Super Jet What blew up this 61x?
- Thread starter tor*p*do
- Start date
Mike W
Infidel
- Location
- North Florida
It looks like one of the rings snagged the exhaust port and grenaded the piston.
- Location
- Ontario, Canada
That's exactly what happened to mine last year other than mine was on the mag side.
DAG
Yes, my balls tickled from that landing
- Location
- Charlotte, NC
Was this the same ski that was having fuel issues?
DAG
Yes, my balls tickled from that landing
- Location
- Charlotte, NC
When plugs back out its often from detonation. Is it a stock head?
If the carb came loose from the mani it was sucking air creating a lean condition.
The only way the 2 are connected is if some sissy girl tightened the bolts on both
If the carb came loose from the mani it was sucking air creating a lean condition.
The only way the 2 are connected is if some sissy girl tightened the bolts on both
- Location
- Ontario, Canada
Is it ported?
- Location
- central florida
Pull the cylinder- it has to come off anyway- crank pin bearing might have failed and the thrust washer pieces cause damage like that.
- Location
- Ontario, Canada
Ahh...what happened with mine was the port chamfers on the width were too long basically guiding the rings to slip too far out of the ring grooves. There was always a slight hammering sound to it, I figured it was the bushings for the starter bendix so I put it on the to do list. The hammering sound was the rings snapping back into the grooves.
How did you determine this? (not questioning the truthfulness of it, just curious how you arrived at this conclusion)
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- Location
- Ontario, Canada
Between the hammering sound that did not exist prior to porting and learning later on from Waxhead on a forum somewhere...can't remember where now though lol...he mentioned the shape of the Race Logic templates had issues with snagging rings. If you recall how they looked, they were rather wide at the bottom and quickly narrowed at the top. With a bit too much chamfer the rings would squeeze out of the ring grooves just enough to be too much. And like in the photos on this thread, you could see where the rings were snapping back in at the top of the port. The bottom however when allowing the ring to go oblonged squeezing into the port and suddenly jarring back into the ring groove is where the stress on the crown starts going to work. I believe that the crown blew off on the down stroke sending the pieces on top of the piston causing the pitted damage. Mine had crumble cake all over the top when I tore it down. When I re-ported, I used your template that I won in "guess how many I have left and you get a freebie" challenge you had last year. Point of interest, your templates are very well done.
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I appreciate that, I spent a good amount of time researching and drafting the design I ended up with, have you run the engine after re-doing it?
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- Location
- Ontario, Canada
Oh yeah, it is noticeably stronger since the previous port work. Your templates are just right too when it comes to reworking Race Logic template work. Yours are just slightly larger than the largest portion of the Race Logic template outlines by enough to in a manner of speaking "completely erase" the Race Logic dimensions. I was hopeful to not go beyond the 70% limit I was aiming for without putting a load of time into making my own templates when I remembered having yours, thanks to your templates it saved me not only a lot of additional work but possibly the cylinders too. I almost thought the old port windows were beyond the max limit, with the bore job making those windows smaller and your templates being just where I needed the size to be, it worked out just nicely.
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