Initial Installation
Winter project 2013. Bought some tapered roller steering head bearings
to upgrade the '89 EX250 via
eBay from Australia, Pyramid Parts brand,
top 30mm ID, 48mm OD 13mm H, bottom 30mm ID 52mm OD 16mm H. The top
seal is about 52mm OD to fit over the 48mm top outside race, and the
bottom seal is about 56mm OD to fit over the 52mm bottom outside race.
Seems the bearings are each 1mm shorter than the All Balls brand.
Used car tires on seat to loft the front end. Did most of the
disassembly at around -1 deg C in the Ottawa garage. Used a drift to
tap out the races from the frame, and the 2-screwdriver method to remove
the lower race on the triple clamp. The tapping of
various bits on the triple clamp was done in the warm basement. Temperature in the garage now about -20 deg C so
the rest of the installation can wait for the next 'warm' spell.
Part Deux
When
reassembling everything, I noticed there was a problem with the lower
seal. It's designed to fit over the lower outer race. It would
work nicely if the lower outer race protruded from the lower steering
head tube. Unfortunately on the EX250, the lower outer race is buried
up inside the lower steering head tube, about 4mm worth.
When
the bearings make contact, the lower seal ends up pressing upward
against the steering head tube with a goodly bit of force and distortion, generating so much
friction I could hardly turn the bars. So I removed the seal and all is well. Then I reassembled
everything (again).
There didn't appear to be any way
to use the other seal on top either.
So if you're using this Pyramid stuff, I recommend not using the seals
they supply. Otherwise the bearings seem fine and the bike is all back
together, with the steering adjusted for no play and no friction. Test ride will wait for
Spring.
Test Ride
Once
the Ottawa snow disappeared (April 2014) and some rain cleared salt and
sand off the roads, I took the Ninja out for a few test rides. Steering
feels solid and there's no hands-off wobble so the preload adjustment
seems fine.