Definative main bearing thread

Nicklewis · May 9, 2015

Bearing bit in oil plug

Hi forum my berg had some oil spilling and I had to much oil (halfway in the window). So I think It spat it out the weephole.
Any how I thought to check the water pump seals on the oil side to make sure
So drained the oil and found a small half circle bearing race part with 3 small half holes for ball bearing and very small, no bigger than 10mm in dia if complete circle.
Along with some shavings on the magnet.
I have not stripped the engine so not savvy on the internals so please any of you experts know what this might be as the big bearing are huge and this is tiny in comparison.
Kind regards
Nick
USA Seattle

bushmechanic · May 9, 2015

do you have a picture?

can pull the clutch side cover off and the rocker cover pretty easy

manual found here

http://husaberg.org/service-manuals/17760-2005-husaberg-workshop-manual.html

Nicklewis · May 9, 2015

Reply

Clutch cover is off and I will take the rocker covers off tomorrow
No pictures I went to find it but It was so small I will look on the oil rags to fin it tomorrow it was so small it would be around 10mm dia and had 3 balls in the 1/3 segment
I looked at the engine manual and the only thing that looked close was the small bearing on the outside of the clutch rod where it met the basket I doubt it would make or through to the other side so not sure
It could be the outer ring of a needle bearing

ORANGEBERG · May 28, 2015

bushmechanic said:
the majority of failures in Australia were the 550 engine

the crank is heavier than the 628 crank and also has a smaller pin, the engine revs more as well

so compared to the 628 you have more forces spreading the crank, less stiffness to limit the spread, typically less endfloat and SKF rollers with sharp radii

Orangeberg worked out the NTNs work better and stands by them as a fix.

this is also the consensus among the RFS engine builders, in fact the NTN bearings were used in the RFS engines as an OEM part for some years so they get to see the difference on a larger scale

Love your work Bushmechanic

Borgschulze · Sep 19, 2015

Got this bike cheap, knowing it needed to be torn apart before riding it.

What's wrong with these photos aside from the totally screwed bearing race.

This is only the right side main bearing... need to get a 30mm socket before I can pull the other side out.

:giggle:

spanner · Sep 19, 2015

Ntn inner and skf outer the best of both worlds

Borgschulze · Sep 19, 2015

Yep... Pretty silly. I've got some new KTM boxed NTN bearings waiting to go in...

Anyone know where to get a rod for a good price for a 550? I think its OK for now, but can't see it being too far off. Cylinder is scored up too, haven't looked at the piston yet.

lachlan NZ · Sep 20, 2015

interesting read .
can someone tell me if there is more to this than the fact it got welded ?
"Was rebuilt because the previous owner was super fussy and he wanted to up grade the crank to the motard race spec by getting it welded."

as in was the motard engine different oem ? or motard people decided welding them was the final solution

06 fe550

cheers

bushmechanic · Sep 20, 2015

spanner said:
Ntn inner and skf outer the best of both worlds

other way round is OK; SKF inner and NTN outer gives 58 microns radial play instead of 46 (NTN inner and outer) and gives you the nice rounded roller end radius.

lachlan the welded pin just makes the assembly slightly stiffer .. they still flex like crazy but it is impossible for the crank to twist on a welded pin.

welded is better but not always good enough also very tricky to retain proper alignment during welding.

Borg; ask orangeberg about a rod for the 550 http://husaberg.org/husaberg/17970-orangeberg-back-workshop.html

spanner · Sep 20, 2015

Laser welding works good, no movement when done.
Costs about $100.

Borgschulze · Oct 1, 2015

Best way to remove the main bearings?

I've got some aluminium round bar, large enough to machine some bearing presses...

Tried baking the left half of the case in the oven at 275f for an hour, and using a socket to hammer the bearing out, but it wouldn't budge.

What about the right half? The hole is even smaller.

I've heard of welding a shaft into the race (to shrink the race)... but I don't have easy access to a welder unfortunately.

LemoneyF · Oct 2, 2015

I know it's probably not best practice, but here's what I did.

Remove the rollers and cage from both bearings. Lightly gas torch the area around the bearings, starting close to the outer race and circling to the edge of the crank gallery. I was concerned I was going to heat warp the cases so i did this slowly.

It took about 15mins per case and it still wasn't all that hot, I'd think about 120c by the way water just sizzled on it.

Then I took an eye dropper and squirted cold water into the races to cool them a bit. This might not have helped, but I did it anyway. Working quickly I then took a screwdriver and lightly tapped at the lip of the outer race in a star pattern. The left race came out easily, I repeated the process twice for the right.

Sounds like you have tight cases, give it a go it might help.

Borgschulze · Oct 2, 2015

I'll machine my bearing presses first, then bake the cases, and use the tools I make.

I'll try without heating the cases first... I probably didn't hit the bearing very hard because I'm not big on smashing things with hammers.

bushmechanic · Oct 2, 2015

I use 320F on hard ones it takes about 40 min in an oven to get there, you'll notice the oil reallly starts baking off toward the end

the roller bearings will just fall out after that, if there are ball bearings they can be very tight and need a drift and a big hammer, a press is better if you have one but its tricky with the hot case

ORANGEBERG · Oct 2, 2015

bushmechanic said:
Johns thread is full of good info but i noticed the last few pages have some people wondering what to do.

viewtopic.php?f=5&t=6195

the ideas here are not just my opinion, there are a great many good minds who have worked out what causes the failures and even better have tried a number of different solutions. the majority of these solutions are scattered through KTM talks RFS section.

what causes the oem roller bearings to fail ?

1) crank spread under its own weight is the main problem

2) misalignment of the bearing bore, seems rare, search lineaweavers posts

3) insufficient crank axial play (end float) with crank spread

what is crank spread?

when the crank spins, its own weight causes it to spread outward opposite the pin
when you add in the combustion forces they contribute further to the spread.

sorry for the crappy pic there is a better one i will add later

in this condition while running the axial play of the crank reduces until the forces deforming the crank outward are matched by the crank resisting deformation (a function of its stiffness)

if you don't have enough end float or stiffness for the weight of the crank and the rpm its doing your end float (axial play) will become zero

with zero axial play the NJ series roller bearings will experience side loads as they are now subjected to some of the force causing crank spread

well explained Bushy, may I add Bearing skid, when the NJ bearing has side load it stops the rollers in the bearing rolling and they skid around the inner race wearing it away.

Borgschulze · Oct 2, 2015

bushmechanic said:
I use 320F on hard ones it takes about 40 min in an oven to get there, you'll notice the oil reallly starts baking off toward the end

the roller bearings will just fall out after that, if there are ball bearings they can be very tight and need a drift and a big hammer, a press is better if you have one but its tricky with the hot case

So I should try 320F for 40 minutes, and see if the rollers nearly "fall" out?

Might save me some time....

I kind of didn't want to replace the counter-balance shaft bearing though, it's double sealed, and I'm not worried if any metal got chewed up in it...

The woodruff keys are VERY tight in the shafts... kind of didn't want to disturb that one in particular because of it.

bushmechanic · Oct 3, 2015

Ta John yes I agree, definitely skidding rollers is the cause of the damage and yes caused by excessive side (axial) loads which prevent the rollers turning freely

borg i reckon if they don't fall out after that tap the case onto a bench if still not falling out use a drift

FWIW the countershaft bearing usually has junk in it even with the seals it worth cleaning if not replacing

Borgschulze · Oct 3, 2015

Are we talking about the same bearing?

The one that the gear for the counter-balancer drives, and has the water pump also driven off of it?

I don't want to wreck the woodruff key, it's in there extremely tight... I tapped on it with a drift, and it didn't budge.

bushmechanic · Oct 3, 2015

yes same bearing

tourist · Oct 5, 2015

Has it been asked before - What happens with too much axial play?

Definative main bearing thread

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