japes1275

Ah, I get it now, cheers I'm all for some proper rules to keep it fair for the more original bikes - getting everyone to agree is where the problem lies! What or who is the ICMTR by the way? Forgive my ignorance if I should already know!

I like the fact smelly 2 strokes aren't allowed! But I wouldn't be happy having to modify my bike from original by fitting a concentric carb to ride in the 'O' class.

Suzuki250, are you calling me insane?! B40rt, that lad would have been given a five if I'd been observing, when he put his foot down the front wheel stopped moving. Forward motion ceased - 5 marks lost!

I started riding in Pre 65 when I was 15 and never had any problems, in fact I was welcomed. I seem to remember at that time if you were under 40 you started off with 10 marks though!!

Not contacted them no but the pictures I've seen seem to be the same as the others. I'd really like to know if I can get hold of a Honda one. I'm tempted to build up the splines with weld (on the sprocket) and grind square if I can't get hold of a decent one. I've done similar on a worn sleeve gear so I know it's possible, just takes ages!

Jon's comment about the ACU sounds right to me. Why do people pay them because as far as I can see they do nothing as a governing body to organise decent rules and regs. As someone coming to trials from a Motorsport background I can't believe how disorganised it all is. I pay the MSA (a lot of money admittedly!) every year and for that I get properly organised events by clubs that have to abide by their rules. The regulations pertaining to my particular motorsport discipline are properly written down and are pretty unambiguous. On the other hand the classic trials rules seem open to misinterpretation and are poorly policed. Things like 'only pre65 manufactured or replica yokes can be used'. What does that mean? I know that obviously the yokes off my 1962 BSA are fine but where does replica come in? To me I would hope it meant some nicely forged steel reproduction ones that look the same and are made from the same material but aren't original. But I'm guessing a lot of people think it means some horrible aluminium 'billet' ones knocked up on a CNC milling machine. Does it mean that? I don't know because it's not clear. Having said that I don't believe stricter rules and a more involved governing body are what most people want for classic trials and the more relaxed events are more important to people than bureaucracy. Unfortunately that will always benefit the people willing to bend the rules and lead to these little chats I'm starting to get used to on here!

My dad is trying to find a decent front sprocket to fit his TL125. I ordered one from wemoto and while cheap enough it has very shallow splines, the splines on the gearbox output shaft are a little worn so we don't want to make them worse. The original (worn) ones my dad has kept have deep splines but the last one we removed must have been one of the shallow splined ones, causing the wear. Does anyone know of a source for original Honda sprockets or recommend a good aftermarket one? A 14 or 15t would be the preferred size. Thanks

I agree totally with Suzuki250. I've just rebuilt my C15 over the last year or so (I'll put up some photos sometime) and I've put about £1200 into it. It's probably worth about £3k (well I wouldn't sell it for much less!) and I don't class that as a lot of money for a reasonably competitive real classic trials bike. Yes I could have chucked thousands at it and made it more competitive but it would have spoilt it. If I'd have wanted a bike I could have ridden harder sections on I would have just bought a decent twinshock.

I did but it was hard work on my old 3 speed treader! It was better when I got my TY to play around on but I seem to remember having to stick to the area around the car park. I remember it being quite bleak up there and I remember the pub well! When I started riding my C15 I stuck to the Y&L events so I don't think I ever actually rode in the Shawforth. It must be over 30 years since I last went.

Deryk, would that be what was called the Shawforth Shake later on? I remember following my dad around on his 500T with me on my push bike in the late 70's. I'm not a fan of the bikes mentioned earlier, whether they exist or are used is by the by but to me they've no place in any trial that comes under the name of classic.

What happens if you leave it a few seconds/minutes after its stalled and the won't turn over? Will it then turn over ok and start? From what you are describing with it popping and running a few seconds it sounds like an ignition issue, possibly timing. You could start by trying the most obvious and cheapest with a new or different plug, then maybe checking the actual timing. Not sure how that's done on a Cub but probably the old measurement of piston height. Maybe it's been set up for timing with a timing light though. Also a check of other obvious things like fuel blockage, crap/water in carb float and fresh fuel just to eliminate them.

Just remembered this, when I rebuilt my B40 (rebored) it was really tight to start with. It would start fine when cold but if you needed to start it hot it was difficult and would not always kick over. With the type of clutch/gearbox on your bike if the engine is tight or right on compression sometimes the clutch slips as you are trying to kick it over. This could be what is happening but you are interpreting it as something wrong as the engine isn't turning over. Although your bike is a fully modified trials bike getting hold of the basic owners manual for the Cub would be a good idea if you've not already got one. It will cover all the basics and some manuals from back then covered the theory of operation as well.

Before you start pulling it apart you should make sure there is something wrong internally or at least try and diagnose where the problem lies. With the clutch disengaged (lever pulled in) you have in effect disconnected the kickstart/gearbox from the engine. All you are doing is rotating the gearbox using the clutch ratchet. If it's doing that smoothly then I would say the chances are that the kick start and gearbox are ok. If you then take the spark plug out and kick it over with the clutch engaged (lever out) and it kicks over fine then I would definitely say all is is well in the kickstart/gearbox/clutch. (Baring a major breakdown in a bearing or sleeve gear which I would say you would still notice) While the plug is out then check that when you kick it over that the piston rises and falls smoothly and that it feels free. If not and it still takes a bit of effort (you should be able to turn it easily by hand on the kick start) then it may have seized. Bear in mind that if the engine is newly rebuilt then it may be a bit tight on the bore till run in. If all seems well then I would start looking at things like ignition timing as that can easily give the symptoms you mention. The last time I stripped my B40 down for something I wasn't sure about I really regretted it as I hadnt a clue what was wrong and only found out what it was by chance as I was reluctantly rebuilding it. Obviously it might not be possible to find out what is wrong without stripping it but it's a good idea to check as much as you can first. Let us know how you get on!

Yes, don't go off my set up, I think most people go for much lower gearing than mine. Though maybe the actual gears themselves are lower in mine due to it being the original 'T' box. Mines a 1962 and previous to that the primary was 18, not sure why they changed to the 23.

Gasser, thanks very much for posting this guide, I'm in the same position as Luke so all that info is invaluable. Cheers!

Not got my head around the new fangled chain sizes but mine is 1/2 x 5/16 chain with 13 x 62 sprockets. Just counted 122 links on it but I was in a bit of a rush and as there's a half link in it I'm thinking I must have miss counted! I'll have another go tomorrow night to be sure. Mine is 13/62 which is slightly lower than it was before at 14/66. That is with the standard C15T 23t engine sprocket so overall a lot higher than yours. I found it fine but it's been a long time since I've ridden it in a section.

Oops, I seem to have started something here - apologies to the original poster about his C15 forks!! Deryk, I was only under that completely wrong impression because that's what I'd been told by someone that was there at the same time as yourself so it's obviously a matter of opinion!! (probably why you keep hearing it) I won't be put off by anything to be honest, at the end of the day it's whatever you enjoy that matters and as has already been pointed there is always the option of joining the 'specials' bikes. Who knows, after my first trial I might be hunting out some fancy forks myself!!

I see what you mean in some ways but then by modern standards the engines from the 50's and 60's are crap so why cant I turn up on a bike with TL 250 engine in my C15?! One of the reasons pre65 trials started was because the modern bikes were getting so good at what they did that the sections were getting harder and harder. By using the bikes they grew up with, folks could still sport that paunch, they wouldn't find themselves balancing on a rock 10 feet in the air and most importantly they could get to the pub before Sunday closing! But now a lot of people seem to want to make their old bikes more and more like the best of the twinshocks from the 80's and because of that the sections are getting harder for the real bikes. I'm thinking of returning to pre 65 trials but am a bit disenchanted by the way things seem to have gone in the last decade or so. It's crying out for a national governing body to come up with some simple regulations with a few classes and for the bikes to be scruitineered before each event. Probably a bit late for that now though!!

Sounds fun! Just seems a bit strange to me, having a classic trials bike then going to a lot of trouble to bolt a load of modern bits onto it.

You could perhaps put some (shock, horror) BSA forks on it! I've got them on mine (they must be good, they've been on there since 1962) and they are great. Rear shocks wise, the world is your oyster. From about £60 for some really basic cheap ones up to a few hundred for fully adjustable alloy ones. Length is another issue, mine are 340mm on a standard C15T.

By the way, mine is an original C15 T and has the 23t engine sprocket and with the gearing mentioned above is fine for me. It's not as low as some would have it but I've managed with it like that for years! The Rupert Ratio book will tell you all the ratios, a good read if you've not already got one.

First thing you should do is whip the primary cover off and check what size engine sprocket it is. 23 teeth for the standard road bikes and late trials models. The early trials models had 18 teeth which is what most people seem to recommend these days. The only way to check what gearbox it is is (apart from taking it to bits) is to turn it over and count the turns of the gearbox sprocket for a given number of turns of the input shaft ie clutch. I suppose the best way is to take the primary chain off and turn the clutch drum by hand while counting the turns of the sprocket. Maybe there is a better way though? Then you will have to look at the specs to see what gearbox you have from the ratios you find. Mine is all in bits at the moment and I've been changing the gearing a bit and fitting new shocks. Mine are 340mm and the rear sprocket is now 62 having been 66 before. I've also gone smaller on the front down to 15 from 16 so I will be worse off from a chain to swinging arm clearance point of view. I'd not thought of that till I saw this post so I'll have to see how it goes! It's already a bit worn but nothing bad. I'll probably make nylon pad anyway.

Thanks aawil, I'll give it a good check over for cracks and look into longer bolts and nuts as suggested. I suppose it's best to beef it up now before the problems happen! Thanks for the replies everyone!

Thanks for the info on the Otter site Charlie, looks to be a lot of reading for me to do there! He mentions that the thread size is 7/32 but mine are definitely 1/4. At least I now know they are BSCY so I can get some ordered.

Dadof2 Thanks for the replies. I'll have a look into opening them out but they've been ok for the last 25 years of trialling so I'm not really sure if I'll change anything. I'm only changing the Allen screws because the new sprocket I'm fitting is thicker so I need slightly longer ones. Dadof2, I take it that means they are cycle thread and not BSF? Although I've owned the bike 30 years I'm still a bit green when it comes to the British thread systems! Thanks