woody

I understand why you are looking to do it, and as I mentioned, your circumstances are different from someone just looking for an advantage. It's the latter I can never understand, someone wanting to build the most competitive twinshock that isn't actually a twinshock. There's nothing different about a twinshock trial. It's just a trial, with sections. The difference is in the bike you ride and most do it as they have some sort of affinity with one old bike or another as it's what they rode years ago and for a bit of nostalgia, want to ride one again. Whether it's because they just like the way they rode or liked the look of them, the exhaust note, or whatever, it's generally about nostalgia and enjoying riding that bike, or bikes. Over the course of the year I'd guess I ride my Bultaco or Ossa in more modern trials than classic. The 'name' of the trial has no bearing for me. It's about the bike. In your lad's case, I don't really know what bike you can move to next, to fill the gap to a bigger twinshock. Converting the Fantic though, I still don't understand the enjoyment factor as it's a mono Fantic whichever way you look at it, so has no twinshock provenance at all, so it's not really riding a twinshock bike. That's just my personal view though.

Yes, don't see the relevance. Pre65 rules are a joke. Build a brand new 2014 James, Bantam or Cub out of all new parts for £7 - £10k and you can ride Pre65 on a bike that looks nothing like. Fit a pair of yokes, forks and wheels from a 40 year old bike to an otherwise standard 1959 C15 and you're in the specials as it has non-Pre65 components. In one club, just altering the shock mounts on an otherwise original bike puts you in the specials.

I'd guess you can expect a lot of disgruntled riders and you may find yourself the subject of a protest and possible exclusion from the result sheet. The bottom line is, it isn't a twinshock so why ride twinshock trials on something that was never a twinshock, something that never actually existed. They're considered by most as cheat bikes, built to gain advantage with results in mind. I can see in your case the circumstances may be different but it doesn't alter the way most riders feel about them. They're not looked upon favourably. A converted Fantic mono is going to have a big advantage over a TY80 or Whitehawk 80. Why not just ride the Fantic in the air-cooled mono class, you still ride the same trials, same sections. Then, when he's grown a bit, move him back onto a twinshock. In the new national twinshock series this weekend, a converted mono was not allowed to compete in the twinshock class and moved to the mono class. The organisers have sent a clear message as to how they feel about them

I've already entered both trials, have the info from Bognor, riding list etc, just Sunday's trial I have nothing on, just curious to see who else had entered.

Is anyone able to get onto the Tongham Tigers MCC website? http://www.tonghamtigers.co.uk/ Trying to get some info on Sunday's twinshock round, rider list, times etc, which appears to be jointly organised by DOT Owners MC and Tongham. Haven't found anything yet, I can't get past the home page of Tongham's website and it's been like that for a couple of days. The entry form is from DOT Owners MC and says entry list will be on their website but I can't see that they have one Regards Tongham's, I don't know if it's their website that's the problem or my browser or PC firewall Anyone else able to get on it? Don't really want to pester the secretary as they're probably busy enough, just interested to see who's entered.

Depends on the conrod kit and piston being used, as they're nearly all aftermarket now, but sometimes there is one full width bearing, sometimes two smaller. There can also be spacers to go between the conrod and piston. That bike is far too good to be a parts bike.

It's a Yamaha frame, not a Godden, so not a frame kit, non-matching numbers could simply be due to an engine swap at some point. As a Majesty conversion it could have been a 175 or 200, or it could be as above, the original engine was swapped at some point. Not unusual on a near 40 year old trials bike. I don't know enough about the 175 Majesty conversions to say whether that is a proper Majesty conversion or not.

The original yellow was a pretty insipid pale puke yellow. I used 1021 when I did mine, much nicer, but it is too deep if you want original. Signal yellow is too 'yellow' as well. I think 1016 is closer to original. There have been other mentions on the forum of it being British Leyland yellow

Lovely One of my favourite bikes and very under rated. Had the Cota 350 model back in the day but all the sections were hopping sections then, needing plenty of clutch and brake for tight turns and the clutch was it's biggest problem. Not on a par with the other later twinshocks for trick riding. But for today's classic events, where very little clutching is needed, fantastic bike

The original bolt is just a normal bolt but with a very thin head to clear the return spring, and a shank that is just long enough for the stand to pivot on. Probably no longer available. I just us a normal bolt and machine the head down in the lathe, or use a button head allen bolt. Doesn't really matter if it has no shank and is threaded all the way. Can't remember though if it is 10 or 12mm, but all you have to do is measure what diameter and length you need.

Only the later seal carriers had O rings, no gaskets, and they were machined to take them. Earlier models used gaskets only. Only the clutch side has an O ring on the crankshaft. If the plug was the correct colour and dry it's unlikely it was burning gearbox or clutch oil. My Ossa has been burning gearbox oil and the piston crown, head and crank are coated in a thin grey sludge. Not sure what you mean by 'wants to rev'. Normally a weak mixture caused by sucking air will cause the engine to run on when the throttle is closed. An engine burning gear oil won't do this, it will just run roughly. Are you sure the carb isn't worn, have you swapped it with the carb from the other bike to eliminate a possible cause, if that one runs correctly.

I understand now, I thought from your original post that it was just that one hole that was not positioned correctly, so yes I'd have done what you've done as you're not altering the unit in any way. I thought you were going to have to elongate the hole in the back plate

The problem I'd have with modifying it to fit is that if it didn't run properly when fitted, for whatever reason, they could refuse to accept a return as it has been altered / modified

In the ideal world, I agree with you However, this is Electrex world...

No, no lights, indicators or reflectors of any kind needed However, your tester may not realise or understand this

They've actually withdrawn their technical help phone number from the website, they only have a sales number now You have to email them for technical help and wait for a reply.

*************** website shop probably which is where my mate got his from http://www.todotrial.com/es/tienda-tt/piezas-aluminio-trial/results,1-1600.html?language=es-ES Don't know why the website name has been blocked, that wasn't me.

I'd suggest you're going to have to be very forceful with them as a mate of mine has an issue with his Montesa ignition which has been going on for 3 to 4 years now, their support service has been abysmal. It was returned to them again about 3 weeks ago for probably the third or fourth time and they still haven't got in touch with him

Just happens I have these which I took for someone else a while ago. No idea if they are better or not. You also need to make the T shaped bracket that fits between the two rear head studs as the bottom head steady mount bots to this

There are generally two clutch / crank flywheels on the Sherpa engines, a big thick single weight on the 250 and a bigger double weight on the 325/340. The smaller and thinner single weight fitted to the 198b may be offset on the ignition side by using the heavier ignition flywheel usually found on the 325/340. When they built the 198b they were probably scraping the bottom of the parts bins and using whatever was left. I also have a '76 325 motor which has a small weight like the 198b but it uses a double row primary chain and clutch basket. I think the thin single weight originates from the Pursang.

From what I've seen of them and from what is fitted to my own, that seems to be the usual size flywheel that was fitted to the 198b As for what it does to the engine, I haven't finished rebuilding mine yet so never ridden it, but you need to ride it for yourself as everyone's perception of good/bad is different. Easy enough to fit the bigger weight normally fitted to the 250 if you don't like it though.

The person at the VMCC who did most of the dating work isn't there anymore, so it may take a bit longer to get things processed with them

You're much better off phoning them you know, the web site just shows that they sell pistons. If they haven't an 83.25 in stock they can get them

They've been modified by smoothing them out, helps them rev a bit more I think. In smoothing them out like that it also means a little metal is lost from the edges so they end up a little oversize. Normally the cylinder would be matched to them. My modified 199b is similar as is a mate's 199a that he recently stripped for a rebuild. Standard Ossa MAR ducts are like that

From your picture, the spring tensioning nuts are wound pretty far in and so is the pushrod adjuster. It could be the clutch needs re-setting as it could have too much tension on the springs to release properly. If you search the Bultaco forum for clutch adjustment or setting up clutch etc. there have been previous topics with good info on how to do it correctly. It's possible to get a Sherpa clutch to work with quite a light one/two finger pull on the lever.