HFS Front Fork Kit – Classic Trial Expert Mk 2

Words: Heath Brindley

Read Time: 8 Minutes.

Photos: Heath Brindley; Linda Ashford

Expert MK2 HFS kit supplied by Lorenzo Real of HFS Suspensiones de Moto SL, Spain.

Let’s give a bit of basic background information first. I picked up a totally standard 1980 Bultaco Sherpa T 199A a couple of months ago and did the normal thing of making a list of all the bits I wanted to change to ‘modernise’ the bike.

But after my first ride at a local Bath Classic club trial I realised that what I actually wanted was to re-live my youth, those great days in the mid 70s to late 80s riding in Kent and Sussex with my sadly no longer with us Dad.

So I returned home and threw the list in the bin, which my bank account would be happy with, and just decided to make a few basic changes to make the old Bult feel a bit better in my hands. But it has to be said that I’m not chasing results or championships, if it rides the good old fashioned sections at the local classic bike events I’m happy. I have a lovely TRS300 in the garage if I want to fall off things from a greater height!

The first two things on the old list had been to lower and move the footrests and get rid of that horrible ’tiller’ steering look of the standard yokes. What I’ve actually done is leave the footrests where they are and just modify some modern steel footrests to fit on the standard frame posts. I don’t want to cut and weld anything on the frame, just leave it original!
I changed the handlebars to a more familiar feeling set of braced Renthal bars. I took a gamble and went for the 5 inch rise. In retrospect I think 5.5 may have been even better but I can’t say it will save me any marks. The yokes have been left standard and although I’ve never been a fan of the look of the laid back bar mounts I have come to the conclusion that going to the expense of changing them won’t make any difference to my riding.

The engine is great, runs lovely and as far as i know is completely standard. It does have a Mikuni carb fitted, a previous owner modification and very common for this bike I’m told. Airbox is the standard 199A unit but with a 199B filter inside.

So down to the only major updates I’m doing, suspension front and back. The rear is easy, just pick your preferred modern made shocks and fit. The front is harder. You can go the route of changing or modifying your forks completely, but that’s not always allowed in the rules (if you ride championship type events) or can be expensive. And in my case I’m trying to keep the bike looking like it did forty-five years ago.

The problem with forty-five year old forks, Betor in this case, is that they are fairly basic. They went down … and up. That was about it. Internals were basic and often the only thing people changed all those years ago was the weight and quantity of the oil in it.

This is where the Spanish company HFS (Hybrid Fork Suspension) can help – yes it took me a while to get to the point I know! They offer a few options to improve what you already have, at a few different price points.

I know I am riding a forty-five year old, not far from 100kg bike. I’m also riding at classic clubs which on the whole frowns upon stopping and hopping, not that I could do it many times on this heavy beast, so i’m going to be realistic and go for just a nicer front end that doesn’t try and push the wheel out on turns and rides nicely over obstacles that I fail to lift the front over. 

I prefer a fairly soft working fork, I had tried some of the slightly longer new fork springs that I believe may be for Bultaco motocross machines but just found all that extra preload just too much. I experienced some front pushing on loose turns and my wrists reported that it wasn’t absorbing as much of the terrain as I would have liked! 

What I needed was some adjustable and progressive internals, but without the cost of the full air system that HFS also produces. 

Enter the Classic Trial – Expert Mk 2 fork kit.

As you can see from the photos the kit comes with different spring lengths, suitable spacers and adjustable preload fork caps to replace the originals. Most importantly it comes with a very good set of instructions that you need to follow to the letter to suit your weight and requirements.

First thing to do is drain your forks of oil and unless you have fairly recently done it i’d suggest either completely dismantling the forks and cleaning any sludge etc out of them or at least give them a good swish through with brake cleaner or similar. Obviously take the standard springs out then push each leg all the way down. The instructions give you measurements for oil height, which is more accurate than just pouring 180cc or whatever in there. It also suggests changes you can make to change the way the fork feels, oil height and oil weight. This is much easier to do with a proper fork oil height tool that you can see I have in one of the images here, but it’s possible with a stick and a ruler or similar.

Then consult the instructions again to see what the spring and spacer pattern is recommended for rider weight. Slide them in both sides and then adjust the preload to what is suggested as a starting point and do everything back up.

Whilst there is no external way to change the pre-load it’s only a few minute job to pop the caps off and adjust. 

A week later I had another trial to ride, and it was in a quarry and its surrounding woodland, which meant around half the sections were on rock or loose stone and the rest on slippery, muddy and rooty climbs with lots of camber turns. Perfect test for the new fork set up.

The best thing I can say is that I didn’t notice it! In that I mean that I was no longer experiencing the front pushing out on the turns, gravel or mud. There were two sections with fairly abrupt drop offs and I saw several over the bar moments and a lot of riders being caught out by the sudden drop as their forks completely compressed or snatched the bars out of their hands. I had none of that, the progressive nature soaked up the normal small bumps and roots etc but stiffened the end of the travel up nicely to keep me in control. 

I think the settings used from the instructions, set according to my weight, seem to be fairly spot on. I’m not saying that suddenly I have forks the same as modern Tech or Showa but it’s a much nicer experience now compared to standard. 

I’ve been made aware of several options to make the front end of these late 80s machines perform better, some of which aren’t either within the rules or not in the spirit of things. But I’ve not entered the older twinshock world to win things, I just want to enjoy a good day out riding period style sections under the rules of the day and having a laugh with like minded people. And you get to look at all the old bikes, and talk bollox! I’m really enjoying the nostalgia trip, I’m sad that my Dad isn’t here to enjoy it as well but that’s life. You’re a long time dead, enjoy the time you have. – Heath Brindley

Thanks to our ‘test’ rider Heath Brindley for this informative suspension test report.

Special thanks to Lorenzo Real of HFS for the Expert MK2 kit to test.

‘HFS – Testing Suspension’ is the copyright of Trials Guru and Heath Brindley.

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