What causes the rod bearing to fail on/m1000

Hardass · Mar 28, 2012

What causes all the rod bearing failures on the cat 1000 motor? What i have seen for failures that are very common are pistons coming apart Which could be avoided some what. But i have a huge amount of rod bearing failure on the crank end of the rod. Is there a way to help make them live longer? also is there a way to tell if your next? thanks

backcountryislife · Mar 28, 2012

I thought mixing oil heavy (like poo guys do) would save it, but I lost mine at 1900, and I had mixed at 32:1 it's whole life & back then I re-greased my cavity often... it was still thick when I tore it down, from greasing 200 miles prior.

Wish I knew a way to avoid it, that's what has cost most of the 1000's I know a motor, we all swap pistons early.

RACINSTATION · Mar 28, 2012

New pistons every 2000 to 2500 miles.

Crank rebuild every 3000 miles.

If you break a belt, YOU HAVE SENT A DAMAGING SHOCK THROUGH THE CRANK.

If you have broken a belt or two, it would not hurt to pull the crank and check runout.

Thunder101 · Mar 29, 2012

I dont know what kind of REAL sucsess there has been with these long stroke engines. 78mm is alot , the 9-862 at 76mm stroke was it that much better ? once you raise the peak rpm I think its a bit of a gamble IMO . On the smaller 7-800 cc twins we add pipes ect also but ussually the peak rpm is not changed. Reciprocating weight on those things must be 4 times the force .

jaysonfreerider · Mar 29, 2012

wouold loosing my oil pump cause this?

Hardass · Mar 29, 2012

No pump no oils Jason YA it would is your pump out?

WyoBoy1000 · Mar 29, 2012

Running lean in any sort would do it, why I always ran mine fat on bottom, not so fat it effected performance but always on the verge of rich.
Running lean just sucks everything through the cavity and it doesn't make its way to the bearings, if you really wanted to oil them you would need extra oil ports directed at the bearings.

IMO

After loosing one just as soon as I hooked up a PCIII that had a major lean bog on the bottom and ran to hot on top I am sure it played a role, 900miles on oil delete with a BD box and 1 ride with a PCIII and it went out. Theres more to the story but I am 99% sure running lean did it in.

mmsports · Mar 29, 2012

What I have found

In all the ported motors I have done the ones that run race no issues. The guy that does the mods and adds no octane looses crank. Pre detonation beating the bearing to death. My .02

Woody67 · Mar 29, 2012

Most I have seen fail have been modified with pipes higher operating rpm and many of those had chowed a piston or two while the owners were learning the nuances of a piped laydown 1000. Don't know all the causes but stock ones go alot farther usually before they lose a rod. Of course around here there are more modified M1000s than stock. I have not seen many mods make it 3000 miles on a bottom end. Not saying there are not any.

Woody

AaronBND · Mar 29, 2012

mmsports said:
In all the ported motors I have done the ones that run race no issues. The guy that does the mods and adds no octane looses crank. Pre detonation beating the bearing to death. My .02

And what exactly does having a ported motor and pre-detonation have in common? If you are running the stock head without higher compression and no timing key they do not relate? I would however agree with adding a lot of rpm's to them after porting or piping. This makes sense to me.

Aaron

WyoBoy1000 · Mar 29, 2012

AaronBND said:
And what exactly does having a ported motor and pre-detonation have in common? If you are running the stock head without higher compression and no timing key they do not relate? I would however agree with adding a lot of rpm's to them after porting or piping. This makes sense to me.

Aaron

He is talking about adding hp requires more octane.

In my case though at 10000ft I'm not even putting out stock hp with mods.

I also switched oil and like what I am seeing.

Hardass · Mar 30, 2012

So when you get a pipe set up and it says 7800 rpm that is going to take the rods out?

backcountryislife · Mar 30, 2012

MBMS said:
Most I have seen fail have been modified with pipes higher operating rpm and many of those had chowed a piston or two while the owners were learning the nuances of a piped laydown 1000. Don't know all the causes but stock ones go alot farther usually before they lose a rod. Of course around here there are more modified M1000s than stock. I have not seen many mods make it 3000 miles on a bottom end. Not saying there are not any.

Woody

Woody, mine was a non piped 09 (other mods though) that had never lost a piston. At that point I had never "BLOWN" a belt, I used carlisles, and the second a thread was pulling... I sent it back for a new one.

Got three buddies who lost rod bearings on stock or non piped sleds in less than 1500 miles too... I'd assume they blew a few belts though.

My motor before that one though... I ran piped, ported, full mod, blew belts to the point of combustion nearly every time, blew top ends (CONSTANTLY it felt like to me!! Probably a total of 6 top ends), had a lot of det the first 1000 miles before I was smart enough to avoid it.... and it went 3800 miles, then went in another sled & kept going.

Thunder101 · Mar 30, 2012

AaronBND said:
And what exactly does having a ported motor and pre-detonation have in common? If you are running the stock head without higher compression and no timing key they do not relate? I would however agree with adding a lot of rpm's to them after porting or piping. This makes sense to me.

Aaron

A ported motor when coming on the pipe can over stuff the cyl making it deto. we all know the pipe stuffs a/f mix in the pipe back into the cyl once on the pipe and some engines w pipes can over stuff the cyl to were the comp ratio says it should run on say 91 octane but bc of the super charging effect of the pipe you may need more octane, AND with P/V in the closed possition it will change the rpm of when the engine comes on the pipe so you could be cruising down the trail and easly have light deto= beating th rod. So mmsports you could be 100% right.

WyoBoy1000 · Mar 30, 2012

I wonder if to many motor mounts could effect it, would be interesting to see how long one lasted if mounted near solid.

But as big as the bearings are I think with the right lube getting to the right places it wouldn't matter.

dogtownbutcher · Mar 30, 2012

I'm running the extra mounts on my turbo 1000, so far so good at 2000 miles, this summer it's getting torn down and checked though.. One of our sleds all stock lost a rod bearing at about 1800 miles last year...I think they are all peices of crap when they break, but sure fun when they run good!!

Goinboardin · Mar 30, 2012

Some rookie, Poo rider's thoughts on deto:

Not a cat 1000, but my Poo 800 just went down, PTO rod bearing, deto with twin pipes. And yes, as was stated, pipes effectively increase the dynamic compression ratio so more octane is required. I have learned the hard way. Running lean edges you closer to deto, especially if you go a little too far, so yes running a little more rich than you can get away with has a tendancy to keep deto at bay. But more importantly; good fuel, good fuel, good fuel. Trying to beat that into my brain.

You have to think about what is happening when detonation occurs. The piston is on its way up, crank spinning away with alot of rotational inertia. Then your ****ty A/F mixture enters the combustion chamber, with too low of octane, so it is very volatile and ready to explode at much lower pressures than a more refined high octane fuel. The piston continues up, cylinder pressure hits auto ignition levels for that low octane fuel and the A/F mix explodes. That flame front hits the piston top, gases expand, and try to seperate the piston from the cylinder head. If the crank is trying to push the rod up, but the piston down, you either break plugs electrodes, pistons, or crush rod bearings (sometimes a little of each). I may be off a little on the nature of detonation: maybe the low octane fuel just ignites when the spark plug fires like normal, but the lower octane fuel just burns that much faster, so cylinder pressures peak before the piston makes it past TDC. Think about it, the rod pin is trying to go up. The piston is trying to go down. The weak link is usually the rod bearings.

I do like the point WyoBoy brought up. When we mod motors, we increase power output, but then go to altitude and then even with mods we're well below stock output at sea level. So for us high altitude riders, the argument that mods put too much force on a stock bottom end and is what takes them out is garbage, unless the bottom end in question was never robust enough to withstand stock (at sea level) power output.

Not a bad year for a sled to break though. ha

CATSLEDMAN1 · Mar 30, 2012

deto deto deto

I agree with MM, deto is main crank failure issue. Ignoring a lean spot in your fuel delivery and riding around that lean spot is not good thinking, maybe the best you can do for a day, but every time you go through that lean spot and you have deto its knocking flat spots on this lower end rollers and eventually when they get toooo flat from going past the deto pounding, things go to pot. Need new crank.

The question I always have is when you have a big twin with lots of rolling crank mass giving good low end, why put compression in these things ? big pistons are deto prone anyway, higher the compression ratio the less top end power you have, you want to climb a hill on the mat at 7500 not 3800 rpm, you want less compression not more. woop *** compression is good for a 440 snow cross sled looking for corner to corner power for 200feet. Hundreds of dyno tech articles have detailed this issue over the years. but you cans still buy high compression heads for big twins and a pipe stuffing more mixture in the combustions chamber making it almost impossible to avoid some deto. 1500 mile crank life is pure genius.

Woody67 · Mar 30, 2012

backcountryislife said:
Woody, mine was a non piped 09 (other mods though) that had never lost a piston. At that point I had never "BLOWN" a belt, I used carlisles, and the second a thread was pulling... I sent it back for a new one.

Got three buddies who lost rod bearings on stock or non piped sleds in less than 1500 miles too... I'd assume they blew a few belts though.

My motor before that one though... I ran piped, ported, full mod, blew belts to the point of combustion nearly every time, blew top ends (CONSTANTLY it felt like to me!! Probably a total of 6 top ends), had a lot of det the first 1000 miles before I was smart enough to avoid it.... and it went 3800 miles, then went in another sled & kept going.

Kaleb, I believe it. Thats why I put my disclaimer in there lol. My observations are based on the ones in and out of our shop. M1000s are an interesting sled and for whatever reasons some seem to be way better than others. And that goes for performance as well as reliability. I know over the years we would have groups of guys with same sleds set up the same and one would just smoke the other. Or one would seem to be very easy on parts and another would have every problem you could imangine.

Woody

m8magicandmystery · Mar 30, 2012

in a ported bigbore with a higher compression head with a 2.5 degree timing key is there any chance that a person may be better off using the stock timing key sometimes..??

What causes the rod bearing to fail on/m1000

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