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Old 05-22-2013, 09:21 PM   #17071
FlyGuy
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Joined: Oct 2005
Location: Middle of Highway 1 California
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FlyGuy goes with wossner pistons

I had previously used the ROSS piston I purchased from XRs only.
I had accumulated approximately 14,000 mi or (22,500 kmi) of adventure fun with the ross piston and was surprised of how well it made the bike run.
I knew my luck would run out on this engine some day and it finally did
The ross piston cracked and the XR turned into a oil pumping smoking train.
The bike still ran so I tried to limp it home some 120 miles away
I added oil at he first notice of the problem (unaware of the actual problem), and kept adding oil till I went through one quart in 6 miles where I threw in the towel due to a hard start (leg failure) some 60 miles later
I made it the additional 60 miles running high oil temp 250f and no higher than 210f on the coolant
(I was happy to have a add on fan as it was running constantly) It was a long day.

Back at home the XR got disassembled to reveal the the problems.
Some may say detonation killed the ross piston, but I won't say it never detonated. but there is no heat signature I can find that would indicate a detonation issue..
The burned look is from trying to get home with a crack through the piston crown, as well it yellowed the entire inside of the engine with burnt oil.
When a single cylinder engine detonates its usually noted with a power loss and jerkie operation.
It is my opinion the Ross piston died of cyclical flexing from high cylinder pressures



Now I compare the two pistons to decide what to do
the wossner piston is more than ⅓ thicker through the crown measuring .280 thousands (top of piston to underside)
the ross piston measured .180 thousands and this is not where the valve reliefs are the ross is very thin where the reliefs are. ross uses a unibrow?

the wossner measures .980 across the inside pin bosses
the ross measures 1.175
I am pointing to the difference.

the wossner pin is a tapered wall with a main wall thickness of .165
the ross is .147

These three things will help the flex issue,the crown thickness is a big one
In addition the wossner is Teflon coated and uses a thinner ring pack
So what does it weigh with pin rings and clips

that's 12 grams more than the ross but 60 grams lighter than stock
there are more things i like about this piston but i don't want to bore ya
i might comment on the rod as mine is due and i plan to keep track of the weights here too
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Old 05-22-2013, 10:21 PM   #17072
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Old 05-23-2013, 04:22 AM   #17073
ZXRaziel
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Location: Grey skyes and rain of Good old England ( NEast)
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Quote:
Originally Posted by FlyGuy View Post
FlyGuy goes with wossner pistons

I had previously used the ROSS piston I purchased from XRs only.
I had accumulated approximately 14,000 mi or (22,500 kmi) of adventure fun with the ross piston and was surprised of how well it made the bike run.
I knew my luck would run out on this engine some day and it finally did
The ross piston cracked and the XR turned into a oil pumping smoking train.
The bike still ran so I tried to limp it home some 120 miles away
I added oil at he first notice of the problem (unaware of the actual problem), and kept adding oil till I went through one quart in 6 miles where I threw in the towel due to a hard start (leg failure) some 60 miles later
I made it the additional 60 miles running high oil temp 250f and no higher than 210f on the coolant
(I was happy to have a add on fan as it was running constantly) It was a long day.

Back at home the XR got disassembled to reveal the the problems.
Some may say detonation killed the ross piston, but I won't say it never detonated. but there is no heat signature I can find that would indicate a detonation issue..
The burned look is from trying to get home with a crack through the piston crown, as well it yellowed the entire inside of the engine with burnt oil.
When a single cylinder engine detonates its usually noted with a power loss and jerkie operation.
It is my opinion the Ross piston died of cyclical flexing from high cylinder pressures



Now I compare the two pistons to decide what to do
the wossner piston is more than ⅓ thicker through the crown measuring .280 thousands (top of piston to underside)
the ross piston measured .180 thousands and this is not where the valve reliefs are the ross is very thin where the reliefs are. ross uses a unibrow?

the wossner measures .980 across the inside pin bosses
the ross measures 1.175
I am pointing to the difference.

the wossner pin is a tapered wall with a main wall thickness of .165
the ross is .147

These three things will help the flex issue,the crown thickness is a big one
In addition the wossner is Teflon coated and uses a thinner ring pack
So what does it weigh with pin rings and clips

that's 12 grams more than the ross but 60 grams lighter than stock
there are more things i like about this piston but i don't want to bore ya
i might comment on the rod as mine is due and i plan to keep track of the weights here too
Thanx for the good information
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ZXRaziel screwed with this post 05-23-2013 at 12:48 PM
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Old 05-23-2013, 07:33 AM   #17074
RideFreak
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It's definately not detonation, it's very obvious when you take apart a motor that suffers from premature ignition (det.) it will appear sandblasted around the outer edges getting worse the further out on the crown and I doubt you'd see that much carbon buildup ether.

I suspect it started off as a casting imperfection in the piston alloy. The scenerio your painting says the design isn't up to the job. I sorta doubt that, there's plenty of race bikes using Ross pistons without this problem or piston failures.

Have you tried to get them (Ross) to replace it or shown them these pictures? I would, you might be surprised.
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Old 05-23-2013, 08:13 AM   #17075
ZXRaziel
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To be fair , the piston did fair amount of work ( miles ) , especialy considering that its a light weight high compression ( call it racing if you like ) , that is respectable result and certainly not a bad quality part , i have seen parts failing much quicker than that . And light weight piston puts less stress on other parts - they last longer , its easy and cheap to replace piston
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Old 05-23-2013, 08:41 AM   #17076
RideFreak
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Location: Out in the NM Dez somewhere
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Quote:
Originally Posted by ZXRaziel View Post
To be fair , the piston did fair amount of work ( miles ) , especialy considering that its a light weight high compression ( call it racing if you like ) , that is respectable result and certainly not a bad quality part , i have seen parts failing much quicker than that . And light weight piston puts less stress on other parts - they last longer , its easy and cheap to replace piston
You def caught it at the right time, could have been ugly
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"Life's journey is not to arrive at the grave safely in a well preserved body, but to rather skid in sideways, totally worn out, shouting ... Holy Shit, what a ride!"
CL Adventure Ride 2013 /CL Revisited 2014 / 700 Miles of Scenic Utah Backcountry / MY VIDEOS / RIDEFREAK TV
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Old 05-23-2013, 10:43 AM   #17077
galland1
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Location: S.W., MI
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Anyone use a 70s pilot jet?

Sent from my SPH-L720 using Tapatalk 2
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Old 05-23-2013, 11:59 AM   #17078
ThereisnoSpoon
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Location: Petersburgh NY
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Quote:
Originally Posted by galland1 View Post
Anyone use a 70s pilot jet?

Sent from my SPH-L720 using Tapatalk 2

Yes
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Old 05-23-2013, 05:49 PM   #17079
Adamco2
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Joined: Sep 2004
Location: Santa Cruz
Oddometer: 127
Quote:
Originally Posted by galland1 View Post
Anyone use a 70s pilot jet?

Sent from my SPH-L720 using Tapatalk 2
I run a 72 and am going to try a 75.
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Old 05-23-2013, 07:20 PM   #17080
jm-2008
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Piston Weights - Balance?

[QUOTE=FlyGuy;21471823]FlyGuy goes with wossner pistons

I had previously used the ROSS piston I purchased from XRs only.
I had accumulated approximately 14,000 mi or (22,500 kmi) of adventure fun with the ross piston and was surprised of how well it made the bike run.
I knew my luck would run out on this engine some day and it finally did
The ross piston cracked and the XR turned into a oil pumping smoking train.
The bike still ran so I tried to limp it home some 120 miles away
I added oil at he first notice of the problem (unaware of the actual problem), and kept adding oil till I went through one quart in 6 miles where I threw in the towel due to a hard start (leg failure) some 60 miles later
I made it the additional 60 miles running high oil temp 250f and no higher than 210f on the coolant
(I was happy to have a add on fan as it was running constantly) It was a long day.

Back at home the XR got disassembled to reveal the the problems.
Some may say detonation killed the ross piston, but I won't say it never detonated. but there is no heat signature I can find that would indicate a detonation issue..
The burned look is from trying to get home with a crack through the piston crown, as well it yellowed the entire inside of the engine with burnt oil.
When a single cylinder engine detonates its usually noted with a power loss and jerkie operation.
It is my opinion the Ross piston died of cyclical flexing from high cylinder pressures



Now I compare the two pistons to decide what to do
the wossner piston is more than ⅓ thicker through the crown measuring .280 thousands (top of piston to underside)
the ross piston measured .180 thousands and this is not where the valve reliefs are the ross is very thin where the reliefs are. ross uses a unibrow?

the wossner measures .980 across the inside pin bosses
the ross measures 1.175
I am pointing to the difference.

the wossner pin is a tapered wall with a main wall thickness of .165
the ross is .147

These three things will help the flex issue,the crown thickness is a big one
In addition the wossner is Teflon coated and uses a thinner ring pack
So what does it weigh with pin rings and clips

that's 12 grams more than the ross but 60 grams lighter than stock
there are more things i like about this piston but i don't want to bore ya
i might comment on the rod as mine is due and i plan to keep track of the weights here too


What effect, has the change in weight had on balance factor?
Appreciate the benefits of minimising reciprocating masses however am interested in changes to the balance factor, or have all the inmates that have changed pistons had the crank and associated parts re-balanced?
Just curious
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Old 05-23-2013, 10:00 PM   #17081
Cpt. Ron
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Maybe the bigger question is, has anyone who HASN'T done a piston change (from OEM) had this happen? Which then leads to, why change to a lighter piston? Being an engineer, I appreciate the idea for reducing the reciprocating mass: quicker acceleration, less stress on attached members etc....For stuff like supermoto I get it. The littlest advantage can make a big difference.

But I haven't been spanked by a modified BRP nor a stock one (stock meaning un-corked here) in the type of riding I do. Within the confines of the OEM covers on my bike, it's all stock. I've ridden with plenty of other BRP riders, and we all have our strengths and weaknesses. None of us have ever thought that the power of the bike held us back (suspension not withstanding....). The stock power plant leaves most mortals going "Holyyyyy Shittttttt" when they twist the throttle. The big differences seem to come in the tuning and rideability of the bike. If it doesn't work, no amount of power will save you. In my mind, it's the total package that matters.

For my dual sport riding and occasional cross-country race, as well as the Kings of the West Rally, the stock internals of the motor work for me. They get me to the beginning AND the end of the event. About the only thing I'd consider changing from OEM is the intake valves for more longevity.

But hey, that's just me.
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Old 05-24-2013, 09:32 AM   #17082
KYLEISCOOL
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^^^^^^^

^^^ +10 with you Ron. I totally concur and the thoughts of having to push my bike from places I go... No thanks. Longevity & Reliability is my main key in a bike. Hence why im sticking with the piggy not going to the more modern "race" type bikes. I can adjust my valves in the middle of BFE in a half hour and be on my way again if need be.
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Old 05-24-2013, 10:46 AM   #17083
bill pierce
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What. Kind of life span are you guys getting out of a set of valves??
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Old 05-24-2013, 10:59 AM   #17084
Cpt. Ron
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Quote:
Originally Posted by bill pierce View Post
What. Kind of life span are you guys getting out of a set of valves??
I don't keep track of miles very well, so I can't give you a definite answer. My bike was original when I got it used in early '06. About four years ago, I did a top end, replacing the rings, valves and guides (the exhausts look fine, by the way). Everything else was well within tolerance. It's been going strong ever since. I've done two Kings of the West Rallys (roughly 1,000 miles each), the Virginia City Grand Prix a couple of times, and quite a few dualsport rides in the Mendocino National Forest with only a couple of valve adjustments and oil changes.
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Old 05-24-2013, 12:44 PM   #17085
slogger
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Quote:
Originally Posted by bill pierce View Post
What. Kind of life span are you guys getting out of a set of valves??
I've got about 15k out of my intakes(on two 650's). At about this point, my intakes would need adjustment ever 300-400 miles. Prior to this, it was ever 900-1200 miles. Also, these are all dirt miles but not super dusty. My air box always has dust in it no matter what I do.
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