More Problems!

[Phill]

So I was out yesterday going WOT for about 10-15 seconds and my ski dies.....just as if I hit the stop button....I try to start up and get nothing, cranking seems a little slow....my first thought was battery. I try starting a few more time and then it goes. Seems to run fine for the next 10 minutes or so. Once again a WOT run...about 10-15 seconds in and it dies again. This time I cant get it going. Slow cranking again. One time it tried to start but didn't.

When I got home I pulled the head and found some scoring on the cylinder walls and one of the domes had part of the o-ring lip (I guess that's what you would call it) broken off, (that's the second protec dome that did that to me). Not sure what happened?? Looking at the pistons I think I might be running rich???? What do you guys think???


Some pics.....spark plug is from the front cylinder (right)

 

[keefer]

What clearance do you have those Wiesco pistons setup at? Looks like a 4 corner seizure to me. Could have been caused by too little clearance or water in the cylinder. Wiescos have to be setup more loose than a cast piston. The dome could have failed due to fatigue of the aluminum. This could be caused by old age or maybe the dome is being hammered because of improper torque, excess clearance beteween the cyl deck & dome edge. Check the deck and head body for flatness or wear in the dome socket of the head. It does not look rich from the plug, you might be lean on top and be getting a little deto from this or / and too much advance timing up top.

 

[Phill]

If I remember right it should be .0045 or .0050 I will look at the head itself for any damage.....should have been torqued right. How would I check for excess clearance beteween the cyl deck & dome edge? I though the same thing about the plug but the top of the piston looks so clean I thought it might be rich???

 

[Phill]

hey didnt wavedemon just post????

 

[keefer]

It does not look rich to me, the plug looks about right. The more I look at that front cyl pic, I tend to lean towards water injestion. The dome must have let water in where the O-ring prolly squeezed out at the point of failure. You will have to use a straight edge or a certified flat surface to determine the flatness of the deck & head body..

 

[keefer]

Also I still would not rule out some light deto that could cause things to crack & break.

 

[Phill]

Something I have forgot about.....Plugs have less than 20 mins on them.....

 

[Phill]

Head and cylinder deck seem to be good checking with a straight edge.....

Also when I went out on thursday I had some problems.....I thought were because of the holes for water spray in the headpipe were plugged (I have since unplugged the holes). Could I have over heated then??? Then made things worse yesterday??


So is this something that can be fixed with a hone and new rings or will I need to get new pistion/bore??

 

[Phill]

Also I still would not rule out some light deto that could cause things to crack & break.

What would cause that??

 

[keefer]

Too much compression with too low octane fuel, too lean main jetting, and / or too much advance timing in the upper RPM range. Have someone double check the flatness of the deck & head. Also check too make sure the cyl sleeve has not dropped in the front.

 

[Phill]

I always run 92 octane....38cc domes at 84mm I think is something like 185psi?? but I also have some porting work done. I couldnt say for sure about the jetting because Matt_E does that for me(You would think I would not let him anywhere near my ski)

Neither sleeve appears to have droped.....

 

[WaveDemon]

hey didnt wavedemon just post????

:sneaky:

 

[Phill]

Nice avatar...