Let’s talk crankshafts

[Buckslyr]

So I am replacing the crank in my CFI 800. Crank is out of limits on the thrust washers, and the PTO shaft bearing will slide on the shaft with a good pull.

I’m looking either having mine rebuilt or replacing with a new oem fuji crank. I can have a standard rebuild done, lightweight rebuild, or built into a long rod crank. Price is all fairly relevant to each other.

do any of you guys have experience with the long rods? Some say the oem rod ratio is bad, others say the It’s the best of the 800s

any experiences with light weight cranks?

let’s hear your opinions

 

[1madbird]

I did a long rod light weight crank from Indy Dan. So far its been good. I think it has a little more vibration but runs good. Not sure if power is any different.

 

[TRS]

I would do the long rod and not the lightweight wheels. The lightweight wheels have added to quicker clutch component wear.

 

[boondocker97]

TRS, I know you put on a lot of miles so you have a bit of experience with durability. When you say the lighter crank leads to accelerated clutch wear, how much are we talking? 1/3, 1/2, 3/4 of the typical life? I'm not familiar with typical life expectancy of the Polaris clutches, just trying to learn how much effect rotating weight has on component life in the real world.

 

[TRS]

Some of the components are less than half. Weight bushings and roller spacers take the biggest hit. I’ve seen them last just over 200 mi.
When the roller spacer gives up, you will witness a slight drop in rpm(50-100) and doesn’t spool up as quick. Usually when this happens your spider is junk and you will need a new primary. It’s something everyone should check daily.

 

[Clarke673]

I chose to stick with my 12crank mainly cause it was in spec and im cheep. I look at It as once that mass is spinning it will keep spinning. Also in a turbo application. Since we are on the topic... anyone know who makes the best engine mounts for a pro? I remember seeing some updates but can't find them now. P.s. on your rebuild it won't hurt to balance the rods Pins and pistons to a tight tolerance! Every little bit helps in the long run ... out. Puns? Ehhh the light weight clutch cover and recoil Starter make sense even with a heavy crank engine. Im playing with some fuel system and cfi mods as well right now. MIght post up some stuff when the snow flys. Fuel cooler/filter combo being one. Another being a balanced set of injectors (mines effectively cfi4 now)

Also seen there is a new rubber vforce reed valve. Anyone have a set yet? Thoughts...

@TRS wow... thats bad. But then again I have went through 4 belts before in less than 200 miles so I guess it depends on the duty cycle lol

 

[sledhed]

Some of the components are less than half. Weight bushings and roller spacers take the biggest hit. I’ve seen them last just over 200 mi.
When the roller spacer gives up, you will witness a slight drop in rpm(50-100) and doesn’t spool up as quick. Usually when this happens your spider is junk and you will need a new primary. It’s something everyone should check daily.

Roller spacers? Items 7 in the image? I noticed Polaris has updated the part number for these, maybe they are improved... What do they look like when they go bad, they just disappear?

 

[TRS]

Yes sir, they wear thin or disappear.
The roller then wears into the spider, your spider is then junk. The fix is a new primary.

 

[Murph]

Agree with Tony. Stay with the full wheel cranks.
Overall, Axys cranks have been fairly reliable. My personal experience has been four broken cranks in three different chassis. I average 2500 miles per year.

As mentioned, Lightweight cranks also accelerated clutch wear. My weight bushings rarely lasted 200 miles— with Comet side washers installed. Also the moveable sheave bushing would wear excessively. Granted, a lot of this has to do with heavy Tahoe snow and my epileptic throttle riding style..... crank failures and excessive clutch wear were occurring on sleds set up with snug belt deflection, .020” belt to sheave clearances and .010-.030” lead in on Secondary so it wasn’t caused by violent clutch action acting as a slide hammer.

 

[MNBlizzard]

Who is everyone trusting to get new cranks from? I saw MCB has a nice package they call stage 3 that includes the fix it kit along with cylinders and the crank shaft. That all is about $2500. Is there a lower cost option to replace/repair?

 

[RickCA]

Agree with Tony. Stay with the full wheel cranks.
Overall, Axys cranks have been fairly reliable. My personal experience has been four broken cranks in three different chassis. I average 2500 miles per year.

As mentioned, Lightweight cranks also accelerated clutch wear. My weight bushings rarely lasted 200 miles— with Comet side washers installed. Also the moveable sheave bushing would wear excessively. Granted, a lot of this has to do with heavy Tahoe snow and my epileptic throttle riding style..... crank failures and excessive clutch wear were occurring on sleds set up with snug belt deflection, .020” belt to sheave clearances and .010-.030” lead in on Secondary so it wasn’t caused by violent clutch action acting as a slide hammer.

I just ordered an Indy long rod 800 for my 2013 pro, with his lightweight crank. I'm running his mountain weight balanced clutch. Are you telling me here in Tahoe I will be swapping out clutch components every 5-6 rides??? 200mi really?

 

[Murph]

I just ordered an Indy long rod 800 for my 2013 pro, with his lightweight crank. I'm running his mountain weight balanced clutch. Are you telling me here in Tahoe I will be swapping out clutch components every 5-6 rides??? 200mi really?

Depends on you- your riding style and maintenance schedule.

Customers/ friends know I pull my belt everyday I ride and clean my clutches daily.

I inspect my weight bushings regularly (almost religiously) and ANY sign of slop, I swap them out.

My riding style is not typical, nor is my maintenance schedule.

 

[RickCA]

Depends on you- your riding style and maintenance schedule.

Customers/ friends know I pull my belt everyday I ride and clean my clutches daily.

I inspect my weight bushings regularly (almost religiously) and ANY sign of slop, I swap them out.

My riding style is not typical, nor is my maintenance schedule.

Right on Murph. For what it's worth my sled is a 2013 Pro rmk. So I believe it already has a heavier crank than the axys 800 motors so maybe I'll be good. I'll keep an eye on the clutch and maybe pickup the weight bushing took from IS if they start wearing out to fast.

 

[chevy_man]

My local dealer won't sell me bushings anymore. Had to order from SLP last time.

 

[BeartoothBaron]

^ That's crazy! And idea if SLP's parts are the same or as good as OE? I had a roller go bad on my clutch; hopefully I caught it before it went too far and ruined the spider. I'm doing the top end thanks to a broken piston (suspect locating pin), and a new clutch on top of that would NOT go down well. Thankfully, I do have a long rod motor, so hopefully that means better than 200 mile clutch life. That'd be basically unacceptable to me; even with the tools and cheapest replacement parts, it'd be a pretty significant cost and time penalty. Then you'd not catch it in time sometimes, and be stuck with a new clutch.

Anyway, I'd definitely say no to a lightweight crankshaft (I think mine's the heavier version, but actually not sure). That said, YMMV, so maybe just keep an eye on it and see what kind of life you get. If your clutch is constantly burning out pins and rollers, I'd try to get ahold of Dan and see what he thinks. Adding a heavier clutch cover might help with that, although it defeats the purpose of a lightweight crank. Taking weight out of the rotating assembly just seems a little foolish to me - part of the reason I think the 9R is going to be an expensive motor all around - but maybe worth the cost to some...

 

[chevy_man]

Yup. I thought it was crazy too. They told me the whole weight is now the service item and if the bushings are bad they want to sell the whole weight.

 

[BeartoothBaron]

Yeah, I recently noticed the weight bushing thing. Fortunately, you can get those from SLP too. I just put a set in; we'll see how long it lasts. Pretty sure you'd never break or damage a weight other than the bushing unless something went really wrong. It's stupid that they want you to buy the whole thing, but hey, profit! Right?