OZ ATV :: The Australian ATV Forum

[slightlydodgy]

It don't do nuffing. Going down to the runoff at about 65k/hr it started bogging First thought was dirty fuel or muck in carb Just got that thought out and we died completely. No compression and the odd clunk when I wound it over. Got it home and later took the tank off to check the valves were moving, pulled the spark plug and found the end missing. Took the head and barrel off and found this Bits of piston everywhere, even in the header pipe
Now for the tricky bit I have a 99 350 big bear motor sitting here that runs beautifully most of he part numbers are similar, the barrel, piston and head look the same, the bore and stroke are listed as the same I have a wrecker who says they are the same but a mechanic said no And what are the chances of not having to split the cankcase (about where my ability ends) Any thoughts please otherwise I'm looking at some big expenses which I can't really afford right now
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Tremble with fear - I've had an idea

[Rattler]

OUCH , Was that the one you were given ??

[slightlydodgy]

Nope its my 08 350 grizzly farm bike used every day
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Tremble with fear - I've had an idea

[slightlydodgy]

Today got the piston head off looks even worse The weird bit is there was no indication of anything wrong before it died but there was a lot of slop in the gudgeon pin when I pulled everything apart The thing that's worrying me is where is the rest of that piston? As I said earlier there was bits of it all over the place. If I run the risk of not splitting the crankcase what's the best way to flush it out as the oil is full piston grit?
As for the big bear parts fitting I pulled the top end off that today and everything looks identical, measures the same (basic vernier calipers) gaskets are all the same, both pistons come to the same height above the crankcase so will hopefully have time to trial fit tomorrow (am hoping to use big bear piston, barrel and head)
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Tremble with fear - I've had an idea

[HST Powersports]

buddy as a suggestion id look at having the cases split just to be sure no signs of contamination are floating in the cases, a small piece of piston can destroy an engine in less than minutes if it is sitting in the wrong place it can become lodged in the cylinder or crank and self destruct. The cost to strip down new gaskets and bearings is 1000 times cheaper than another engine failure.
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***** HST POWERSPORTS*****
0437652393

[dangerman4]

dodgey pls dont even consider putting your ok parts onto that bottom end.

why cant you bolt the complete other engine in.

that damaged motor has had a total failure and will certainly have metal thruought its internals.

send it to scrap metal or the bottom of the sea.
dont waste your time or money trying to fix it as you will have damaged "profanity removed" everywhere letalone replacing every single bearing below.

[slightlydodgy]

Thanks for the advise guys I think I'm going to have to suck it up and consult my local shop He's both a yammie dealer and a wrecker so usually can get parts fairly easily . I can't change the whole motor over as it is a big bear with stuffed starter gears and clutch assembly The mounts are different and the drive outputs aren't quite in the someplace but the barrel piston and head are the same and appear to be reasonably fresh
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Tremble with fear - I've had an idea

[slightlydodgy]

Got to spend a bit more time over the last couple of days taking advise the whole way I pulled the stator cover That wasn't easy the bolts holding the footplate in were seized - one snapped and I had to grind the head off one Behind the flywheel there is a plate that gives access to the bottom of the crankcase There was one small piece of metal (about 5mm square) sitting in there and as the yamaha mechanic said plenty of space I rigged up a pump and used it to pump about 40 litres of petrol ( kindly supplied by my employer and yes he does know) through the crankcase I strained the runout and stopped when it looked and felt completely clean I then followed it with 5 litres of kero The plan is to run it for a few days and then do an oil change just in case there's anything left The mechanic had a good look when he dropped off the new gaskets on his way past an declared it good to go Now I'm into the fun bit putting it all back together There's a healthy lot of praying going on Theres also the distinct possibility of a trade in in the very near future
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Tremble with fear - I've had an idea

[slightlydodgy]

Got the top end all reassembled and torqued down early last week Everything fits perfectly I set the timing last thing on Tuesday then went on holiday for a week. I had 1/2 an hour spare today so filled the oil and wound it over Now here's the embarrassing bit when I set the timing last week the chain had come off the bottom sprocket!!!! Now I have to try and get it to go on from the top or drain the oil and take the stator cover off so that I can get at the bottom sprocket
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Tremble with fear - I've had an idea

[slightlydodgy]

it lives!!!!! Well sorta. I finally got the motor back together fitting it around work etc and after dropping the timing chain 3 times I fired it over last thing Thursday before going away for a couple of days It ran a bit rough and smokey but it ran Now just got to find time to refit everything else and give her a tune up
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Tremble with fear - I've had an idea

[Rattler]

Great news Dodgy I was wondering how you were going with it.