Alrighty, as most know, I just got my stock bore together, and on our trip to St Anns, I got her running well. I started giving her the juice, and she took it well.

A cold front moved in and dropped temps by forty degrees. I took off riding for a evening ride, and like most of my rides end up at the drag hill. So I run a few motor passes, then talk to a few folks that have had some engine problems already that day. Turn on the nitrous, make a few solo passes, then run with my brother and a banshee a few times. The banshee wouldnt race anymore, so I turned the nitrous off and ran him all motor. On the way dow after the run, Jeremey looks up at me and starts pointing, after I figured out what he was pointing at, I looked down to see blue smoke coming from my tail pipe. Quite a bit at that. So we head for camp. On the way there, I didnt notice much smoke, as we were moving good. But as soon as I hit the trail into camp, I could tell she was still smoking. By the time I made it to camp she was a smoke stack with oil dripping out of the header pipes, exhaust seams and all.

Now I have it torn apart and this is what I see.

Cylinder had some horizontal grooves on the exhaust side right at the top 1/4 inch or so like the ring was protruding from the piston. The cylinder has some vertical grooves, but I expected them.
The piston on the exhuast side has the first ring land folded down and pinching the second ring, and the second ring is pinching the second ring land and pinching the oil deflector. The top land is bent up slightly. The second ring cannot be removed. Now I have had this problem before with running to lean on nitrous, but I am sure I was still rich on nitrous. I am also sure I was probably lean on all motor though. There is carbon build up on the center of the piston, but the outer edges are clean. Not much oil in there after that ride back I expected more. The plugs are just oil soaked but in good shape.
The head looked somewhat oil soaked. On the exhuast valves there is clean streaks coming from the valves. Now I took one valve out, thinking this all started from a leaky valve seal, but it looked good. The exhaust ports are covered in oil, but the intakes look good. One exhuast valve has some flaking on it. I am not sure if its coatings on the valve, or the custom coating I gave it with the oil.

So here's my questions. First. Can I get enough oil blow by from the rings being pinched to really bring that much oil into the cylinder. I mean alot of oil. And then burn that oil off the piston like it was never there.
Second, if the oil came from the vavle seals, how do I tell for sure?
Third, the cause. Now I new better to run the Ron woods box with as much nitrous as I was running. And I had been leaning back out to 100 octane by the time this had happend. But I know I was rich on nitrous. Now the temps dropped alot, and I am sure I was lean on motor. Everything ran just great until I shut her off at camp. If there was no oil coming from the tail pipe, she would still be together.
Any and all thoughts are appreciated. Thanks.

 

sounds like detonation for sure, thats the only way you'd collapse those ring lands. I've heard detonation is equivalent to hitting the ring lands with a ball peen hammer at full swing. on a two stroke once the rings collapse and stick then the oil is wiped away next, after that you get a siezed piston, enough oil i guess is why you'rs didnt do that. defeneatly went lean and detonated, maybe an air leak somewhere? good luck...josh........

 

the only time I've seen horizontal marks on my jug were when it detonated on the hill in Nevada, right next to the place where it punched a hole thru the ring lans and down thru the piston- sorry man! that thing was running FAST Friday night I was really impressed both on and off the bottle, that bike will be hard to beat come DS Days.

 

In two words; Hell yes.
You don't have a valve seal problem, so don't worry about them.
Just how much juice were you spraying? And what was the total timing set at when you were on the button?
Detonation is insidious. It will knock the ring seal out and then it will burn the oil off, which starts to scuff the piston and then the rings sticks and then it will really start to heat things up and if your on the button the O2 will drill a hole in the piston or put so much heat in the piston it will stick the piston so hard you won't be able to get it out with a sledge hammer. A lean out will do the same thing, but not as fast.

All in all, detonation will break things, lean will melt things. You should be able to tell from the piston.

 

I just went through a similar situation with the exceptions of NOS and I had no horizontal grooves. Only the vertical. Mine came about due to improper ring gap that I was responsible for.

Here is what I found:

I had tremendous increase in blow by, oil running out of the exhaust ports, consistent but mild smoking that would load up until I revved it up and cleaned it out. I went through two sets of valve seals assuming they were the culprit before I pulled it out and tore the motor apart. The last straw was when the motor blew the lower oil line off while riding and it had a tight clamp on it!

What I think was happening was when the rings bound initially they scored the cylinder. After a few hours of binding when under heavy load and higher engine heat circumstances (racing) it eventually warped the piston and made tiny fractures in the outer edges of the rings. The blow by was bad when the rings butted together and warped themselves compromising the compression seal. The blow by was much worse after the piston warped. I had enough crank case pressure to blow the lower main oil line off with a tight clamp.

If someone here is an expert on the DS oil system, I will defer to your experience because I am not entirely sure about my next conclusion but..................I actually think the tremendous crank case pressure greatly increased pressure under the valve cover through the oil system forcing oil through valve seals which are weak by design. They don't need to do much except scrape the oil off the valves. Apply pressure and the oil will run right through them. The first set i pulled out were torn to hell but only had about 5 hrs on them. The second set only got another 2 hrs before i knew the valve seals weren't my problem. Btw, I had some oil in my intake ports as well.

My point in telling you this is (1) I have been there and it ain't fun!.....and (2) this is another theory that could have contributed to so much oil making it to your exhaust ports after your rings got out of place and stuck..............Obviously most of the oil must have been coming past the rings.

How do your oil rings look? It seems like they would have a hard time doing their job with a ton of compression blowing by the compression rings.

 

Thanks Curtis. I should not be trying to be so cheap on fuel and such.

I dont know the exact timing that is run. I do know that I have been told that the procomm and Ron Woods boxes are similar in timing on the top end. I have seen failure with procomm boxes melting plug straps with anything over a 20 shot. With everything up to and including vp110. I have had great success with my vortex running a 25 shot on mix 91 pump and vp110. I think that yields about a 96 octane.

I have seen many times what deto does with two strokes. Way too many. But on the edges of the cast pistons that we run in them, the edges will start to pepper if you will. Then start to melt the edges.

This piston shows no signs of deto on the edges of the piston, but its forged. But the ring lands are folded, saying she got too hot. I had this occur last year but ran the piston for the rest of the season with nary a problem. Maybe this one was just to much.

I was pushing a 30 shot, mixed fuel as mentioned, on about a 70hp N/A motor. Running a JR9B plug. Now when this has happened before, the center plug grounding strap melts and I loose performance. I have only had the outer plug go once, and she quite. This time the plugs both look good. Its just the piston. Were the ring had engraved into the cylinder makes me think that when in was in the upwards motion, it detoed and pushed down and out on the ring pushing the end of it into the cylinder. Now its not bad enough that in went through the nicasil. Its just an indentation......well a few of them. And you can see the ring spinning on the piston making different marks as it turns.

Just for your info, this was at about 5000' in elevation at about 45 degrees. Man was it cold.

I new darn better to run that little of octane with that box. Heck I was unsure about that octane with a retarded map on my vortex!

 

Sorry to hear about the issues Jed.

FYI from what I know - mostly for others.

Valve seal will typically show-up only on initial start-up of the engine (again, from what I know - others may chime in.)

I've had one instance where after engine assembly the springy looking ring between the oil-rings got overlapped at the edges. . . usually put a little oil in the cylinder after engine assembly but, the blue just didn't seem to burn-off. That's when I found the overlapped edges.

 

Thanks Mark. Kindof what I had been figuring. With seeing oil in both exhuast ports and none in the intakes, I figured it had to come from the chamber.

Nut, sorry, you posted at the same time I did and I did not see your post until I seen Duneme post. The vertical lines I believe are from sand. The scoaring of the cylinder is mild, and just small grooves like I had taken some sand in. I have had them before. The horizontal lines are just right at the top, and they look like the very last inch or so of the ring protruded from the piston and left an indentation. There is about four of them all in the same place, just turned a quarter inch or so. The upper ring does have a crack in it as well. About and inch and a quarter long, like it snagged something, but held together.

I will chalk this one up to another nitrous condition that I should have solved with better fuel. For those of you who are going to run this big of shot, remember all this. Even at this altitude, you will need good fuel. I started my weekend off with straight 110, and started leaning it back to mix throught the weekend. If I would have left it alone, I probably wouldnt be posting this. We did run my brothers bike on a 25 shot with the mix with no issues. Both these bikes have 12-1 comp.

Doctorturbo, I would sure like your one last approval of my thoughts before I am fully confindent. It's always great to have people of your caliber, that have had these experiences before to call on for help. As well as all you others, thanks again.

Oh and Ron, your going to need it, trust me. Holy crap does this bike run.......when its together,lol!

 

I am glad it is running hard[img]i/expressions/face-icon-small-wink.gif[/img] I will try to bring enough[img]i/expressions/face-icon-small-smile.gif[/img]

 

650VIPER, I think your on it.
Some of the things I would check on the next build.

Like DS said, and VERY smart of him too say is, check the top ring gap. VERY good call DS!!!! (the more I think about it he is on the money, and I missed the mark) Check and recheck the gap on the build.

Find out what the over-all timing is. Now you can get around this with good fuel but I would want to know what that figure is before I hit the button.!!!!! You can only get away with so much fuel.

If you see no burnt edges on the piston, you had too little gap in the piston like DS said. Or you detonated it to death..............or both.

If you check these things on the next build, your engine should have a long life and you should suprise a lot of people.!!! [img]i/expressions/face-icon-small-happy.gif[/img]

Damn, I'm late for work!!!!!!