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My own MAR starting smoking suddenly one day, but had been fine when ridden the previous week. turned out to be crank oil seal on clutch side had somehow got stuck to the crankshaft and was rotating with it ! { no idea how this could happen, but it did } fitted new seal with some adhesive and its been fine since, worst part of the job was removing the cush-drive off the Crankshaft to access the seal

I think its the Petrol that does this . I don't know the proper scientific term for it { but I am sure someone does, and will be along shortly} its as if the plastic is porous and the petrol soaks into it. Perhaps different types of Petrol and the different Premix oil cause different effects / colour changes ? and of course could be explained by different types of plastic being used to manufacture two tanks that look the same ? as for prevention, I guess you could get a new tank and fill it and drain it on the days you ride without leaving petrol in overnight may work ?

Sorry you haven't had any replies , I cant help as I have never owned a pre65 bike maybe you have had no replies because you are thinking of using actual real old 1964 parts ? most people these days would be fitting - New Billet "pre65" yokes into a New "Replica Pre65" Frame Have you contacted any of the classic specialists ? like Sammy miller products , Terry Weedy

Would bikes like Beamish Suzuki count ? ( British built frame & tank , assembled in Brighton ? ) or Yamaha HL500 ? ( assembled by NVT in the UK , with British built Frame )

Okay , so if Brexit was cancelled we could have a 2019 UK World Trial GP with free entry ? Because everything in the EU is wonderful { and free } ? maybe Greece could have a world trial ? with all the bail-out money they have got it could be sponsored so free entrance ?

nothing to do with Brexit, more likely these events have some financial support from local council / tourist board / local business's etc. which probably doesn't happen in the UK an element of money-grabbing is possible depending on who the organiser is ? but I wouldn't think must club type organisers would do this ? £30 entrance would probably put off any casual fans or newcomers , but maybe there isn't room at a UK venue for a large crowd, so this would be one way of keeping the audience at a manageable size ?

sorry if this is the wrong place to ask , but just gone to look at ORRe on here but its gone, replaced with a message. can anyone explain ?

Removing the Cush Drive can be done, some bikes have something similar on the clutch instead of the rear wheel, some bikes don't seem to have any Cush Drive on any part of the drivetrain I have an OSSA MAR with a Cush Drive on the Crankshaft { I have no idea why they fitted this ! } I think the general idea is to protect the Chain / Gearbox etc. from shocks , so it cant do any harm and may extend the life of these parts. the problem is when the Cush Drive wears you can end up with a wobbly sprocket etc. , if parts are easy to get & sensibly priced then probably easiest to leave as it is, if not then making it solid wont cause any major problems I would think up to you really, hope this helps

when I was looking for a replacement rear brake cable for the worn one on my MAR , all the replacement ones that I saw seemed to be made from thinner cable than the old one - they were the same thickness as the Universal Brake/Clutch cable kits that are available, but just not as thick a cable as the old one. anyway , I purchased and fitted one of these cables and it worked okay, but did seem to stretch/flex a bit in use. I wasn't really happy with it and ended up getting a Ford Transit Clutch cable with the threaded rod on one end and modified this to fit. the Transit cable I used is the same thickness as the old cable that was on the bike, and it does seem better at braking and resisting stretching / flexing now as has been said - good linings + a good cable + proper adjustment and the standard setup can work well , despite looking like it shouldn't work !

I am not familiar with the layout of those engines, you say you have a manual but not sure if its right for the engine , maybe try looking at an online parts diagram if you can find one have you got flywheel & clutch covers off to make sure everything is removed that needs removing ? gear box sprocket, gear lever , kick start lever etc. ? maybe a little circlip on one of the shafts ? sometimes clutch basket or the gear on the crank that drives it will need removing

I really hope this works out for you , and that you can still enjoy motorcycling through riding Trials in the future. I cant really add anything to what others have already said, other than - have you cleared this with your doctor ? wearing a crash helmet and possibly falling off and hitting your head 6 weeks after surgery may not be recommended while you are healing ( you know what doctors are like } good luck , and maybe post an update when you have had a go

thanks for this info, but I still don't see any victories in a major Trial or Championship mentioned ? the oil leak is no surprise though ! I will concede they look and sound okay , but not enough to justify a world record price for an old Twinshock , if I really wanted a 4 stroke Twinshock I would get a Honda

that's good advise , O rings come in different types of rubber and different thicknesses also, may only need a firmer compound or a fraction thicker material to make the difference, if your clutch cover just slips straight over the gearshaft with no resistance/friction then the O ring may be too thin even if its the right diameter , problem is the easily available O rings all seem to be soft cheap rubber and not as thick as you may need

If your Oil pump has been left on the engine and is still rotating with the engine running , yet has no oil passing through it , I wouldn't think this does the pump internals any good. I could be wrong but I would guess this would cause a lot of wear in the pump , I personally wouldn't trust the pump now and would use Premix or get a new pump if they are available

Hello, on my MAR there is a sort of - 'felt' washer on the gear lever shaft as well as the O ring , when both are in good condition the leakage is reduced , but not eliminated. Have looked at machining the cover to accept an oil seal but haven't got round to it as I think there isn't enough thickness of metal to remove to get to the size of hole needed for an oil seal ( I could be wrong ) I did think of moving the side stand from the left side to the right side to eliminate the oil drip when the bike is parked up ! At the moment I have given up on this annoying drip and just accept it as part of owning a 1970s Spanish bike Hope this is helpful