So there is some bad castings then for the jugs out there?Here is a brand new 2016.
Sled has ran for less than 10min.
I wonder if mine happened within the first 10min?
GS6
Powervalve hitting piston
- Thread starter summ8rmk
- Start date
did a little googling as i am curious how to prevent...
http://www.hardcoresledder.com/foru...-ok-lets-hear-apv-valves-hitting-pistons.html
http://www.snowest.com/forum/showthread.php?t=316038
http://www.arcticchat.com/forum/z-z...cougar/271270-power-valve-hitting-piston.html
theres a lot of threads on this.
sounds like theres a pin in the valve that gets worn?
also, steel valve hammers down aluminum stop.
your pic of the brand new motor is odd. if its just off the net, maybe thats somebody's cold seize?
i think the first time i clean mine, im just going to take a file to the valve edges.
im curious what big bore kits do. maybe they dont use stock cylinders, i havent looked at them much.
http://www.hardcoresledder.com/foru...-ok-lets-hear-apv-valves-hitting-pistons.html
http://www.snowest.com/forum/showthread.php?t=316038
http://www.arcticchat.com/forum/z-z...cougar/271270-power-valve-hitting-piston.html
theres a lot of threads on this.
sounds like theres a pin in the valve that gets worn?
also, steel valve hammers down aluminum stop.
your pic of the brand new motor is odd. if its just off the net, maybe thats somebody's cold seize?
i think the first time i clean mine, im just going to take a file to the valve edges.
im curious what big bore kits do. maybe they dont use stock cylinders, i havent looked at them much.
Is there any benefit to just doing a power valve delete? Or to much loss on the low end with that?
Factory tooling could be some of the problem as well. IF,, cat is coming out with their engine then it would make sense to not upgrade equipment to make parts so it might be a build issue. I am curious about the 1000 engine having the same problem,
and wonder if the stm power valves might be the answer.
and wonder if the stm power valves might be the answer.
Re: What do the big bores do...
I'm in the process of installing my brand new RKT 925 kit, Kelsey supplies thicker exhaust valve plates to step the valves away from pistons, this is needed due to larger diameter cylinder bores. I've seen other kits provide re-shaped exhaust valves. My old M7 big bore simply used a washer to limit valve travel.
After seeing this I'll probably grind the corners of exhaust valves as a safety precaution, since I'm poised to re-install as soon as my valve seals arrive.
Thanks for the thread!
I'm in the process of installing my brand new RKT 925 kit, Kelsey supplies thicker exhaust valve plates to step the valves away from pistons, this is needed due to larger diameter cylinder bores. I've seen other kits provide re-shaped exhaust valves. My old M7 big bore simply used a washer to limit valve travel.
After seeing this I'll probably grind the corners of exhaust valves as a safety precaution, since I'm poised to re-install as soon as my valve seals arrive.
Thanks for the thread!
My 1000 has the same issue. The valve stop is in the cylinder, not sure how a shim would help. The only way I see a fix is to have the cylinder stop welded then machined raising it. Mine wore 1 side and the valve cocked letting the valve lean in on 1 side further to rub.
Shims, double gaskets and blocks transfer all of the load to the cables instead of the stop in the jug. Yes it will accomplish what i want, more clearance. Now u rely solely on the cables to protect ur piston. It may last forever? It may last for 1,000miles?
I believe Grinding or machining material off the end of valve near the piston is a more permanent solution.
GS6
I believe Grinding or machining material off the end of valve near the piston is a more permanent solution.
GS6
A more permanent solution is to machine the jug and install a hardened steel stop that will not change dimension over time. I know a few Polaris engine builders that do that to very high milage cylinders, but I'm not familiar enough with the Suzuki side of things to recommend anyone. This can't be a new problem? There are multiple threads a year about it from the Cat owners.
I think some of the problem is when you have the valve resting on the valve stop, it will vibrate on the, and the harder steel valve will actually grind down the aluminuim stop.
I dont see a problem that is it limited by the wire. In my mind, the stop is there only to avoid the valve from falling into the cylinder if the wire goes off.
We always adjust the wire a little tighter then recomended. This has served us great, and we have found that to help on sleds with a bottom bog, expecially the down hill bog.
I dont see a problem that is it limited by the wire. In my mind, the stop is there only to avoid the valve from falling into the cylinder if the wire goes off.
We always adjust the wire a little tighter then recomended. This has served us great, and we have found that to help on sleds with a bottom bog, expecially the down hill bog.
noticed mine doing this on both top ends that I have installed....
sanded them down and it helped. probably check and sand them again this year.
pretty annoying though... such a simple thing that could cause such a huge error.... had 5500 miles on my first top end and replaced it for ****s and giggles well cuz its time at that point.
pisses you off though when you install a brand new top end run it take pipe off and take a look into cylinder and u see those fine lines on your brandy new pistons
sanded them down and it helped. probably check and sand them again this year.
pretty annoying though... such a simple thing that could cause such a huge error.... had 5500 miles on my first top end and replaced it for ****s and giggles well cuz its time at that point.
pisses you off though when you install a brand new top end run it take pipe off and take a look into cylinder and u see those fine lines on your brandy new pistons
J
jim
Well-known member
Happened on my sled (09 M8 PG turbo). I have analyzed a lot of metal and that was not the problem...no wear or seating of the metal at all. No deformation of the stops at all (you can see it). No mushrooming of the metal the metal interfaces (showing that the metal migrated or was smashed out).
Turned out the powervalve clearance was minimal. The valves has a slight build-up of carbon and, bingo, rubbed the pistons. And it happens quickly. I checked one ride...minor scuff on one piston I thought was just due to debris or something coming through. Two more rides and checked again...both pistons had scuffs. I run redline synthetic. Guy I bought the sled from ran whatever...and it made a mess in the engine.
I rebuilt the top end and cut the powervalves back...a lot. And polished them up. Especially at the corners (which are very close if you look at them). No change in performance. Valves are clean now as well. No more PV issues.
IMO, it's a tolerancing and engineering issue. First off, the tolerance stack up is obviously not controlled well enough by AC. This seems to be a common occurrence. Also, the powervalve is closest to the piston at the corners...where you have the most material...where you will also see the most thermal growth in the PVs.
Some say it's not common...but I bet this has been responsible for a lot of mystery burn-downs. I caught mine in time...but the top of piston was deformed and the rings marked. I'm sure I was close to snagging a chunk of metal and having major issues.
Turned out the powervalve clearance was minimal. The valves has a slight build-up of carbon and, bingo, rubbed the pistons. And it happens quickly. I checked one ride...minor scuff on one piston I thought was just due to debris or something coming through. Two more rides and checked again...both pistons had scuffs. I run redline synthetic. Guy I bought the sled from ran whatever...and it made a mess in the engine.
I rebuilt the top end and cut the powervalves back...a lot. And polished them up. Especially at the corners (which are very close if you look at them). No change in performance. Valves are clean now as well. No more PV issues.
IMO, it's a tolerancing and engineering issue. First off, the tolerance stack up is obviously not controlled well enough by AC. This seems to be a common occurrence. Also, the powervalve is closest to the piston at the corners...where you have the most material...where you will also see the most thermal growth in the PVs.
Some say it's not common...but I bet this has been responsible for a lot of mystery burn-downs. I caught mine in time...but the top of piston was deformed and the rings marked. I'm sure I was close to snagging a chunk of metal and having major issues.
Happened on my sled (09 M8 PG turbo). I have analyzed a lot of metal and that was not the problem...no wear or seating of the metal at all. No deformation of the stops at all (you can see it). No mushrooming of the metal the metal interfaces (showing that the metal migrated or was smashed out).
Turned out the powervalve clearance was minimal. The valves has a slight build-up of carbon and, bingo, rubbed the pistons. And it happens quickly. I checked one ride...minor scuff on one piston I thought was just due to debris or something coming through. Two more rides and checked again...both pistons had scuffs. I run redline synthetic. Guy I bought the sled from ran whatever...and it made a mess in the engine.
I rebuilt the top end and cut the powervalves back...a lot. And polished them up. Especially at the corners (which are very close if you look at them). No change in performance. Valves are clean now as well. No more PV issues.
IMO, it's a tolerancing and engineering issue. First off, the tolerance stack up is obviously not controlled well enough by AC. This seems to be a common occurrence. Also, the powervalve is closest to the piston at the corners...where you have the most material...where you will also see the most thermal growth in the PVs.
Some say it's not common...but I bet this has been responsible for a lot of mystery burn-downs. I caught mine in time...but the top of piston was deformed and the rings marked. I'm sure I was close to snagging a chunk of metal and having major issues.
Im having the same issue with mine. Im thinking its a carbon build up issue too. I have marks on my pistons, mag side worse than pto, but the rings look fine and I have 148(mag) and 152(PTO) for compression. Im just going to grind down the corners and slap it back together and run it. I cleaned the power valves before I noticed the scratches so I didn't get a chance to look at markings or carbon on the edges of the valve.
