Basket Cases

[David Lahey]

The M99 rear backing plate should have a chamfered edge that matches a chamfer in the hub.
I think the M49 rear backing plate should have an edge that is curved towards the brake drum. Both should have the two pins for the brakes shoes to pivot on. So in your photos, the backing plates are sitting next to the wheels that they match.
Yes the two holes are for the speedo drive.
I would like to think about your cryptic comment about my all alloy hub but there are no clues to start my thinking because I was not thinking about any particular motorbike when I was looking at it. It came in a milk crate full of rear hubs with no clues as to its origin.
As for your other cryptic message are you meaning that the " model 99 hub" might be from a model 66 which might explain why it has a skinny rim? A model 99 wheel should have a nice wide rim.
Your model 49 rear wheel in those photos looks just like mine except for the bolts in the small spoke flange where mine has rivets.

[David Lahey]

While thinking about model 99s, found this photo of my model 99 taken in about 1976 in the front yard of my parent's place at Balmoral in Brisbane. I was 17 years old and had just repainted it.
What a shame the rear hub isn't visible. I remember the chamfer on the rear brake plate though.
Notice the black, solid aluminium Inter-Am handlebars. They were fabulous.
This bike was road registered but I had the lights off it at the time to ride it in a trial.

[David Lahey]

So I decided to have a closer look at the all-aluminium rear hub I posted up a photo of a couple of days ago. When I lifted it up for a better look I found another all-aluminium rear hub hiding underneath.
I then realised that they are quite different and this might give clues to Bultaco experts who might see this posting to identify what models they might be from.
I see that one of them has 28 spoke holes while the other has 36 spoke holes. I figure the 28 spoke hub is made for a small diameter rim because old 18" wheels usually have either 36 or 40 spokes.
Both have 140mm diameter brake drums.
Does anyone know what s they are from?

[brent j]

I'd heard and read stories of how RL 250's can be hard on LHS main bearings, largely due to the extra flywheel weight and a lack of lube with pre-mix. When I got my TS250A engine (for the clutch mechanism) it had the oil pump and slinger in place. The RL cases are drilled and tapped for oil to the crank so I fed the cylinder oil feed back into the pump inlet line and dropped the 250A crank in complete. The TS crank is the same as RL and was in better condition than mine.
Now I have a dedicated feed to the LHS main bearing and big end. There is no cable to the pump so it stays in the idle position.
I'm running about 50:1 premix and the little Suzuki racing kit oil tank last about 3 tank fulls of fuel.

[Finally1]

Hi guys.What premix oil ratio should I be using in my RL250 if using synthetic 2T oil. I haven't owned an old two stroke since the 70s. I dont want to over oil her but am also mindful of keeping enough oil up to the left hand crank bearing. I have read so much conficting info so I figure whatever you guys, that are regularly riding them use, would be a better measure. Cheers.

[Greg Harding]

Hi Everyone,

So I decided to have a closer look at the all-aluminium rear hub I posted up a photo of a couple of days ago. When I lifted it up for a better look I found another all-aluminium rear hub hiding underneath.
I then realised that they are quite different and this might give clues to experts who might see this posting to identify what models they might be from.
I see that one of them has 28 spoke holes while the other has 36 spoke holes. I figure the 28 spoke hub is made for a small diameter rim because old 18" wheels usually have either 36 or 40 spokes.
Both have 140mm diameter brake drums.
Does anyone know what :Bultaco: s they are from?

You are on to it David, 28 spoke holes is what I got when I first laid eyes on that hub of yours. My first thoughts were Tiron but the hubs are different and looks like many more spokes to me?

1604183324980.jpg (149.92 KiB) Viewed 2741 times

While we are going, I think this is outside Post Classic Era but has 28 spokes in a 19inch Akron rim:

1604183001694.jpg (172.56 KiB) Viewed 2741 times

Interesting as it skips spoke spaces that have never been drilled and no valve or rim lock holes, the valve comes through an unused spoke hole!

1604182980348.jpg (189.3 KiB) Viewed 2741 times

Now I have a dedicated feed to the LHS main bearing and big end. There is no cable to the pump so it stays in the idle position.
I'm running about 50:1 premix and the little Suzuki racing kit oil tank last about 3 tank fulls of fuel.

Love your work Brent, I always wondered what that bracket was for, it is a neat little oil tank.

Hi guys.What premix oil ratio should I be using in my RL250 if using synthetic 2T oil. I haven't owned an old two stroke since the 70s. I dont want to over oil her but am also mindful of keeping enough oil up to the left hand crank bearing. I have read so much conficting info so I figure whatever you guys, that are regularly riding them use, would be a better measure. Cheers.

Hi Mate, I am with Brent at 50:1, I use Castrol TTS in all of my old 2 strokes, the Town Bike gets ridden a fair bit and runs well on TTS

[David Lahey]

Hi Everyone,
You are on to it David, 28 spoke holes is what I got when I first laid eyes on that hub of yours. My first thoughts were :Bultaco: Tiron but the hubs are different and looks like many more spokes to me?

1604183324980.jpg

While we are going, I think this is outside Post Classic Era but has 28 spokes in a 19inch Akron rim:

1604183001694.jpg

Interesting as it skips spoke spaces that have never been drilled and no valve or rim lock holes, the valve comes through an unused spoke hole!

1604182980348.jpg

That is seriously dodgy spoke work there Greg. As well as the deliberately missing spokes, it looks like not enough rake on the spokes. Surely that's not the original rim for that hub

[David Lahey]

As for my 28 spoke rear hub, I finally decided to do a google search and was rewarded with someone selling a set of 28 spokes for a Mercurio. With that info, I then did a google search for photo showing the back wheel of a Mercurio and there it is.
One mystery solved. Now what about the 36 hole all-aluminium rear hub?

[David Lahey]

Seeing I was on a roll working out the identity of old Bultaco parts, I had a go at identifying the other all-aluminium hub which according to this UK eBay listing appears to be early Pursang. Wow
https://www.ebay.co.uk/itm/Bultaco-Vint ... 2546912588

[brent j]

Hi guys.What premix oil ratio should I be using in my RL250 if using synthetic 2T oil. I haven't owned an old two stroke since the 70s. I dont want to over oil her but am also mindful of keeping enough oil up to the left hand crank bearing. I have read so much conficting info so I figure whatever you guys, that are regularly riding them use, would be a better measure. Cheers.

You'll get as many answers as there are people to reply.
I run my PE250, TS90MX, whipper snipper and chainsaw on MOTUL 800 at 40:1 and the RL250 at 50:1.
With MOTUL 800 I've found that if I pull the head or pipe and look at the cylinder and piston I find everything covered with a film of oil but it burns clean and I'm getting about a year out of a spark plug.