Monday, 14 July 2014

Yambits

Fannying about in the back of your car trying to assemble a new set of forks is not where you want to be on race day. The fitting of my freshly re-hardchromed 6" over XS650 chopper forks should have been a doddle. (the XS wouldn't fit in the Berlingo whole + Mrs + 2 kids, so I used the previous short set to manoeuvre the bike to the car and had not yet had the refurbished stanchions on the bike).
When my normally calm, lateral thinking engineer's brain went into melt-down, I cried out for the help of See See Thor, and then XS650 race veteran Travis (photo above). But they were as foxed as me, why the fork caps would not screw down - it's normal to to have to exert considerable pressure to engage the thread, to stop the caps becoming dangerous projectiles, but these bastids were being ridiculously stubborn.
I had replaced the rusty pipe sections that had previously been used to fill out the space above the springs, with new PVC pipe of the same length (151mm). Apart from a set of new Hagon progressive fork springs (same length as the old shot ones), nothing else had changed....
Thor and Travis were both busy preparing their own bikes - The Sideburn Enfield, and Skooter Farm Dave's GS chop, so had to dash.
Then, a guardian angle in the shape of a hairy biker, Rod, racing his even more hairy, rusty springer Triumph also in the chopper class, came to my salvation. He noticed that the spring top was slightly mushroomed where it had been cut and flattened in its manufacture. The new springs were getting caught inside the stanchions at the top, so not dropping down as low as they should.
Thank fud I had my Dremel in my tool kit, second thank fud, there was just enough beef on the minuscule disc to grind down both tops.
Fast forward a year and I haven't done anything to the bike. I knew the fork travel still wasn't good and wanted to investigate Before the big day next Saturday. So I've just rebuilt them twice more over with a few tweaks.
The old fork tops - the 3-position pre-load adjusters, were properly shagged. But not all parts for the XS are readily available. After a bit of cross-referencing I figured YZ250 caps which also have a 28mm fine-pitch thread might just marry. These repro beauties are from the very friendly and efficient Yambits in North Yorkshire.
The lower oil seal retaining rib needs to be filed down a little (it still does its job). And an Nth has to come off the top section. But it fits!
Bangtidy. BP

17 comments:

747 said...

Mighty fine!
Go get 'em Ben!!!

Jon Lawson said...

North Yorkshire to the rescue .. ;-)

Adi said...

Good work mate. I was about to buy some Hagon progressives, would you buy them again or go with a different set given the issue?

Sideburn Magazine said...

Hi Adi
I bought mine from Heiden Tuning in Holland
- I didn't realise they were made by Hagon in the UK.
But checking their price afterwards it's much cheaper to buy them from Heiden!

On the box they are actually listed as 'Honda VF1100C V65 83>' which is a V4 factory custom bike otherwise known as a Magna.

Yes I would buy them again - maybe mine were just a bad batch. & even if they're all like this, it only takes a couple of minutes to grind the ends down with a proper sanding disc.

Adi said...

Thats weird they're cheaper than direct eh. 60 euros is very good. I need a set for the XS and the SR, I best check the same springs are totally interchangeable, I think they are, both are 35mm. Thanks ben

Sideburn Magazine said...

Adi NB not all XS650 or SR500 models have 35mm forks (the external stanchion measurement).

you can see in the 3rd photo down these springs are 24.8mm wide - thats crucial.

Heiden must have cross-referenced hundreds of fork springs before discovering that the Magna ones are compatible for the 35mm. So I wouldn't bother looking any further.

Ben

Adi said...

I've checked mine and both are 35mm I guess I should just confirm that there's no oher difference between those used on the SR and the XS. Both are 1978 and US spec too which is good.

Sideburn Magazine said...

....they are most likely exactly the same then.

if you check their original Yamaha part numbers they should match too.

Adi said...

I just thought ben, these springs from Heiden / Hagon are longer than stock arent they, do you think you can still use them on a lowered front end? I'm keeping my SR stock length but I was lowering my XS 2in with the spacers I have from HHB.

Adi said...

an interesting thread on the subject from a while back... http://xs650forum.proboards.com/thread/2321/long-fork-springs?page=1

Sideburn Magazine said...

Adi,
No these are not are longer than standard- hence my plastic tube to make up the difference. - these are 6" overs' = 151mm.

I think if you want to lower your forks, as well as the spacers you need to cut your spring down by the same amount???
(which is no big deal with a thin cutting disc)
BP

Sideburn Magazine said...

my new springs poke out the top 14mm before you put the caps on (under some pressure = pre-load).

You should try the 'Minton Mod' of drilling extra holes in the dampening rod too.

http://www.650central.com/tech/mintonmods.htm

Adi said...

Sorry mate do you mean they 'are' longer than stock or 'are not'?

From a quick look into this they are longer than the stock ones. Hagon - 525mm, stock 485mm.

Mine also has the adjustable dampers. I'll strip em all down, measure anc check stuff before I order them. Sounds like they'll be cool for my SR though.

Sideburn Magazine said...

Adi
we have enough info here to start are our Forking Blog!

My Hagon springs Are longer than the standard original fitment - But are designed to replace them.

(previously stated, I meant...) they are not longer than they should be because I've got extra long forks.

The adjustable tops make sense, but mine were fucked, & it's difficult / expensive to find new replacements so I went for the shorter plain ones.
I also figured I wanted less pre-load as the headstock is raked out.

Adi said...

haha. I'm massively confused now so I'll just go back to cleaning my chain.

Stevie Coles said...

That's why I like this blog.
15 comment's on fork springs!!.
Keep up the good work B, G, and M!!.

Adi said...

Hey Ben, here's the reply Hagon sent me yesterday, worth knowing...

"Our replacement fork springs are compatible for use on both XS650 & SR500 models, and are 24.70mm in diameter and 520mm in length.

The springs are progressively wound, so if shortening you will alter the characteristics of the spring depending upon which end you cut down. We are unable to supply any suitable springs that will lower the fork legs".