Help: Need an "easily improvised tool"

[Rasputin]

The following is from Yamaha's parts list pages. This is for a 79SF which is what I have. Looks like Tapered Roller Bearings to me.

Tag Description Req Price
1 BEARING, TAPERED ROLLER
1 $34.64
2 BEARING, TAPERED ROLLER
1 $34.64
3 COVER, BALL RACE 1
1 $2.57
4 NUT, FITTING (137-23454-00)
2 $6.91
5 CROWN, HANDLE
LOW GLOSS BLK (backordered) 1 $0.00

[bikerphil]

Now, if I only had a way to get that bottom bearing off of the stem

A bearing splitter and a harmonic balancer puller coupled with threaded rod works well. Break the cage off first and attach the bearing splitter to the bearing sleeve lip. Or you can carefully use a hammer and cold chisel worse comes worse.

[Rasputin]

Comments for this Part Number
Lamric commented on Sunday, 18th January 2009
Markings on Bearing read "Koyo Hi Cap 32006 JRRS"
Lamric commented on Monday, 16th October 2006
30mm Bore x 55 mm Outside Diameter x 17mm Height
Lamric commented on Thursday, 9th March 2006
32006 taper cone bearing and cup

[motoman]

Some scoots come stock with the ball bearing races. My ST HAD them and changed them out for the AllBalls Tapered roller set.....that stopped the biggest part of tire cupping. Of course being a radial and front braking, never gonna get rid of all of the cupping. My Venturer has the original tapered roller set.

[fredintoon]

If you look at the manual, you'll see the original bearings in there were regular ball bearings, and there was no kind of seal or cap under the bottom bearing. Now-a-days tapered are the only kind sold, but if someone has a pure stocker, it would, I believe, have normal balls in there.

As to replacing the bearings, right now I'll be lucky if I can even get the bottom one off of the stem since they were put on so darned tight.

Hi Drake,
not in my Clymers it don't. The races are shown as plain cylinders which is bad drafting but there is NO indication that there's a ring of loose balls in there.
The XS650 has crowded ball headraces just like an old bicycle and the very first mod is to put Timkens there instead.
But AFAIK the XS11s all left the factory with Timken head races installed.
Wash the cones and rollers with kerosene and a dead toothbrush.
If the lower roller cone cleans up nice and feels smooth on a trial assembly you don't need to remove it.
If it feels bad you don't want it any more so you can get medieval on it to remove it.
Try a BFH & cold chisel placed perpendicularly to the shaft between the bearing and the tee forging.
Whack each side in turn to get the bearing moving.
There's only a short length of shaft that's made to fit the bearing so it ain't got far to go.

[draketrumpet]

Maybe I mispoke with my limited exposure to ball bearings. I wasn't meaning to communicate that there were loose balls, but something along the lines of the wheel bearings. Not tapered. That's what it looks like in the clymers, but I accept the possibility of being wrong, even the likeliness. I mean, I've only moved on to the street within the last 4 months, so, completely possible that I have no idea what I'm talking about.

[fredintoon]

Maybe I mispoke with my limited exposure to ball bearings. I wasn't meaning to communicate that there were loose balls, but something along the lines of the wheel bearings. Not tapered. That's what it looks like in the clymers, but I accept the possibility of being wrong, even the likeliness. I mean, I've only moved on to the street within the last 4 months, so, completely possible that I have no idea what I'm talking about.

Hi Drake,
I reckon you mean angular contact ball races? Agreed, the Clymer's drawing does look that way.
But no, I doubt they'd use those for a head race.
A crowded ball race (two hardened grooved rings and a circle of balls touching each other) costs half as much as an angular contact bearing and is twice as strong.
A Timken tapered roller race is more expensive than either but is ~5 times as strong as a crowded ball race.
You do find crowded races on race bikes because they have less friction and who gives a hoot about longevity on a bike that only runs a few hours between rebuilds?
I'd say that the recent trend to use crowded ball races in place of Timkens on race-bike styled street machines was another triumph of marketing over engineering.