Summer maintenance check list for 06 M7 - 07 M8

[Janus]

I got my first sleds this season: two m-series, a 06 m7 and a 07 m8, both in their “mid-life crisis”. The M8 got 5000km and the m7 4000km. Here is the maintenance list I’d like to do. I am pretty new to sled mechanics so I am reading thoroughly the service manual and searching all the forums but since nothing beat first-hand experience, I have questions for you guys:
( i m trying to dump all of them in the same thread rather than making different thread... Since this thing is likely to get messy, I ll try to make a cleaner document at the end of the exercise summarizing what I did/learned)



- Engine:
[FONT=&quot]o [/FONT] I seized the M7 on my last ride. Not really sure why. After a hard pull (going up an icefield WOT in heavy slush) we stopped at the top for perhaps 10mn or so. It was rather warm outside (+5C). We then proceed to go back down. I was reving around 7krpm when after 1 or 2 mn max the motor shut down. The recoil was seized. We were able to spin the engine couple time actuating on the clutch itself. We then tow the sled back to the logging road. There I was able to restart it and ride back the 25km. As of today the recoil feel “tight” but the engine start. Upon inspection of the left cylinder through the exhaust port there is some scratching but hopefully not too deep. Compression test is 95 in the scratched cylinder, 105 in the other one.
§ Question 1: Why did I seize? Could it be the cold rush of coolant? I restarted too hard without enough warm up? Did I went too lean (hence coolant pump is dead)?
§ Question 2: I am going to put new pistons/rings but I wonder after the cylinder. I am short on cash and replating is like 300$. I read in few motorbike forum guys only refinishing the cylinder with a 3M scotch brite pad., lots of debate about flex-hone tools and other polishing tools. What’s the consensus here?
[FONT=&quot]o [/FONT]While I am at it, should I rebuild the M8 as well? As of last ride it was pulling strong I haven t done the compression test on it yet.
[FONT=&quot]o [/FONT]Clean air filters
[FONT=&quot]o [/FONT]Clean spark plugs
[FONT=&quot]o [/FONT]Empty gas tank
- Chassis:
[FONT=&quot]o [/FONT]Clean thoroughly
[FONT=&quot]o [/FONT]On one ride this winter I broke the steering column on the M7 and replace it. I am going to go through both chassis to find potential cracks. Is anybody has a check list of the classical failure spots? My A-arms are slightly bent on both sleds. Are those indestructible or should I plan on installing new ones?
[FONT=&quot]o [/FONT]Re-grease all the pivot on the suspension
[FONT=&quot]o [/FONT]Add grid to side panels for better clutch cooling
[FONT=&quot]o [/FONT]More zip ties to the M7 hood/panels (or is somebody got a very cheap replacement?)
[FONT=&quot]o [/FONT]Re-tension the track properly
[FONT=&quot]o [/FONT]Is there some particular bearings I should look after?
[FONT=&quot]o [/FONT]Set-up suspensions (damping/springs)
- Clutch/brake
[FONT=&quot]o [/FONT]Change the oil of the diamond drive
[FONT=&quot]o [/FONT]Clean thoroughly for dust and leftover belt pieces (I blew one hard last ride :S)
[FONT=&quot]o [/FONT]How to check that the clutch is in good shape? Are some bearings prone to break?
[FONT=&quot]o [/FONT]Anything special to check on the brakes?
- Electrical/pumps
[FONT=&quot]o [/FONT]I don’t have any engine light on, which is good, but is there anything else I should look after?
[FONT=&quot]o [/FONT]How to check the oil pump?
[FONT=&quot]o [/FONT]How to check the coolant pump?
[FONT=&quot]o [/FONT]How to check the gas pump?
[FONT=&quot]Am I forgetting anything else obvious?[/FONT]

 

[minet]

The three pumps are fine probably.

The m 7 needs to be tore down and replace all bearings..
dd.brake driveshaft.. skid idlers

Every bolt and part removed ... down to.just a bulkhead and tunnel . Inspected and re installed
It should get a new top end. . So gaskets and piston kit.
all.shocks rebuilt. . Figure 40 each
. Empty the gas tank and clean it with a rag. Then run a can 09 sea foam through it when you break in your top. End

 

[minet]

M8 same treatment

 

[minet]

Both primary and secondary tore.down. replace rollers on secondary. New springs in both
Inspect primary well. And wash both in dishwasher

 

[minet]

Oh your m 7 will need a renic acyl. So maybe look at upgrading to a big bore now. I know a guy with an 800 speedwerx 800 kit for that motor. . So the m 7 would use m8 pistons. .or.buy a used m7y cyl

 

[Janus]

thanks, sounds like a lot of work (beer nights) to me!

 

[Mjunkie]

You can't know about the cylinder until you tear it down and look but if it doesn't have any scratches real deep, I wouldn't hesitate to hone it (not with a scotch brite pad! Only a real hone). And btw, snowmobiles don't have air filters there shouldn't be much dirt on a snow covered mountain! There are the screens to keep snow out so maybe that is what you meant but they shouldn't get very dirty either for the same reason.

I'd check your motor mounts to see if any rubber is torn, definitely go thru the diamond drives, not just drain and change oil, but pull apart and inspect. As someone else said go thru your clutches and you're probably good to go with the other routine things.

 

[ultrasks700]

One big thing i always do is pull the skid out, and take the whole thing apart and go over it with a fine tooth comb. Inspect for wear and tear on any of the bushings, bad bearings, broken bolts, worn parts, ect. I them put everything back together and hand grease all the bushing. Then Torque everything TO SPEC.

it seems every year i find something wrong that could lead of failure later in the season...

 

[Janus]

I started working today beginning my the engine of the M7.
Looking from the exhaust port I was hoping that the seize wouldn't be too bad. I also redid a compression test this time with the throttle wide open.
I got 135 on the good cylinder but also 125 on the other. So I was optimistic.
I tried to flush the coolant the best I could by disconnecting the right hand side main hose. I gather 2L or so of coolant and it looked like the hose was lower than the cylinder. So I proceed to remove the head.
More coolant started leaking, perhaps 1/2L more. I don t think I got any inside the crankcase. I blew into the hose and got rid of the rest before proceeding to the cylinder bolts.
I then pull out the cylinder, one was pretty hard to get out, bent threaded rods in the back perhaps?
Then I inspected the cylinder, one is fine with very tiny vertical scratches. The other one is very bad... Here are some pics:
http://postimg.org/image/azsc681bp/full/
http://postimg.org/image/v1k8hnwoz/full/
http://postimg.org/image/v2u6b2yir/full/
http://postimg.org/image/fimskjoeb/full/

Here are gone my hopes of just having to re-hone the cylinder. It needs badly to be re-coated.
Any idea about why it seized?

 

[HIDY]

M-Rite from modrods

 

[vinpie1]

I rebuilt 3 M7's last year that smoked a cylinder due to a crank seal leak. They are just getting to that age...

 

[boondocker97]

Things I would look at for sure are: motor mounts, cracks in the bulkheads just ahead of the diamond drives, cracks in the rails around the bottom out bumper and bolt holes, remove diamond drives for inspection and tear down, secondary rollers and excessive play in the large movable sheave, clean/inspect drive clutch, new clutch springs. If you change the motor mounts, be sure to get a clutch alignment bar and make sure everything is still aligned when you are done. If the a-arms are just slightly tweaked then run them until you really hit something. A-arms started to be considered an engineered failure point starting around the mid 2000's and save the bulkheads from bending.

 

[fasta76]

Take them completely down.. Or you will kick yourself later.

 

[Janus]

I want a garage like yours.....
bad...

It would be fun to do a complete tear down/clean/rebuild.
But My sleds are in the common underground parking lots of my building.
Ain't going to happen.

At least I got the answer about why I seized:
http://www.arcticchat.com/forum/m-series-mtn/354213-why-did-my-06-m7-engine-seized.html
Seems like an odd coolant rush caused the deeds.

I hopefully finish to re assemble the top end this week, I am waiting for a buddy torque wrench, then I ll proceed to the diamond drive I think.

 

[fasta76]

Replace all your motor mounts and the bearings and seals on the brake side of you drive-shaft. Simple and good peice of mind when you're riding.

 

[Janus]

Allright, time for a quick update.
I need to give it back to minet. You were right, I had to tear down to whole thing... But I needed some help.
Living in the city my sleds are stored in an underground parking lot. No so much room for wrenching on them. Plus I m just an average mechanic.
I found an awesome repair mechanic who owns his own shop. He agreed that I could work in his shop (I brought my tools) and to give me a hand and advices when needed.
So I went and we strip down the whole sled. Lots of work was needed. We rebuilt the top engine, replace the intake fiberglass flaps, transmission bearings (brake side), diamond drive oil, clean up the chassis, half of the bearings on the skid were shot, the rest of them on their way, re-welded two cracks in the skid too, re-welded a crack in the engine y pipe, change the track for a better one, clean up and re-grease all bushings on the skid (including the one without grease ports), re-charge the air shock (it was down to 60 psi instead of 200), clean-up and re-polish the clutch.
This all I think of right now. I worked two 12hr days on it. Now we are waiting for couple parts to finish the job. One motor mount was shot, two plastic rail guide for the skid spring, two wheels for the skid, a rebuilt kit for the clutch rollers. And that should be it.
Only thing if I haven't started working on the second sled!
More fun to come.

 

[Firetrail]

Skid

Consider skid relocation brackets on the 2006. The 2007 should be OK.

 

[Janus]

Time for update.
After another 18h or so, we started the M7 and finished to rebuild the M8.
From what I recall:
Motor was fine, didn't touched it. Next year, I ll do the top end.
Rebuilt and re-align the two clutches.
The bushing at the bottom of the front suspension was out of place. The shocks was floating on the smaller diameter spacer... We bang out it back in place.
New carbide on the skis, and change the anchor point for a narrower stance.
We opened the diamond drive. It had been opened before and a bit of water had leak in. They were a bit of corrosion starting. Nothing too bad. We changed the main bearing, cleaned it thoroughly.
We swap the track direction as the teeth were too bent leaving not enough traction.
We disassemble the skid, full re-grease change the hyfax, and replace half or so of the bearings.
I guess that was it...
Oh total cost for the full rebuild the two sleds was around 2400$ ....
I guess not that bad but still a pile of cash for me.
Now I really hope they will survive this winter.
I can't wait for the snow!!!!!!!!