woody

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

It was some kind of fibre packing originally, I just use silent sport wool for mine

I guess you can if you don't remove the clutch but if the engine is unknown then I would be replacing the mains as a minimum which means clutch off and a complete strip in which case, when you split the cases the shafts will stay in the RH case. That is the case that you also reassemble into when putting it back together. You'll need to buy or improvise a puller to remove the tapered fit sleeve from the crank that holds the clutch cush drive assembly. These can be a very tight fit and difficult to remove. When you split the cases do it very gently to keep all the shafts in the RH casing as if they fall out they have shims on both ends and you need to make a note of which shim goes where to make reassembly easier. You don't want them all over the bench / floor.They aren't just on the two gear shafts, they can be on the selector drum too and they are also on each end of the kickstart shaft. They are also on the crankshaft.

As above replies, silver. The old Ford Silver Fox colour used in late 60s early 70s is a very good match as they weren't a bright silver colour. They don't look good they are done bright silver

That could almost be a cut up Sherpa alloy tank/seat unit ... The way the fins are cut on the cylinder makes it look more scrambles orientated as that was more in line with what they did than trials. It's a later engine due to points in the side, not distributor. Check the engine number as it will say what it is, C15, B40 etc in the prefix. If it's C15 and the letters SS or just S follow then it's a sports / scrambles motor which means big valve head and sports cam - not good for trials. It it has F or G it's a road engine which are ok if standard and not messed with. If it's T it's a trials engine but that's going to be unlikely

Another possibility - Steve Goode. He's reasonably knowledgeable on Cottons, probably hasn't anything himself but may know sources for Minarelli parts A real long shot is Vale-Onslow in Birmingham, they used to carry parts for just about everything in the 70s and still have stock from then. I'm not sure how hard they'll try to look for stuff but maybe worth a try

Have you tried Paul Powell at Cotton Owners. They have Minarelli parts http://www.cottonvilliersspares.co.uk/

You can get these from TY Offroad as I saw them on the stand at the Telford show, I think he has them in his development TLR. From what I've been told they work well http://www.tyoffroad.co.uk/

It fits ok to the 199b air filter hose and as they all use Bing carbs those bikes should be fine You'll need the step down inlet rubber from the cylinder as you would with a Mikuni etc as the Bing is a bigger diameter than other carbs. In Motion sell them

All the same on those I've had, the bigger pistons are used to keep boring out the 325 so if they were different they wouldn't work effectively (I'd guess)

I can't be sure but it would explain why the 159 I owned and the one my mate owned had a much quicker pick up than any other model I've ridden. The only one that comes close is my 198B which also has a Pursang type weight on it. The 159 we had made our other mate's 151 feel docile by comparison. From the 159 on I don't think the engines changed much. As the porting seems the same on all of the 159 on 325 / 340 barrels, and I can't see the slight differences in the exhausts having such an affect, the only reason I could think of was lack of weight. Unless it was done by smaller ports in the crank case mouth and crankcase compression?

I've compare the porting of a 199B, 199A and a 159 and they were all the same. If there is a difference, I missed it. The 159 is more aggressive due to the lighter clutch weight. Fit a 250 ignition flywheel and clutch weight to the 199A or B and either will spin up everywhere

The big difference between the 250 and 325/340 is the pulling power of the bigger bike which can use 3rd where the 250 can't (not often needed and probably never in today's classic trials anyway) The 198b actually picks up and revs up quicker than the 340, again, due to a light clutch weight. They'e all got enough power, 250 / 325 / 340 If you're looking for OKO carbs at Telford watch out for copies. Google OKO copy to see the difference. Even the box is a give away in the way the writing wraps around the corner at the bottom. On the copy the writing is set further to the right, so less 'text' on display on the front of the box. Plus the genuine OKO doesn't come with spare jets (the jets are different in the copy as well) If your Bing is set right and not worn out, you're not going to notice any difference with the OKO or anything else