Trials Australia Forums

Much to my astonishment and despair ........ after 40 years and 3300kms of faithful service.......... my beloved TY250A is now in need of a new chain and sprockets.

I actually use him for trail riding and patrolling after unruly cattle in the paddocks, so the standard 13(I think)53 tooth combination works quite well.

He ocassionally ventures to Denman, but it is safe to say that the gearing of the bike is not really the issue when analysing my placement in the field.

A quick scan of the net tells me that TYTrials in the UK can help with a dished sprocket but the gearing is 10/44 (a similar outcome to 13/53).

Similarly BJRacing can supply a 53 tooth flat sprocket and spacer along with any prefered size for the front.

I think we are talking 520 pitch which is fine.

Comments on how you all solved the same dilemma and happiness with the outcome would be great.

Alastair

Alistar,
How many teeth was the dished 428 pitch sprocket I gave you? Or did ya forget you had it

Alastair if you use a flat sprocket, the mounting screws/bolt heads need to be lower profile than the standard ones, or heads recessed or countersunk to prevent the heads from hitting the swingarm, and it can be difficult to prevent sprocket fasteners that screw into the hub from loosening without locking tabs.
The 520 chain kits with dished rear sprocket work well, but you might need a bigger rubbing block on the chain tensioner
Pretty sure TALON made dished 428 rears for TY250 a while back, but probably discontinued
When the original Yamaha dished sprocket wore out, my TY250A was fitted with a flat aluminium sprocket (a sprocket blank) and spacer bought from John Titman and it was held on with high tensile countersunk phillip's head screws. Despite using loctite I was forever having to retighten the screws. To get away from the re-tightening, I then bought a dished gold-anodised aluminium 428 sprocket from B&J Racing, which is still on the bike. I think they sold out of them a while back.

So your TY250A is a "him"? How can you tell?

Hi Gary. I am fairly certain that the sprocket that you gave me was 41 or 43. I had not forgotten about it, simply hadn't checked yet.

I was at Berrima on the weekend but busy making safety adaptions to my 85 years young dads latest off road machine courtesy of Southern Highland Motorctcles. He refuses to slow down ... So the task now is to keep him in the machine.

I have a ton of TY parts, just trying to retain them for the disasterous occasion when bits are unobtainable. TY BANKING if you like.

I am only assuming he is male David as to date he has never complained and has always risen to the task I have asked of him no matter how difficult.

It was just my assumption ... I hadn't thought about it until now.

I will make a few supplier email enquiries and report my findings.

Thank you gentlemen.

Alastair
0409 603 880

AS YOU WERE GENTLEMEN

We can all sleep straight in our beds tonight.

B&J Racing have confirmed they are in possession of a mountain of 53T dished sprockets.

Alastair

Sprockets arrived ... got enough to see me out ... but I suspect the mighty TY will still be going strong well past me pushing up daisies.

Alastair

tat ty wrote:Sprockets arrived ... got enough to see me out ... but I suspect the mighty TY will still be going strong well past me pushing up daisies.

Alastair

Alastair that is how I think about wheel spokes when I am respoking a TY wheel from some long-suffering basket case for the sole purpose of making a wheel look pretty.
Should I get shiny stainless steel spokes at a price premium, or zinc plated like the originals?
Knowing that the original basket case spokes suffered their 40 years of neglect quite admirably and that my bikes are kept clean and garaged in a dry shed, I'm pretty sure that zinc plated spokes will outlast me by many years.

So true David. Comes a time where vanity pales away to practicality.

To take it one step further David ... Occasionally I am asked why all my TY250s are "A" models, and why I have so many "trail seats" and footpegs relocation kits ?

The answer is twofold.

The "comfy seats" and footpegs kits have been accrued in provision for the day when our knees command their use. Perhaps drawing nearer than I like to think.

The A model issue relates to registration laws here in NSW. You can register an A model to ride on the road in NSW, and as such can ride in many national parks ... which means in times ahead when the "fun police" (thank you Gary Boniface) completely close in on us ... We can legally head off on our comfy A models and enjoy our day trail riding at a slow considered pace.

The only part of this still requiring refinement is my right knee against the compression ratio of the mighty TY.

Alastair

Shame on you Alastair - practicality should never give way to vanity when it comes to bikes... OMG what is the world coming to.

spare comfy seats????
unheard of!!