Blew up , what went wrong ?

[Grappletractor]

I recently put a new piston in my Jounsered 630, 1st time doing so. Well after starting it I could not get it to keep running at idle so I purchased a carb kit ,it had not been run for close to 10 years .Well the carb kit did the trick it started on the 3rd or 4 pull and seemed to keep running nicely for half a minute till it stopped dead in it's tracks . When taking the plug out I found that I had not tightened it and could unscrew it by hand. I looked inside to find pieces of what must be the ring ? Any way I did something wrong but what could that have been ?

 

[sedanman]

Piston in backwards, ends of rings clip port, ring lands break. Been there, done that..........once.

 

[superman_36]

i agree with sedan

 

[Grappletractor]

Only thing is I probbaly ran it total of 3 minutes before new carb kit trying to adjust and get it to stay running , wouldn't it have clipped port and broke ring then ?

 

[JimL]

I put a piston in backwards once too. it ran for prolly 10 minutes, both wide open and idling, when it broke it was at idle.
020T.

 

[460Ted]

Did you look yet to see if the piston is in backwards?

 

[Crofter]

Only thing is I probbaly ran it total of 3 minutes before new carb kit trying to adjust and get it to stay running , wouldn't it have clipped port and broke ring then ?

Pistons installed backwards have a life expectancy of exactly 3.5 minutes!

The rings might survive a number of cycles up and down but as soon as they rotate past the locating pin it is game over immediately.

Sedanmans guess would be a good one I think.

 

[West Texas]

Remind us again, as to which port the arrow on the piston points to. I've done this several times and had no trouble; just made sure it was like the one I was replacing. Tom

 

[Husky nut]

arrow points to the exhaust port....

 

[Husky nut]

or better yet the locator pins go to the intake side for those messing with a used piston and cant find the arrow

 

[Grappletractor]

Ok guys, ready for a good laugh. 1st take a look at the two pics and guess what happened :bang:

 

[Simonizer]

Ok guys, ready for a good laugh. 1st take a look at the two pics and guess what happened :bang:

Do not try this at home.

 

[Grappletractor]

OK, what do you think about this idea? What if I filed and sanded the broken edges of the piston then totally cleaned all these nastey metal chips from the piston and jug and bottom or what ever you call that area of the saw and put her back together again . How long do you think the piston would hold up with that huge gash in the side and chunks missing from the bottom ?

 

[Simonizer]

OK, what do you think about this idea? What if I filed and sanded the broken edges of the piston then totally cleaned all these nastey metal chips from the piston and jug and bottom or what ever you call that area of the saw and put her back together again . How long do you think the piston would hold up with that huge gash in the side and chunks missing from the bottom ?

 

[timberwolf]

You won't even have to take 1.5mm of the intake side of the piston, looks like that has already been done.

And as simon sugested it is only removed in the middle where the port is.

 

[Crofter]

Bit off more than it could chew! What did it swallow?

 

[Grappletractor]

No damage was done to the jug , hell even the ring is A-OK

 

[04ultra]

Hi-heat Superglue and ducktape.. LOL

 

[Grappletractor]

Bit off more than it could chew! What did it swallow?

That mangled screw on top of the carb is what it swallowed That was the 1st thing I saw when I separated the jug from the base and right away I knew this wasn't a case of the piston is backwards .

 

[Crofter]

If everything else is ok, you got lucky. New piston and ring and bob's your uncle!, make sure there are no nicks at the port edges. I had a wing nut fall out my shirt pocket and swallowed by a ford v8. You usually only do that once is enough!