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Discussion Starter · #1 ·
Hello there, I'm one of your newest members to the forum, and I've got a question. What all is involved with rebuilding a crank, generally speaking? I've got a '96 xcr600 and it seems I haven't read anything good on the engine whatsoever, and I don't want to be SOL in the middle of the woods someday. It seems that the conclusion is that the cranks need rebuilt and the oiling "hole" needs to be drilled bigger as there was a problem when the blocks were cast from the factory, so the PTO bearing side, or whatever, doesn't get enough lube.

Can it be done without machine work? Is it just as simple as replacing the bearings? What are your thoughts about the '96 triple? I'm really wanting to keep it. I got it last year and rode it some. It has 2950 miles on it and a new long track, 133.5". I really like this machine.

Any feedback is appreciated.
 

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Welcome!
Another case of the mono-block crank failure? Same thing happened to my 96 xcr 600. Crank twisted on me. These engines are great really, they have good smooth power, and are fairly light-weight for a triple.....if only Polaris could have made the crank stronger and better oiled it would be very reliable.
However, many XLT/XCR owners go thousands of miles without any of these problems. Lucky? Maybe. Most of the mono-block crank failures i've witnessed occured after the owner did something to the engine, such as: a rebuild, aftermarket pipes, or any mod work. For example, my 600 went 3500 miles on a stock engine with no problems. I felt it was due for a rebuilt top-end. Well, one week after i put in bored pistons and rings, the crank twisted on me at W.O.T.

I talked to several professional crank-rebuild shops that told me they could replace all the crank bearings and "true it up". However, when i brought it to the shop they all looked at it and said "NO, we will not fix it" because it has splines holding the pork chops together and that pulling them off and pressing them back together will result in an even weaker crankshaft. I think there was something else too, but i forget.

They all recommended me to a specialty shop that successfully fixes these cranks, but it costs too much, PLUS there was a 6-month waiting period!! So i ended up buying a USED crank for the same price. To make a long story even longer; the engine then ran so well i became afraid to drive it, so i sold it.

Now the thing with the oil hole being drilled out larger. I had that done to mine and it still twisted the crank! Why? Because i increased the HP of the engine with a bored-out new top end. The crankshaft simply cannot take any more horsepower or higher RPM than stock. But, some guys add triple pipes and have no problems.......i think they are just lucky. Eventually, they fail too just like another guy i know with this engine.

Here's my theory; I think the crankshafts fail due to a combination of a low-oiled bearing and that the crank can't handle the increased RPM of a modded engine which results in even more load on that bad bearing! The bearing fails from lack of oil. The crankshaft twists from increased RPM and increased drag from that faulty bearing Most triple pipes make more power at higher RPM's than a stock single pipe. In my case, i increased the bore size, resulting in more HP, which raised the RPM to around 9000 because it was not RE-CLUTCHED for the added HP!!!! I think that was my mistake right there! I was too lazy to re-clutch it to bring the RPM back down. My crank twisted at about 9000 RPM while flying through the ditches.
Many Fuji engines have the notorious outer bearing failure. It happens to Indy 500's and 488's too, albeit not nearly as often, BUT at least the cranks don't twist!!! Simply replace the outer failed bearing and it's good to go! I got 7000 miles on my stock Indy 500 before that bearing had to be replaced.

My conclusion is that you cannot rebuild the crankshaft of a Fuji mono-block triple without extensive work and maybe welding too. If your crank fails, its cheapest to replace it with a used one. I paid $300 for a used one, new from factory is a whopping $900. Rediculous. If your re-building, drill a bigger oil hole to outer bearing, replace the outer crank bearings because they are easy, keep the engine as stock as possible and keep riding it!

I miss the sound of a triple..

Good luck.
 

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Discussion Starter · #3 ·
Hey, I really appreciate your feedback. There is nothing better than getting the scoop on something from somebody that has owned one first hand. Thanks.

Well, as far as the engine goes, I don't want to mod it at all. The only thing the previous owner did was to put on the 133.5" long track kit. There are no engine mods at all. My dad seems to think that there would be some indication of wear before that bearing would go. He says the PTO side would probably leak, there would possibly even be some end play. But he's first to admit that he has no experience with snowmobile engines so he says he's no positively for sure.

I know what you mean about the sound of a triple......mmmmmmmmmm, nice. I just got back in to sledding last year, after not being in it for over 15 years, so I wasn't to "up to date" on what was good and what wasn't. I saw an ad in the paper for this sled last summer for $1600 with a bunch of extra's, new powder skis (old skis too), new carbides, and the new long track kit with 1.5" lugs, and a few little extras (2 gallons of Polaris oil mix...) I'm in Idaho and the people I bought it from were moving to Arkansas, (apparently they don't get snow down there....hmmm, [:D]

The only thing I think that possibly might need to be changed (because of the bigger grippier track) is the clutch spring. The one in there now is blue, and I believe that it was stock. However I see that the replacement is supposed to be Yellow/Green, so maybe it was replaced. I'm calling the dealer tomorrow to see if I can get a service manual for this machine anyway.

Thanks again.
 

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Originally posted by MegaMan
[br]Welcome!
Another case of the mono-block crank failure? Same thing happened to my 96 xcr 600. Crank twisted on me. These engines are great really, they have good smooth power, and are fairly light-weight for a triple.....if only Polaris could have made the crank stronger and better oiled it would be very reliable.
However, many XLT/XCR owners go thousands of miles without any of these problems. Lucky? Maybe. Most of the mono-block crank failures i've witnessed occured after the owner did something to the engine, such as: a rebuild, aftermarket pipes, or any mod work. For example, my 600 went 3500 miles on a stock engine with no problems. I felt it was due for a rebuilt top-end. Well, one week after i put in bored pistons and rings, the crank twisted on me at W.O.T.

I talked to several professional crank-rebuild shops that told me they could replace all the crank bearings and "true it up". However, when i brought it to the shop they all looked at it and said "NO, we will not fix it" because it has splines holding the pork chops together and that pulling them off and pressing them back together will result in an even weaker crankshaft. I think there was something else too, but i forget.

They all recommended me to a specialty shop that successfully fixes these cranks, but it costs too much, PLUS there was a 6-month waiting period!! So i ended up buying a USED crank for the same price. To make a long story even longer; the engine then ran so well i became afraid to drive it, so i sold it.

Now the thing with the oil hole being drilled out larger. I had that done to mine and it still twisted the crank! Why? Because i increased the HP of the engine with a bored-out new top end. The crankshaft simply cannot take any more horsepower or higher RPM than stock. But, some guys add triple pipes and have no problems.......i think they are just lucky. Eventually, they fail too just like another guy i know with this engine.

Here's my theory; I think the crankshafts fail due to a combination of a low-oiled bearing and that the crank can't handle the increased RPM of a modded engine which results in even more load on that bad bearing! The bearing fails from lack of oil. The crankshaft twists from increased RPM and increased drag from that faulty bearing Most triple pipes make more power at higher RPM's than a stock single pipe. In my case, i increased the bore size, resulting in more HP, which raised the RPM to around 9000 because it was not RE-CLUTCHED for the added HP!!!! I think that was my mistake right there! I was too lazy to re-clutch it to bring the RPM back down. My crank twisted at about 9000 RPM while flying through the ditches.
Many Fuji engines have the notorious outer bearing failure. It happens to Indy 500's and 488's too, albeit not nearly as often, BUT at least the cranks don't twist!!! Simply replace the outer failed bearing and it's good to go! I got 7000 miles on my stock Indy 500 before that bearing had to be replaced.

My conclusion is that you cannot rebuild the crankshaft of a Fuji mono-block triple without extensive work and maybe welding too. If your crank fails, its cheapest to replace it with a used one. I paid $300 for a used one, new from factory is a whopping $900. Rediculous. If your re-building, drill a bigger oil hole to outer bearing, replace the outer crank bearings because they are easy, keep the engine as stock as possible and keep riding it!

I miss the sound of a triple..

Good luck.
That was really informative for me because I own one of these sleds. I hope I am lucky and have no problems with mine. I also love the sound of the triple escpecially when it is a triple/triple like mine.
 

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Stuff600......you've got nothing to worry about because you have the SP or SE version of the sled in the Aggresive chassis which uses a completely different engine block! Yours in not the traditional mono-block, so no worries. Ride hard!

Just thought i'd let you know :)
 

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i have a 94 XLT SP. 5600 miles on it. Bone stock never rebuilt. been a great sled. selling it this year to move to something newer. but i would recomend it to anyone.one of my friedns with the same sled had crank problems but he had it piped. SO i have never even thougth of doing anything to mine because we were told when he got his fixed that these motors don't like mods.

Rich
 

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Glad to hear all of this. I have a 96 Ultra RMK with SLP pipes with 2,500 miles on it. Turns out this past Saturday, I gave the sled some gas to hop out of minor burial in the hills, and "clankety-clank-clank," the sled stopped. I opened 'er up to find the primary clutch laying on its side, and the crankshaft twisted off just outside the crankcase. I almost cried.

Now I read the forum...wish I would have seen this before hand...maybe I could have lubed the thing effectively before this happened. Now I'm out a sled, and have to shell out big $$ for a new crankshaft. Well...there's my sob story...my sympathy to all others who had (or will have) the same experience.

Nate
 

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for the most part those bottom ends are super strong, if the oil hole isnt there you can do it with a drill,
recreational does a good job at a cheap price, falicon can do the balancing, key it or weld it, and rebuild it,
 

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Its not a pleasing feeling to hear your crank is shot. I know, mine was. Its all rebuilt now and runs perfect...its now stronger than stock.

Its not a cheap repair, as I found out. Just be sure to have a reputable shop do it for you. Crank repair is NO place to skimp! Have it done right and it should last as long as you own the sled.
 

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I found a used but good condition crankshaft on ebay off a 96 Ultra...bought it for $160 to replace the broken crank on my 96 Ultra RMK. I'm going to install it next week. In finding so many posts about crankshaft twists/breaks from the extra 40-45hp introduced to the 680 engine by piping it, I'm almost thinking I may yank my SLP pipes and put the stock can back on. I just don't want to play with fire with this thing any longer...especially when I'm 40+ miles back in the mountains...all of the forum posts regarding this have got me good and scared.

Other than losing the gained ~40hp, I'm not too worried about the effects on my riding. I don't race or do lots of hillclimbing, and rarely put myself in situations of pushing 30-40" of powder up steep hills.

So, can anyone see any reason why I shouldn't reclaim more reliable crankshaft performance by yanking the SLP pipes and bringing the horsepower back to stock (105hp)? It's the only mod I've done to this sled (other than the tuning/clutching to accomodate the pipes). This sled is in great shape and I don't want to part with it. Advice would be appreciated.

MegaMan, your post really made sense to me, mechanically-speaking. A jump in horsepower from 105 to ~150 probably wasn't considered when Polaris first designed these cranks. Of course, you don't consider it until it's too late.
 

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Most of the crank problems with a mono block tripple are caused by the owner. The 2 biggest problems for the bearings, are not fogging the motor for summer storage and running the sled with a wore out clutch. You may get lucky not fogging your motor but it will catch up with you sooner or later. As far as twisting the crank goes that is usually caused by a high clutch enguagement and going from an idle to full throttle without bringing your motor up to enguagement speed before hammering it. Something has to give and if you have studs it will be the crank. In a stock form the mono block tripple is a good motor but add piped and other mods and be prepaired to do some crank work. Riley
 

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If you want to run your pipes, I'd definately have the crank rebuilt. I wouldn't run a used one. It may last a year or two, or it may last a day or two. Do you like to gamble? By your post it doesn't sound like you do.

If have the crank inspected/rebuilt by a reputable crank shop that knows you'll be installing pipes, you'll then have a little peace of mind that those extra 50 ponnies won't strand you some where. Its your call.
 

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I'm yanking the pipes today and bringing that 680 back to stock condition. I'll also have the local crank guru inspect the crank I plan to put in it before I get too far into the work. Thanks for all of the advice...this is a great forum.


There's a set of SLP triple pipes for a 96 Ultra for sale as of today. If you know anyone who wants some big horsepower on their 680, have 'em give me a buzz. The pipes are in Northwest Montana.
 

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akparasite the crank on the 680's don't have a problem. There are a number of aftermarket companies that build big bore kits based off the 680 Ultra bottom end that make some serious horsepower. There is no big problems with that crank. I am running over 160 hp in my improved stock 700 Ultra and the crank has held up fine. If I were you I would have the crank checked out and put it back together with the pipes on it. The sleds everybody is talking about with the crank problem are the XLT anf XCR mono block motors. Riley
 
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