trialsrfun

Thank you for an enlightening reply, so the Amal MK1 Concentric is very definitely not Pre 65.

Does anyone know if the Amal Concentric MK1 carb was available before the end of 1964 which is meant by Pre 65, were any bikes of the period fitted with the MK1 when new? I think we all accept that bike developement/changes are somewhat negative to classic trials and should possibly be limited to a reliable ignition system, but the horse has bolted so it is far too late for that now. Unfortunately all too few original bikes are in regular use now but surely the severity of the current sections are leading the way in encouraging changes to be made to the machines that are being ridden.

No need for a choke make life difficult, give it a good priming & have petrol flavoured socks to complete the authentic Pre65 look.

Yes I agree, my Greeves Anglian has Ceriani forks with the original fitment stepped top yoke.

A MK1 1/2 carb is the same as a MK1 but with a choke fitted, this makes for easier starting, saves overpriming & seeing precious petrol running over the gearbox & onto your boots & the floor. There are some bikes using the MK1 1/2 carb but I understand that they are no longer available new. What sense does it possibly make to ban them?

Why not get the Villiers kickstart made by Terry Weedy, they fit and work well.

A friend has just emailed it to me, this is it, enjoy http://archives.tsr.ch/player/motards-trial

Does anyone have the link please to the trial held in Belgium in the 1960's where a young Jacky Ickx was riding a Bultaco.

Thank you Charlie, that nice machine looks to me like a later model Sprite (no tubes between rear of tanl & s/arm) Do you know if the earlier machines which I presume mine to be had double / triple digit frame numbers. I have not yet found the number on mine, where might it be stamped?

I also have a Sprite trials frame for a Villiers engine which is all very nicely brazed, not too heavy & now definitely Pre 65 so I think I will be building another bike to ride. Does anyone have any Sprite pictures to put here on TC. It is a great shame that Sprite have for so long been completely overlooked as a serious trials bike. http://www.localhistory.scit.wlv.ac.uk/Museum/Transport/Motorcycles/Sprite.htm

Smooth power as on my Model 124 is good, it aids turning and makes it easier to find grip than on a bike with sharper power delivery. The 124 turns better than my Model 199A but that currently has the ignition a little bit too advanced, it kicks when being started and the power pulses are really noticeable. Must retard it a little. Need to get a ride on a 238, most of the Bults owned by friends are 350 models 325cc.

http://www.mistgreen.com/ Try the above link John you may find it there.

Cheers Feetupfun the above sums up very well the way my Model 124 rides but I have yet to ride a 238 but know of one for sale, must get a ride on it.

How much different are the engine power characteristics between the earlier & slightly smaller capacity later Bultaco 250 models. In the Bultaco book the earlier 244cc bikes seem to be around 20/21 bhp, the later 238cc engines 14.1 bhp, very odd that they lost 1/3rd their power when reduced by 6cc's.

When fitted and running properly was the Electrex system worth the hassle over the points system, was it a worthwhile improvement?

The opening question that started all of this was could anyone identify the frame. With hindsight I should have asked Dave Renham but he was rather busy, I never associated it with Reg May which was a great pity because I was speaking to John later the same day. Personally I simply admired the workmanship and attention to detail, it was also quite a contrast to the model 10 which stood next to it. I thought many features on the rear frame were similar to the experimental Bult later built by Reg May and ridden by Vesty. Wonder if Bultaco were aware of the bike or considered including any of the features in their production models? Sometimes the trouble with shows is that you pay too little attention to what are really the most interesting exhibits, then later when you think about the things you have seen it is too late.

Is the frame std Bultaco modified or a specially built one, does anyone know???

At the recent Telford show there was a Bultaco trials bike with a chromed frame standing next to a Model 10 near to Dave Renham's stand. The front half of the frame looked std Bult but the rear was quite different, do you know the make of frame or reason for its modification.

I would get it welded, drain the fuel, remove the tank, remove top, taps, everything, then hold the tank filler top up to a car exhaust while it is running either petrol or diesel will do. The tank will warm up quite quickly, hold it there for several minutes it will then be totally safe to weld/ have welded. tell the welder what you have done to the tank.

My understanding of the P65 title is that AMC stopped production of AJS & Matchless models during 1964, a friend owned for many years one of the last 350cc AJS made reg no ATV 350B. Ariel had long since ceased production of their single cylinder four stroke likewise BSA with the Goldstar. In 1965 Bultaco started to produce the Sherpa, all the early trials for classic machines were for four strokes only so P65 was deemed ok. All very well & good but what about the two strokes which were produced until around 1970 with the Villiers engines fitted. To this day the P65 title has caused trouble when organising a classic trial so surely it is time to change the name of our classic events.

The many trials we ran were always 'British Bike' never P65, the P65 title should be dropped everywhere right away it is pointless. How can the Scottish P65 organisers refuse an entry to someone with a Greeves Anglian which is only marginally different to the earlier Scottish models while accepting entries from people riding newly built stuff with few original parts. I am not against the modernised bikes but there must be room in all events for both types of machine and for this reason all of the sections in all classic trials should be laid out so as to allow genuine British machines to be ridden competitively.

Last time we rode a Yorks Classic Trial (no fork gaiters) we were followed round for almost all the trial by one club member who never stopped moaning at us for committing this heinous offence against yorkshire decency, needless to say we have not been back.

Smooth power delivery is the goal, the bike runs very well as it is yet the carb is in rather poor condition with definite and pronounced body wear, a carb in better condition must surely improve things further. I cannot really fault the Amal Mk1 other than for its lack of a choke, relying on messy overpriming for a cold start. As I said the bike rides really well with plenty of power and although I have only yet ridden it in one trial (a slippy one) it seems to find grip better than the 325 and is much easier to start than the bigger bike. Starting when hot is good so I guess after the carb job another decision is whether or not to fit an electronic ignition to it. To date I have heard good and bad about the various ignition systems from other Bultaco owners.

My Bultaco Sherpa 250cc Model 124 has the original fitment Amal 627 carb which is quite worn. The bike still continues to run ok with it, but I must assume that a better carb would improve things somewhat. The question is though what replacement carb would be most suitable, Amal Concentric Mk1 as now Amal Mk11 as used on the later Sherpa's which I think are stub fitting only Mikuni VM26 I think there is an OKO flat slide available Is there anything else that I am unaware of that may be better than the above, what have you tried and how did it work?