Super Jet what happened? Spark plug closed shut

[rossthaboss11]

Ski runs great besides the fact I was blowing O rings. Got a new ADA head shell and flattened the cylinders to fix that issue. Rode through a full tank just fine after that. Went out again a week later and about a half hour after riding something went wrong. Didnt have much power and I figured I blew another O ring or exhaust coupler. It had a little trouble starting but worked better with primer. Took the plugs out and the back plug was closed up like the piston hit it shut. Checked compression and that cylinder was low at about 90psi. Other is at 175psi. What could of happened? The motor never ran hot and was tuned very well IMO. I was jumping around a lot in the coppy surf when it happened. any ideas?

62T ported 727cc. Duel 44's. MSD Enhancer. Factory type 4 pipe. ect.

 

[rossthaboss11]

I did ride it for a bit after it happened to get me back to shore so I wasnt stranded. Really didnt want to cause I didnt want to break it anymore then it already was.

 

[Bobert540]

Did you get the domes recut to make sure you have proper squish?

 

[Big Kahuna]

sounds like FOD damage. Loose bearing or part of your piston came loose and smashed the electrode and then luckily got blew out the exhaust port. But to have that much compression loss you have smoked a cylinder.

 

[rossthaboss11]

I did not machine down the domes. .005 was taken off the cylinders. My cylinder has gotta be fried. Doesnt seem like an O ring because the pisser wasn't sputtering like it normally does when an o ring goes. a broken piston could seem logical because I was running for a while before with no issue so unless if the bearing went then that's what had to have happened. Otherwise the piston doesnt randomly travel further for no reason

 

[BruceSki]

take it apart and inspect. you have had a mechanical failure for sure and pieces are going to be in the cases.

 

[icecoled007]

I dont know what your exact problem is but....

Make sure you tighten the ADA head up more than ADA says..... their specs are NOT tight enough.

I know lots of people that had issues with bolts coming loose with the ADA specs

 

[matth113]

Do you park next to Kawis ?

 

[Shonuff]

That's funny but the ADAs use ES plugs like the Kawis.

I love to read stories about running ES plugs on stock Superjet heads.

 

[WFO Speedracer]

That's funny but the ADAs use ES plugs like the Kawis.

I love to read stories about running ES plugs on stock Superjet heads.

Pull the head
inspect the damage
report back
your motor, she be dead

 

[rossthaboss11]

f.ckkkk. i'll rip it apart tomorrow and let you know what happened. I guess ill look at the bright side and say, this means its time to go with a bigger motor setup.

 

[rossthaboss11]

well i figured out what happened. piston chipped right where the exhaust port is. looks like the chip got out of the cylinder quickly. cylinder wall is scored as well. thanks for the help