feetupfun

If you can still kick it over with only three springs then it will probably work OK. There are many ways to reduce the clutch pull force

Posting a video on youtube may take a lot of guesswork out of answering your question

Tony the B models in Australia came with the same engine covers as the C and D models

This is a series 1 M80 frame with the tank resting in place

"top of the frame mountain"? If you mean those non-standard mounting lugs, they are definitely non-standard and yes they would be in the way of an M80 fuel tank. Would it help for you to see what a standard series 1 M80 frame looks like? A stand mount on the swingarm is also non-standard for a series 1 M80 but would be a great improvement if done properly.

The kickstart shaft and the return stop for the kickstart shaft needs to be set up so that the return stop holds the ratchet teeth apart. Some people accidentally leave out the shim that johnjsy is talking about and the ratchet teeth may not fully disengage. This MAY be the cause of your noise Another possibility is that maybe there was a problem with the return stop or the shim was missing before you rebuilt the motor. You didn't say what the history of the motor was so I have no idea if this is likely or not. I know that I have discovered many mangled kickstart return stops and kickstart shaft shims missing when disassembling 5 speed Bultaco motors.

I see the messages about this on facebook and agree that the spring shape is not quite right

Second photo is correct fitment of spring. The arm should be pretty much vertical when it contacts the spring. Spring only has load when pedal is depressed

I don't know what Greg Harding did to his Fantic 240 forks but that is what I'm comparing mine to.

If your clutch spring posts are adjustable, set the spring preload so that the kickstart will just transmit enough torque to kick the motor over cold. Also set the individual spring preloads so that the pressure plate remains parallel with the plates as it moves in and out. There are so many variables with clutch hub design and plate thickness and number of plates and spring length and spring stiffness and nut thickness and post length on Bultacos that there is no logic in recommending anything for someone else's bike regarding where the nuts should sit relative to the posts.

Unlikely to be crank seals. Sounds like gunk in the pilot jet. If it is air ingress, check the cylinder base gasket before you go pulling anything apart. These bikes have a weakness in the seam of the main chamber of the exhaust which sometimes splits when there is a decent "backfire". If you had said that the exhaust sounded louder I would have suggested checking this out. If it revved high for a long time before you got it stopped it may have done some damage to the cylinder, piston or rings. You can check for damage by looking up the exhaust port with the pipe off. Sounds a bit odd that you say it stopped with a backfire when the fuel supply was shut off. It usually takes quite a while to stop an engine just by turning the fuel off. Next time I suggest you block the exhaust outlet or turn the bike completely upside down to stop a runaway motor.

Good to see it going. Very cool-looking header pipe. Did you make it? Also where is the beautiful fuel tank from?

Have Racetech gold valves in 34mm Yamaha-Kayaba TY250 forks on 250 Godden Majesty. Better than standard forks but I wouldn't claim them to work better than well set up 35mm trials Marzocchis. Racetech don't list TY250 forks either but Yamaha MX bikes with 34mm forks of the same era have the same design damping internals as the TY250.

TY250 twinshock for trials with 428 chain 12/53 for trials with 520 chain 10/44

75W80 is what would be used in a manual transmission in a car and yes it has a higher viscosity than ideal for a Beta clutch and yes the viscosity is the problem. There are easily available oils for trials bike gearboxes that give the best clutch action possible. Which one is the best is often the subject of discussion on these forums.

Bike in photo looks like M85 Alpina (round barrel) 250cc. This model was introduced in 1972. M99 is (square barrel) 325cc

The 75W80 will probably lubricate the gears and bearings OK but may cause clutch drag problems

yes kill switch goes between coil wire and earth. Kill switch should be the "normally open" type ie it should be open circuit in the "run" position and closed circuit when activated.

It should be fairly easy to source a FEMSA magneto flywheel. I thought that some of the kits came with a flywheel

There is a moulded plastic piece that the airbox is normally riveted to that forms the lower rear mudguard. Replicas of these are available. Lots of choices for the mudguard that fits behind the seat. High quality replica plastic available ex UK in white or yellow. Low quality replica plastic available ex USA in white. Fibreglass replicas are available from time to time. Universal (Gonelli) plastic rears from many sources and lots of colours - but needs additional brackets. Note that the 1974 (A) and 1975 (B) TY250 rear guard is a shortened version of the 1976 and later (CDE) mudguard if you use the original fibreglass seat surround

Yes sorry I was thinking clutch cover. I've got a TY250A magneto cover in great condition I'm thinking about selling. There are some rules about selling things on this website. I'd better read them before I say any more.

If you are talking about shocks at the cheaper end of the spectrum, it can cost the same or even more to rebuild a set of shocks than it costs to buy a new set

There are about 10 of them advertised on eBay at the moment

Yes the pushrods and ball can only fall out via the right hand end of the clutch shaft. From your description it sounds like you are expecting to be able to rotate the sprocket by hand with the clutch pulled in. Even a perfectly good clutch will have too much drag to allow this to happen.

except TY and RD forks are 34 mm not 35 mm