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Discussion Starter #1
Hi all, newby here, southern ontario .
I dont have a ATV but my friend has a 2007 400 ho max , it had a sudden backfire popped a hole in the valve cover .
I know little about ATV's but Im willing to help a friend out.
looks like the timing weight blew apart. found a couple pieces of it , the rest maybe inside the lower part of the head.

lots of reading to do here
 

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Its probably the decompression mechanism.
I had an 07 400 with 4 thou on it and never had a problem but I've read that others have .
 

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2015 Outlander XMR 650
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Welcome to the site, sorry to hear that failed on your friends bike before he had a chance to remove it. Hopefully it hasn't trashed the rest of the motor......

But yeah, me and Jungleman come to mind, for threads/posts detailing how to remove that thing. Plenty of other material on here as well, search for decomp or decompression lever, couple threads come to mind of failures the owners had to tear their motors down to repair.

Good luck with it!
 
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Discussion Starter #5
mods please move to proper thread if needed,


Hi ,
After 80% tear down of my friends ride 2007 Outlander , it needs a few things repaired.
I removed the engine then the head . all the broken Decomp pieces from the Engine ( only removed the head) inspected the rest with a borescope, . everything looks good , con rod bearing, wrist pin, piston & all rings , crank all feel & look ok , cleaned out the case with gas and drained it, cleaned out the oil screen , got small amounts of aluminum out , good thing it was at idle for a few seconds when it exploded the decomp and stopped
I made a 8 mm crank stop bolt to lock down TDC
This engine has been apart before , not surprising lots of black RTV sily cone everywhere .
I need to repair a stripped oil drain plug ( coated with RTV ). head gasket set, maybe a new timing chain , looks stretched to me. I need a shorter 800cc cam bolt or i can cut this one down.
note to self, figure out how to get correct cam timing

Front suspension / chassis problems : I do not know the history of the bike or the abuse it has endured
The shock towers & front top rad & fender support bar indicates something is bent or damaged in the front suspension
left side is 1.5" higher than the right side
left side shock has 5 degrees more angle than right one , meaning Right shock is more vertical.
the right hub / a arm hangs a lot lower when sitting on a jack stand under the frame
right hub bearing is shot too, almost floppy with tire on grinding when turned by hand.
I cant see any frame damage even slight bends, I am going to take measurements of everything and see where the issue is.

Any hints suggestions or tips would be a great help.
Will update as I progress
 
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