woody

Details now on the front page but in case anyone doesn't read the front page, here they are again: On 17th June, South Birmingham Club are running the twinshock solo team trial. In addition to the twinshocks, the event will also incorporate two additional classes. Following the cancellation of the Pre70 team trial in Cornwall, a class has been added for club entered teams for Pre70 British solo bikes and there will also be a class for modern sidecar teams. Anyone can submit a team, so it is an ideal opportunity to get together with a bunch of mates and have yourself a ride in some excellent trials country. The course will include roadwork and be on the Clee Hill, which in past years has hosted British Championship nationals such as the Vic Brittain and Greensmith as well as many sidecar championship nationals. There will be two routes. The twinshock teams will ride the harder route whilst the Pre70 class and sidecars will ride the easier. The hard route sections will be pitched somewhere around the level of an average Normandale round and will be intended to give a challenging but certainly not severe test to the riders. The B route should compare to one of the more challenging Miller rounds. The rules will be no-stop, as per Miller and Normandale series. The nature of the land will allow for good natural flowing sections with no hinge-in-the-bike tight turns. The terrain for the sections will consist of rocky streams, mud streams, mixed mud/rock streams, mud banks, mud climbs, roots – pretty much a mixture of most types of going. Groups such as Bedlam, Beech Trees, Park Farm, Nine Springs (collectively, long continuous rock stream with steps, loose rocks mud banks) Starvecrow, Silvington, Silvington Wood, Clayhanger, will all be familiar names to those who have competed on the Clee Hill over the years. The structure of the teams is: Twinshock teams will be 4 riders with the top 3 scores being used to determine overall team placing. Pre70 teams will be 3 riders with the top 2 scores used. Sidecar teams will be 3 sidecars with top 2 scores used. If anyone wishes to enter the twinshock class on British bikes in order to ride the harder course, either as a complete team or together with twinshock bikes in a team, this is acceptable but obviously you will be a twinshock team, not a Pre70. There is no twinshock class on the easy route. All twinshocks ride the harder route. So, this is a rare opportunity to get your classic bikes amongst these old Clee Hill sections as the opportunity to ride up there does not arise too often these days with ever tightening land issues. If you’d like to make the most of it and enjoy a good traditional type road based event on the Clee, get your entries in now. So far, 9 or 10 twinshock teams have entered but obviously more are welcome. For Pre70, the class has only just been added following the cancellation of the trial in Cornwall, so you need to get organised quickly and get your teams in. Particularly all you BMCA boys, it’s a local event for most of you so get those teams in, especially those of you riding in the Manx Classic in the not too distant future. An ideal opportunity for a bit of practise on sections with similar features to those you will encounter on the island. Regs and contact details are available in TMX ‘regs available’ section. Entries close 4th June. Event organiser is Tim Fairbrother who can be contacted on 01562 754827

Details now added to the front page. Also repeated in the trials review/preview forum.

I'm assuning you've tried Bultaco UK Try also: John Collins at Port Talbot Motorcycles (Bultaco dealer back in the day and still has a lot of stock) Wakefield Offroad (broken loads of trials bikes) Sammy Miller (broken bikes in the past) Or this ebay seller http://www.ebay.co.uk/itm/Bultaco-350cc-twin-shock-trials-clutch-cover-/230791805227?pt=UK_Motorcycle_Parts&hash=item35bc43792b I know this case is for the later bike but he has broken a few Bultacos, so may be worth a try asking him. Or, you could always fit this case if it came cheap enough. I know it is for the '74/75 model but it would fit ok. Doesn't matter if it is from a 250 or 350, they are the same case. If you do go for it, bear in mind the fixing bolts are probably different lengths from yours and the drain plug on this case is the bottom middle fixing bolt which serves as both (available from Bultaco UK if needed) - so get the bolt set as well if he has it.

The inlet manifold will fit ok as they are the same Clutches were altered more than once up to the 1976 models. Some had threaded nuts on the end of the hub pegs with nuts to tension the clutch springs, some had unthreaded pegs with a hole through it at the end through which a pin slots to retain and tension the springs. Although that is the only real visual difference, there are differences in the thickness of the boss at the back of the basket and the hub so they aren't all interchangeable - although I daresay if you could adapt them with machining. However, once past the '76 models I think that the clutches changed but then remained unaltered from '77 bikes, so a 199 should be fine on a 191. They use the latest type with the nuts to tension the springs The crank counterweights were also shaped differently to suit the type of clutch case fitted (not an issue from 191 to 199 as same case)

Christian, I have a Delorto on my 340 with the following jets etc. Pilot 40 Main 98 Needle tube AV264 Needle X2 Slide 4.5 Crankcase has mild transfer port changes and the exhaust has baffles removed and replaced with perforated tube and packing (like earlier models) but I doubt it makes much if any difference to the jetting. I think these settings are reasonably standard fare for most trials bikes fitted with the Delorto. It runs very cleanly and revs out very well.

Never ridden one but yes, the engiine is the same unit as the 280 SWM. Whether it's in a different state of tune I don't know, but I'd guess the bike is similar to a late SWM to ride.

Yes fork extended and spring out and ideally damper rod fully extended. Unlless it is held fully extended it will sink back into the leg under its own weight. Bit of a 'fussy' process but no other way with cartridge forks. Old style damper rod forks don't work as well as cartridge, but so much easier to service...

Yes, that's what I would do to. There is no stress on the casing, doesn't have to keep oil in, so I'd repair it with a piece of alloy cut from a sheet and metal putty or silicon or such like. I've done loads of Ossa ignition cases like that in the past where the chain has broken them in a similar manner to the Cota kickstart. Stripping an engine just to have that case welded really isn't worth the hassle. They can be a real pain to strip, shims in the gearbox and crank, the needle roller arrangement on the gear shafts, the counter weight and cylinder studs as mentioned above. Avoid it until you have a problem which leaves no choioce but to strip it, then get it welded. Until then, just plug it - and position the kickstart so that it doesn't happen again.

Yes, fully extended, but this is the bit I can't rmember too well. You need enough oil to ensure that the internals are immersed in oil so that when you move the stanchion down, which draws oil into the chambers, it only draws oil and not air. If in doubt leave about an inch or two gap to the top and keep an eye on the oil as you slowly move the stanchion down. The level should drop a bit as the stanchion moves down, spreading the oild thorugh the internals, but if it looks as though it is going to spill over, empty (pour or use a syringe) a bit more out and try again but if you do, be careful not to let any air into the damper internals or you'll have to start all over again with the damper rod bleeding. Hopefully you can marry this up to the pictures in the manual By the way, the manual says something like 440cc of oil per leg but it's too much. I think Mick Andrews used to say 400cc but whether you use the volume or the air gap method, you still have to go through the bleed process to distribute the oil fully through the internals. I've been told that if you just put 400cc into the fully assembled forks in situ in the bike and them just pump the forks a few times, it is enough to distribute the oil. Fact is I don't know the answer to that, but given the specific process Yamaha give in the manual, I'd say that the air gap method is the only and correct way.

Found this that I posted for someone else some time ago. I used to use 10W and it was fine for me and I'm 17.5 stone. =============================================== From memory... First loosen but don't remove the allen bolt at the bottom of leg before starting to dismantle as the spring tension should enable you to undo it without holding tools, especially if you have an air/electric ratchet and you compress the leg whilst undoing it. REMEMBER, the damping adjuster screww is inside the head of the allen bolt so screw it right in before inserting the allen key, otherwise you may damage the adjuster screwdriver slot, it's only brass (bitter experience) Count the number of clicks for resetting it afterwards. Undo the fork caps from the stanchions. Once undone, the fork caps are still screwed onto the internal damper rod and secured with a locknut underneath them. To remove the cap from the damper rod you need to hold the locknut with a spanner and undo the cap. Bit fiddly as the spring/preload spacer is in the way. You can then remove the spring and spacer etc. making a note of their fitted order. Turn fork upside down and pump out oil, also pump the damper rod as this holds oil too. Then remove the allen bolt from the bottom of the fork leg, hold the fork leg in one hand (or vice) and pull the stanchion sharply out. You probably need 2 or 3 goes to shock it free of the bushes. Watch that the damper rod doesn't fly out and disappear as it is now free, no longer held in place by the allen bolt. May be better to remove it before trying to shock the stanchion free. This is the messy part as when they seperate, any oil left inside will come out. Once the stanchion is out you can replace the seals and bushes, just note their order before sliding them off. Reassembly is the reverse. To fill with oil you need the leg upright with stanchion fully extended but no spring. Fill to the top with oil, then pump the damper rod 7 or 8 times slowly through its full stroke to distribute the oil internally. The level will drop. Refill to the top and then slowly pump the stanchion itself 7 or 8 times but not quite right through its full stroke to completely distribute all the oil. The oil level will fall again. You are looking for an air gap of 95mm from oil to top of stanchion (Birkett's recommendation to me) Add or remove oil as needed. Refit spring/spacer and cap and screw cap back into stanchion. Think that's it, been a long time so I may have overlooked something but I don't think so. Reset your damping adjuster in allen bolt in bottom of fork leg back to original position.

Engine and frame numbers didn't always match exactly from the factory so that in itself isn't an issue. The first two numbers should match as they denote the model type but the remainder can be different. You don't say what the numbers are, if you have them, post them as most Bultaco enthusiasts on here can tell you what they relate to. The wrong engine / frame combination will devalue it in some people's eyes, even though it may not affect the way it rides (depending on the frame/engine combination of course. A Pursang engine in a Sherpa for example wouldn't be much use) There is a Sherpa on ebay I noticed yesterday which was listed as 1967. Is it that one you're looking at? The frame on that is an early 70s frame, either a Sherpa or Alpina, whereas the engine looked an early 5 speed which would be 1967. The combination would work but there would be no real value in it were you to want to sell following an expensive rebuild.

My 4RT was the same, the holes in the seat let all sorts of mud and crud straight onto the filter. I just used car body repair gauze stuck to the underside which kept the mud out

Depends who you talk to, I know three people who have had real problems with them - wrong polarity, timinng way out, advance curve retarding too soon and the after sales service and ability to sort the problems out hasn't been as good as it should have been. Conversely, I know there are people who are quite happy with them. So all I'm inferring is don't rule out the igniion, it could be at fault.

Without any facts to hand it is impossible, so that is a pointless response to a genuine question. If you know, why not just answer the man's question. You ask enough of them on here, maybe you'd like that sort of response to yours.

I don't understand, I really don't.... http://jkhirst.com/store/index.php?main_page=product_info&cPath=90_3_4_18&products_id=308

Don't have the jetting for the 247 but for the Bultaco of the same age with the same carb, from memory, they were 25 pilot, 106 needle jet, 160 main, 3 1/2 slide. Same sizes also for the 250 Ossa with same carb. So the Mont must be very close to that. Would be a good starting point. 40 for your pilot is very rich for MK1 Amal (generally) When I can next get to it I'll check my Clymer and see if the 247 spec is in there, but won't be until the weekend.

A few there to keep you going.

Or a bit of polish and chrome

Closer to tradtional 340 colours (mine)

red / silver

Navy - a bit gaudy this one... nice blue though

All red

Black one

I don't but they are available on ebay from various dealers at competitive prices and carriage is usually £10, regardless of the number of tyres ordered.

Up to the 150/151 models, the 250 and 325 Sherpas shared the same frames. With the 158/159 models the 250 had a different frame from the 350. It had a bend at the top of the downtube by the headstock and was a shorter bike overall (and had shorter forks) This practise continued to the 190/191models. With the 198/199 models, the 250/350 reverted to sharing the same frame. May be why your 158 feels as though it has been tucked in. I don't think the head angle was changed on any of the frames for the 350 models (or later 250) from the 159 to the 199b. It's been said that the 199b had a different head angle (for the tighter sections of the day) but I can't tell any difference riding it from any other. The 250 is a very under rated bike - everyone seems to want the big model. I've a 198a to be done one day, when I get time.