Exhaust port Chamfer is vital to eliminating scraping
LeakDown results- post em up
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Exhaust port Chamfer is vital to eliminating scraping
Just a continuation if anyone was curious. I've been keeping track of mine since I picked it up in early December. I had to back out of a trip so don't have as many miles as I'd like yet but it is what it is. I've never had a problem with this sled and it has ran great. At this point, I'm not worried, but I'd be lying if I said I wasn't just a little concerned with the leakdown tests creeping higher. Although they were done in a colder enviroment this last time around (not sure if that affects it much). Hoping to sneak out west one more time to put some more miles on the wknd of the 28th-31st if I can find somewhere with good snow/weather and I will check it again.
504 miles, 42 engine hours
4.25% - 4.5% leakdown both sides
132psi both sides
This last test, both were done when sled hadn't ran for a week in a semi-heated garage at 45* compared to 60* in my shop for the earlier tests.
I think Cat should start worrying about Polaris. With the new homoerotic colors of the Khaos all the lifer Cat guys are going to switch to Polaris
You are doing yourself a great service by testing your motor as you go.
You know more about your motor right now...... then if you took it to 99% of the Polaris dealers out there and ask for a health report on your motor.
Not to slam dealers but but for the most part most just don’t do leak down tests.
I would be concerned as well..... it’s dangerously close to needing a top end.
I hope you get another trip in.
If it goes past 5% it needs to come apart.
Dan
got a link to the video?
I'm guessing it is more important in this case as the other parts of the piston look fine, it is just in one location. If the finish was to blame I would expect to see damage, more even over the piston.
If it’s a cylinder finish problem you see the damage first
On the lower intake side of the piston
Dan
How many miles on the piston shown?
The pic and piston in question is the exhaust side, correct?
So some people have put their sleds away for the season and some are still lucky enough to still ride. If your still concerned over this and need help (Ive walked a couple people through this over the phone). Your welcome to stop by my shop if your in Upper MI. Ive also done a couple in my enclosed trailer out west. I keep a separate tester in there if you see me out or stop by if your in the Yoop (Send me a PM 1st). I'm guessing "most" sleds are fine but some are still nervous over this. If your numbers are low, the off season would be a good time to get it to the dealership.
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20 hrs
All these posts and 3 or 4 people have posted leak down numbers. Seems all these threads are about IndyDan now.
My 18 and 19 are both 4%, cold 60° garage temps. Not ran for a few days.
Legends ZX2 SR [emoji58]
2006 M7 w/ orig top end 5000miles 
PTO: 6%
Mag: 4%
PTO: 6%
Mag: 4%
2006 M7 w/ orig top end 5000miles
PTO: 6%
Mag: 4%
Nice, but it’s time. Do they still make pistons?
What do you mean by this ?
Leak down tests are the only way to check the the true condition of the top end.
it’s surprising how many people will not do it.
performance problems cannot be trouble shot accurately without leak down numbers.
Dan
Quote:
Originally Posted by AndrettiDog View Post
All these posts and 3 or 4 people have posted leak down numbers. Seems all these threads are about IndyDan now.
Originally Posted by Sheer View Post
"This whole thing seems like a giant waste of time to me... unless you have a prob with your sled, low power, runability.... why bother... its not known for top end issues for 1, 2, if you suspect something bring it to dealer and get them to do it, you got a 4 year warrenty why not use it??? 3, if you dont trust the dealer or think the diag is wrong yea shure maby than do it... aside from that if your want to know where your engine sits than shure go ahead.. but i got better things to do than leakdown test a brand new sled.... maby i will go check the amp draw in the heating element of my brand new coffee maker just so i can keep tabs on it till it goes off warrenty"
I get this so this is my past reply:
(Originally Posted by Prayn4snow) "Sheer, I total understand your point. "Most" people will never do this or need to do it. The OP wanted people that did this test to simply post results. There were comments from some that wanted to know the how to do it and what to use. I simply like to help people make up their own minds if a product (bumpers, pipes, tracks, gearing, big bore, clutching, piston durability kits, turbo's etc) are right for them. Im the type that does these tests regardless for my own 2 cents. I have a log of base lines for each sled and race car I build. I just twisted the crank a year ago on a ProCharged (Intercooled supercharger) 70 Corvette for example. When you risk smoking a $15,000 motor you tend to look at the little things including ultra balancing rotating items. In this case the manufacture of the crank rated it to over 1000hp. I made 1000 my goal, and with enough boost and the right bolt on components and machining this is now a reachable goal. Because I documented everything the crank manufacture had to admit they messed up.
These are useful tools, and 4 years of warranty is rare in snowmobiling. These test are helpful for the 1 year warranty baseline, diagnosis, buying used sleds (or any engine). Its quick, easy, fairly cheap (some parts stores will rent you the tools for a day even) and for some gives peace of mind. Others are weirdos with ADD like me, I don't know, my teacher said I was special but my mom had me tested . Enjoy the snow and the sled"
To each there own on if you should do a leak down test to create a base line. For me this had nothing to do with Indy Dan. Yes, he has some valuable insite and recommendations. And yes he is good at ruffling peoples feathers lol. Regardless of what people think about him his shop does outstanding machine shop and engine work which is a fact. The other fact is leak down tests if done correctly don't lie and give you the owner a valuable tool of insight that you cant get from another means shy of complete teardown, measurements and inspection, even then it's still valuable.
__________________
Originally Posted by AndrettiDog View Post
All these posts and 3 or 4 people have posted leak down numbers. Seems all these threads are about IndyDan now.
Quote:
Originally Posted by Sheer View Post
"This whole thing seems like a giant waste of time to me... unless you have a prob with your sled, low power, runability.... why bother... its not known for top end issues for 1, 2, if you suspect something bring it to dealer and get them to do it, you got a 4 year warrenty why not use it??? 3, if you dont trust the dealer or think the diag is wrong yea shure maby than do it... aside from that if your want to know where your engine sits than shure go ahead.. but i got better things to do than leakdown test a brand new sled.... maby i will go check the amp draw in the heating element of my brand new coffee maker just so i can keep tabs on it till it goes off warrenty"
I get this so this is my past reply:
(Originally Posted by Prayn4snow) "Sheer, I total understand your point. "Most" people will never do this or need to do it. The OP wanted people that did this test to simply post results. There were comments from some that wanted to know the how to do it and what to use. I simply like to help people make up their own minds if a product (bumpers, pipes, tracks, gearing, big bore, clutching, piston durability kits, turbo's etc) are right for them. Im the type that does these tests regardless for my own 2 cents. I have a log of base lines for each sled and race car I build. I just twisted the crank a year ago on a ProCharged (Intercooled supercharger) 70 Corvette for example. When you risk smoking a $15,000 motor you tend to look at the little things including ultra balancing rotating items. In this case the manufacture of the crank rated it to over 1000hp. I made 1000 my goal, and with enough boost and the right bolt on components and machining this is now a reachable goal. Because I documented everything the crank manufacture had to admit they messed up.
These are useful tools, and 4 years of warranty is rare in snowmobiling. These test are helpful for the 1 year warranty baseline, diagnosis, buying used sleds (or any engine). Its quick, easy, fairly cheap (some parts stores will rent you the tools for a day even) and for some gives peace of mind. Others are weirdos with ADD like me, I don't know, my teacher said I was special but my mom had me tested . Enjoy the snow and the sled"
To each there own on if you should do a leak down test to create a base line. For me this had nothing to do with Indy Dan. Yes, he has some valuable insite and recommendations. And yes he is good at ruffling peoples feathers lol. Regardless of what people think about him his shop does outstanding machine shop and engine work which is a fact. The other fact is leak down tests if done correctly don't lie and give you the owner a valuable tool of insight that you cant get from another means shy of complete teardown, measurements and inspection, even then it's still valuable.
__________________
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Great question....... I can't give a 100% positive answer to that.
But my opinion is that 12 rings would be about the same as one ring.
Zero difference in leak down numbers. ( if the rings are set up correctly )
In a 3.346 / 85mm bore ( Top ring ) end gap on a modern 2 stroke would be about .018.....
( Lower ring ) I don't care much about this one as long as it's bigger then the top ring.
And it's vital that lower ring end gap is bigger ( to make sure there is no pressure created in between the rings ) causing the upper key stone ring to float and not allow it to get the floor making the bottom ring the primary ring.
The bottom ring is not a performance helper...... It's along of the ride.
It's main help to the motor getting heat out of the piston into the cooling system via the cylinder bath.
Single ring set ups are fine.
As I have said a thousand times...... In a silicon carbide plated motor it's all about ( cylinder finish ) the smoother the better.
Nice write up ( praying for snow )
Dan
