DiscoDans mid-season engine build

Danbot · Jan 29, 2010

Well, mag side piston got toasty today, very fine alum deposits on the spark plug, and just a few small balls in by the porcelain .
The sled was running fine, I got off the throttle to negotiate some whoops, and when I get back on the throttle it was only only running on 1 cyl. No funny noises, or seizure, I hope it will just be a top end and seals.
35+ mile tow out, at least I wasn't up in steep alpine when it let go.

Updates to follow, I'll tear it down when I'm finished dayshifts on wednesday

GBCB · Jan 29, 2010

35 Miles!

Man, that had to be dreadful. I can't imagine getting towed half that far. Did your friends take turns? Are they still your friends? I've read a lot of your posts and hope your repairs go smoothtly.

Danbot · Jan 29, 2010

One guy towed me out, he's awesome. I would do the same for him, my group is tight.

94fordguy · Jan 29, 2010

well, glad to hear you got her out of there.... any guesses on what may have caused it?

Danbot · Jan 30, 2010

No not yet 94, I'm hoping it's the mag side crank seal... or maybe excessive piston / ring clearance. There's about 1800 miles on this engine.

Redd · Jan 30, 2010

Pics?

Danbot · Jan 30, 2010

Redd said:
Pics?

No, not yet, gotta work for 4 days, and then I'll have plenty to post. I only had time to put it in the garage and get to bed lol.

triple650 · Jan 30, 2010

WOW that sucks dude, all that trouble to get your clutch off and then that. well i dont know if you have ever had your engine out before, but really its not that bad once you do it, you feel better once its done lol i know i did. well hopefully it dont cost you to much and good luck with that! post some pics! lol. :face-icon-small-hap

Justin.

Danbot · Jan 30, 2010

Yeah they come out nicely after the first time lol, I've had some practice.
I just hope I have clean cylinders!

Danbot · Feb 3, 2010

I'm going in!
Mp3 player full of Slipknot, and I'm off to get my busted 900 out of the chassis. I want it on my work bench in the basement this afternoon, so I can size up the damage, and get stuff ordered. Downtime is killer, pics to follow

guidoxpress · Feb 3, 2010

good luck man..sucks you even have to do it right now...

i have been down forever it seems with a busted shock

Danbot · Feb 3, 2010

guidoxpress said:
good luck man..sucks you even have to do it right now...

i have been down forever it seems with a busted shock

I'll trad ya my shocks for your engine lol, yup sucks to be down bro

Danbot · Feb 3, 2010

Ok here it is so far, this is my second broken 06 piston.
2 years ago I lost a skirt and it completely took apart my upper and lower cases at 1000 miles and JUST outside of warranty.
This time it's a chunk just below the ring land, the damage seems located to the mag cyl and piston, although tearing down the bottom end may reveal more.

This engine was installed used last year with 900 claimed miles on it, and I have put on another 800 or so. Compression was good when I installed it, but I have not checked it since.

Danbot · Feb 3, 2010

And the bottom end:
All seems ok, the chunk of piston is in tiny little bits everywhere but there seems to be no damage to anything in the bottom from what I can see.

So, what it looks like from here....
One of the jugs from this engine is dirty with aluminum deposits, the other looks fine. Luckily I have a clean jug in my collection, making the parts list not too bad if everything measures up within spec.
Piston kits, wrist pin bearings, and crank seals, could have been worse.
I'll start phoning Poo dealers in Alberta tomorrow to locate the parts.

As to the cause of this... I would be inclined to think this was a straight up piston failure, hopefully this is the case, and I won't have another issue to deal with after installation. The break in the piston does not appear to be melted, and where I cleaned off the aluminum film I can see good wash pattern. This cylinder was still making some compression and you can see the rings are free, and any damage seems to be from munching up the missing piece in the exhaust ports and combustion chamber.

Thoughts?
Dan

BIGGDAWG · Feb 3, 2010

can you get a close up of the piston? man that does suck though. hopefully you can find parts.

Danbot · Feb 3, 2010

BIGGDAWG said:
can you get a close up of the piston? man that does suck though. hopefully you can find parts.

Yeah I'll give it a shot, my camera doesn't seem to like the close-ups:face-icon-small-dis, be right back

Danbot · Feb 3, 2010

Best close up I could get with my camera

donbrown · Feb 4, 2010

What is the likely cause ... heat warp or pre existing crack in the skirt?

BIGGDAWG · Feb 4, 2010

to me dan that looks like the exhaust valve caught the ring or just plain piston failure. thanks for the pic.

Danbot · Feb 4, 2010

BIGGDAWG said:
to me dan that looks like the exhaust valve caught the ring or just plain piston failure. thanks for the pic.

The rings, and the valve show no evidence of contact, so piston failure seems likely. Thanks for your opinion. I guess the 06 pistons aren't invincible either.

DiscoDans mid-season engine build

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