woody

The TR77 came with different carbs, Bing for the 350, Amal for the 250. Either will have roughly the same position for the pilot (airscrew) which is around 2 turns out for a starting point but there is no 'fixed' setting as all bikes run differently. On an Amal the idle screw is at 45 degrees and the pilot is 90 degrees to vertical. On a Bing they are both 90 degrees. From your description of the airscrew and idle screw you have a Bing. The larger is the idle which just controls the height of the slide so if you screw it in it raises the slide and lets fuel through which increases engine speed. The smaller one is the air mixture or pilot screw which controls the amount of air through the pilot circuit at up to 1/4 throttle opening. In shuts air off, out allows more air through Most if not all TR77 (green MAR) had points but some may have had CDI. The CDI ignition from an earlier MAR or a Gripper will fit straight on should you want to. The backfiring and missing is generally the result of a weak spark. On the MAR, the wires from the stator up to the coil exit through the bottom of the casing and they can often get trapped between the bashplate and become frayed or broken so check there. They also become brittle with age which increases the chances of them breaking as they have to ben 90 degrees. If this has happened it can cause a weak spark or kill it altogether. It may not be just a points issue. A mod is to run the wires behind the stator plate and out through a hole you will have to drill in the top front of the casing and straight up the front down tube (as standard they go up the rear of the frame) You also have to grind back the ribs behind the stator to give room for the wires. There are topics on this mod in this forum if you search. The MAR engine will go straight into a Gripper frame as they are the same basic engine but the exhaust will prove an issue as will the carb as the Gripper frame won't take the MAR exhaust and the carb may well foul one of the rear frame tubes due to it sitting higher on a Gripper barrel. The Gripper exhaust won't fit a MAR barrel without modding. Probably more trouble than it's worth when the TR77 frame will handle nicely with good shocks and the forks pushed up through the yokes by up to 2" as they are too long.

That's right yes, it would be really fair to put a 1970 standard Bultaco Montesa or Ossa up against a modified Cub / James / Bantam But that obviously isn't an issue as you have no interest in twinshocks I have nothing against a class for standard machines but what you keep failing to acknowledge is that there is going to be a real problem scrutineering the bikes and deciding which is in the correct class. The last two Northern rounds have had around 120 entries. If a club can even find someone with the knowledge that is willing to do the job, when exactly are they supposed to do it? Before the trial? If it took just 2 minutes on average to do one bike that's four hours that someone has to spend checking bikes. Add on time for dispute and discussion and that's how long? Event organisers have their hands full dealing with all of the other issues involved in running a road trial and getting the event underway without having the extra burden of dealing with that. Will the ACU provide a dedicated examiner to travel to each event? You're citing a problem that doesn't exist as the reason for the Miller series 'failing'. I've pointed out two other series run to the same criteria where eligibility clearly isn't an issue as neither of them have riders moaning about the fact that they both have standard and modified machines running together and no scrutineering. Where are these riders you mention?

You're again taking the issue away from what is responsible for the decreasing entries in the Miller series, which is what the topic is supposed to be about It has nothing to do with eligibility rules. The Northern series, the Manx, these both run to the same criteria as the Miller series. they both have a huge range of machines taking part including rigids. No--one moans about the mix of modified and near original bikes, or the lack of scrutineering and they return year after year This topic has been done to death, if you want to start a series for standard bikes and put modified bikes in a modified class then that's fine, go ahead and start one up. That is not what the Miller series is now about and if it goes back to excluding twinshocks I think it will be a great shame

Please, can we put to rest this issue of 'cheating' and 'cheat bikes'. Times have moved on whether you like it or not. It's now the norm for Pre65 bikes to be of the modified variety and has been for years. Pre65 is just the class label - is it really that important that it needs to be constantly nit-picked? They aren't cheat bikes for god sake, they are only cheats if they are hiding modifications that give an advantage. Tehy were cheat bikes when they first appeared nearly 30 years ago yes, when no-one knew what some top riders were having done to their bikes, but now, none of the mods are hidden or unknown as they all have them, they are the norm and these are the bikes that people choose to ride. This talk of eligibility and rules is just distracting the topic from the real issue which is 'what is wrong with the Miller series' - and it has nothing to do with eligibility. If you really think clubs can provide 'experts' to examine each and every machine for 'rule' flouting then you're in fantasy land. None of the competitors are bothered about who has what components fitted to their bikes. I've just come back from the manx classic - approx 200 Pre65 bikes and 60 twinshocks. No scrutineering and no complaints from anyone about this or that being fitted to any bike. Everyone happy. I've ridden Northern British Bike championship rounds - over 100 entries, no scrutineering, no complaints from anyone about machine eligibility. What's the problem? Sections in the Miller series are NOT unsuitable and I get fed up reading comments that they are from people who never ride in it. Look at the results from this year and class winners on the easier route, including rigids have been in single figures. How can that be too hard or unsuitable? I also hear it said that the sections are now geared towards twinshocks which is again not true, it's rubbish and also a joke as the modified Pre65 bikes are far better than any 70s twinshock. My 1972 standard Sherpa against a modern James or Bantam or Cub? Which do you think is more competitive... It's true that on the harder route one or two of the events can have had some tight (too tight) sections but some of us have pointed out constructively to the organisers that those type of sections aren't necessary or desired Having ridden both Miller and Northern British bike rounds for several years, I can say from experience that on some occasions the British Bike rounds have been harder than Miller rounds, yet they regularly attract 100 plus entries of British bikes. So why don't a reasonable percentage of those riders compete in some or all of the Miller rounds as well, as in most events the section severity is of a similar standard. Perhaps because they believe some of the claptrap written on the net that the Miller series is now suitable only for twinshocks. I submitted my suggestions as to how I thought the Miller series should progress and it included twinshocks. I think it would be a great shame if it excluded them from the series in the future. Twinshocks have always been the poor relations when it comes to national series. Pre65 already has several dedicated events - Northern British Bike championship, BMCA series in the Midlands, Pre65 Scottish (4 speed Bultacos excepted....) Manx Classic (yes it has a small number of twinshocks but it is still a mainly Pre65 event and which uses twinshocks as section scrubbers) There may also be a Pre65 only series in the southwest, I can't remember. What have twinshocks got in terms of a national series? Nothing. The KIA is not a twinshock championship, it also has classes for Pre65 (yet another series they can take part in...) and air-cooled monos. It's also not road based so if twinshocks lose the Miller series they have no road based events to compete in. Personally I don't see much wrong with the Miller series and don't understand why it is losing numbers when the Northern Brit Bike series enjoys big entries using sections of a similar standard. I think a couple of revisions to the class structure would be all that was needed to get some interest back.

Martin - did you put any proposals forward in response top the questionnaire the ACU sent out?. I took a fair bit of time to put suggestions forward but none are in there. I didn't get any response either. I don't get the split between Spanish and non-Spanish, I voted no on that one and preferred a Pre and Post 1977 class split for twinshocks which is a lot fairer. They just seem to have copied the KIA format. Still no class for the Pre-units so they are still competing in the same class as trick lightweight Cubs, Bantams etc, It appears also that I can no longer ride my Ossa as it has a reed valve which was fitted about 30 years ago - and something that Keith Horsman was fitting to Ossas, Montesas and Bultacos back in 1975... As used by Ossa UK from 1974 onwards

I've used the beige woven linings, had them done by both Villiers Services and another brake specialist in Blackheath (Midland Brake Linings I think) I had them oversize and I've been able to turn them down no problem and I'm no engineer - don't even know what tool or tip, or whatever they're called, I've used, I've used several different ones as I've done about 20 pairs of these over the years. If I can machine them, then anyone who can use a lathe can. 95% of the time they work fine and stop well even when wet but on a couple of bikes they don't bite so well - one happens to be a Grimeca hub although the other Grimeca is fine. I've never bothered with oversizing the brake plate hole as I just don't understand how that's supposed to work. If the shoes are machined to the hub whilst in a slightly open position, surely that isn't necessary anyway? I've found off the shelf shoes pretty ineffective and the linings are that thin they can't be machined to enable full contact as they go over the cam if they are EDIT: Just seen your last post. Not sure what you call high speed but I think I used about 800rpm which I think is on the slow side? Didn't use brake cleaner or anything to keep them cool and only had one snag moment in all I've done. Lots of brown dust though...

I had mine apart for rechroming a couple of years ago. I don't remember, but can't categorically state, having to remove and refit an external bush. The recess shown in your photo doesn't look deep enough for a bush.

The frame pictured above is definitely not a 199. As already mentioned it will be a 183 or 191 as it is a 350 frame. The 199 frame is a nice frame and maybe a bit more stable than the A and B versions as they had the engine lifted making those bikes feel a bit top heavy.

or both.... What tank is it?

Slosh or Sureseal both have good reviews For what it's worth, Shell V-Power ranges from 0 to 5% ethanol content. It varies across the UK with Devon Cornwall and Scotland having the greater content. I only use V-Power from my local station and haven't had any problems, even with untreated original 70s fibreglass tanks. About 6 months ago I half filled a jam jar with V-Power and put a piece of old fibreglass resin into it which I chipped off from an old fibreglass repair on a seat that was done some years ago. The piece was about the size of a credit card and about half an inch thick. As of now, some fuel has obviously evaporated away but what is still in there has no water separation and the piece of fibreglass is unaffected by the petrol and still solid. This fibreglass is just Halfords normal resin, not ethanol resistant resin. I'd guess the V-Power in your area is of the same ethanol content as here

Each of the model 10, 27 and 49 had Sammy Miller decals on them as these were the models he developed and rode for the factory, so they could all be referred to as Miller replicas, but there was never a specific 'Miller Replica' that differed from the production models released or sold by Bultaco. From the model 80, the Miller badge was dropped and Lampkin and Rathmel were the factory riders, whist Miller had retired from full time competition and began development of the new 325 (as far as I know) So there is no such thing as a Miller replica from Bultaco that differed from a normal production bike, but as mentioned above, he did make a load of his own brand parts for the Bultacos, including frame kits called the Hi-boy which he used on his own bikes, so maybe what you've seen referred to as a Miller replica is a bike fitted with one of his own Hi-boy frame kits (which were always chrome plated and had alloy bash plates rather than frame tubes under the engine) Tjese won't have the usual Bultaco frame numbering, they had numbers beginning with SM.

They were only fitted to the MAR or Explorer (which was just a geared up MAR) As above you can get a weld repair. It doesn't have to be threaded as the threaded cable adjuster has a locknut which can be used to set the position of the adjuster in the post. Or you can grind it right off and fit a Bultaco type front brake cable holder which bolts onto the torque arm on the Bultaco. It just needs a hole drilled in the brakeplate to locate it - but I'd opt for the welded repair if you can find someone to do it. You also need to watch the rear brake plate as the alloy casting isn't that strong and if you apply the brake hard the pressure on the slot on the brake plate can snap the top side off meaning the plate will no longer locate on the lug on the inside of the swingarm. This usually happens because the slot in the brake plate opens up slightly with use over the years which means it is a loose fit on the lug. If you find you have play in the fit of the slot on the lug you can add metal to the lug on the swingarm with weld and then dress to size, or if you can't weld, get some thin sheet alloy or tin and wedge it in to take up any play.

Yes, they are 20 x 1mm. I bought this for a Marzocchi yoke which should do the job as it fits the Ossa thread also http://www.ebay.co.uk/itm/131705365599?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Check that the crankcase screws are fully tightened, you never know. If the are, lie the bike on its side, clean off the affected area with brake cleaner and apply plastic padding petrol patch or such like - something that is oil / petrol resistant. I stopped one leaking like this once until I had time to strip it and find the actual cause (crack in the casing in my case due to the bashplate being hammered out of shape from hard use over many years and therefore touching the cases) I've used araldite to fix a split in my Commerfords slab tank and this has lasted a few years now, but you'd have to put the bike upside down to use araldite, as if it's only on its side, the araldate will just run downwards away from the required area when applied

You can send me a PM if you want with any questions but to be honest you're better off just putting them on the forum as there are several on here that are knowledgeable on Ossas, so you're more likely to get the answer you need than just asking one person Putting the forks in the other way around was done by some to improve the front brake action, I believe the idea behind this was that when you roll a bike backwards the brake always seems to work better than when it's going forwards, therefore if you reverse the front end so that the wheel in forward motion is now going in the same direction as it was when it went backwards in the conventional position, the brake will work better Never been convinced of this myself as the brake will seem to work better backwards as there is no weight on the front wheel therefore less resistance / force for the brake to overcome, plus the wheel is barely moving when going backwards, in comparison to the speed it will be rotating, or the forces imposed on it, when going forwards. It won't actually cause a problem fitted that way around as the axle is in-line therefore steering and handling aren't affected. The fork drain plugs though, are now at the front instead of the rear of the legs. Re: the bashplate - I'm referring to the fact that it is still what looks to be a perfect fit on the clutch side which means it hasn't been bent up in the middle, which forces the back down and away from the frame due to repeated impacts from hard use. None of the bashplates I have can be bolted up to the frame at the rear on the clutch side as the two don't meet

The cylinder is the definitive ID for 250 as only the 250 up to the MK3 inclusive had solid fins. All 350 had split fins. On a MAR it isn't possible to fit a 250 barrell to a 350 engine and vice versa due to different stud spacing. But that aside, your engine / frame number is also in the MK3 250 sequence range. Your bike is identical to the one my brother had. Only the MK1 and very first MK2 MARs had split outer fins on the head, the 350 and later MK2 and MK3 all have solid outer fins. The green models had a different style head with mounts for a head steady The chassis ID charts must have come from Ossa records originally but no idea who obtained them, but not all are as comprehensive as others with some missing number sequences that others have, and some sequences missing from all of them. There are still the odd few bikes out there that have had little use, even some that have never been sold or used from new if stories are to be believed, but yours definitely looks as though it's had little serious use, if any.

Frame number lends itself to the 76 250 - the series that begins 56**** so they could have run into the 57 too with the MK3. The Ossa frame numbers aren't as well documented as the Bultaco for example and some number runs don't appear on any listings. I had an all green bike which began 700 with matching frame / engine but there is no mention of a 700 number run on any of the lists available. Your also has the correct features for the MK3 with damper position, swingarm and forks. The early MK3 had the short front pipe and torpedo silencer but later MK3 had the longer front pipe (or maybe only on the 350 version?) with much longer back box, as seen on the green models. Not sure about your front pipe from the picture as it isn't clear whether it's original Ossa or not, so it could have originally had the longer type? My brother had a MK3 250 back in the era, it was the same as yours. All 350 trials motors had the barrell with split fins, only the 250 up to the MK3 had solid fins like yours has, the green model 250 changed to split fins Your bike looks as though it's done little competition use as the bashplate still fits both sides...

It's a '76 250 Looks to be in original spec apart from the rear silencer which should be the 'torpedo' shape

It could well be a Keith Horsman conversion as he was a Montesa dealer in the 70s, rode a 247 and developed a reed valve for them (Harpower) although I don't know which carb he would have uised on the Mont. He subsequently fitted them to Ossas and Bultacos. He did an Ossa for me many years ago and it gave an increase in torque and let them rev a bit more, so yes they're a worthwhile improvement. A clever man was Keith, self taught engineer who sadly died a few years ago now. I enjoyed a few trips to his home when he was doing work on my Ossas for me - always had a tale to tell

If your bashplate has taken a beating and pushed up in the middle it can touch the engine which means impact shocks transfer to the crankcase and can cause cracks - it's not always the sump plug that causes the problem. When the bashplates were new there was enough clearance that the sump plug was well recessed and nowhere near protruding. Bashplates can be pressed back into their correct shape.

I've just put an OKO 28mm on mine (non power jet) as the original carb was no longer any good. Initial jetting is 48 pilot, standard 112 main, needle, needle tube and slide all standard (by standard I mean what they come with) Needle raised one clip from standard First impression is good, It has loads of torque, picks up very well of idle and pulls really well in first to third up climbs. I've a spare flywheel fitted with about 10oz shaved off it which helps pick up but I doubt it needs it. It's a strong motor. I haven't yet given it any real stick as it's a new engine build but at most I may try the next size up on the main as there is the faintest trace of pinking when hot.

Steve's Ossa business is part time, not his day job, but he will reply to phone calls when able as long as you don't block your number. He doesn't, as don't many of us, answer if a number is blocked.

ok thanks Andy, will do next time

Glad you and your son enjoyed it Roger. It was very slippery in places but nothing overly demanding - a good learning exercise for riding that type of condition.... I remember he had 3 good cleans on my section and rode it well. The results go straight onto the club facebook page when done as most of the riders are on there looking for them before I've got home..... Then I normally put them on the front page here but hadn't got around to it immediately and ended up fairly busy last week so overlooked it. A soon as I get Admin to the club website sorted they'll be on there as well but not sure how long that will take. I used to e-mail them out but lost the group email I had and it's a lot of effort to create that again, plus not everyone puts their email address on the entry form. Hope to see you at future events and hopefully the next one will be a little drier. 28th May (Saturday pm) 28th August 30th October 26th December

I've uploaded them onto the news page but no idea how long it will take for them to appear as TC administrators have to authorise it. The Stafford Auto website is not up to date. I've just taken over running the club and don't have admin access to it so I can't put the results on there, or do anything with it until I do, and at the moment I don't know who previously maintained it. The results are on the facebook page which is public, so any facebook user should see them. If your not on facebook then no you won't see them. Facebook is real time and a lot quicker and easier to use which is why a lot of clubs use it now. I can send you a copy if you PM me your email address