woody

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

To be honest I don't know that you'd notice any real difference over the course of a road trial whatever carb is fitted if the bike is running correctly If I do a road trial of say 25 miles I can probably get around on a tank but carry a litre bottle in my rucksack just in case. Any more and you really need provision for a top up somewhere around the route. For me this applies whether I'm on my slimline 325 or my 340 and even my Ossa although that holds slightly more fuel, so there's a bit more leeway on that. You're never going to get it down to a precise figure as some single lap trials of the same overall distance may have more roadwork than others and if there is a good amount of moors riding mixed in with the roadwork you will use more than if it was all roadwork

Spud, I object to you stating what I do or don't want and why, as you have no idea. And if you actually took part you'd know I've ridden my BSA in Miller rounds on many occassions as well as my twinshocks I don't want to lose the twinshock class as twinshock has bugger all else in terms of a road based series. As I've said before the KIA is not a twinshock only series and it isn't road based. Pre65 has the Miller, NBB Championship, Pre65 Scottish as well as other Pre65 only events. Does it need another. And yet again you're dragging the topic away from its intended purpose which was ro ask people involved with the series whether they think there is a problem with the current format and if so what. You aren't offering any solutions.

Ignition side is a lot easier to change and makes a difference - whether you need to is personal preference though as there's not much wrong with the pick up of a 325 Bultaco motor, especially for classic trial sections

Just seen the pictures of the bike on the classified ad. If you don't find any electrical issues, the silencer is not standard so I'd also check that as well. There is no reason another silencer won't work but that is from some other bike so you need to be sure it isn't restricting the engine or blocked. It looks as though it is the type that has a perforated tube running through it with packing, if so the tube needs to be roughly 25mm diameter. As it looks a repackable type it may be worth pulling it apart and repacking. Try running the bike with it removed first. The standard silencer is welded onto the middle box on the green bikes, they are one unit, so someone has cut the tailpipe off and replaced it with that one. Not a problem if it is a suitable type. The silencer on the green bikes is considered by some to be restrictive by some, I've never had one so can't comment but I've known them to be modified to be less restrictive Also, it's been fitted with a MK2 swingarm which is the same length but the shock mounts are further forward. On the TR77 they are over the rear spindle. If the shocks are the standard length, standard is about 13.5", this would have the effect of raising the back of the bike. However, the shocks look shorter than standard but the back still looks high - it's possible the the rear mudguard loop has been bent upwards a little to give more clearance. The green models had longer forks than the MAR by about 2" and generally, they sat a bit high at the front, so usually the forks were raised through the yokes with about 1.5 to 2" protruding from the top yoke to drop the front and level the bike up, as well as reducing the chopper effect. Your forks are flush so it's going to feel like a tall bike with that set up

Yes 350 Bing, 250 Amal

The symptoms of the poor running bescribed by the previous owner sounded more like electrical problems than carb - it's on the other topic which is just titled 'Ossa TR77' http://www.trialscentral.com/forums/topic/61308-ossa-tr77/ I suggested some things to check on there which are common issues on the wiring harness of Ossa if they still follow the original routing If the dellorto has been taken of a GasGas or suchlike, it should be pretty close to Ossa jetting and at least run without the symptoms described. It might need fine tuning to get it top run perfectly but it should still rev up. I've just had a similar problem on my Bultaco when it suddenly began missing, backfiring, spitting back and wouldn't rev up. It was the spade terminal onto the coil which had corroded and was hanging by a thread. It was enough to give a spark when checking but under compression the spark wasn't strong enough and the bike wouldn't run properly. New spade connector and it ran perfectly again. Personally I'd check the electrics first before spending about £150 on a carb you may not need. Also, from the previous owner's description I didn't realise it was a dellorto fitted. If it is the conventional type, PHBH or PHBL, they don't have an airscrew, it's a fuel screw if it is on the inlet side of the carb in relation to the idle screw and they work the opposite way around to an airscrew - In to weaken the mixture and out to richen, so it's possible that is out of adjustment too

The TR77 had a MK2 Amal as standard which you can still buy new from Amal Carburetttors. But before you do that - Is this the bike from the classified ads on this site which the previous owner was asking for help with poor running - see previous topic in the Ossa forum