woody

There aren't any actual timing marks, what you do is line up the hole in the flywheel with the hole in the stator plate and that is the firing point, so you just move the stator so that they line up at whatever point before TDC you want it set at. The hole in the flywheel is about 5 o'clock with the engine at TDC (or about 8 o'clock if it has an earlier ignition fitted) To line them up there is an actual motoplat part called a timing pin but you can use something like a pushbike spoke or similar. Did you use a genuine TR80 piston if you have fitted a new piston?

Ultimately it's personal choice, you can set anywhere between 2mm and 3.5mm before TDC depending on the response you want from the engine on pick up from idle

Sherpa t 325cc 1972/73

It's just an earlier manifold from a 158 to take the M92 pipe as the early 325 and later 250 are the same fitting

The original bars for the 159 were about 8 inch rise as were virtually all of the bikes from that era, with no brace. The black braced bars came in about 1978/79 on the M198/199 I think

As Steve said, frame is an early frame, from the headstock and frame tube layout I'd say series 2 model 91/92 from 1973. The exhaust chrome pipe is an M92 type and is the same diameter as later 250 pipes. It's definitely not a 198 frame. Engine looks to be a 198 type so if the numbering is not altered it should be the original engine. Maybe the original frame got damaged and someone acquired that one and stamped it to match. I've recently had some issues with DVLA whereby someone was applying for a V5 for a model 92 Sherpa that belongs to me. Turns out he must have had the engine that my bike left the factory with and stamped a frame with that number to apply for an age related plate - I'm assuming he knew engine/frame numbers matched from the factory and that he could date it from the engine number. The frame number flagged up as already registered so I had to prove that I had the original. DVLA wouldn't show me photos of the bike that he was applying for but the police who came to inspect mine did and I couldn't believe what had been done. It was a later frame and looked as though it had had the frame number chiselled into it, so no surprise really if you have one that has been tampered with

No idea why he told you that about the gearbox, the 303 shares the same engine components as the TR80 Gripper and MAR trials bikes plus numerous other models. Not really describable as a hodge podge either, it's basically an evolution of the TR80, with frame changes presumably eradicating the weak points where they could break. The engine is TR80, exhaust is TR80 redesigned to go over not around the cylinder and a new slimmer tank seat unit was fitted.

Sounds as though you may have a case from an earlier model Pioneer as most early Ossas had small crank assemblies. The early MAR - MK1 from 72/73, engine number begins 34 - also had a smaller crank assembly than the MK2 onwards - yours will be a NK2 as it's 74. As it is a 74 model the layshaft will run in bronze bushes so you need one from 74 - 76 engine, in late 76/77 the layshaft assembly was changed to run in needle rollers not bushes and although the shafts look identical they are slightly different in length and diameter so won't interchange (they might assemble but the gearbox won't work properly) You need an engine from a MAR that begins 21, 22 or 23. I don't know much about Explorer specs but think one beginning 44 or 45 might match the MAR but not sure - if you could find one as they're rare in UK. Ossa ID chart here with chassis numbers (applies to engine also as they're the same) http://ossa.2y.net/ossa/reference/ossaref.html

Hi Sandy, no, sold it some time ago and it went to Denmark. I gave it a total refurb along with a Cota 350 at the same time. Rode both a few times and out of the two I preferred the 350,

Puma bike uses an exhaust from a 335, common mod in Spain

The regs have now come out for the first round, Cotswold Cups on 24th March. It seems this trial has two class categories, one for the new championship and one for the Cotswold Cup. They're available on the South Birmingham MC website http://www.sbmctrials.co.uk

Ossa MAR - probably my favourite trials bike, just glad to help if I can I'm reasonably sure it's a Whitlock frame but another thing that is missing is the rear brake pedal mount as that was located just behind the left hand footrest as the Whitlock didn't have the same brake spindle arrangement as the Ossa frame I think the swingarm is either modified or a replacement. The bottom shock mounts are the wrong type and their positioning is wrong. The Whitlock frame was made for upright shocks as on the MK1 and MK2 MAR and the s/arm mount was just about in line with the front edge of the rear hub, the same location as the MK1 and 2 MAR frame, although the MK1 had a 1 1/4" shorter arm than the MK2. On the TR77 they went back to a short swingarm like the MK1 but put the shock mount right over the spindle. On yours the shock mount is further forward than a TR77 Ossa arm which is why the arm is pushed down at such an angle. This has left the shock angle somewhere between that of an earlier MAR and the TR77 and a steeper angle on the forks with the raised back end, the mounts need to be over the spindle to match the top mount and put the shock angle right. I can't think of anything else but someone else may have something to add as there are other Ossa enthusiasts on here

Only bad if you're bothered about originality I guess. The Whitlock frames were said to be good frames, lighter than the Ossa frame. I've never had one so don't know. I'm reasonably sure it's a Whitlock from what I can see, but not sure about the swingarm as it doesn't look like the Whitlock one, but it could have been altered as well I take it you can't remember the reg number, if not and you're certain of the history of the bike, I'm assuming it would have been registered using the original frame, so you should be ok filling the V62 out and applying for the V5 using the frame number

No. it's not an Ossa frame, it's a close likeness but there are a few differences. It would explain the lack of frame number It could be a modified Whitlock frame as he made some for the earlier MK1 bikes.The footrest hangers look very much Whitlock. There are other likenesses with a Whitlock frame but then there are differences too - sidepanel mounts, additional mount for headsteady (maybe) top shock position moved, bottom shock mounts changed, Swingarm spindle slot is normally open ended on the Whitlock frame. Whitlock frames were nickel (or chrome, not sure) plated as yours is undernneath Miller didn't sell an Ossa frame but Cheney did although it doesn't look like a Cheney. I'd guess at modified Whitlock but not sure

The MK3 generally had black legs but some early versions with the normal up and over chrome front pipe may have had plain alloy (not a criticism of what you've done, I'm no purist or originality obsessive when it comes to paint jobs) The MK3 changed a bit during it's short run, early bikes had the normal MAR exhaust, then they fitted the longer front pipe and some later versions had the TR77 style rear silencer That's a good shine on that paint for silver fox - I might try some of that on a Cotton tank I have to paint

If you're absolutely certain that the engine and frame are the original pairing then the frame number will be the same as the engine number, just prefixed B instead of M. If you fill out DVLA form V62, leaving the reg number blank if you don't know it and using the engine number for the chassis number but prefix B, they will match the chassis number to the reg number and send you the V5. As you will be the registered owner on their records it should simplify things but I'd put a covering letter with the form saying you've lost the V5 which is why you're applying for it I don't know why your frame isn't stamped (replacement maybe?) as generally, after the MK1, the trials bikes were stamped on the headstock, stick on numbers were only used on the MK1 as far as I know If there is a frame somewhere with your number on it and it is registered to someone else, be prepare for some questions from DVLA as t why you're applying for someone else's V5, but from what you've said I'd think that unlikely I'm currently in a tussle with DVLA as someone has sent in a V62 applying for a V5 which I own.... Because it's a Bultaco and the frame and engine numbers didn't match on early bikes because of the way Comerfords sold them, I suspect someone has the engine that came with my bike from the factory, has an unregistered bike, and has applied for a V5 using the engine number as the chassis number in the hope they get a V5. 12 months on and DVLA still haven't sorted it...

VW/Audi Mars red is a good match

Engine numbers start with an M, the frame number starts with the B. The identification chart quotes frame numbers which is why the prefix is B, but the engine and frame numbers matched when the bikes were built. On early MAR the frame number was on a sticker sticker on the headstock but from around 1973 they were stamped into the headstock which is where yours should be

There's not much info on it and as far as I know it's not an 'offical' ACU series which is maybe why there is nothing on their website about it, I haven't looked. Tim's idea was to run as a regional pilot this year with 4 or 5 rounds and if interest took off expand to a full series next year if clubs are interested in organising a round It's called the Central England Classic Championship - Cotswold Cup, Sam Cooper, Greensmith and Guy Fawkes. I haven't seen any dates other than the two Midland Centre trials as they're on our calendar, Sam Cooper 26th May and Greensmith 20th October I just hope there is room on the calender for all these events as more and more are appearing and there are going to be clashes Some info here https://www.oldbikemart.co.uk/coming-up-in-the-december-issue-of-obm-central-england-classic-trials/

Common answer is petrol but if you look at the underneath of the tank is that discoloured too? Usually not, my SWM tank was still perfect yellow underneath and also under the tank badges if they were removed, whereas all surfaces touched by sunlight went darker.The entire tank surface should be affected if it's caused by petrol shouldn't it? Ultra violet from sunlight discolours plastic, just look at garden furniture or kids toys like slides, plastic bikes, swings etc. If these tanks seeped petrol vapour like they're said to, if you left one in a closed garage for any length of time it should reek of petrol, so why don't I smell any?

No is the short answer and I've no idea how or why claims like that originate. Not a full 350, only 302cc so no Bultaco 325 type power on tap but noticeably more than the 250 which is fairly flat. It will pull 2nd or 3rd gear better where the 250 struggles. Later TR77 versions supposedly have sharper porting than the white bikes but never tried one so can't comment. Mine is the first model from 1975 and is a nice bike to ride. Just shave a few ounces off the ignition flywheel for quicker pick up if needed

KIA series in the Spanish class - just me and Chris Myers on Bultacos The rest seem to be facebook queens...

I have one of these kits and it worked fine to remove the drive gear on my 247 https://www.machinemart.co.uk/p/cht249-14-pce-bearing-separator-angle-ge/

The shock bolts are normal M6 on the earlier bikes, MK1 2 and 3, they went to M7 on the green bikes Strangely, the fork yoke bolts are M7 on the earlier bikes and changed to M6 on the later bikes... Fitting the engine, I've never been able to fit one with the barrel in place, or remove it. I take the barrel off before removing and fit it after the engine is back in the frame - I could never do a rubik cube either...

Ford silver fox used around 1970 is a good match but not sure where you can get that now unless a local paint shop can mix you an aerosol for it. I don't know the RAL code. NOTE - If you use Halfords paint it will dissolve at the merest touch of petrol, it will need a coating of petrol proof lacquer otherwise you'll be really peed off with the outcome. And whereas Halfords paint does spray very nicely and evenly out of the can and leaves a really nice finish, their petrol proof lacquer doesn't, it splutters out so you need to be very careful when applying it