Super Jet Am I Boned? How did this happen.

[CBiDrive]

Just started my motor off of a bore and port job. Went up to 83mm with new Pro-X pistons motor ran for between 30sec an a min and never started again, somehow lost spark. Decided to pull off the head and found similar scoring on both cylinders intake side.

 

[TheBuzzard]

that looks freshly bored, but did they even bother to finish hone it? looks like crap and its already chewed. rip it apart and look at the pistons.

 

[Jetfiend]

Are the rings lined up correctly with the alignment pin? I've seen that happen on a MX bike.

 

[CBiDrive]

I did everything exactly according to installation instructions. Kept double and triple checking steps to make sure I was doing it right. Bought all of the correct tools for the job, lubed all aspects of the install. If I screwed up I don't know how I made the exact same mistake on both pistons.

 

[Jetfiend]

Can you take a pic from above the engine with the head off and post? Buzzard is right, take that thing down again and inspect everything.

 

[tstewart]

...looks kinda like a tpe...mark...?? but about your problem-- what was the piston / cylinder clearance "set to"? Ring end gap ? And how was it actually bored?

 

[CBiDrive]

This is my first time doing assembling a motor. Not sure how it was bored and install instructions never said to measure end gap or piston clearance so I didn't. I got everything done and pistons from the same place. What could I have done or not done assembling it to have caused this. This ski was a was a huge project for me and I'm kinda sick to my stomach about this right now.

What is a tpe mark

Pic requested

 

[MADMAT]

That looks odd and I feel your pain. Sucks bad man.

I have not seen a cylinder do that.

 

[powerhouseperformance]

The thread title made me laugh so I had Ti see what this was about. Chris, as someone said earlier in your thread here you didn't get your alignment pins positioned right to the rings and the pins are pushing on the ring in those spots. You can see perfectly cleat on the bore where you had excessive pressure there and it probably wasn't sealing very good in the bore due to them pushing the rings out of round. Take it back apart and reassemble. Millennium did the boring on that cylinder...probably not a better place on the planet to have that done

 

[Yami-Rider]

pull the cylinder off and look at the pistons. Alignment pins is the only thing i think that could case that.

 

[WB1994]

Yeah , those cylinder walls look like crap and Im not talking about the score marks. It doesnt even look honed. No crosshatching.

 

[CBiDrive]

I'm not questioning the work done by PHP or the bore shop at all you guys have been great. I'm not quite sure how to correct for the pins. I did not know that they could be off. Am I correct in thinking you are referring to the ones between the case and cylinders. Next question is, are these cylinders even usable anymore. I can get a fingernail to catch the grooves.

 

[naticen]

On the piston, there is a pin that fits into the end of the piston ring to hold it from spinning and catching on a port.

Definitely needs a new bore and hone and then it'll need new pistons to fit.

 

[Yami-Rider]

Yeah , those cylinder walls look like crap and Im not talking about the score marks. It doesnt even look honed. No crosshatching.

I thought the same thing, but PHP said its good, so its got to be good. I figure it may be the picture idk. He will need a re-bore anyways.

 

[powerhouseperformance]

On the piston, there is a pin that fits into the end of the piston ring to hold it from spinning and catching on a port.

Definitely needs a new bore and hone and then it'll need new pistons to fit.

Exactly. If there pins on the pistons themselves aren't lined up right with the ring end gaps the pins will push out with excessive pressure on the rings in those spots and cause the grooving in your pictures. I'm sure the ring scraping like they did caused what look like machining marks on the bores. Millennium Technologies does all the cylinder/boring for us. They are second to none for quality of cylinder finish and keeping bores perfectly round. Unfortunately if those gouges are deep enough to catch your nail on them they will have to be rebored to the next size up piston.

 

[Harbor]

Pics can be deceiving, you can see the hone and cross hatch peaks between the score marks and starts heading down the bore on both sides, the camera defiantly makes it look odd

 

[WB1994]

Id like to see better pictures of those cylinder walls and crosshatching.

And how the hell do you get pistons into the hole if the ring gaps arent lined up with the piston pins? You'd have to smash em in.

 

[WB1994]

I thought the same thing, but PHP said its good, so its got to be good. I figure it may be the picture idk. He will need a re-bore anyways.

It doesnt got to be good , everyone makes mistakes.

 

[restosud]

that motor ran 30sec to 1 mn and there is already carbon on crowns?

 

[powerhouseperformance]

I agree, but in this case I know it was perfect. I even think I have a picture of the bores before they were run somewhere I sent Chris to keep him in the loop of his cylinders progress. All cylinders piston to wall clearances are set specifically and double checked before anything leaves our doors. If those pins aren't lined up the rings wont compress to the bore size and will be putting incredible pressure on the cylinder walls...hence the grooves made in 30sec-1min of idle run time. Every time I read the title of this thread it cracks me up! Only you Chris lol!