ty 250 mono aftermarket parts

[Ferretflasher]

Chris Kock attracts a lot of criticism when he rides that Cotswold of his but it is still basically a Yam mono but with 2 rear shockers, I see it every time I ride a Normandale round .......... and yes .... it is within the rules so fair din-cum !!
Phil's bike is however far from a original 300 bike ......... for starters it has the newer reed valve engine out of a 307 with bigger clutch, its built by Chris at Classictrials and can no way be described as original, it has ( from memory ) GG PRO forks inside Marzzochi outers and the head angle has been increased, etc ..........I shall confirm that next time I see him / it at round 7 on 7th August .... !!
Anyway my Yam Pinky suits me fine, a bit heavy, forks a bit wooden .. all I have done is give it a tubeless rear rim, 4 pot front brake and the Mick Andrews barrel ..... next job will be wide foot rests when make some brackets .......total cost so far ..... about 900 GBP .... ouch !! My best result was with the Bemrose round .... but that was scrubbed ... so I scored a big fat nowt !!

[FM350]

The bike Chris Koch rides is fitted with a motor which is just about as far as you can go with the TY Mono, and in comparison to a good piston port Fantic its not that great, and not comparable in any way to a good reed valve Fantic.

The bike Phil Wiffen used to win the 2010 is fitted with a reed valve motor, which is more powerful than the piston port motor he had used to win previous Brit championship series, but doesnt grip as well as the piston ports, so is not something that provides that much of an advantage overall.

Phil always used to have stock 35mm Fantic forks (to which it is impossible to fit 38mm internals), but all in all other than changes to the steering angle and footrest position, and fitting the later motor, his bike is pretty standard and cannot be compared to Majesty Yams or TLR Honda's which are nowhere near as competitive, and in modified form are now selling for £6K!

The TY mono can be improved with alterations to the steering angle and footrest position, and I would imagine a very close look at the stock induction system, as well as binning the very poor exhaust system would improve it quite a bit. TY mono remains an excellent clubman type machine, but not likely to be the first choice of anyone serious about winning an air cooled mono series here in the UK.

[Ferretflasher]

The results of the Redford & Bootle trials indicate otherwise but lets not argue & bitch like on TC.... just see who won and on what !!
Anyway the thread here is about after market parts for the TY Mono ...........well there ain't any anymore ...... you have to make 'em yourself now .........I have see how others do it ( the inlet ) and so gave it a go myself .... and if I can do it , heck anyone can !!
My latest project is a modified rear shocker that is some 28mm longer than stock and so shall see how that copes with a bit more ride height, dont worry though, it only cost me 18 GBP! Next outing is in a month so have time to see how it performs.

I have noticed though how Mono parts are getting more expensive on the bay, certain items do and will continue to fetch silly money, namely alloy kickstarts (same with all marques) and plastic seats & tanks. While I have plenty of engine spares, the forks and platics are a different matter, not possible to DIY here so you just have to pay out top dollar, but most other trick parts you can do yourself or get someone else to make.

[FM350]

Chris will probably win the Normandale series this year, but as there is no one on a Fantic taking part who is anywhere near as good a rider as him, thats not altogether surprising! Have you tried Chris's bike I wonder, and if so what did you think?

[Ferretflasher]

Right ... moving on ........ shall try having a chat with Mr Koch at Westmoreland round on 7th about the engine mods. I meanwhile have now obtained a 70mm piston for the spare #2 barrel and need to modify it. Apparently the mod MA did was to fit a twin-shock piston into the mono with a crown height some 5mm lower, to counter this ... AND .... increase crankcase compression it was necessary to machine 1.75 mm off the barrel base and a similar amount off the head giving you some 3.5mm back !! This is a double-whammy because you get more scavenge pressure (estimate I have reduced crankcase volume by about 48-50 cc) and you recover piston top pressure, so double bonus.
Now twin shock pistons are typically cast items made with about 10 thou taper (sorry to mix my units) while a 70mm YZ MX forged piston is made with only 2 thou taper therefore the barrel can be bored out much smaller, I plan to bore my barrel to 69.88mm or thereabouts giving a tight fit. <Crown is smaller than skirt as it runs hotter and expands more> ....
This should bring the displacement up to some 261cc more in-line with the original Mick Andrews engine I have (but never opened it up yet to measure). Anyway once the barrel machine work is done (I can do the base machining my self) I have to pay for the rebore (32 GBP) and then can move on and see what needs doing next.

People may question the need but so far its been a case of copying the master plus the engine needed a new piston anyway and the machining can be done on any modern lathe, just use what you have access to !!

All standard Mono's do tend to be a bit gasping & weesly but my MA example certainly sounds far better and most of all never pink's unless its about to run out of fuel.

[FM350]

Is the Chris Koch Yam state of the art in terms of air cooled mono Yam motors then? All of the modified TY's I have tried tend to rev much more freely than the stock bikes, but grip less well in slippery conditions. Person in the UK to talk to about the TY mono is Nigel Birkett, as not entirely sure if 1980s type modifications are ideal for the conditions you find today, and he would be able to advise on this.

[Ferretflasher]

I have to admit that the little I have seen of the Koch bike is that it looks like a standard 53Y engine with its Jap Oil pump type clutch casing ... though I doubt if it still runs an oil pump !!
The stock bikes tend to be sluggish and suffer from excessive running-on with a closed throttle, this being a combination of flywheel weight and those poorly set up JK carb's. I do plan to try a flywheel minus the steel band, reduced weight by some 0.9 kg but will alter the engine characteristic considerable.
Nigel is still the remaining authority on mono's as MA is now retired but regarding grip I just have to watch Dan and Rob, both of whom run tubeless rear, so IMHO grip is down to rear tyre not the engine. As regarding ability, the mono can do anything within its limits ..... on a traditional no-stop trial ........... it was never designed to do today's trick technical stuff and would soon be out of its depth with what is last century's suspension. The front is non adjustable and the rear is too little travel ... and NO-ONE makes any rear shocks except a place in Holland but again too much money (400 euro!!) TY is not for technical sections within reason .......... but put Dan Thorpe into the equation ...... and then owt's possible.

I do ride my modern stuff along with the Pinky, yes its heavy and steering like a barge ... but its not so dated as you may imagine .... I can still clean stuff on both bikes the same it's just harder on the Pinky.

[FM350]

I admire you for having a go at a project like a TY Mono, as they need an awful lot of work to help them go well in modern conditions! They really need the chopper head angle altering, footrests moving, and most important of all a rear shock that works reasonably well. Back in the day the only real advantage the TY Mono had over the better TS bikes, was the rear suspension and soft motor helped them find grip with the rather poor tyres around then.

Have the TY Mono which won Brit air cooled mono championship a couple of times now, and will be interesting to see how it goes in comparison to the 5 stock TY Mono's I owned back in the day.

[Ferretflasher]

Dont quite follow that last sentence ....... is there a typo??

My whole point is that like every bike since Adam were a lad, is that the stock standard item is pretty poor compared to what the top men use or would build. Its same as any TS, those you see in the ACU rounds are not what one can easily buy.

[FM350]

I now have a TY Yam which won a couple of Brit air cooled mono championships. Mods on it have been carried out with modern conditions and tyres in mind, and will be interesting to see how it compares to the 5 TY Mono's I owned back in the day, which were totally stock.