woody

Rear 42 teeth, front 11 teeth. Tyres are normal trials tyres, 4.00 x18" rear, 2.75 x 21" front Chain tensioner is fixed to the brake pedal pivot spindle, not fixed to the swingarm / chain guard. If yours does someone has modified it This is what the tensioner should look like http://www.ebay.co.uk/itm/OSSA-MICK-ANDREWS-CHAIN-TENSIONER-OSSA-MAR-OSSA-EXPLORER-NEW-CHAIN-TENSIONER-/381111480886?hash=item58bc03b236:g:IoMAAOSwyZ5UqCc8

Fine spline is for early bikes up to about '72, maybe '73 and applies to UK bikes too, same with gear shaft. As for new knuckle, I know someone who bought one of the new knuckles from Ossaworld and it snapped straightaway. I'd look for an original used kickstart personally, there's one on ebay UK now which looks to be coarse spline. You need to look at the spline on your shaft and determine whether it's fine or coarse. http://www.ebay.co.uk/itm/OSSA-mar-trials-bike-kickstarter-lever-70s-80s-/162677469118?hash=item25e0552fbe:g:KxgAAOSwn45Zvt1e

Buy some Barnett friction plates which allow less tension on the springs due to their higher friction material. If that isn't enough lengthen the clutch arm on the casing which will give a lighter pull. You hardly need to use the clutch on a MAR anyway. Not sure about rules for hydraulics, probably varies from club to club but I'm not convinced it would make much difference on a standard set up

Try Keith Lynas in the US at Ossa Planet, he preps Phantoms and has NOS parts. Only other I can think of is Hogan's Cycle Shop, also in the US.

The frame and swingarm are standard 198b, there is no swingarm mod so not sure what you've seen No idea on availability of GasGas 280 pistons but I believe the 270 is easier to find. I have an M49 with 26mm OKO and electronic ignition (set on full advance to overcome the curve that isn't really needed and makes them too lazy on advised setting) and to be honest I don't see that it needs anything else. These had the Matador barrel/porting, they aren't lacking in power and rev like hell. They're just a bit woolly at the bottom due to the porting but going bigger on the piston won't change that - my 49 is on 73.50 using a Wossner TSS piston - they go to 74mm so you don't need the GasGas piston. The inlet skirt just needs trimming to match the trials piston. If you use the GasGas piston you may also have to cut the inlet skirt to match the Bultaco piston

Riders need to check which tyres they have fitted for road trials if they want to avoid that kind of charge

Regs and entry form for the Greensmith Memorial trial should be appearing on the front page shortly. This is no longer a round of the ACU Classic but retains the same format as previous years which is one lap of around 35 miles around the Clee Hill in Shropshire. The trial caters for the usual British bikes and twinshocks, there's a class for rigids and British / twinshock sidecars, but this year the trial is also open to over 50s and over 60s on modern bikes. Two routes will be set as usual and I guess if you're over 60 and want the hard route, just enter as over 50... Let's not let this one slide away into the mists of time, these trials need to be kept alive so get your entries in. Entry limit is 100. The Northern British bike round at Llangollen had 100+ entries last weekend for a road trial and that was British Bikes only, so riders are out there.

You'll need a different inlet hose though as the Oko has a smaller inlet stub than the Bing. In Motion have them

yes, fits ok

Tim has confirmed tonight that the Greensmith is definitely going ahead on15th October starting from the Farlow & Oreton Village hall in the Clee Hill area of Shropshire and as in previous years be suitable for all British & Twinshock classes including sidecars. So there you have it from the organiser - definitely on, just not part of the Classic championship

And now the next round bites the dust as well. Mid Wales have cancelled theirs which was scheduled for this weekend. Around 14 entries was the last I heard How many clubs are going to want to put a round on next year with this level of interest? Doesn't bode well. Two rounds left this year with the Greensmith opting out of the series. Be interesting to see how many entries they attract.

The allen bolt bottom centre is also the drain plug

As usual Spud, you're not in the same solar system with your reasons for its failure. In case you hadn't noticed, it hasn't been a Pre65 only series for decades, so Pre65 rules have nothing to do with it. And if they did, how do you explain the bumper entries in Pre65 only series like NBBC and Pre65 Scottish, not to omit the Manx classic. All of these series attract the same type of bike and rider so Pre65 rules have no bearing on the Miller series going down the pan. Ultimately there are too may trials and a lot of the classic bike riders have modern bikes too and can drift between modern and classic events. Date clashes mean you can do one or the other, not both, so it depends on which the rider considers the better trial on the day. Some have said the Miller trials have got stale because the same route / sections are used year in year out, but that can be said of most trials. As Jon has pointed out the class structure introduced this year for the Miller (now ACU Classic) series is a mess. Far too many classes and this caused a lot of disinterest amongst riders and organisers when it was mooted. The ACU sent out questionnaires before introducing these classes, asking for opinions. I sent a detailed reply which was ignored, as was my follow up - didn't even get an acknowledgement. I know the same happened to others. I don't see the point of canvassing the people who run and take part in the events and then ignoring their opinions. I don't know of any rider or organiser who thought the classes were a good idea. Rather than run the risk of losing entries as a result of the disinterest in the class structure, Stratford still ran their trial but opted out of the series and ran 'normal' classes. Result - decent entry, which puts another nail in the coffin of your self agendered rules argument. South Birmingham have also followed this approach with the Greensmith in October. There is no single issue that stands out as to why this series is failing but the class structure is definitely very unpopular. Pre65 rules however, have got nothng to do with it.

Colour scheme or decals won't tell you anything as it's 40 odd years old and they can be changed - as per the tank which is a UK alloy tank, not the fibreglass original. A couple of possibilities. 1) It could be a 250 cylinder from a later green model which were also slotted but the head is MK2 MAR 2) It is a 350 MAR - If the engine number starts 430 then it is. Not all Ossa numbers appear on the charts. A 350 top end won't fit a 250 as the stud spacing is different - except a Gripper which had the same spacing for both The engine number will give you the definitive answer

Thicker drive plate goes on the inside of the basket. Only personal choice but I've never wired the spring screws and never had them come loose.

When you slide the counterweight on the key can ride up at the back which stops the weight sliding all the way on. Make sure the key is a tight fit, if necessary loctite the key in and let it set, then try again. Make sure the weight is seated properly and the nut torqued up as they can come undone and when it comes loose on the shaft it can sound like the death of your engine... The clutch springs have cups over the end of them which you can use a pair of pliers on to depress the spring enough to get the pin in. Or you can cut a slot in an piece of the correct diameter tube and use that to compress the spring. Or you used to be able to buy a tool to do the job but not sure who would have one of those now. Any 5 speed Sherpa manual will have the info you need. Ebay always has them - Haynes, Clymer or you can buy a workshop manual from In Motion (UK) or Hugh's Bultaco (USA) not sure where you are

Glad it's sorted - they're always stiff when running through on the bench, but as long as they all select they'll be fine when all assembled and in the bike

You have to be kidding... have you ever picked up a TY250 engine, they're a massive lump. Frame is light but combined weight gives it the same overall weight as anything that was coming out of Spain. TY was bottom gear only, shut off on a hill in 2nd and it would just die if you tried to bring it back in. Maybe the 175 Bulto needed a run up but the 250 and 325 had no problem with hill climbs. A 325 has immediate throttle response, will lift the front in third from idle and will go up climbs from a standing start at the bottom

I've never had a problem adjusting the cable on the MAR ? Brand shoes are pretty crap compared to having them re-lined with modern material. Villiers Services, Safetec and others can re-line your shoes with a much better material that actually works. Mine works fine with the cable, front and back. A lot easier than trying to concoct a rod and which ultimately, will still be operating less effective brand shoes

There isn't a parts diagram for the 340, as far as I know If you can go through the gears successfully with the drum then the gears and selectors are assembled correctly With the crankcases still assembled, remove the selector mechanism and see if the drum will still operate the gears now that everything is tightened up, as opposed to operating it in just the one crankcase half - it can be done. If so the problem is with the selector mechanism which obviously worked fine before stripping. Have you got the selector pawls the right way around so that the are engaging properly with the drum, they are handed if I remember correctly as they have a smooth and sharp leading edge Have you got the spacer / shim on the end of the layshaft. If missing it wouldn't cause a problem when shifting through the gears in just the one half, but may do when all bolted together

Hi Martin, the clutch action is controlled by a dished spacer at the back of the clutch pack and there are different sizes with more or less curve on them. These can make the clutch sharper or softer in take up. Best having a word with Pete and describing what's happening. They don't need a lightener

With modern shoe linings machined to fit, the MAR brakes work fine. There's nothing wrong with the cable arrangement, as tortuous and contrived as it is, it works fine as a mechanism for operating the brake arm - but only if the linings are good. A rod operated brake is still no good on any bike with duff linings so replacing the MAR cable with a rod will achieve nothing. Using a decompressor or just using the engine braking with no idle is fine in dry / grippy conditions but useless in slippery conditions or mud as the rear wheel will just lock and stall the engine. The biggest problem with the rear brake is the weak casting of the brake plate. If the brake snaps on too hard it can break the casting on the brake plate slot that sits on the lug on the swingarm (it usually takes the cable locator with it...) If that happens there is no way of holding the brake plate in place and it just rotates when the brake is applied. This is usually because the slot wears over time and can chatter on the lug. If there is any play between the slot and the lug it's best to pack it and remove any chatter. This will at least reduce the chances of snapping it.

60 for a pilot jet in a Mikuni is huge... On Yams, Bultacos or Ossas I've never used bigger than 35. Listening to a bike on a PC completely distorts the sound and makes them sound worse than they are, but yours sounds as though it needs the exhaust repacking, it sounds noisy. If it's blown all the packing out of the middle box, or it's gummed up, and the same with the bottom half of the rear box, it will definitely make it run rough off idle

If it's any help I know someone who had a Saracen when new and has some Saracen frames now and they all start 6960. There was a Saracen with a Bantam engine at the Telford show.

They aren't piston slappy no, if everything is right they run without noise. Conrod does have side to side movement, they are designed like that, you have to centre the crank with shims when assembling