Time To Rebuild it!

[94fordguy]

So this summer I'm going to rebuild my 9. As most of you have probably read, I stripped out a bolt on my 900 causing a coolant leak and forcing me to think about the proper way to fix it for the long run. The original parts of the motor have about 4800 miles on them with over 2700 on it since it was last rebuilt just before I bought it. The original rebuild included a new '06 crank, mag cylinder, '06 pistons, and a stator.

If I'm going to spend the money to rebuild the thing again I want to do it right so I think I'm going to replace that mag side cylinder so I don't have to worry about it. The question I have is should I replace the PTO cylinder while I'm at it as the PTO cylinder is original from 05 and has 4800 miles on it? I'm worried that replacing 1 cylinder and leaving 1 with that many miles on it might cause problems or cause premature wear.?.?.?.?

I wasn't planning on doing a new crank in it since it already has an '06 crank and the top end will run me $1,100, I'd hate to throw another $1,300 at it if I don't 'need' to.

I'm looking for thoughts and opinions as I haven't fully made up my mind yet. It may have 4800 miles on it, but I still love it and want to put a few thousand more on it before I retire it.

Thanks!

 

[letsgosleddin]

i have 2 '05 cylinders in the garage with 1200 miles on them. might be a cheaper way to go with swapping both of them. Im a believer if your going to swap one, do both, so you dont have to worry about one being weaker than the other.

 

[guidoxpress]

i agree with ^^

i would try and get 2 used cylinders with low miles that are pretty equal or from same sled...most guys on here will hook you up with a set (im sure letsgosleddin is offering his to you, so i would jump on them)

as for the crank, i would leave yours, you can have your dealer do the crank runout if you want just to see...what i would do is just go thru it all good...and then spend your money and have dan do his MAGIC on your primary clutch, and get that baby a clean, fresh rebuild...the clutch is the #1 thing to crank longevity...and this will keep that crank spinning straight...

 

[94fordguy]

Thanks! Due to my current work schedule I'm not ready to begin actually wrenching yet, but I do want to start thinking about how deep I want to go and what options I have. I know there are a lot of guys here who really know what you're talking about when it comes to engine building, so thanks for letting me pick your brains!

 

[94fordguy]

Well I've picked up all my parts to get the sled rebuilt. Thanks to letsgosleddin for hooking me up with a great deal on some good looking used cylinders Along with those I got a brand new set of 06 pistons and new base gaskets to add along with the O-rings I put in the sled a few trips ago. I'm planning to tear into the sled next week and get it back up and ready for next season just as we finish our last ride of this season this coming weekend.

I've really missed not getting to ride the sled much this spring with these circumstances, and seeing it sitting in the garage slowly bleeding coolant on the floor has just killed me... Like I said before - I LOVE my 900 and I'm not done with it yet, I have a goal of seeing at least 6,000 miles on that odometer within the next few years.

 

[Cerialsledder]

6000 in the next few years? I can do that in a season and a half for ya if you wanna bring it my way LOL!!! We rode just shy of 4k miles this year hense the reason all my sleds need top ends now ... Oh well that's why they make replacement parts right? LOL

 

[94fordguy]

6000 in the next few years? I can do that in a season and a half for ya if you wanna bring it my way LOL!!! We rode just shy of 4k miles this year hense the reason all my sleds need top ends now ... Oh well that's why they make replacement parts right? LOL

I typically average 40 miles a ride, that adds up to right around 1K miles per year riding only on the weekends and now I've got a second sled to split the miles with so they don't rack up so fast. If I hadn't bought the 700 at the start of last year, my 900 would have over 6,000 miles on it right now!

 

[Cerialsledder]

I typically average 40 miles a ride, that adds up to right around 1K miles per year riding only on the weekends and now I've got a second sled to split the miles with so they don't rack up so fast. If I hadn't bought the 700 at the start of last year, my 900 would have over 6,000 miles on it right now!

Oh I do love it when you talk dirty to me.... LOL!!!!!

 

[05900]

Hey Now!!! You two are gonna get all those non believers panties in a wad talkin like that. Remember the IQ 800 is so much better !!

 

[Cerialsledder]

Hey Now!!! You two are gonna get all those non believers panties in a wad talkin like that. Remember the IQ 800 is so much better !!

I would take your 800 on any day with my 9 lol

 

[94fordguy]

WTF?????

Alright, I picked up a compression tester from SLP the other day and did a compression test on the 900 this afternoon. I wanted to make sure I got an accurate reading so I performed the test multiple times using different techniques (I've never performed a compression test myself before).

First time, 5 pulls throttle closed, 5 pulls throttle open, cold motor
112 PTO --- 98 MAG

Second time, identical procedure
125 PTO --- 98 MAG

Third time, 5 pulls throttle closed
137 PTO --- 118 MAG

Fourth time, 5 pulls throttle closed
127 PTO --- 111 MAG

I then replaced the plugs and started the sled and let it run for 5 minutes till the temp read 125, then shut it off and tried again (sled was smoking like crazy from all the oil in it as I haven't ridden or started it in 2 months)

Fifth time, 5 pulls throttle closed
127 PTO --- 111 Mag

Average of all 5 tests gives me
126 PTO --- 107 MAG --------- 15% difference

I'm trying to figure out why my numbers are varying so much even with a brand new gauge? All I can think is that maybe the more times I pulled on it, the more oil was getting pumped into the cylinders, helping seal the rings better, and artificially inflating the numbers from the original 'dry' readings?????

For the record, the last time the sled had a compression test was 3 years ago by the local dealer, and read 120-120. How's it possible for my gauge to show 127 on the PTO 1700 miles later? In addition to my coolant leak (the primary reason for pulling the engine down) I have noticed a performance loss over the last couple years. I've always run identical clutching and RPM, the sled just hasn't pulled as hard as it used to 3-4 years ago.

I'm rebuilding the top end tomorrow with my friend's help, I'm just trying to figure out if the amount of oil in the cylinders is why my readings are so different? It's also strange that the MAG is weaker than the PTO as the MAG cylinder is 2100 miles newer than the factory original PTO cylinder.

 

[Cerialsledder]

when the dealer did the compression test were the rings brand new, no break in? Usually the compression will go up as the rings scrub themselves in. What side was the coolant leak on? Base gasket not being tight enough allowing your compression to be off....

 

[94fordguy]

when the dealer did the compression test were the rings brand new, no break in? Usually the compression will go up as the rings scrub themselves in. What side was the coolant leak on? Base gasket not being tight enough allowing your compression to be off....

Dealer did the compression test at 1K miles after the rebuild, it's been 1700 miles since that test was done and I don't know what method or brand gauge they used to perform it.

Base gaskets are unaffected, the leak is in one of the head bolts that goes into the water jacket. O-rings under the head have about 100 miles on them.

 

[Cerialsledder]

That's just plain LoCo man... Never seen a difference like that unless one side was running leaner than the other..... funky chicken

 

[xc_rider08]

is it just me or does that compression seem awfully weak?


doing a top end is easy seth. just take your time and dont rush. if u gots questions u know my number.

 

[94fordguy]

is it just me or does that compression seem awfully weak?


doing a top end is easy seth. just take your time and dont rush. if u gots questions u know my number.

120 is typical compression for a 900 from everything I have read on here over the last few years... The MAG side is low and more importantly is also out of the 10% maximum deviation.

Ya, Mark and I rebuilt his 900 engine 4 years ago from the bottom up, it wasn't hard to do at all... mine should be even easier as we don't have to pull it out of the sled

 

[94fordguy]

Just for kicks I did a compression test on my 09 700 this afternoon while I was in the garage. I was curious what it would read given the same procedure - cold engine, 5 pulls, throttle closed. I did the test twice, and both sides read exactly 121 psi both times. After doing a search for what a 700 should read, I'm doing perfect... the 700 RAW CFI seems to average 120-125 psi depending on the gauge and altitude.

 

[volcano buster]

I've always done the compression test with the throttle open...

 

[05900]

You really cannot compare gauge to gauge due to " manufacturing differences " or operator error, type of fitment etc etc...
Your gauge new shows a cylinder difference worthy of inspection. Rings, Oil, Reeds all play a part as does temp and like Volcano Buster noted throttle position ??!!
How tired was your arm ?? What did you find?

 

[94fordguy]

Story continues......

http://www.snowestonline.com/forum/showthread.php?t=348411