Point for TONY!
Yes, straight cut TZ350 primaries. Now, normally, that would be a tad expensive, but I was fortunate that I found a guy with a damaged primary 1H4 (TZ350C) gear and... well we can come to that in a mo.
A couple of other things though, the 520 conversion sprocket and the TZ gear lever, although I will probably use rearsets that keep the normal UP for UP gearchange.
So, what next.....
Yes, opened up. I think the crank can come into the picture...
Yes, the crank. The RD (until the 2R8/9) uses the crank with lead balance weights. The weights do have a habit of becoming loose at high mileages. Also, adding weight to balance makes the assembly a little heavier. Yamaha had introduced a new crank for the TD/TR3 bikes that used large lightening holes either side of the crankpin to get the balance without lead weights. Yamaha copied that onto the 2R8/9 range 5 years later. So, 42 years later
I am using a 2R8 crank. This is nothing new on RD track bikes and provides a good crank at low cost. Yamaha also used slotted b/ends on the TD/TR3 rods for extra oiling so, I have got slotted rods. In fact, this crank came with the slotted rods from a previous rebuild. The outer bearings were tired but everything else is reasonable so, I have fitted new outer main bearings and we will go and see how she runs.
Overall, I think the crank is good for my shakedown stage. All the deflections and play values have been checked. That said, you can never be sure about the internals so, my policy here is that I don't mind If I have to redo it later. Things will go wrong!
One thing that you can also easily check on a "previously loved" crank is the small end eye where the needle roller goes. Check for any sign of wear or rust/pitting. If there is any, it needs a rebuild.
So, back to the clutch. There I was with a bargain TZ350C straight cut Primary, damaged! Well that is why it was a bargain, the splined centre drive extension was shagged (and I am not certain how, except, it may well have been due to failure in a race). I decided that I could design a way to mount an RD clutch outer basket onto the TZ gear. Now, the standard RD basket has four alloy drive posts that stick into an rd gear and have rubbers either side for cush. The TZ drives through the centre drive extension but, that had gone.
I decided to use 6 of the 9 holes in the gear to fit circular alloy driving pucks and rubber cush rings. My thinking is that 6 steel-riveted drive pucks will be strong enough, the RD just drives through the four alloy pegs. So, an OK 250D basket assembly was used. I drilled off the four rivet heads and punched out the rivets to leave me with the rear steel plate and the alloy basket. The old drive pegs were machined off the back of the basket and the bare basket was then set up and "clocked" on a special milling machine that could be set to give the very accurate placing of the 6 holes being used from the 9 in the TZ 350C gear. The steel plate was done similar, although one hole was welded up first. The configuration is nicely balanced, with the 3 pairs of drive pucks separated each by a single blind hole in the gear. You should be able to see the pairs of rivets and the edges of the pucks behind the outer steel ring. Now, I cannot claim the skill of the machining as that was done by my friend Mal!
Cheers
5port
