Crank Main bearing codes / part numbers

[kiwi-craig]

the crank mains bearing code is:

NJ206ECP/C3 doesn't matter what brand, they look up the SKF reference then cross match

real important though to get ECP/C3 match

EC = Optimized internal design incorporating more and/or larger rollers and with modified roller/end flange contact

P = Injection moulded cage of glass fibre reinforced polyamide 66, roller centred

C3 = Radial internal clearance greater than Normal


I gave up trying to use the online timken bearing part number finder, bloody useless................

Over the counter OPTIONS

another bearing to look at:

brand: NTN NJ206 ET2XCS46 this available through KTM, part Number 50330082000

the code ET2XCS46 tell an interesting story

E = bearings with a carburised ring, allot more durable if the clearance run out under thrust loading

T2= nylon cage

X = special radius on the roller rings, same deal as E more durable when things are at the limit

CS 46 means the clearances are precisely set at 46 micron, thats between C3 and C4 ratings.

this is a pretty special bearing.

This is the KTM SMR 560 main bearing.

if you want to know what all the codes mean for NTN go here.

http://www.ntnamerica.com/search.asp?CSERI...E=1.1811&


I picked this up on an all old KTMTalk thread dealing with RFS SMR 560 crank problems, they kill main bearings apparently, the NTN was a factory "fix"

the NTN rollers (50330082000 CYL.ROLLER BEAR.NJ206 ET2XCS46)

last longer in the berg engines than the SKF.

IMHO its because the roller end radius on the SKFs is too sharp and their clearance range is too tight and varied. they spec C3 but some can be very tight and still fall within the C3 range whereas the CS46 on the NTN means they're sposed to be all 46 microns clearance which is nearly C4.

NTN also list a CS42 clearance option which might just be "perfect" for the SX-F engines

NTN NJ206 ET2XCS42

[harry_ss]

Great info!! thanks for sharing!!

[997GT3]

I contacted DRG for some ceramic crank and cam bearings and it looks like they are not available at a reasonable cost.They are roller bearings used in F1 cars and cost over $1500

Ceramic radial bearings are available however.But do not know if they will work in our engines???

[mickley.28]

has anyone had any problems with the stock sx crank bearings? I've heard of people getting over 100 hours on stock bearings and not sure why anyone would go with something different?

[997GT3]

has anyone had any problems with the stock sx crank bearings? I've heard of people getting over 100 hours on stock bearings and not sure why anyone would go with something different?

I don't think the stock bearings are problematic in these engines.But figured why not upgrade them while the cases are split.I would have paid $100 per bearing for the caramics because of their ability to roll with less resistance,low weight and longevity.But so far no dice :/

[sticko2]

Keep us informed of what you find out. I have run both the ecp/c3 (skf) -50hrs, and the ntn cs46 (ktm)-40hrs so far. Both without any hassles, and both set with an axial clearance of about 0.3mm (manual recommends 0.25-0.35). price wise they were very similar, but as you would expect the ktm one comes in slightly more expensive.