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Old 05-23-2013, 12:59 PM   #17086
ThereisnoSpoon
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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, 06:49 PM   #17087
Adamco2
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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
I run a 72 and am going to try a 75.
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Old 05-23-2013, 08:20 PM   #17088
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, 11:00 PM   #17089
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, 10:32 AM   #17090
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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, 11:46 AM   #17091
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, 11:59 AM   #17092
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, 01:44 PM   #17093
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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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Old 05-24-2013, 02:37 PM   #17094
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My pig is dying on me in death valley. I'm at a small camp ground in panamint springs using the interwebs.

My pig will kick over, run with no lack of power, then in a few miles starts to lug as if she isn't gettin gas. Eventually dies, but will kick over again after a few minutes if she's feeling nice. Then repeats. Exhaust sputters and pops a bit louder than normal when engine braking, but that could be me misremembering what's normal. She did this a couple times about 700 miles ago, but ran seafoam through two tanks and she quit the shenanigans.

Camped in death valley last night and did the following: removed and disassembled petcock, there were a few burrs on the inner rubber gasket, but cleaned that up and flipped the gasket over so the good side is against the petcock lever. Disassembled/reassembled carb, nothing amiss. Adjusted valve clearances to spec, but did not take off crank cover to ensure exact TDC, so could be a little off. Repacked muffler. Checked, but did not clean, air filter. Also, cursed a bit.

My theory: carb float needs replaced, and/or a swift kick in the ass.

Ideas?

KonaTheHusky screwed with this post 05-24-2013 at 03:02 PM
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Old 05-24-2013, 03:13 PM   #17095
RideFreak
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Quote:
Originally Posted by KonaTheHusky View Post
My pig is dying on me in death valley. I'm at a small camp ground in panamint springs using the interwebs.

My pig will kick over, run with no lack of power, then in a few miles starts to lug as if she isn't gettin gas. Eventually dies, but will kick over again after a few minutes if she's feeling nice. Then repeats. Exhaust sputters and pops a bit louder than normal when engine braking, but that could be me misremembering what's normal.

Camped in death valley last night and did the following: removed and disassembled petcock, no obstructions. Disassembled/reassembled carb, nothing amiss. Adjusted valve clearances to spec, but did not take off crank cover to ensure exact TDC, so could be a little off. Repacked muffler. Checked, but did not clean, air filter. Also, cursed a bit.

My theory: carb float needs replaced, and/or a swift kick in the ass.

Ideas?
Looks like you did the obvious. Carb floats usally don't go bad, infact it's really rare and easy enough to check. They also wouldn't cause that symptom, the carb would be getting too much fuel if they were bad. To me it sounds like fuel is trickling into the carb and demand isn't keeping up with flow. As a test, run it, as it stats getting ready to die, flip on the choke, that will pull a bit more of the remaining fuel out of the carb. If you do that and it will run a short while longer then it's running out of gas. Cause can be up at the petcock (easy to check) or in the float area, Pull the fuel line, turn on the gas, see if you have good flow out of the tank. If that's ok it's possibly something is blocking the inlet screen at the float valve or the floats are hung in the upward (almost closed) position but even that should cause some leakage out the overflow. If the floats were bad (ie: they don't float ) the fuel wouldn't shut off in the carb and it'd be pissin all over the ground. If you narrow it to the carb, I'd pull it and give it a good inspection, look to make sure the float assy isn't bent and that you can blow freely through the fuel line with the floats hanging. (float valve open). Shake the carb once it's together before you put it on the bike, you'll hear the floats bouncing up and down confirming that they aren't in a bind causing them not to work correctly. Check your gas cap vent too, that can cause the same thing, if you got one of those little check valve things on your gas cap, throw it away and replace with a piece of fuel line, they're junk and cause as many problems as they solve (I'd do this check first since it's easiest).

Good luck and have a great ride, we expect some pictures when you return.
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Old 05-24-2013, 03:25 PM   #17096
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Quote:
Originally Posted by Adamco2 View Post
I run a 72 and am going to try a 75.
That's a big pilot jet, What's your fuel mileage? Is there some modification that allowing in (allot) more air? 68s seems to be the preferred size for sealevel. Asking because some folks don't realize, the metering passage in a pilot jet will slowly get smaller as the crappy fuels we get dries out. It forms a microscopic layer that will change the jet size over time, in the main jet it's impact is minimal but it can be significant in a pilot jet. If your mileage is reasonable than this is probably whats occurred, if it's crappy then the jet is allowing all the fuel into the motor.
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Old 05-24-2013, 03:48 PM   #17097
bill pierce
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Quote:
Originally Posted by slogger View Post
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.
Thanks, I adjusted my intakes about 500 miles ago when I bought the bike. Looks like they need it again already. Most bikes I have owned would do at least 3k between adjustments.
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Old 05-24-2013, 05:18 PM   #17098
KonaTheHusky
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Quote:
Originally Posted by RideFreak View Post
Check your gas cap vent too, that can cause the same thing, if you got one of those little check valve things on your gas cap, throw it away and replace with a piece of fuel line, they're junk and cause as many problems as they solve (I'd do this check first since it's easiest).
I knew I didn't like that gas cap. Popped off the valve and drilled out the mini ping pong ball in there, breathes really well now. Went up the hill without it dying, but it was studdering and did die on the way down the hill. I think the float is sticking. Since I took it apart last night to no avail and have no carb cleaner with me, I'm gunna get the bike towed to ridgecrest in the mornin.

Probably pick up a full carb rebuild kit for it.

Thanks for the help.
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Old 05-24-2013, 06:44 PM   #17099
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Quote:
Originally Posted by RideFreak View Post
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.
RF
I am happy I had the ross piston for 14,000 miles no complaints here.
No warranty necessary
it was a forged piston and it failed where you would expect.
It could be developed further, but it is int worth the time for ross
After seeing the wossner it was an easy decision. I am Not saying it will go further than 14,000 miles, But I am betting my money it will. $179 to my door
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Old 05-24-2013, 07:21 PM   #17100
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Quote:
Originally Posted by Cpt. Ron View Post
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.
The XR650r is used in so many ways that it might be good to know how the bike is used
The XR is my daily rider, this includes freeway riding as well,
I ride a happy 72 mph at 47?? rpm for long distances. (off a calibrated vapor)
I weigh 250 lb 300 lb when packing gear
550-600 lb gross weight range
my bikes are geared 16/40
I have 2 XR650s and one is stock (uncorked and TM40)and the other bike (the one with the cracked piston) had
advanced timing 3 extra degrees
11 to 1 light weight piston (ross)
blended ports (no porting just seat blend to wall)
and a current big guns modded to go on a old wihte brothers E series muffler.

OK i agree with you that the stock XR is more durable as is
But the few mods the modded one had, Made a nice difference, I has more grunt and revs quicker
smoother at the same power settings
and Just easier to go faster

In the mean time I ram riding the stocker bike and rebuilding other
There are other issues with the motor I should point out later
Happily riding the stocker But dreaming about the rebuilt Model
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