On your crank bearings.

There is an assembly hole for installing the balls into the bearing races. Make sure this half moon hole in the bearing races are installed to the outside. If not installed correctly the balls will bang the assembly half moons every time they pass this area causing the bearing to fail prematurely.

On my job we found out why our gear boxes were failing so soon in the field for the same reason if the ball bearings were installed incorrectly

seems unlikely ? got any pictures ?

If you go to the 1986 shop manual it explains what I figured out 30 years ago with the gear boxes with the ball bearings put in a side thrust end play installation when they have an assembly hole. When installed incorrectly the inner race and outer race can force the balls to bang this assembly hole and suffer from a premature early death.
Go to the tech ref open the 1986 2t shop manual and look at the crank bearing installation info.

On the dynamometer test stand the gear box we tested lasted 72 hours running 24 hours a day.
We had no clue as to why they had a low bearing life. I guess the Swedes figured it out too.

This one way installation applies to all ball bearings with that assembly slot that's in the races.
Watch and pay attention when disassembling any ball bearing application.

With the assembly cut outs towards the seal with the solid races towards the inside the outer race is a shallow bath tub so it will hold the two stroke oil longer inside the bearing.

That only applies to the double main bearing on the ignition side. It has the oils channel grove that needs to be installed that way.

I have installed the latest version of this 3205 - plus note in has been redesigned and has two less balls.

The other bearing have no in and out locations. Interesting only SKF has been upgrading steel quality and design these last few years.

Others has really been doing value engineering. I don't mean Chinese either. In was interesting to talk with about this with four or five + manufactures and their engineers

on what that they are producing today. 3 Japanese companies, Swede based SKF and eastern european companies who were who I talked to.

SFK?
Not SKF?

GaryM is correct. Last year the closest thing I could find to replace my skf c3 3205, double row, 14 ball per row, metal caged, right crank bearing was a skf with 13 balls per row. Thats after talking to skf engineers who directed me where to find that replacement bearing. I called them after the first bearing I recieved was only 9 balls per row. 13 per row is what they make now. Motion Industries is who they directed me to for my bearing purchace. $102.00 I believe it was.

That is why I always tell people to only replace original Husky (or KTM/Penton, Maico etc) bearings if they NEED to be replaced. In most cases it is not possible to buy a new bearing of the same quality these bikes came with.

I purchased some of these double row ball bearings from www.mcmaster.com these bearings have less balls like you said. I used the lesser ball bearings with no problems on 250's. There. 's industrial supply house in New Jersey all the factories used them for many years. The have everything from fasteners to building supplies. I use them for fasteners to dowel pins etc. They also have very fast shipping.

The last set of mains I bought had the nylon separator... apparently the nylon allows an amount of "flex'.. which limits (in certain cases) the bearing from failing, as it would if it had the metal inners.. I had my doubts.. but now find that many of the new Katos have this style bearing.. still expensive tho..

Yeah,
Be careful skimpy on those bearings, cause I did that long time ago when you had trouble getting parts from Husky. It cost me a piston and new bore. Really got frustrating when I was loosening flywheel nut and the end of crank threads snapped of. I was even turning nut the correct way too! Took 3 months to get a new crank shaft on flywheel side.
On that slot in bearing. I dis assembly 3 engines and slot was up by oil hole.
Interesting after looking at 86 manual.

Using ZKL 3205c3 new force max capacity from Czech Repuplic.14 balls steel caged.

This is the $102 SKF high-speed high-efficiency bearing that Old Bike Dude mentioned. Its hard to pass up a less expensive bearing alternative when spending big bucks on a complete rebuild but one must weigh the cost of a failure like dartyppyt had. This is especially true of bikes that are raced or ridden with the throttle WFO most the time.

Look like a good bearing and like the cage on it!

http://online-business-news.blogspot.com/2014/04/how-to-choose-and-distinguish-skf.html

And beware of plastic cage bearings, stay away from those on the crank

I purchased a set of crank bearings (the ZKL 3205c3 New Force Czech Republic bearings) that dartyppyt mentioned a few posts ago. I got them from John at Vintage Husky for $85 per set! A lot cheaper than $200 per set for the SKF's.

I did some research and found that the main difference between the two bearings is the speed limit. The SKF's are rated for 12000 RPM compared to the New Force at 8000 RPM. However as far as I can tell the New Force is a bit higher in the fatigue load limit department.

I'm not an engineer and don't have any formal training reading these data charts so I invite you smart guys to check these data tables out and let the rest of us know if the New Force bearings can meet the challenge of a 7500 RPM 360 Mag engine or the 450 and 500cc torque monster motors.

The bearing of interest in the tables is the 25mm x 52mm 3205c3 and 3205A.

Just be careful which direction you install them in on the ignition side the half moon assembly slots go to the outside towards the seal. This allows the full lip of the bearing race to hold the two stroke oil in the bearing race area like a bathtub. The oil is captured. If we install the outer race with the assembly slot at 12 o'clock.

$102.00 USD

I might have four engines to rebuild. Maybe I can get a discount at a bearing distributor. I had a business before and got a discount from a bearing supplier. I wonder if a group buy would work.

I found out when I had the business there is a 100% Mark up from wholesale to retail most of the time. If it costs $20 wholesale it was $40 retail.