FOAK U/D fork fiddling

Today I returned from Magnum with an Avon club race tyre fitted on a
17inch 3.0 rim built on to a spare front hub for the YZ250.

I had carefully measured up clearances and checked tyre dimensions
before plumping for a 120/70. I went for the AM22 partly because I have
a suitable AM23 already that will drop on to the standard rear rim,
partly because I liked AM22/23 when I had the Husky, and partly because
there was good deal on Ebay for one in what, by the thumbnail test once
it arrived, is a nice sticky compound.

I had new bearings fitted while the wheel was being built and on putting
it in was pleased to see that my fettled oversize disc and caliper
fitted with fancy pads all came together without a hitch. It certainly
revealed how knackered the bearings in the old wheel were. Spun well
with a nice brake action, at hand spin speed anyway.

It was always going to be a tight squeeze on the way up through the fork
stanchions and slider protection guard guides but my calculations had
predicted a safe margin for error.

What I had omitted to take account of though was that the wheel is very,
slightly offset between the stanchions. The rim is perfectly aligned,
and I notice that the lad's YZ85 is similar, except offset towards the
brake side. I was pretty certain I hadn't left a spacer off the spindle
or got them in the wrong way, and quick check with a straight edge shows
that the wheel centre is perfectly in line with the centre of the
steering head.

I've used all kinds of dodges to try and measure that all will be well,
but can't be certain. Not being a fat bastard, I can't lunge the forks,
even with the tyre up against a wall hard enough to get the widest bit
of tyre through the gap IYSWIM. I can get it close enough to see it is
going to be close, but not enough to ensure clearance.

I can get the bike up on a stand with the forks fully extended and wheel
clear of the ground, so I wondered about taking off the top nuts so that
I could then let it down and the wheel should travel up to its limit.
Are the springs going to escape with great force and will I get them
back in to place again?

The conventional Marzocchis on the Morinis are fine in this respect but
I've never opened up U/D forks.

In the worst case scenario I reckon I can remove the slider guards and
guards to gain a couple of mm., as I know of at least one NHCA rider of
a MX bike (another 250 as it happens) that has done the same. No
shrapnel being thrown up by the bike in front on hill climbs!
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| Pete Fisher at Home: |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
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Ratchet straps?

 

Now there's a thought. I've got a pair of FOAD ones that use on the
trailer.

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+-------------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Yamaha WR250Z/Supermoto "Old Gimmer's Hillclimber" |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+-------------------------------------------------------------------+