TY Mono Rebuild by Rob Sloggett


Posted on November 30, 2017 at 9:00 PM



The bike was picked up and whilst running, it needed some TLC. The main issues were general tidiness and one footpeg hanging off. Oh and the rear shock was shot to pieces as I later discovered!

The end game was to attach a Rushden chair purchased from Jim Droughton and have a go at learning sidecar trials. I had been interested in this since the early 80's where a local chair crew (Ivor Manning and his son from what I recall) competed regularly on a Montesa outfit. But when offering it up to the bike it quickly became obvious that the rear shock was not really up to the job for an outfit. I wanted something that I could experiment with spring weights etc. so the obvious choice was to convert the rear to a twinshock set up, offer up a pair of RockShocks to which I had various sets of springs and whilst frowned upon by some people, have the Mono as a twinshock rear end. The bike was never going to be used in National Rounds, and if riding at Aqueduct I would just register as Air-cooled Mono class so no harm done.

Jim kindly offered to modify the rear swing arm with an adjustable angle set up and also fabricated some brackets to carry a universal rear mudguard as opposed to the standard molded TY Mono one. The logic here being we were likely to roll the outfit at some point so breaking a universal mudguard was cheaper than the originals!

Once all of the framework had been done, the frame and swingarm were sent off for powder coating and a yellow and black colour scheme was chosen. This was paired with a Yellow Shedworks tank cover and seat unit which I think in the end gave a really nice look.

On Bert White's advise, the sprocket combination was taken to an usually low ratio, the larger rear sprocket making first gear ideal for sidecar use.

Bringing it all back together, the only thing left to do was to attach the chair and play around with the geometry on a few shake down rides and "bingo", a nice viable outfit to play around on.

I must admit, I have thoroughly enjoyed learning sidecar trials. It is a different set of skills and much slower in the sections (with more thinking time needed) but a definite lack of people willing to go into the chair and a lack of events locally for beginners has sort of put it on the back burner.

With that in mind it was time to re-commission the TY back to a mono and following some rough running I took the decision to get the engine treated to a full rebuild courtesy of a club member and taken up to 270. Another club member helped with modifying a Gas Gas rear shock to fit (with new Hagon and Rockshocks being £300+).

The only other running repairs has been a replacement HT coil (following a DNF) although I did buy a new CDI unit and pick up coil which are on the bench if they are needed. The front springs were replaced with Magicals and the usual day to day maintenance such as fork seals, oil changes and regular brake servicing makes it a nice easy to maintain back up bike.

The bike still did not pull 100% and after riding Ian Emery's mono it was evident that the bike was "fluffier". Now I know that no two bikes are the same but I still think their is room for improvement. I have recently had the exhaust cut open and cleaned out / repacked and that certainly improved things. I have also put a smaller sprocket on the back and will see if that improves the rideablilty.

The only other thing I am playing around with is the carburettor. The theory of all of the fuel circuits and jets intriges me and the original carb is probably a bit worn so I have a brand new Mikuni VM26 on the bench along with a good range of jets, needles and slides. Someone has provided me with a base configuration and with the carb being so easy to access my plan for 2018 is to experiment during our practice sessions. Once that is done the only other thing that has been suggested to me is to take some weight off of the flywheel.

As you can probably gather from this, I'm a bit of a meddler but having been bought up by a Dad who was a mechanic and who use to maintain my bikes when I rode in the 80's, now I am older and have more leisure time on my hands I find it quite enjoyable starting to learn more about the 2 stroke engine. The TY is a great bike and I can't see myself parting with it.

I have got to close by thanking both Jim Droughton and Paul Cartwright who have been great in providing the time and specialist skills to do some of the bigger bits of work when I have been working away from home and have not had the time (or skills) to do it.


The Mono project. Twinshock to outfit and back to mono!

It seemed a good idea at the time, trade my Beamish 325 in against a TY Mono then bolt a sidecar on it. The sidecar was already bracketed for a TY Mono so that was the reason for the choice of bike. Whilst I liked the Beamish, I already had a twinshock (Bultaco 175) and whilst great in the stream sections, I could never really get the Beamish to grip in the muddy stuff so it was time to move on.