
use a rag or sumthing around the air line so its
a tight fit.
 

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Discussion Starter · #9 ·
Yes I used a wet shoprag. Seems like about the same amount of air going in and going out. He only other thing I can think of doing is to heat up a bunch with a torch to try to burn what might be in there
 

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Discussion Starter · #12 ·
Everything else seems ok. Took a pry bar and re motor didn't move more than normal
 

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Mmm. are there any other mounts
or springs to hold pipe that are
missing or rusted off?

im trying to think but im tired.:p
ive been tearing apart my formula 3 parts sled all day:D
 

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The spring should be hard to pull back, and you can't do it by hand. You should have to use quite a bit of force and a pliers. If you can do it without tools, then those springs are week.
 

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Discussion Starter · #16 ·
Not that I can see. I brought it back in the garage and turned on the heat. Maybe somethings frozen somewhere?
 

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Discussion Starter · #17 ·
Artco hex shaft clutch on it?

Check it for worn/broken cams.
OK. I've been using my phone on here and didn't see your post until I got back to my computer. OK. Maybe this is where I need to be. How do I check these. I've never had to mess with clutches before. Not sure what I have to look for.
 

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If that clutch has any issues, it will cause excessive vibration which you can even see at idle.
You can take the outer cover off with it in place. Instead of flyweights (cam arms), it uses double arms and rollers against stationary ramps. The bushings for the arms get sloppy and they then twist and break.
 

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Discussion Starter · #19 ·
OK. At this point I am leaning more on what you are saying RJ. I think I have enough flow through the muffler where it shouldn't be making the sled vibrate like it is. The last time I rode it I just went around the house. It vibrated so bad I could hardly stand to hold on to it.
 

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gotta be a bearing problem.
how is it when u rev on a stand?
 
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