Any body had problems with piston rings hanging up on cylinder porting?

[portgrinder]

If these cylinders were bored, then the ports should have been chamferred slightly back to keep rings from catching ports.

Yup. Immediate cause was the piston in backwards...ouch!

Very secondary cause could possibly be an improper chamfer on the exhaust. Maybe it would have went a couple more hours.

I knew an engine builder back a few years ago. When doing big big exhaust ports he had to chamfer the ports AND the exhaust edge of the piston to keep things working well.

 

[WFOPOWDERHOUND]

Thanks!

I was unaware of the fact a piston could be installed backwards. my instructions did not indicate anything of the sort. not sure if it was suppose to be common knowledge or not. Either way it looks like i F'ed up! I'. going to finish tearing it down and find out if there's any other damage. I'll eply with status report.
Ted

 

[sled_guy]

You can't see it in the photos but the ring pin is right where the piston blew out

Bing, Bing, we have a winner. Pistons in backwards.

sled_guy

 

[Rixster]

I was unaware of the fact a piston could be installed backwards. my instructions did not indicate anything of the sort. not sure if it was suppose to be common knowledge or not. Either way it looks like i F'ed up! I'. going to finish tearing it down and find out if there's any other damage. I'll eply with status report.
Ted

Yeah, there should be a arrow (pointing to exhaust port) or a dot or some kind of mark in the top of the piston to mark the exhaust side.

 

[Beels]

That's an expensive lesson....

 

[WFOPOWDERHOUND]

Total Damage 1700.00 - Stuck with the back up sled for the rest of the year

Cylinders salvageable
Crank will need to be re-done
Both halves of the crank case have holes in them.

Just a $1700.00 F-UP.

 

[JROD]

Those pictures are all too familiar

Looks like you found your problem. This happened to me when I didn't run enough ring gap while using nitrous. The top ring butted and then spun around the dowel pin that was barely in the ring groove. It grabbed on the exhaust port and came to a complete stop. Good luck

 

[Snowbyrd]

Cylinders salvageable
Crank will need to be re-done
Both halves of the crank case have holes in them.

Just a $1700.00 F-UP.

That sucks... Big Time, I feel for you bro. here's a few 's for you to help with the pain.
who's kit was it? No instructions on installation is not good, worst part is it could have been avoided with a installation instruction sheet.edit: not trying to say it should have been done but just an idea to include simple instructions for future buyers. Nothing will ever totally eliminate the need to get expert advice if you don't know something....some education is more expensive than others...
look at the bright side, at least you weren't way in the backcountry when it happened.

 

[Skadi]

my 2 cents -being a novice wrencher who is trying to do all their own wrench work. Installation instructiosn can only go so far back into the process. I think it's considered general knowledge that there is a front to back on pistons just like and up or down on rings!

My solution being new to the wrenching but still wanting to do it. get some good buddies and ask questions!! Anyone who has done top end work would pass a few tips along to you and there are MANY tips to be had!!

another way to know from and back of pistons is that locating pins for rings should ALWAYS go in the back -so they don't catch those ports!! If you're going for round two with this motor make sure you get your rings gapped and installed correct side up. Also, when putting wrist pin circlips in it's best to have them oriented so that the 'gap' is either up or down. In vertical position. I know a lot of people who don't do this but I figure any trick to keep my motor from blowing is a good one!! Especially if it's as easy as that!

Good luck next time around!!

 

[07 Phazer]

Try to keep the gap on your wristpin clips up to keep the center of gravity low on the sled.

 

[MARCUSO]

Actually, you want it the opposite...

Because a higher center of gravity will make the sled carve easier.

I was told to keep the wrist pin clip opening either up or down... I keep the opening down just in case of detonation, which is supposed to be like a hammer, and to think of it, the clip would try to compress if the opening was up.. I guess it is like splitting hairs... blonde ones/

 

[07 Phazer]

These hairs that you speak of...they are fine, and hard to find these days.