My Long Rod Conversion Report

[The Fourth Wolf]

After Christmas I dropped off my 12 Pro 163 with 2,286 miles at A2D Sledworks in Anchorage for a top end and an LR upgrade.

I got the following:
-PAR crank & rods
-PAR 12.5:1 head
-SPI double ring pistons
-New primary spring (I had it clutched last year)
-Clutch weights adjusted
-The usual gaskets and fittings that come with a rebuild

Chad called me today to say it's ready minus some steering post bushings.

I babied this sled since owning it (Dec 16th 2012) and was curious to know how the inside looked--Good news and bad news.

Good news:
A compliment that the sled was obviously well cared for. I did have some very minor piston scuffing--much less than expected for a motor north of 2,000 miles. The rings were pretty well flaked but that was expected. SO, turning up the oiler and religiously warming it up works.

Bad news:
The brass gear on the crank that engages the gear that drives the oil pump was badly worn (I forgot what it's called). I was, in Chad's professional opinion 500 miles (give or take) from catastrophic failure. Progressive wear of that brass gear translates into faulty oil delivery and eventually it would stop oiling the motor enough. Or brass shards could foul one of the other bearings. Either way, bad JuJu.

Otherwise the crank was in good shape.

I'm curious to know why Polaris would use a brass gear in a high rpm application? Especially since the gear it engages to drive the oil pump is steel.

Next step--break-in. And I've got a hundred miles of untracked river powder tucked away for just such an occasion!

 

[frontierfire]

I had chad put the exact same thing in my sled last year on my new 13 pro and it rips you will like.

 

[pulltype_polaris]

That center brass gear on my 600 was worn so bad we weren't sure if that cause my engine to fail or it was just that close to failure. Kinda think that when anybody does a top end that they should try and get a good look at that gear. Pretty important since it drives both water and oil pump.

 

[dstrbdxpak]

100 miles of virgin pow...you sniffing and not sharing, Erik??

 

[Leaf27]

I'm curious to know why Polaris would use a brass gear in a high rpm application? Especially since the gear it engages to drive the oil pump is steel.

Next step--break-in. And I've got a hundred miles of untracked river powder tucked away for just such an occasion!

What did they replace the brass gear with? Or did they use brass again for your rebuild?

 

[IQRIDR]

There's no alternative to the brass gear. So it now has a brand new factory gear on it.

 

[NEWDUCK]

Purpose of the brass gear is to break if something were to stop its rotation. That way you replace just that and not a crank gear.

 

[The Fourth Wolf]

100 miles of virgin pow...you sniffing and not sharing, Erik??

50 miles up one side and 50 miles back down the other...

The upper Big Su is likely unridden (well, maybe a couple of trappers on Tundras have been on it but it's not tracked up)

 

[Woodsrider]

Bass gear

I was told that it is wise to fill gear area with grease to prolong it life.

 

[IQRIDR]

We pack them with Ski Doo Isoflex grease, it's amazing stuff.

 

[Fast_XC]

Turn your oiler up. I had a CFI 4 motor which had about 5k miles on it with no visible wear. Run it at about 32 or 40:1.
Neil

 

[IQRIDR]

His oiler has been turned up from very early on in his sleds life. We do that with every pro that comes in the shop.

 

[The Fourth Wolf]

Finally breaking in the new motor

Between the crap winter and my honey-do list I finally got some seat time on my new LR conversion.

Logged 111 miles today.

62 trail miles
49 back country miles

Went in to my friend's place with two buddies. Trail in was icy but enough loose snow on the margins to keep running cool for most of the trip. Temps read 145 or less most of the way but did creep up to 168 in stretches. Towards the end, anticipating better trail conditions I broke away wanting to get in some WOT time. Since I'm in break-in mode and running a high comp head I knew WOT intervals would be for 10 seconds or less. Sled ran flawless and was VERY torquey. I had 2285 flawless miles on this sled before the upgrades and it pulls SO much harder now.

I was able to get some sustained runs in the 8000 rpm range and the sled went into DET mode twice. I attribute this to insufficient octane booster. I'm in break-in mode running Non-Eth 90 pump with Torco added. That initial tank had 12 oz Polaris Blue and 8oz Torco for about 92 octane. Going forward I'm upping the Torco to 1 OZ/gallon (1Qt per 30 Gal drum)

Will monitor the Torco/fuel ratio carefully. So far so good.

The seat-of the-pants analysis of the LR? Mid-range engine buzz is gone. 5900 RPM used to be the "rattle trap", Now, that's gone. Engine is smooth through the powerband. Mid-range snap is nearly doubled.
Granted, it was the first ride of the season...but I'm sore.

Sled pulls and pulls and pulls.

If you're in Alaska, own a Pro and want the best in parts and workmanship, go see A2D Sledworks.

 

[BILTIT]

So you are saying the 12.5 par head is high compression? What elevation are you at? I ran the 12.5 at 2200' no det. On my long rod.


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[AndrettiDog]

We pack them with Ski Doo Isoflex grease, it's amazing stuff.

That's the super expensive stuff right?

 

[Sheetmetalfab]

Add some midrange fuel and that det will diminish.
Icy trail wont help.
I have a season or so on my long rod with 12.5-1 head and the added fuel really helped.
Chad set me up with the pcv.

 

[The Fourth Wolf]

So you are saying the 12.5 par head is high compression? What elevation are you at? I ran the 12.5 at 2200' no det. On my long rod.


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I ride below 6,000 feet. Usually in the 1,000 to 4,000 range.

I was under the impression that PAR's 12.5:1 head was higher than stock but I could be wrong.

 

[icr]

I think stock is 12.4

 

[BILTIT]

From what I understand stock is 12.0 vs par 12.5, just I wouldn't call that high compression myself. Just wording. I ran the par 12.5 at 2200 on non-E 91 with no det. I now run par 13.6 at 1800-2200 and 6-8500. I run about 25% 110 race when at low elevation. Haven't had it at the mountains yet with the higher compression head. Very noticeable increase in power down low though, gained 250rpm. Need to weight heavier (~2g).

I have a pcv map for the '11 800 LR&12.5 heads if you like, from chad. Might be different for the '12 though?


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[3beans]

Just I heads up I have a par 12.5 head from chad and his pcv tune for 92oct and I have found the sled runs best with 5gal av gas and 5gal premium. Torco works but I don't think it does what it says on the bottle.