Yamaha TT500, a four stroke

After seeing a few TT500’s at the Telford Show this year, I found myself in Atherstone and Huggy’s Speed Shop.

Yamaha TT500 (1978)

A choice of bikes, including early and late XT’s and TT’s. Decided to plump for a later TT, with alloy swing arm and leading spindle front forks. Engine and frame numbers also matched which was nice.

More to come, as time permits.

Husqvarna WR250 Road Trial

I’ll keep the information on this page up to date as I get information about the bike.

Husqvarna WR250 RT Parts List

Bearings and Seals (all available from SimplyBearings )

Bearings :
Mains : 3205.BC3 (J.30)

Final Drive Sprocket Bearing 47 20 14
Gearbox 6303 NY (with snap ring)

Crankseal : 28 52 7
Drive sprocket seal : 25 35 7

Carb :
VM – 34
Emul Tube : 2-6
Main 150

Parts Suppliers

Husqvarna Vintage, Charlie Preston
+44 1509 815066 (telephone)
+44 7814104242 (mobile)

Jef Bens : +32 14 264653 (phone) +32 476 855613 (mobile)

Starting work on the Husky

I’d got the bike running back in October, but it sounded like the main bearings were completely shot. Also, the carb was full of old and decaying petrol, which needed sorting out.

I’d got some parts from Charlie Preston including a brake cable, bearings, air filter etc. However, whilst over in Belgium went over to see Jef Bens and see what he could help me with. The RT was a bit unique and whilst the engine is standard, the air filter housing isn’t. Unlike the CR and WR’s, which have the circular air filter housing with a metal connector to the carb, there is a rubber connector for the RT. Hidden away in the shelves, Jef found one, as well as a set of shoes for the full-width hubs for the RT.


Anyway workshop time involved getting the engine out of the frame and having a look at the piston, bore and starting the complete engine strip. Removed the Power Dynamo set up and then took out the engine mounting bolts. The lower rear bolt was a pain, but all of them gave the impression of having not been removed for a while.


With the engine on the bench, removed the four head / cylinder nuts, to find a pretty good fitting piston, with only limited wear marks on the skirt. Little end bearing and gudgeon pin also looked and felt okay. Drained the oil and then left it to move on to other jobs.

One of the main things was to look at is the petrol tank. I’d got a replacement tap., but the tank itself was internally pretty rusty. Looking at the interweb, I tried the electrolysis method which seemed to be pretty good.

Further stripping of the engine was okay, with the clutch side being fairly straightforward. One of the bike challenges was removed the front sprocket. Like similar vintage Montesa’s the sprocket sits on a taper shaft, rather than splines [Husqvarna changed to splits in 74 I think ]] and if it slips, it tends to weld itself to the shaft. I tried removing it before going to the [Telford show but failed. A repeat attempt with the assistance of Mark (and his Montesa specifically built pullers) also failed.


The engine then did a road trip with up to my parents. Only with the use of oxy-propane heat, a long chisel and a very large hammer did the sprocket finally come detached. Speaking with Charlie Preston it seems that in many cases, an angle grinder is commonly the only solution.


I’d also managed to find the original part, crankcase splitter (which is shown in the Clymer manual), which actually works a treat. One of the main bearings was completely bollocksed so hence the noise when running. The big-end bearing seemed okay, with no travel etc, but you never know and this might need replacing in the future.

Cases were easy to split and with the procurement of a oxy-propane welding kit from Welders Warehouse getting the bearings in, was straightforward.


More on the rebuild and further work on the Husky to come.

Classic Off Road Show : Telford 2013

Once again time to load up the van and head north (via Tredegar) to Telford for the auto jumble at the Off Road Show.

Despite not thinking I had too much stuff, managed to fill the trailer, though this included two bikes I’d acquired in Bargoed during the week. The Yamaha XT350 was a runner, with V5 though a bit tatty, whilst the Honda XL200 had a Chinese engine fitted with the Honda one as a spare. Both good value (I thought), but neither sold on the day.


Despite snow on the way up (seem familiar ? ), it was only rain for most of the day. Once again the gazebo came into it’s own …a great investment that. We’d arrived at 07h40 as per usual other traders and the early birds were swooping around the stalls looking for the rare bargins.


Taking the usual approach, of everything has a price, I managed to sell a lot of spares quickly, even if there were a little too cheap in some cases. Made for happy punters and some space in my garage. A lot more interest in MX250 spares than I’d seen before, though not much for SC500 bits and pieces.


Had a walk round inside around lunchtime and the usual crazy prices applied. In fact, not so much in terms of the motocross stuff, some of which has always been expensive, but more so for the trials bikes and spares. I’m amazed on what people want for a Montesa 247, which they’ll never get. Mark sold his 247, for a good price, but a reasonable and fair one. Two grand for a Montesa is stretching it a bit.


That said, there were some good deals to be done. XT and TT 500’s for a grand, which is good value given current market. Did a long look at an Ossa Explorer, which had I sold either the XT or XL, I would have procured. A nice looking machine with V5. Needed a lot of work, but a great project for sure. (Didn’t manage to grab a picture whilst I was there).

There were a few MX250’s, 360’s and SC500’s for sale but all a bit pricey and a bit too original to race. I need to do an article on race prepping these Yamaha’s at some point, because though they may spark, the original ignition units are pretty awful. Moving to PVL transformed the MX250, as well as some other tuning .


Chemical magic

One of the problems with sorting out petrol tanks is that some of the chemical liners that people did use now run the risk of interacting with the high-level of ethernol in petrol.

A little bit of research on t’Internet and I came across a chemical process. There are some youtube clips and a few alternate suggestions, but you may need some modifications yourself.

Getting ready to start.

Basically, I used :
– a transformer, 12v DC 2.5 amp. Whilst most people use car battery charges it seems, there is a snag. They are getting a bit too intelligent and my Optimate charger knew there wasn’t a battery in the circuit. Something from the model railway or Scaletrix I would suggest as a good choice.
– soda crystals, or soda carbonate. Tesco’s have it (ordered online for home delivery in my case). You’ll need 1kg of crystals for 10l of water, approx.
– a coat hanger, or something similar as the ‘sacrificial anode’; this is where the rust ends up
– a headlight bulb or a meter. I soldered in a 12v headlight bulb to give me an indication of the current passing through the circuit.
– some wire to make the circuit and some clips.
– a plastic cap, off an aerosol can, with a couple of holes in it and poke the anode through it.

Place the positive wire on the sacrificial anode and the negative on the tank, where there is a good connection. Make sure the anode is in the solution, which you’ve poured into the tank, and that it’s not touching the tank itself.

Electrolysis after a couple of hours

Turn on the circuit and the bulb will initially be quite bright. You will see the solution will effervese and bubble slightly and after a few minutes, the bulb will dim a bit. Within the hour, inspect the anode and you’ll see that there will already be a collection of rust on it. Clean the anode, the bulb will brighten again and repeat.

It’s an impressive process and you keep collecting rust as the process continues. I changed the solution after 24 hours and then repeated again. I’ve order some inline filters, but this should make the petrol tank useable.