feetupfun

1. I use different fork oil in different bikes, ranging from 5WT to 30WT. Bel-Ray, Maxima, Motul, Castrol, Penrite. 2. I have no knowledge of the dimensions of the forks from the first model 247. They are probably 35mm tubes, but may be a different length, travel or axle offset to the later 247 forks.

The spring and the square piece that the spring acts on function as a non-return valve or maybe a better term is an excess flow valve

Photo A is correct

It's usually easier to fit the damper rod and piston (plunger) in from the top but sometimes there is rust in the upper part of the tube so if yours is rusty you should either make it smooth or fit the damper rod from the bottom end. As for your other questions I don't understand what you are asking.

I've got a 1960's rear rim that width taken from a Bultaco so I'm not surprised to see that your old Cota has one too.

It certainly is 1975 vintage and looks exactly like mine apart from yours having a British fuel tank. I too have looked through on-line OSSA ID lists and not seen a prefix 43 model mentioned. I have a suspicion that your bike model may be very rare hence not well known enough to be listed. The production sequence number on yours (92) is extremely low which could also align with there being not many of them made. I'm wondering if it might originally been a 175cc Mk2 MAR rather than a 250cc Mk2 MAR

The tyre clamp size is the distance between the flanges in inches. 1.85 clamp fits rim with 1.85 inches between the flanges

Same here in Gladstone so far with small engine shops. I'm still waiting for a reply from Aspen

I'm in the process of trying to find an Australian supplier for Aspen 2

There's a photo showing the spring fitment on this expired ebay listing. Photo found in about 10 seconds using google search. After you open this link, click on "see original listing" for a big photo of it https://www.ebay.com/itm/Montesa-Enduro-125-H-Cota-247-Rear-Brake-Plate-p-n-3855-148-NOS-58M-1977-1978-/293384263589

I have no idea but there are lots of possibilities apart from him not bothering

Maybe that's not the reason he hasn't replied yet

Measure 10 pitches with a mm rule and divide by 10 to get mm pitch

If that's the original seat/tank unit, it's the last version of the Cota 247. I'm thinking it would have been made around 1980. Here's something to help you with ID http://www.southwestmontesa.com/modelyear.html

If you have got it, why can't you measure the pitch?

It's normal to release the brakes to take the brake plate out of the hub. You don't have to take the chain off the bike but do need to take the chain off the rear sprocket. After you undo the axle nut and the brake link, slide the axle forwards to slacken off the chain tension and it will usually come off the sprocket. I see at least one missing rear wheel spoke. Yes it's common to fit a tube in a tubeless tyre. That rim/tyre combination won't hold air pressure without a tube. You will need to set the wheel alignment and chain tension when you put it back together. You can make a mark if you want, but are you sure it is set right at the moment? That dodgy-looking brake return arrangement is to stop the brake sticking on so you may find that there are problems inside the brake hub that are causing it to stick on (missing/wrong spring, worn linings, worn brake drum). Looks like someone has extended the length of that brake arm too.

If you google search "Cota 247 images" you will find plenty of photos of what yours originally looked like. Some things that will enable you to tell your model from other 247 models are: Your model fuel tank is more bulbous than later models. Your clutch arm is under the motor. Later it is on the top. Your fork sliders have a distinctive large diameter section at their bottom end. Your intake tube is much longer than later models. Your rear brake pedal is on the left. Later it is on the right. Your shift lever is on the right. Later it is on the left. Your bike may have had a later model front wheel fitted. Hard to be sure of the rim type in that photo.

Nice bike. It's an early model 247 but not the first model. Great to know that it is going to be ridden. A friend of mine Paul Walker rode one of these in trials back in the mid 1970s. Being 5 or 6 years old, it was regarded as an old trials bike at the time. So far it has been the only one of that type I've seen in the flesh.

It's a standard work-around for a failed thermostatic switch, which is a pretty common thing

Pretty easy to do a test fit with the clutch in place to work out which pushrod it is. There should be a ball between the mushroom ended rod and the plain rod. Some else's 104 pushrod length won't help you because yours might have a different clutch.

Cota 247s are not popular in vintage trials competition nowadays but are great to look at. It's harder to find parts for them than for the popular vintage trials bikes because not many were sold at the time. They are nice to ride though. If you want to ride something different to others, they would be a good choice. As for being a 1973 model, the 247 model had very little product development after 1970 so a 1973 is as good as they get. The early models 1967/68/69 are rare and desirable but not as good to ride.

I still use the original type and reckon they are fine. In fact it is still the original lever on the bike. I've got others too but am even further away than Guy

The square float bowl AMAL concentric came out in about 1977 and Cota 200 was something like 1981 so based on that it would have had the square type. As far as I know the round bowl type is Mk1 and the square bowl type is MK2. This photo shows a Cota 200 with what I call a Mk2 AMAL carby

Is the reason you want an aftermarket lever that you don't like the original lever or you can't source one?

You can ride a twinshock in any competition. Lots of us do that for the same reason as you have mentioned. There are mild modern bikes though if you want to ride something new. The Beta 4 stroke 300 is a popular older person's modern bike