The squish design is not focaling heat to the middle, it's using a wider larger trapping area to quench more of the piston.
Explain this ring failure,
Explain this ring failure,
XP big bores - lets compare
- Thread starter deaner
- Start date
- Status
So you're saying that the wide quench area is used to cool? the piston?? Under compression that would mean. Are you sure?? That seems like a long shot. Explanation?? Not trying to bash
Ring explanation...
Took the head off the other day because the motor was down on compression. It was down nearly equally on both holes. Figured I would take it apart and have a peak at it. I have an engine tech head. Domes are modified a bit. Turned on a lathe, altered quench angle because piston crown is different on 08 and 09 pistons. Head was designed originally with 08 pistons, angle needed altered for use with 09 pistons. The sled gets run really hard, its jetted lean and runs hard when it runs. (A bit inconsistent) What I found when I lifted the head was a few hundred ping marks on the piston and head, the pings match each other. Not ping marks caused by detonation, but marks caused from pieces. Where the pin in the piston, the cylinder is scored. The ring broke at the end and went up through the edge of the piston. That sent piston and ring pieces loose throughout the chamber...thats the theory anyway. I havent disassembled the rest of the way yet. I got megasick. The pin possibly could be trying to back out. Not sure yet.
Any ideas are much appreciated. I am going back to the stock head. I have to get a handle on the parts breakage and try again.
Ring explanation...
Took the head off the other day because the motor was down on compression. It was down nearly equally on both holes. Figured I would take it apart and have a peak at it. I have an engine tech head. Domes are modified a bit. Turned on a lathe, altered quench angle because piston crown is different on 08 and 09 pistons. Head was designed originally with 08 pistons, angle needed altered for use with 09 pistons. The sled gets run really hard, its jetted lean and runs hard when it runs. (A bit inconsistent) What I found when I lifted the head was a few hundred ping marks on the piston and head, the pings match each other. Not ping marks caused by detonation, but marks caused from pieces. Where the pin in the piston, the cylinder is scored. The ring broke at the end and went up through the edge of the piston. That sent piston and ring pieces loose throughout the chamber...thats the theory anyway. I havent disassembled the rest of the way yet. I got megasick. The pin possibly could be trying to back out. Not sure yet.
Any ideas are much appreciated. I am going back to the stock head. I have to get a handle on the parts breakage and try again.
sounds like you lost the ring retainer pin(pin comes out, ring turns into port and boom...)..every time I have seen that happen it is due to getting deto........
No, the ring never turned. The end just came off. The motor ran fine, it just was down on compression. Both cylinders, same failure. Mag side slightly more ping marks
hmm, that is strange....both pistons did this?..sounds like the end gap closed up and they touched, I have seen that before but on a big block chevy running lots of nitrous( 2 500 hp NOS fogger kits)..it broke the second compression ring amost dead opposite the ring ends on 4 pistons(it leaned up on fuel just a touch(took the porcealen out of those 4 plugs(lean deto)..
Ya the funny part is the only other time we have seen this was on chevy too. For the same reason, the ring touched. The odd part to me was that I have ran a bunch more compression on this same motor and worked it harder than I had worked these pistons and it never broke. Now it grenades with lowered compression. I really dont get it. The only thing I have done is narrow the quench area slightly, and loosen the squish by about 15 thou.
be willing to bet it raised piston temps enough to get the rings to touch...if it is salvageable open the end gaps another .003-.005 and it should solve it ..unless it sticks a piston....
Now I have a question for all you big bore boys...trying to decide on either a carls 860 or a turbo for my dragon..would enjoy hearing your thoughts if you have ridden with em....
Kinda what I was thinkin. It ate the cylinder, both slugs and head. I can save the head if I want. Thinkin I may go back and just mill the stocker and run it. I just dont understand why this thing is so finicky about its head. The dome design I have is far superior to factory dome for output. We developed this dome on a YZ125 that will beat up on ported, piped 250f's. It works well, and it built good power on this sled until it broke.
I would guess it has to do with the way the piston/ head/cylinder/cooling system get rid of heat...that fine line between good/great/junk is very fine....my guess is the other head had more piston dome cooling...
Less actually. It was a modified stock head and this is a billet head surrounded entirely by water.
TNT, does something about how the 800r breathes promote ring heat??
TNT, does something about how the 800r breathes promote ring heat??
The Struthers 860 Dragon is a beautiful riding machine. My buddy has one 1,600 miles now and it's been awesome. Hasn't skipped a beat. The runnability and mapping is spot on. If you ride below 8,000 feet, I'd definately go with the 860. IMHO, the 860 will be more reliable than a turbo.
I have done a dragon, and to be honest I talked the customer out of doing 860, the cylinders are so thin that if you should get it hot, I don't think it will survive.
Now I did a aggresive trail port with twins and it's strong running sled, less money then a BB and very reliable and not finicky like most twins seem to be.
Just food for thought!
Now I did a aggresive trail port with twins and it's strong running sled, less money then a BB and very reliable and not finicky like most twins seem to be.
Just food for thought!
I have had some major heat issues withsome billet heads, they don't have proper water channels and create hot spots in the cylinder and head.
Detonation and high ash producing oils are big ring killers!
If the ring bottoms out on locator pin it will snap the tips off the ring!
Make sure you can colapse the ring flush to the locator side of the piston and it doesn't rock on locator pin.
If the ring bottoms out on the pin before there flush with the side of the ring lands, file the step in the ring for clearance.
Detonation and high ash producing oils are big ring killers!
If the ring bottoms out on locator pin it will snap the tips off the ring!
Make sure you can colapse the ring flush to the locator side of the piston and it doesn't rock on locator pin.
If the ring bottoms out on the pin before there flush with the side of the ring lands, file the step in the ring for clearance.
G
GRAHAM
Member
Yes it does! ,,,I,ll be on my backup sled tomorrow, Have the Raves out for a little work on the 880.....Sucks!IT RIPS!!! Watch out bob! LOL.
Dam, already making excuses lmao.
Be interesting how well it runs after 10hrs.
Agree that's why Struthers 860's do NOT use the stock cylinders. Food for thought.
Someone posted that the 09 is off the clock at 3 hours, They posted copy of the page right out of the manual.
rpm
what are you guys seeing for an engagement rpm? mine is 4500 with a yellow team primary spring.
what are you guys seeing for an engagement rpm? mine is 4500 with a yellow team primary spring.
- Status
Similar threads
