Lost my crank I think...

[sledhed]

Second to last ride of season for me, maybe 3 weeks ago, riding the Dragon 860 on way back to the truck, heard a funny kind of tinny sounding clanking and hit the kill switch. Checked the sled over for branches or obvious suspension issues, nothing, so restarted the sled and still sounded funny at idle, and the primary clutch was wobbling around way more than it should. Killed the motor and grabbed the primary and could move / wobble it around by hand. Bolt was not loose. Towed it back to trailer and brought it home.

Had a buddy tell me the exact same thing happened on his Dragon a while back and it was a broken crank at the pto rod journal and the only thing holding it together was the connecting rod, allowing it to wobble like I was seeing.

Pulled the head off the other day and there is no damage that I can see up top.

Having never done a bottom end on a sled before, how hard is it to replace the crank? What should I look for in a rebuilt one, or should I buy new? My understanding is that they interchange with the 11-15 Pro-ride crankshafts, knowing the 13-15 are better should I look for one of those?

Now I just have to find the time to pull the clutch off and then pull the motor out and put it on the bench...

 

[volcano buster]

Tear it down first to see what you have.

 

[sledhed]

I know, short on time (who isn't), I just sat down this evening and it is 9:45PM... I shouldn't be able to wobble the clutch around by hand for sure, I'll pull it first when I get a chance, since I recently replaced it with a new take-off that was balanced... hopefully it will come off easy...

Assuming I need a crank (I am pretty sure I do), what is the best rebuilt one for the money? Or should I spring for a brand new one? Not sure I want to drop that much coin into a 2008 sled... even with the 860 engine I don't think I can get more than the value of a good stock sled for it.

 

[Drewd]

I put a new crank on a 700 IQ last winter. It was not hard but took a little bit longer than an experience pro before there were a lot of firsts for me...first time pulling a sled engine, first time splitting a case, etc..etc..

You can do it yourself and save a ton of money. I'm sure IndyDan has a crank that will surpass the quality and reliability of the OEM one.

Since you have an IQ 800, consider a "fix kit" while you are working on the engine and other goodies such as a high compression head that you may be able to find used on Ebay.

 

[sledhed]

I put a new crank on a 700 IQ last winter. It was not hard but took a little bit longer than an experience pro before there were a lot of firsts for me...first time pulling a sled engine, first time splitting a case, etc..etc..

You can do it yourself and save a ton of money. I'm sure IndyDan has a crank that will surpass the quality and reliability of the OEM one.

Since you have an IQ 800, consider a "fix kit" while you are working on the engine and other goodies such as a high compression head that you may be able to find used on Ebay.

Likewise I have done top ends before, but it has been a long time since I split the cases on anything or pulled the motor... I have done the top end on this, and replaced injectors with harness, stator, primary clutch, but nothing below that.

Engine is a Carls 860 which is the ultimate "fix kit", got the sled in spring of 2012 if I recall correctly, for a price I could not pass up (basically the same as a stocker of the same year)... bottom end is stock except for some porting by Carls to fit the custom cylinder castings and porting. I think at a minimum I will rering it while I am in there, I would have to check but I think maybe 800 miles on the top end.

 

[sledhed]

It is apart... broken crank, and more piston wear than expected on mag side

So, the crank was broken at the rod journal pto side. Funny coincidence that I changed the primary clutch (put in a new take-off professionally balanced one) a couple hundred miles before. Also the exhaust side of the mag side piston showed more wear than the pto side, have no idea why, the prior set of pistons I took out looked way better than these do, so I am replacing pistons too. Got a crank coming (new take-out Fuji, the broken one is a Mape) for about $850, top end parts for about $600.

Pictures attached... of broken crank halves, small piece of debris in the bottom, pics of both sides of current pistons, and both sides of the last set of pistons I took out (which look way better even though they had 1500 miles on them vs. 800-1000 on the current set)...

 

[diamonddave]

Those look like a newer designed piston than the last 860 I worked on. I’m not really surprised by the piston wear as fueling the CFI-4 motors with the type of ECU logic Polaris used was sketchy at best. Partial throttle injector timing overlaps with full throttle injector timinglleft big holes in fueling. They are crazy lean in the mid range and cannot be ridden with steady throttle down the trail.

I would highly recommend if you’re going to put this much money into this and want more longevity, that you add a fuel controller either a Power Commander or Boondocker Box and tune it with EGT’s.

I set one up with Power Commander using the Dynotech map for 800’s and adjusted from there. Basically drowned the mid range in fuel til I lost runnability and backed the fuel off. I also had my Own Y-Pipe on there with EGT’s that the guy ended up buying from me. Didn’t have to venture far from the Dynotech map. Its amazing how crazy hot (lean) these motors get in the mid range and how quickly they do it.


Last I heard, that gentleman had 1,200 miles and had no intention on going in for a new top end.

Jacks reflash for the 860 makes for a good running sled but there’s more longevity available if you want it. The problem is differences between sleds, elevations, and the ECU logic of a control system like this requires each sled to be individually tuned.

 

[sledhed]

Those look like a newer designed piston than the last 860 I worked on. I’m not really surprised by the piston wear as fueling the CFI-4 motors with the type of ECU logic Polaris used was sketchy at best. Partial throttle injector timing overlaps with full throttle injector timinglleft big holes in fueling. They are crazy lean in the mid range and cannot be ridden with steady throttle down the trail.

I would highly recommend if you’re going to put this much money into this and want more longevity, that you add a fuel controller either a Power Commander or Boondocker Box and tune it with EGT’s.

I set one up with Power Commander using the Dynotech map for 800’s and adjusted from there. Basically drowned the mid range in fuel til I lost runnability and backed the fuel off. I also had my Own Y-Pipe on there with EGT’s that the guy ended up buying from me. Didn’t have to venture far from the Dynotech map. Its amazing how crazy hot (lean) these motors get in the mid range and how quickly they do it.


Last I heard, that gentleman had 1,200 miles and had no intention on going in for a new top end.

Jacks reflash for the 860 makes for a good running sled but there’s more longevity available if you want it. The problem is differences between sleds, elevations, and the ECU logic of a control system like this requires each sled to be individually tuned.

The sled does have Koso EGTs in it in the y-pipes, and the remapped ECU without a controller... I know it can differ from sled to sled, but what might be considered on the high side? I usually see mid-1100 degrees when climbing under full load, I have see a bit more at other times, but I generally try to be in and out of the throttle some like I used to on stock 800 Dragons (and did not have a failure there).

I was considering selling the sled after I get it back together and a couple break-in rides to make sure everything is OK, so adding a fuel controller and adding some fuel to the mid-range might make the top end last longer? I could snap a couple pics of piston wash (there basically none if I recall correctly) and post them up...

EDIT: Measured ring end gap on that mag side, .022, within Polaris specs... interesting... no notable wear or damage to cylinder anywhere either...