Trials Australia Forums

The left flywheel is TY250A and the right flywheel is TY250 BCDE

Ray this is to show how much/little I've trimmed the width of the steel band on a TY250B motor flywheel

Hi Everyone,

David, would it be a fair estimate that is about halfway between the "A" and "B" model flywheel effect? It is something that I have considered as both original options seem to be either side of what I would like.

Kurt wrote:
I've been working on a Cota 247 project.
The bike came with a Mikuni VM26 in place of the AMAL mk1 minus the slide, spring and needle.
Down to the local wreckers and I found a loose spring and slide and he had a selection of needles.
The Queen provided the retainer plate for the cable and needle.

Kurt, any chance of some more photos of the Queen? Is the clutch actuator arm under the motor?
Hopefully you have a good bike wrecker, they are super handy if you can browse through comparing parts. Our local one is well laid our and only do dirt bikes and I can find things fairly easily without assistance. My last visit did not help much as I needed a throttle return spring for this Mikuni, on the right:




It came to me with the TLAhhhhh, there was no inet manifold, no original Carby and an incomplete air cleaner. Just this 22 MM Mikuni and neither I or the previous owner know what it is originally off:

It interests me as it seems to not be common, two whole aisles at the wreckers dedicated to carbies separated into different makes, 2 and 4 stroke and even large and small but not a single one of these. The industrial supplies had a huge assortment of springs but none suitable! The 3rd bike shop I asked had a spring that fits so now I can try it.

Up until now I have been using to carby on the left off the BLOODY , as it is identical. The only difference is the 200 has a 98 main and 250 has a 100 main jet. My problem is I can't have both bikes ready to ride if they share a carby. The other problem which I can't seem to tune out is the variable idle and iregular smoothness off the bottom.

This is especially for Bullylover, but if there are other people who like this sort of thing then even better.
After doing without one since I inherited an antique Myford ML7 lathe in the 1980s, I''ve finally bought a 4 independent jaw chuck.
I'm wanting to machine an eccentric bush for some experimentation on my KT250 steering and only had a three jaw scroll chuck and a faceplate.
Luckily there's an active facebook group for these particular lathes and I found a person in South Australia was selling off their Myford parts which included this chuck.

Greg Harding wrote:Hi Everyone,
David, would it be a fair estimate that is about halfway between the "A" and "B" model flywheel effect? It is something that I have considered as both original options seem to be either side of what I would like.

Yes I think so Greg and it is indeed "Mama Bear" for me too

Looks a lot like this one Greg
https://www.ebay.com.au/itm/39317598319 ... SwXBxgQzKR

There's a couple of twinshocks for sale near me (a long way from main population centres)
They would both need attention before they could be used in competition.
If anyone is interested the listed location is Turkey Beach. I can't remember if they are on FB classifieds or Gumtree.
Anyway if anyone is serious about them I can go and have a look at them for you. It's about 20 minutes away from home.
A couple of friends have phoned me asking about them already so I thought I'd offer to check them out for others.
I don't want them. I've got enough KTs and Italjets are too new-fangled for my taste

Is that chuck a Pratt Bernard? one David? They are what came standard on the ML7s. My standard one is a 3.5`` one. I have only used the independant 4 jaw on mine once for an odd shaped part I needed to drill a hole in. They are very handy to have though!

Bully fanatic wrote:Is that chuck a Pratt Bernard? one David? They are what came standard on the ML7s. My standard one is a 3.5`` one. I have only used the independant 4 jaw on mine once for an odd shaped part I needed to drill a hole in. They are very handy to have though!

Yes Graham that brand. They are known for making good quality lathe chucks. The only new 4 jaw independent chuck I could get small enough needed to be bolted to a faceplate which put it a long way out from the headstock compared to this 4 jaw which has a recess and an internal thread built in.
I'm going to machine the ID of a bush to start with, move the job across a tiny bit then machine the OD.
The other fun thing is I'm going to bore the top triple clamp axle hole a few mm bigger by clamping it to the faceplate. The handlebar clamps will be very close to the bed on that little lathe but I've mocked it up already and reckon it will clear it. Photos when I do the job.

Hi Everyone,

David Lahey wrote:I'm going to machine the ID of a bush to start with, move the job across a tiny bit then machine the OD.
The other fun thing is I'm going to bore the top triple clamp axle hole a few mm bigger by clamping it to the faceplate. The handlebar clamps will be very close to the bed on that little lathe but I've mocked it up already and reckon it will clear it. Photos when I do the job.

David, it always amuses me that we generally end up with the same result BUT go about things differently. For example, the amount that you intend on offsetting the bore, I would machine the outside first and then grab it in a 3 jaw chuck with a packer on one jaw to offset it and then bore to suit. Are any of these gears suitable for your Myford lathe, try to ignore the phallic symbol in the background.

Also Thankyou for the link to Mikuni carby David, apparently there are originals and copies but I don't know how to tell the difference. Mine have the square inside a square Mikuni symbol on the Jets and I have seen jets without the symbol. This carby has haunted my memory until today when I realised I actually have 2 off them both with symbols on the jets:


This one was fitted to the TL 125S loan bike and it made it go much better than the standard carby even if it was a shade too big. Now back to the Mikuni on the TLAhhh, it is actually a better fit than the standard Keihin with 25.4 mm bore matching the manifold:

The standard Keihin is 24 mm inside and offset in relation to the manifold, in fact the TLR Keihin is a better fit ( match ported) on TL 125 manifold: