section swept

Beta specific pages will point you in the right disgnosis direction.

Before you take the bike apart thoroughly check the frame for cracking or signs of misalignment. Bearing in mind you think the rear suspension linkage is worn does the bike stand straight....rear wheel in line with the front... use a good straight edge. If you think the rear linkage is with you may also find the head bearings are on their way out to. Take photos of everything before you take anything apart, mark any spacers, shims, washers with permanent marker pen and number items so that you know where they go atvrebuild time. Go to the Sherco specific pages and you will find the guidance needed and plenty of advice??

Think you’ll find that many bike owners have the same take on life as you, there’s a deal of satisfaction preparing a bike and making modifications and fitting ‘trick’ parts. The other side of the coin is returning a bike to its former condition as it left the factory and researching the background and the chase for elusive parts? welcome from me, hope you enjoy your new obsession?

If you drain the transmission even if you leave it to drain overnight there will be a small residue left in there. Pouring in 550 ml will mean that you might be overfilling. If however the transmission has been apart ( cases etc slit and so on) then most if not all of the old oil will have been removed. So as capper suggests fill to half way up sight glass, ensure bike is at the correct position ie upright and not leaning over. Pour the oil in slowly and allow it to settle and any air trapped in the pouring process to clear. When you have got the level right turn the back wheel in gear to make gearbox internals move the oil around, stop and allow to settle, re check level and top up if needed. If you measured the oil being used you will probably find it hasn’t taken the full 550 ml.? obviously too much oil will be bad as there is a good chance when the bike is used that the transmission oil will overcome the oil seal and or the breather creating a leak.

What did you use to lube tyre wall when fitting, or did you use nothing?

Can you repair it or has it done a lot of damage?

Your frame looks good is that powder coat? The mounting arrowed in your photo looks the right shape but I’m not sure it would have been mounted that far back and the location would see it underneath the saddle and probably causing fouling issues with the air box and the horn might be so shrouded as to not be audible when the engine is powering the bike. My friend of many years past ran an Ossa MAR and the horn was mounted up just underneath the head stock sitting neatly between the twin down tubes, as his favourite practice sections tended to be rivers the horn rarely if ever worked. The regulations would dictate a forward facing mounting before the engine to allow it to be heard. In the interests of authenticity I’m not sure what the arrowed bracket is for but I’m certain you’ll be informed.

Totally agree with you baldilocks, and the Beta clutch fix seems to be still going on with more posts....removing the dried compacted glue and generally removing excess manufacturing product, doing what the factory should have done in the first place. I know there aren’t any dual mass flywheels used on bikes...yet...but they might develop a much smaller version?

Please re-read what was stated. We all have ways and means to carry out difficult tasks and my observations if you feel they were out of kilter then feel free to “report post”. As for resident Troll I feel that was totally uncalled for. And as papapitofu posted some very useful photos and it’s their post let them decide about your suggestion??

God bless the little dependable TY 80 what a sweet bike??

Yes and how right you are. Having spent a good deal of time working with ‘modern clutches’ of all types I have to say the dual mass flywheels that fall apart and diaphragms that crack, together with multi plate competition clutches that only work on or off no matter how careful you are the old ones are the best. In the effort to provide a slim clutch assembly, which is lighter and has little inertia the manufacturers have created a whole new raft of potential faults and transmission issues. Small,wonder then that modern day super bikes and smaller commuters with selectable gears still use clutches that are similar to the ‘older types’ all be it the operation is hydraulic and ramps allow varying stages of engagement. I suppose the telling question is how often was the Bultaco clutch stripped apart compared to the ‘new’ offerings, on modern day bikes.?

Check out the private sellers before you spend your dosh. As Oni Nou states the trials bike market is slow right now and you may be able to pick up a good bike straight from the owner which is usually better than buying a bike with no history. Remember it’s only the profit that makes things expensive. The dealer you mention sells a lot of bikes not just trials, so a specialist dealer may bring more to the negotiating table. A few tips, get whoever to start the bike from cold, if you think the bikes been run just before you arrive be very cautious there may be starting issues. When the bikes running allow it to warm up, it should idle relatively consistently and the cooling fan needs to cut in and out reliably. Try the clutch when the engine is hot, cold oil will stick the clutch on many bikes so be fair to that, it should disengage or clear easily without excess effort at the lever. The exhaust will smoke a bit as the bikes been standing idling....if it keeps stopping it needs sorting before you go any further. You may be able to have a paddle on the bike....I used to have a secure compound with a skip and a few obstacles for the more able rider when trying bikes... if you are offered a go don’t think you’ve got impress anyone, no big handfuls of throttle etc. just pootle slowly and try the gears selection. Stop and find neutral now operate the brakes pushing back and forth with your legs and at the same time feel and listen to the suspension working. If there’s no test ride on offer and that may be because the dealer is unsure of you or your riding....it’s a bit scary letting a relatively total stranger hop on your stock and ride about. Bear this in mind it doesn’t have to be a deal breaker, you may even be offered a warranty of sorts but at the age of bike suggested I doubt you’ll get anything apart from fcw ( forecourt warranty) once across it you’re on your own! Should you be buying blind ie not seeing the bike personally but over the net and then courier delivery think about it carefully, the courier services....the ones that advertise do a good job mainly, one I have used a few times is excellent. But they could be delivering the biggest bag of horse manure to you, it won’t be their fault either, so for the sake of a few hours travelling make the effort see before you buy. Hope this info helps and that you buy a good bike with no issues and plenty of history??

A good auto paint shop supplier may be able to exactly colour match you frame colour. Except you’ll possibly have to buy at least a litre of the stuff.

Now he’ll tell you it’s the forks he needs quantities for?

Looks like you need about £200 worth of clamps and pullers as well as a good heat source?

If it all goes pear shaped there is always the option of thread inserts.

My 72 Sherpa with careful assembly and attention to the clutch pivot shaft has a clutch that can easily be worked with two fingers and the clutch has all of its springs (new) and does not slip, judder or cause grief of the type these modern clutches do. Here’s a mod throw the clutch away and fit an early Bultaco unit????

That tamper proof block was intended to be a problem so that when the owner had running issues and returned the bike to the dealer, they just cleaned out the tamper proof block curing the problem and looking amazing so you would keep returning to the dealer for the smallest thing. A profit generator I call it!?

They slide with the fork tube up and down....you know this I’m aware.?

Just ensure any anti freeze that you use is compatible with aluminium. Better than plain water use distilled water as this will be contaminant free (chemicals etc) but mix the anti freeze and water in a container so you have the correct ratio available and don’t have to guess how much of what to put in. 50/50 is a ratio that I use as the anti freeze raises the boiling point of water but about 15%. Good anti freeze will have a lube additive in it for the water pump seal and corrosion inhibitors to keep everything nice and clean in the cooling system. A little plastic bag with some Cayenne Pepper will be invaluable if you hole the radiator (small pin prick tiny stone nick etc) add the Cayenne into the cooling system and add water, run the engine and when the Cayenne meets the atmosphere it solidifies and stops the leak. It’s messy on a bike and will need to be flushed out during repairs, a similar kit ( little cardboard box ) used to be sold in auto shops as rad leak stopper, the contents of the box looked like a small dog turd and that’s what the trade called it but it was basically Cayenne Pepper. I’m suggesting this as you might be miles from anywhere out in the sticks and no one around, hope you’ve got a good aim as you’ll need a water supply to be squirted into that small rad cap hole???

Have you tried just altering the position of the lever on the handlebars. Are you wearing gloves, very often these can affect how you operate controls, i.e. too thick and the material deadens the feel, too grippy and the lever doesn’t slide through the fingers but sort of judders if you will. May be an alternative shape to the lever may help, some levers are able to be bent without breaking....you’re on your own with this if it snaps hard luck mate. Seriously some levers look nice and trick but are awful to use in action. I once broke a brake lever and was left with just enough to work the lever with two fingers which is what most of us do anyway, but the missing part really allowed better operation of the lever! Have you made sure that the hydraulics are in good order, the slave cylinder (the piston assembly at the clutch / engine could be sticking, or corroded. Pivots may be dry and need lubing. I’m assuming you 260 has the 2 map option, does the clutch action feel the same in either map? Hope this is helpful?I know the engine map isn’t connected to the clutch but the way the engine delivers its power may influence clutch feel.

That’s either an illegal whisky ??still in the background leaning against a tree or a left over WW2 A Bomb????

Just use any engine or gear oil on the chain, let it soak in or you could use WD40. If you use proper chain lube spray it will dry sticky and attract all of types of dirt you don’t want and end up causing more wear, that stuffs ok for clean road work but as mentioned before the runny oil is best. When you wash the bike off ( you will want to keep it looking as good as it is at the moment) you’ll wash most of the oil off and that will carry most of the dirt away too! When you’ve finished a good liberal spraying of WD40or other proprietary brand will drive out any moisture and prevent rusting of the links etc. Some people use a paint brush to apply the oil to the chain which works well, an oil can can be tedious and a bit more messy. I suspect you’ll be riding on fairly dry dusty terrain so I would carry a small aerosol of WD40 to lube the chain after a few hours running?

Unfortunately the British Motorcycle Industry had access to many types of threads, BSW, BSF, BSC (cycle) and of course Unified. At some stage all of the aforementioned may have been used on one type of bike or engine or both and this makes selecting replacements difficult. Possibly a reason why no one has responded with an answer. A thread gauge will only be of use for bolts and some nuts. One solution might be to drill out the unknown gearbox to crank cases threaded holes and tap them to a known size, not a hard job to do if done with care and planning. At least you will be able to have a choice of fastener types and this wouldn’t detract from originality.

It’s poorly designed there appears to be very little of the gear selector shaft (smooth sealing area) protruding for the seal lip to slide against. Can the seal go into the recess further, does the shaft have too much float (in and out play). An alternative would be a sleeve resin bonded to the shaft to allow the seal to work on or a shaft with a longer seal land area. I would even consider working the seal housing so that the seal can actually fit further in by a couple of mm. Not had one of these so I could talking nonsense, however from each idea comes another. It does look as though there is insufficient smooth surface for the seal to work on in my opinion.