ty 250 mono aftermarket parts

[Ferretflasher]

Its quite amazing what a new carb can do !! No more surging or rough running ..... dont know whats wrong with the old carb but the new 'un runs very well !!! That old one would , if the revs are high enough, begin to self ignite or whatever and allow the engine to rev its nuts off even on a closed throttle with kill switch on. Must be a leak somewhere allowing fuel in.
NB also fitted new LH crankshaft seal while motor was in bits so maybe that was allowing some air in and setting the whole mad revs sequence off ????

[Ferretflasher]

Pinky rear fenders are now dis-continued from Japan ..... so if you want one .... too bad they are history !! Only white new available from now on !!

[Ferretflasher]

Have decided that a short-stroke mono is to be my next little project. The crank from an IT250 looks like it will fit the bill and with a few mods should do the trick. The standard TY crank is 68mm stroke while the IT crank is 64mm stroke, the IT diameter is some 15mm smaller (not a problem) and the crank width is 4mm less than a TY. 2 x 2mm shims behind the mains should centre the crankshaft and the overall width is the same at 220mm. Only area where it will cost me is having to reduce barrel base by some 3.5mm (maybe $30 machining) and the crank (actually $51) plus a new standard piston ($150) ... everything else I have laying about in the chicken shed !!
Anyway with a stroke of 64mm and bore of 68mm should give 231cc and hopefully a much more reving engine, the flywheel weight will be sawn off to give the engine a more modern reving feel to engine.

So if any one has an IT 250 rotting away in the barn or shed, get that crank out and start playing !

[Ferretflasher]

Received the IT crank at last ......... and what a difference in sizes. Dimensionally it is the same except the width, the bearing and shaft sizes are the same, so is the taper and the clutch end, just much lighter and more skinny. Naturally the stroke is now IT size (64mm as to 68mm) but with a few 2mm shims, it should fit !!
More later.

[Ferretflasher]

Slight prob spotted with the flywheel, the IT crank taper is smaller and so requires the corresponding IT flywheel to mate to it, cannot use TY flywheel. The IT flywheel must be the earlier one with the boss riveted on the inside. The ignition pick-up/trigger is also out by some 120 deg (because key-way is shifted by 120 deg) so the back plate needs to be turned so pick-up/trigger is about at 4 o'clock position as you look at it. Fortunately the fixing screws all line up so not too bad.

The trigger appears to work due to the key-way slot in the flywheel boss/hub passing over the trigger at TDC and it must sense the air-gap or change in reluctance due to the slot (it disturbs or reduces the magnetic field in that hub piece) and so triggers CDI box. Anyway not difficult to shift the stator around, just make sure wires are tucked away out of harms way.

[FM350]

If you are trying to make a TY run more like a Fantic, would it not be a lot less hassle to sell the TY and simply buy a Fantic?

[Bully fanatic]

Hello all. Just to answer FM 350, probably but nowhere near as much fun though. It is really enjoyable trying to make something work much better than original and a hell of a lot off fun. Sorry for answering for you Ferretflasher but I know where you are coming from. Good luck. Graham.

[Ferretflasher]

I have had Fantic's ............ and that's why I stick with Yamaha now .......!!! Better made, better built, better engineered, etc Not is same league unless you have a Chris special. As a point, just take the Yam clutch, its far superior and over half as big as a Fantic, they never slip and are super light with a good cable. All Fantics of mine were heavy.

Plus I can mix-and-match parts quite easy. So far the crank has cost equivalent $50 US and the flywheel will be same. Machining of barrel about $80 and the rest I can do myself. I am not trying to take-on the Montesa factory here you know,but just let anyone remotely interested know what they can do with an old Yam and a bit of practical shed engineering and the pit-falls I encounter.
The main problem with the old Mono was (is) weight .... anything that can be done to cut the weight can only improve a basically good bike further.

Onwards and upwards !!

[FM350]

The Fantic motors seem to work very well indeed in bog stock standard form, and was good enough to win several WTC's. TY is certainly a good choice for anyone who enjoys improving a bike though, and sensible changes do make the TY run quite a bit better. However in terms of running one in the air cooled mono class, a modified TY has to be pretty good to come close to a well built 245/305 Fantic, which dont need the steering angle changed, suspension upgrades, or extensive alterations to the motors.

[Ferretflasher]

I think we finally agree .... a standard Fantic is better than a standard TY .....I cannot argue over that as I have ridden both ..... but when both are modified then it's purely subjective as both are pretty good. However I could not afford some of Chris's goodies, for example he would NOT sell me a forged 70mm piston for the reed valve motor I put into a 240 Pro, neither would he sell me a slimline plastic tank of his. On the other hand, if I were to send him my bike and commission the work to be done, then no problem. Its just unfortunate that my pockets are a bit shallow!!! I still maintain a Team Hamilton Yam is about as good as they get except for Shirty's bikes .... but we cannot buy these now ....you HAVE to make them yer'sen cos no-one else will !! Not even Chris !! They don't exist in the market place anymore

However with the TY then I am not reliant on anyone, just ask the Thorpes or Scarlett's of this world what is best to do or what Shirty did with barrels, pistons, brakes etc .... and just do it myself. No good moaning about lack of brass ...... someone somewhere always has cheap bits for sale ..... example my short-stroke project. IT parts non existent here in UK but plenty is USA, prices low but offset with import tax into UK. Estimate $200 US with crank, flywheel + a new piston plus a bit of machining ...... you try buying an engine from Chris for $200 US !! $200 gets you inside Chris's workshop door ... thats all!! Then you start to spend!

Anyway watch this years Normadale series in UK, no-one will win over Dan Thorpe even on modern bikes ( he rode Hillsbro classic for zero !!!) And that bike is a shed to look at not some polished bling special dripping with un-obtainium ...... its a scabby shed to look at with a bent back wheel !!!