Gear Selector Problem

Before I dismantled the bike is was apparent that only two gears and a neutral could be selected in the gearbox. I'm not familiar with these bikes so I sort of work it out as I go. But I'm a bit stumped with this. The gear selector lever operates a shaft which extends through to the clutch side of the engine. This shaft the operates a pawl which rotates the shaft that selects the gears. The problem is that the shaft that the pawl operates appears to be either incorrectly assembled or missing a part. I'm not sure. The parts book is a little vague on how it should look.

The Pawl mechanism pulls or pushes on the pins that protrude from the shaft end. See how one of the pins does not protrude. I have an idea that it should however I'm not sure. The parts book doesn't help. Any ideas? I've posted on a few websites however no one seems to be able to assist. I may have to take this to a specialist however the one I use is very good but very unreliable. It could take months to get the engine back.

TA Clutch Basket

As is usual with unknown bikes there always seems to be another problem or two....or three.

The clutch was very heavy when operated so with the engine out it was time to examine it.

The tabs of the basket are very worn and this is probably causing the plates to stick when the clutch lever is operated. Now I could file them flat again however it is extremely unlikely that I would get each one flat and in the same position regarding the clutch plates. This would of course mean that I would be getting more pressure on some of the tabs and little on others. This would end in tears as the tabs that have more pressure would probably break and cause more to fail and then you have a bike travelling fast with lots of bits of metal flying around in the clutch. So I'm trying to source another basket or get this one professionally machined by someone who knows what they're doing.

Cylinders Removed

It's almost Christmas and I won't have much time for a couple of weeks but I thought I'd have a look inside the engine.

First the heads and cylinders removed. You can see in the photo below that the pistons are in good condition and have been purposely scuffed with emery to hold oil.

 Looking at the photo of the top of the piston it's obvious that this piston has never been run. There is no colour on it at all.

The bores are in excellent condition.

I removed the other cylinder and it was in the same condition as this one. I'll split the crankcases after Christmas. I've never worked on an engine with vertically split cases before (excepting lawnmowers) but I guess it can't be too difficult. Gotta work out what's wrong with the gearbox.

TA125 Engine Removed

Well it's been almost a year since I had the time to start on the TA. I did manage to get the 1972 GT380 going so that's ready for club plates. I will build a stand for the TA but just to get the ball rolling I took a heap of photos today and then removed the engine. Digital cameras are wonderful for anyone working on old bikes, cars etc. You often dismantle parts and don't get back to them for long periods and then you find that you can't remember exactly what went where.

For the moment I'll concentrate on the engine. The bike hasn't been started or anything since I got it and before I removed the engine I checked the spark and gearbox etc. Well there is only spark on 1 cylinder and the gearbox appears to have only one gear. This is a problem buying things sight unseen on the internet. But even if I had been aware of these things I still would have bought it.

Engine Out

And on the Bench

I am a member of an amazingly useful site - The TZ Website. It has a great range of resources and knowledge. I am posting on the discussion board. If you are interested in Yamaha Racing Bikes go and look.

I'm not sure what the ignition is on this bike, if anyone can assist in ID on it I would be most grateful.





The Tacho has perished rubbers and is mounted on an angle, I don't know why but the previous owner set the redline at 14,500 rpm. Seems rather high, I'll have the crank rebuilt as I reckon that the bearings will be cactus if he has run it at that speed.

Front Forks

Can anyone help me re the front forks on this bike? The previous owner didn't have dust seal on the top of the forks, just rubber concertina covers that he fitted. That's strange to me but what I really would like to know is why the front forks don't have casting to fit the front guard to. Other TA's have two threaded castings on each fork to take the mounting bolts. This bike has smooth forks, any ideas?

Thanks

Why This Blog Is

I did a fair bit of motorcycle racing in Victoria and SA in the late 1970's and early 1980's. I first was a sidecar passenger for a friend on (believe it or not) a Ducati powered sidecar. It was an old front exit frame with torsion bar rear suspension. The engine was a Ducati 750 sport engine which had been converted to 900cc using Ducati 450 barrells heads etc. The engine was prepared by Bob Brown and ran on methanol. As a sidecar it was not a success. The characteristics of the engine did not suit sidecar racing. We did place second in one race at Winton to Geoff Taylor, he had his TZ700 sidecar and it was a handicap race. The owner of the sidecar sold the chasiss and put the engine in a Ducati 750 sports frameand used it registered as a road bike. It was a very fast bike the engine suited solo use well, unfortunately he was till running it on methanol and that destroyed the fibreglass fuel tank. He sold it to bloke in Darwin.

I then bought a slightly later model sidecar with a Honda 750 engine running an 810 Yoshimura Kit. It was a pretty fast good handling machine however the Honda kept destroying engine bearings and crankshafts. This was when most outfits were running Kawasaki 900's or TZ750's. So with the engine expenses and the difficulty of getting a good passenger becoming greater I sold the bike.

I still wanted to race so I bought a Yamaha TZ250 'B' Model. I bought it from Uncle Dons Cycles in Bell St Preston. I can't remember the same of the rider (maybe Brendan Otto) he had on it at the time. I think it cost me $1800 with a stack of spares. 'Uncle Don'had bought the new 'C' model with cantilever rear end and the 'B' had to go. I was told that it was Greg Hansfords last Yamaha before he went to Kawasaki however whether that was true or not I don't know. Here is a picture of me on the bike around 1978 at Calder. I had changed a few things and had taken it for practice to see how it was going, I forgot my boots and so was wearing runners. I was just feeling how the bike was and didn't push it.



It was a great bike, cheap to run and rebuild, reliable and quick. The only problem was the rider. I was consistent, I never won a race. I placed quite often but never could crack it for a win. I should never have sold it but I did in 1983 after it had sat in the garage for a few years. The bloke who bought it put the engine in supercart and I don't know what he did with the rest.

In 1979 I went to Mac Park in Mt Gambier, I took the TZ but a friend gave me a TA 125 to take with me for a race. I had never been on a 125 racebike before. I did my usual mid field finish in the 250 races. However I had a few practice laps on the 125 and took it out in the 125 race. Amazing I was suddenly competative. I finished 3rd in my 125 race, I should have won, I lead three times but ran wide on the same corner three times and couldn't get back to the lead on the last lap. I was invited to start in the A Grade 125 race and ran off on the same corner once but still finished 6th in a field of about 20 bikes. I had a ball and loved the bike. I wanted to ride it again however the owner sold it while I was over there and I never saw the bike again.

I did buy a TZ750 sidecar in the early 1990's, it was a short bike rear exit. Amazing machine and just so fast. I had a great passenger and loved racing it. I mainly did club racing and some historic. However after a messy expensive divorce I could no longer afford the bike so I sold it. A collector in Wagga bought it for $6500, there were a stack of spares. I delivered the bike to him. I found out then that all wanted was the engine for his TZ750, the sidecar engine had fairly new sand cast crankcases from the US and as most TZ owners know, if you don't look after your crankshafts they will vibtrate and damage the cases. So many engines damaged that way.


Anyway, I wanted to go racing again and I was looking for a TZ250 or 350 however they have become so expensive I just couldn't afford one at this time. Then I saw a TA 125 on ebay. I bid on it and now I own it. The seller couldn't give me any history and I have no idea when the bike was last raced or started. It's in pretty good condition, I hate the colour. I will strip it down and make sure everything is ok. Probably give it a coat of paint and then take it out for a practice session. If all goes good I'll have a crack at racing it.


This blog will follow the process and the racing. I won't be able to start for a month or two so posting will be light till then. If anybody recognises the bike can you please email me and let me know.

Thanks.