woody

The Clymer and most other manuals were written before the TR77 was in production. All earlier Ossas used electronic which is why they don't mention points. Can't help with the problem as electronics are a mystery to me but check that the wires aren't broken where they exit the crankcase and bend 90 degrees, if they still exit at the original point. This used to be fairly common issue, especially if they've gone brittle through age

Judging from the consultation paper that the Dept of Transport have issued, they have no desire to implement this. They could have implemented this years ago if they had wanted to interpret the original directive in the way that the EU Court of Justice did, which is what's kicked it all off now. It's not just competition that is affected either, it concerns any use of motor vehicles, even on private land

I think the suffix number was for external differences, such as on the MK2 and 3 Ossa MAR, which was a push in fit as opposed to bolt on like the other bikes, but the same inside. Also might denote which side the tickler or pilot and idle screws are etc. Most Ossa, Montesa, Bultaco trials use very close, or same, jetting specs I agree with Jon about Surrey Cycles. If Burlem don't have one built up they won't build one to order for you, you have to wait until the time they have scheduled to build that particular carb, which could be weeks away, which is a crazy way of doing business. Also just realised my first reply was badly worded as I meant the 427 suffix was for the 247 Cota. I remember the carb that came off the MK4b that I rebuilt a few years ago was the same internally as all the others I've had on Ossas and Bultacos, and I'm assuming it was the original carb as it was a two owner local bike that had sat unused for years

That is the original carb for the 247 from that period I think Amal have reproduced most of the carbs from that period so they may have them. If they don't have 27mm, the 26mm 626 concentric will work just as well

Just been having another look for M7 as I have some bar risers to fit on my MAR and the existing bar clamp cap heads aren't long enough. Searched ebay again but this time no sign of the M7 countersunk screws I saw before. If you're struggling you can replace those in the front of the sump with M6 which is what I've always done. At the rear you can always drill out the threads in the frame lug on the sprocket side and use M8 nut and bolt which also gives a bit more leeway than just trying to use a bolt if the sump is out of shape and holes don't line up fully. On the clutch side I've never had a bike, since the one I had nearly new, that has a sump that is still straight enough to fit the bolt on this side so mine are only ever secured on the sprocket side. If yours does line up you could always tap the thread out to M8 x 1.mm pitch, they should prove easier to find

They're not common in the UK either but when I've searched and bought them off ebay in the UK, I've also seen them available in the US on ebay. If you search for M7 Cap Head you should find them easy enough

I can't tell you if the Amal MK1 and IRZ cables are the same as I've never had an IRZ - best bet is to ask Alex Snoop or Keith Lynas as they are long time Ossa dealers

Are they different? I thought all plastic tanks were the same, there is only one tap for plastic tanks and that's the one with two 6mm screws? They screw into metal inserts on the tanks I've seen but they can pull out if you over tighten

I'm no electronics man but not sure the flywheel has a protective coating? Sometimes, flywheels are skimmed to improve engine pick up and if they are, the original finish of the surface is skimmed away. I've done a couple myself and they don't corrode. Still shiny in fact. I wouldn't worry about it but I guess you could always use engine lacquer on it

200 in a Sherpa leg is too much - 180cc max The hole in the top nut should work as a valve to release air and stop the forks pumping up with air pressure but in my experience, even when they new, all they do is spew oil in your face. The air leaking also reduces pressure in the fork on compression and softens the fork action. I just drop a blob of araldite in each hole and have never had any problems with pressure build up in the fork They weren't air assisted but you can by fork tops from In Motion fitted with valves which you can use to either add a bit of pressure which also acts as an increased preload effect or just use them to bleed off air pressure build up, if you get any. If you use them to add air pressure you only need about 10psi max and you'll need a mountain bike shock pump to do it properly as it has the correct adaptor to fit the valve without losing all the air when you release it Your springs may also be past it but 200cc won't help rebound so try again with correct volume and then decide

The fibreglass sumpguard was replaced with the alloy version sometime in 73. Alloy version is better

The MAR was introduced in 72 and didn't have a rear silencer. They were a bit crackly... The pickle silencer appeared sometime during 73 so both 72 and earlier 73 bikes had no tail pipe You can buy new pickle silencers, I haven't tried one but the originals did mute the exhaust effectively Alternatively, you could easily make an effective silencer that doesn't spoil the looks of the bike. I used an old YZ250 2-stroke rear silencer and cut the body to the required length, re-placed the internals with a 25mm straight through perforated tube with new wadding and replaced (or sleeve down) the inlet and outlets with 25mm (YZ inlet, outlet and core is 30mm if I remember correctly) I have these on my 250 and 310 MARs and they work very well I wouldn't bother repacking the centre section until you've run the bike as it's not a nice job and no point doing it if it doesn't need it. If it does need packing, as well as being a bit loud the bike will also be a bit lumpy off pilot as a well packed silencer makes them run very smooth. There are few bikes as smooth as a MAR off pilot Example of type of silencer body here http://www.ebay.co.uk/itm/2005-YAMAHA-YZ-250-SILENCER-PROCIRCUIT-A-05-YZ250-TWO-STROKES-/142162425062?hash=item21198a74e6:g:XSUAAOSw5cNYEkka

PMK - The rear silencer on a later TR77 is different from the MAR silencer. The TR77 rear silencer is stuffed full of wire wool and has two small exit holes underneath at its end. The centre boxes are the same, but on the TR77 the centre and rear are welded together whereas on the MAR they are seperate items

The centre silencer on a MAR isn't baffle plate, it contains packing around a perforated tube. Only the rear silencer on a MAR is baffled. The packing may either have disappeared completely or be full of gunge. Using a torch won't do anything as the only way to restore the innards to proper working order on one of these (assuming that's what's needed) is to cut it open, remove what's left of the original packing which is also wrapped in wire, clean out the holes in the tube if necessary, then repack it and weld back together.

As above, it's the seat that holds the rear of the tank. If you have the original seat it does the job fine but if it is a Miller seat it probably won't fit snugly against the tank so you can use a releasable cable tie of jubilee clip etc across the tab to hold the back of the tank. You'll also need something under the tank as if you just sit it on the frame tube it will move around and vibrate like hell. You can use the foam tubing that is sold for pipe lagging or use rubber strips cut from old inner tubes etc. Originally they had foam pads or something to stop the vibration. Beautiful job on the tank

Colin at TYOffroad makes and sells the kit you need which keeps the footrest clear of the kickstart. It was his bike that was featured in CDB with Mick doing the test http://www.tyoffroad.co.uk/store/p34/FOOTREST_LOWERING_KIT_%28BOLT-ON%29_TO_FIT_YAMAHA_TY175._.html

I don't have a Verde no but they are virtually a MAR - same frame and swingarm, longer forks, angled shocks. Tank slightly different shape. Engine is the same with a few minor design upgrades, different porting in the cylinder and longer exhaust with that hideous back silencer. The original colour was similar to Ford Modena Green I think but the bikes you see now have mostly been repainted so hard to know whether you're looking at an original colour or resprayed The carb is just a normal 2 stroke Amal MK2 26mm

Can't help with a paint code. but if you're going to paint it all green and fit the green mudguards, I'd buy the mudguards first and then get the paint matched to them. If yo paint it first and then buy the guards, the chances of a colour match are virtually zero as the guards available now are probably some way lighter than the originals. The 250 Verde had an Amal MK2, the Bing was fitted to the 350.

Too many classes, some too confusing and not consistent across all routes What's a Pre85 British twinshock? Armstrong Hiro or Rotax? Well that's a foreign engine with foreign components in a British frame - same as a Beamish, TL Highboy, Bultaco highboy, Godden Majesty, Whitehawk etc etc. So do you have Yamaha framed Majesty in class 3 and Godden framed Majesty in class 4? It's already causing confusion and debate amongst organisers and riders. I don't understand what purpose the twinshock split between Spanish/British and Japanese/Italian serves. In the latter a TY175, or KT250 still has to go against a Fantic 240/300 and in the former a 1970 Bultaco or Montesa still goes up against the latest Cota 330 or 350 or Bultaco 340 or a Merlin (maybe an Armstrong) so where is the incentive to enter them. People seem to have been brainwashed by some of the drivel written on forums over the years that the sections in the Miller series are 'modern classic' sections suitable only for cut and chopped Hondas or Fantics and they think that an older twinshock is not up to it. They are, they are perfectly capable of being used in these trials. They're harder work than the much more capable later twinshocks obviously but they can still do it. Sadly I think too many believe what's been written, on many occassions by people who don't even ride the series, and think the bikes can't cope. I think if the twinshock class was to be split, a better split would have been post and pre-77, giving older bikes a chance to compete against machines from the same era and maybe then more riders would bring them out. There must be hundreds lying unused. This isn't 'having a go' in a negative way, it's based upon my own opinion and discussions that we had after today's Miller round with both organisers and riders, and also upon the suggestions I sent into the ACU in response to their survey. All that was wrong with the current format was the omission of unit / pre-unit class split for the British bikes class over the last few years. The rest of the classes were fine, although I'd still like to see a Pre77 class in twinshock Another possible issue with the current series was maybe with the same clubs running the events every year for the last eight or nine years, some riders feel it has gone a bit stale and just don't want to ride the same sections / groups every year, but if other clubs don't come forward to stage a round then there isn't anything anyone can do about that. There was also the severity of some events that were not testing enough on occassion. The trials need to be challenging enough to take around 10 marks from class winners. Having several riders going clean or losing just a few marks isn't challenging enough for a national series and riders won't travel 2 to 3 hours if the challenge isn't enough when they can find it at a local event. Anyway, thanks to South Birmingham MCC today for an enjoyable trial with their round of the current series. Overnight and early morning rain to spice up the sections, sunshine for most of the trial, nice variety of sections with some good old fashioned mud and a nice ride around the Lower Clee Hill. It was a good event with about 60 riders entered.

If it starts B-700 it will be a 250 verde yes but the 700 run never appears on any of the ID charts. Some of the earlier model number runs don't either, B-43 for example

Measurements: The shaft is 16mm long measuring from it's end up to the spacer inside the oil seal With the sprocket with the flange fitted, there is 6mm of the shaft left visible. I don't have a nut with the flange, only a plain nut and that is 8mm thick, so it overhangs the shaft by 1 - 2mm. The flat nut is about the same thickness as the nut with the flange With a flat sprocket fitted the nut sits virtually flush with the end of the shaft. Early Ossas used to have flat sprockets fitted from what I can remember. I've just taken the sprocket off a MK1 MAR engine and it is flat. How this works with chain alignment between the two different sprockets I don't know as there are no other differences in the external measurements of the final drive shaft between a MK1 MAR engine through to a Gripper Original gearing was 11 / 42. If you want slightly lower, as I do, try 44 on the rear and stick with the 11 tooth front as 10 can give problems with the chain, 11 is less hassle. 11 / 44 is low enough to be honest and the rear dished sprocket available these days just happens to be 44

The thrust washer is approx 2mm in thickness. It's a snug fit with the ID on the shaft, the OD is 30mm. The spacer is also a snug fit on the shaft and 5mm - 6mm in length (digital vernier packed up) The OD is 22mm, slightly thicker than the sleeve which is 20mm

You can also just tap the bearing down the shaft using a tube I've used Pyramid bearings a number of times in the past and they have been a correct fit and depth. Check the size they have supplied to you. They should be is 25mm x 45mm x 12mm. They used to have them listed as Bultaco classic bearings

Timing is personal choice but yes, somewhere between 2 and 3.5 BTDC is the range most commonly used Can't help with points gap or wiring as never had a points ignition Ossa All MARs were fitted with electronic as were Grippers. For whatever reason the TR77 was fitted with points although a few may have had electronic. The MAR or Gripper electronic system will fit straight onto a TR77 as the engines are all the same.

The gold sprocket is the correct one and the raised boss faces inward. Make sure that the spacer is pushed fully home through the seal. When you first push it in it will meet resistance against the internal lip of the seal which can feel as though it has butted up against the bearing. Grease it so that it pushes through the seal easier. There should be plenty of room to get the retaining nut on if the spacer is the correct size and fitted correctly MAR, TR77 and Gripper are all the same