WTF happened - blew up today

I haven't posted in a long time. Been busy. Have a 2 month old baby boy at home, been playing mister mom in the mornings and working in the afternoons. No time to read the X. :(

I got a few spare minutes tonight so ATS_Scott and I headed to Lake Lewisville. After about 20 minutes of riding I noticed I was losing power. I turned and headed for the boat ramp. 30 seconds later the ski died. Scott towed me in (used my hood strap as a tow rope). We didn't have much daylight left, so I convinced him to hang around for a few minutes and we pulled the head.

Sorry, no pictures yet. The rear cylinder is perfect. The front cylinder is trashed. The outside of the top of the piston is pretty chewed up. The center looks nearly perfect though. What causes that kind of destruction? Too lean? Too much timing?

I should probably back up, I don't think the destruction happened all tonight. In fact the ski has been slow to crank/hard to start for the last couple of outings.

Early this season I had a starter drive shell out on me and take out the stator, I soldered the charging coil back to continuity and replaced the pulsing coil. The CDI I have (Advent) doesn't use the exciter coil. I didn't check timing after I installed it, I just tried to make sure the old marks lined up.

I have felt it kick back during a hot start, but usually only when it is turning over slowly...I blamed it on a low battery and possibly a botched charging coil repair job. I installed a new battery before the last time I went out.....it barely lasted a day and a few times I had to let the ski cool off before it would restart.

I have and always had great flow out both water outlets, so I don't think it overheated on me and the good cylinder looks really rich if anything. Even the bad cylinder's aluminum covered spark plug still looks rich.

This is the Walmiton's ski that I bought from Superramjet early this summer. He had (I think) 3 seasons on it with no issues other than a broken cylinder dome o-ring. I made no tuning changes since buying it. The engine is a Team Scream stroker, with 84.5mm bore. I was told it's a 61X cylinder with big bore sleeves so hopefully if I need to go 85mm I can.

Any ideas?

Aaron
 
crap. i bet the crank finally went. this would be season 4 on it. I had lots of hours on that one, hopefully chuckies sleeves and cases are okay. the sleeves are R&D big bores you have lots of bores left. Chuckie said to get the 760 wiseco yamaha pistons, non flat top.
 
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SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
4 seasons is pretty good for one of my 5mm stroker 809cc-828cc package! I'm sure its the crank or rod bearing that let go first, then sent crap up to the top end...
Looks like you have a winter rebuild to do.
I'm sure I can fix it up as good as new. Look at the sleeve very close and see it its broken, if not then we can bore it, if it is...I can replace the sleeve, port match, rebore and make up a new set of domes for the new bore.
The crank is re-buildible billet core and can be redone.
PM me after your inspection and I'll get back with you.
Chuck"SUPERTUNE"Quenzler III
TEAM SCREAM RACING
1988 Carroll St.
Clearwater, Fl. 33765
(727)442-7700
 
Wow, Superramjet diagnosed my stuff from 400 miles away. I got the cylinder off today and sure enough the front rod can stand up all on it's own. The detonation was caused by the excessive heat from the failing crank.

Sleeve doesn't looked cracked, but will need a bore.

Chuck - your phone is about to ring.

Aaron
 
4 seasons is pretty good for one of my 5mm stroker 809cc-828cc package! I'm sure its the crank or rod bearing that let go first, then sent crap up to the top end...
Looks like you have a winter rebuild to do.
I'm sure I can fix it up as good as new. Look at the sleeve very close and see it its broken, if not then we can bore it, if it is...I can replace the sleeve, port match, rebore and make up a new set of domes for the new bore.
The crank is re-buildible billet core and can be redone.
PM me after your inspection and I'll get back with you.
Chuck"SUPERTUNE"Quenzler III
TEAM SCREAM RACING
1988 Carroll St.
Clearwater, Fl. 33765
(727)442-7700
What’s ur email chuck
 
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