woody

Turned out it was the offset after all. The original wheel that came out of the bike has the MK1 hub, flanged rim and is fitted with a flat sprocket. The wheel I had built is a MK2 hub with a dished sprocket and non-flanged rim. In trying to compensate for the different measurements of the different components, I got something wrong, so when checking the offset of the new wheel against the old it looked correct but as it turned out, wasn't. Once I had had the measurements I needed from an original bike still fitted with dished sprocket, I dug out another original MK2 wheel and found an old dished sprocket to fit to it. Put this in the bike and checked the measurements against those I'd been given and they matched. Checked this wheel against my new wheel and the difference in offset was apparent. That's now been corrected, chainguard is fitted and ready to go, I hope, for the weekend.

I have the measurements I need now Thanks to John at Twinshockshop for scrabbling all over a MAR this morning with a tape measure

Well that's the strange thing as the chain seems to line up ok, I've also ridden the bike a couple of times with no chain issues. Although the wheel is noticeably set to the right it doesn't affect riding but I can't get the chainguard on and this weekend' s trials could be very muddy and to ride the Ossa, it will need a chainguard I need to have another look tomorrow and see if I'm missing something obvious. I've already had a go at machining the brake plate but things didn't go quite to plan... I absolutely hate loathe and detest that flat sprocket conversion. Original looks much nicer and I have a spindle a mate made me some time back from better material than the original, so no bending issues. I also have one of Keith Horsman's spacers with extra bearing that gave more support to the spindle to go with the dished sprocket but can't find it at the moment.

Having a few issues with rear wheel alignment on my MK1 MAR Does anyone know the length of the original spacer between the sprocket and swingarm please - this is the original dished sprocket with the longish spacer I've now fitted a new dished sprocket on a newly built wheel in place of the old flat conversion but the spacer is long gone. Normally I'd just measure the gap and make the spacer but I've an added problem. The wheel that came out of the bike was the original MK1 with thinner brake shoes but it had some damage. The wheel I've rebuilt is a MK2 with the wider shoes and the MK1 brake plate won't fit (I'd forgotten there were differences and the brake plate for this wheel is broken) When the wheel is tightened the brake plate lip fouls the hub as the boss on the inside isn't long enough. It needs spacing to stop it fouling when tight, but when the wheel is then fitted it is 10mm too far to the right and I can't get the chainguard on. The wheel offset is correct so either the spacer I made isn't long enough and the swinarm may have closed up, or there is still some sort of issue with the brake plate that is pushing the wheel over. I could do with knowing the original spacer length so I'm at least starting with the correct measurement on the sprocket side, so if anyone can help it will be appreciated

Probably a little more substantial than I was thinking....... but illustrates the point nicely about masking off the tyre Looks very much like a Bultaco guard

Physically yes, but I'd go for a 240 or 280 (the 280 is also referred to as 320 but it's actually 280cc) Older twinshock 125 engines are pretty gutless, especially if you're used to modern bikes. A 240 can be bored to 280. Older red/white models can be aggressive in the power delivery as they had lighter flywheels, the yellow bikes are smoother. Nice bikes.

I never knew that (never seen that parts diagram) So sorry Yellow_Cad, I gave you wrong info there. You can see how it fits as the top hoop must fit around the lug that the rear chainguard bolt mounts to. The bottom mount on the chain pad would just need a long enough bolt to attach to I used a brake shoe spring mounted like that some years ago on a bike that had a broken main spring, at a time when they weren't available to buy

It's pretty straightforward... if you ride in deep stodgy mud, the mud will stick to the tyre sidewall and get carried around as the tyre rotates. If the build up of mud is thick enough, and you haven't a chainguard, or one of the right depth, the chain will act as a scraper and slice the mud off the tyre which will then sit on the chain as it goes onto the sprocket. If the mud is thick enough or has stones or grit in it, expect trouble as it will unseat the chain Running the chain slack won't prevent this, it's impossible, as the stone or grit will still go between the chain and the sprocket. Running the chain slack will just increase the chances of it jumping off the sprocket if the suspension rebounds quickly On motocross / enduro bikes it's not such a problem as there is a lot more clearance between tyre and chain Bondy, I've no idea as I've never had an original guard fitted.

If you haven't got a chainguard, that is the reason. A chainguard needs to completely block off the tyre between the top and bottom chain run, otherwise the tyre just deposits mud on the top of the chain on the bottom run which then gets dragged between the chain and sprocket. The guard will also stop mud being carried onto the front sprocket. Slackening the chain won't stop mud building up If you have a guard fitted make sure it is effective and blocks off the tyre from the chain.

I think it was the green TR77 models a second spring was added. Don't know how they fit though as I never had a green model, only earlier MAR.

They do, as I've ridden two or three bikes with very effective rear cable brakes, one only yesterday. I can't make mine work though...... even with relined hub, longer arm etc.

They only had one spring, the one that fits onto the brake pedal spindle. The spring that is attached to the frame ? (swingarm?) has been added which some people did as the original spring isn't overly strong, but it does the job. So it's up to you whether you want to connect the second spring. Can't advise on the silicon spray question as not sure why you want to do it

Why not sell it and buy the one that's already been converted in Colchester which has been advertised on ebay several times now and is still unsold It's probably still unsold as no-one is interested in it as twinshock interest for most is about the bikes themselves, not about riding under the label of a class within a trial, or a t/s trial itself. Most people ride twinshocks as they have some sort of affinity with the bike they used to ride back in that era. Contrary to what you were told, it's not really a common conversion for that reason as no-one rode a TY Mono with twinshocks, plus they aren't elligible for 99% of twinshock events.They'll be allowed in probably but for no points if it's a championship or no award. Accepting that in your area they aren't fussy with rules, it's your bike and obviously up to you what you do with it, but as the seller in Colchester is finding out, a converted mono is likely to be an unwanted item should you ever have to sell it.

No choice - you just have the MILF on the Fantic...

Again, purely out of curiosity, how can a Mills frame be eligible for the Pre65 or Pre70 class at Yorks Classic? Their rules on replica frames state that it must be recognisable as the original and the Mills frame isn't a replica of anything. Neither do they allow the rear shock angle to be altered, even on an original frame It would have to be ridden as a special You've got to love the logic behind some of the rules that are out there. My old C15 had an original 1959 frame and 1962 engine. I lowered the rear subframe which is allowed but had to move the shock mounts as well to do it. I also changed the top mounts from the awful shrouded type to pegs the same as is standard on the swingarm so that the shocks were a more practical push on fit. I cut off the huge ugly rear mudguard loop because I hated it. All of these mods were achievable prior to 1965. But, even though it was an original (and bent and twisted) 1959 frame, those changes meant it was a special and it would have had to compete in the specials class against all sorts of modernised machinery. A brand new Cub with the 'correct' new components, with 290cc which wasn't achievable before 1965, and fitted with a brand new Dellorto carb, can compete in the normal unit class - but mine was a special...

purely out of curiosity, why not? Unit singles are genuine pre65

You're not going to get a definitive answer on a forum as there is only one way you will know and that is to send pictures to the secretary of the event and ask them. You'll get all sorts of opinion on a forum but only one counts. It shouldn't be eligible as the frame isn't a copy of a Pre65 BSA frame (and as far as I'm aware the Mills frame isn't eligible) But as we know, bikes that clearly don't meet entry criteria and shouldn't be accepted, sometimes are - maybe it depends on the rider.... If you're thinking of entering with it I'd send the email first. If you just send in an entry, if it is rejected on the grounds that it isn't eligible, by the time you find out it may be too late to enter on something that is

There may be an issue with the mainshaft diameter on the clutch side between the two gearboxes. If I recall correctly, the diameter changed but can't remember exactly which year. Also the M49 mainshaft locates the clutch hub by woodruff key, so if your M98 has the splined mainshaft you will have to use the M49 clutch hub and basket as well. There are differences in the length of the clutch hubs and in the thickness of the spacer that sits behind them so you have to get the right combination to keep the chain true to the crank sprocket

I've had it happen but usually because the exhaust middle box has got out of shape somehow, meaning that the silencer body touches the panel. If the exhaust is as it left the factory there should be sufficient clearance between it and the panel not to cause a problem. The two MARs I have now don't burn the panel. Take the panel off and put a straight edge across the brackets and see if it touches the exhaust or runs too close. If it does it is possibly because something has caused the angle in the pipe to close up (where the smaller diameter part of the pipe exits the middle silencer and bolts to the frame) which has the affect of pushing the silencer body outwards with the result that it either touches or is too close to the panel. I've had one that actually prevented the side panel sitting flush onto its brackets If this has happened you can open out the angle again so that the silencer body sits back inside the frame. It's possible to do this by tapping it hard with a hide mallet whilst still fitted to the bike and see if it will move back (I don't mean sledgehammer it...) Or, take it off and bend it back If the silencer has been cut open and repacked it's possible for it to distort when re-welding, depending how / where the cuts were made

The top and bottom yokes are what you see fixed to the headstock in the picture and what hold the fork stanchions. No idea what the letters on the headstock are, pictures may give some others on here a clue

I remember looking at Ossacels with a view to buying some Ossa parts a few years ago but came to the conclusion that if you were outside of Spain it would be a very difficult process, so I didn't try The situation for Ossa parts has improved a lot in recent years though and parts are more readily available from a number of suppliers - what is it that you meed

If the weather keeps to its promise of more rain, you'll have no problem with a soft landing... The venue is mainly banks, tree roots with a small stream, sections are mainly in and out of the stream (not a rock stream) and are a mix of short or long (depending on weather) climbs and cambers, with and without roots - quite slippery when wet.

Having difficulty posting this on the front page news for some reason We have a club trial at Manor Farm, Milwich, Staffs this Sunday, usual classes catered for: Expert, Inter, Novice, O/40, twinshock, Pre65, beginner Three routes, hard, medium, easy with an additional 50/50 route that will use a mix of hard and medium route sections Start time is 11.00am, enter on day.

I had a standard KT a few years ago, not a Gollner, and rode it for a couple of years in various trials including a good number of Miller rounds. I found the engine to be very good, torquey enough meaning 2nd and 3rd gears could be used in sections without problem. Much better than the TY engine. No detonation issues either in sections or on the road. The clutch worked well and wasn't too heavy. Suspension was comparable with most from that era but the front forks were not quite as good in their damping and spring rate as an Ossa. Rear suspension had Falcons and worked well with plenty of feel. Brakes were very good Chassis felt like an early 70s Sherpa with a long fork rake and slow steering but it felt more stable when trying to clutch/brake in tight stuff. I liked it a lot and it was perfectly capable of dealing with anything in most of today's classic events. In its era, with a little more development I'm sure they could have been a great bike

Unfortunately Larry, I missed the best trials era by a few years, I was 11 when the model 80 came out and it was another couple of years until I saw my first trials bike, a Bultaco, being ridden in our local quarry by one of the UK's offroad legends, Arthur Browning. It was like the series 2 M92 in my picture with the alloy UK tank unit except that it was all polished alloy, no colour. Looked absolutely fantastic to us. It was a 250 and I'd guess it was an M91. The fork braces on my M92 were standard fitment from about '74/75 I think. On this bike they don't help much with fork flex as I'm forever kicking the front wheel straight after riding a rock stream. It gets twisted very easily.