Pre-65 Bikes

Could someone advise a solution to a small problem please, I fitted a PVL ignition to a cub I'm building, it has the plate that mounts on the crankcase bolts rather than the modification of the 3 posts. when I try to fit the primary chaincase the bottom plate mounting stops the case going on. So before I grind off anything and completely B***s it up does anyone have a suggestion? Thanks

Good day all, question for those in the know. I have obtained a 1964 D7 Bantam 3 speed engine in quite good condition. I have had a good look at it and think it could be worth converting to trials format. It already has in its favour a B175 barrel and head plus a modified clutch. However here are the first problems found which leads me to my questions. I would like to reduce Primary sprocket from 17 to 12 the same as my BB175. I have spoken to Rex Caunt Bantam specialist who informs me if I fit the smaller sprocket he supplies the primary chain will not line up. ? 2nd I would like to reduce the gear box sprocket ideally to 12 but the D7 has a seal housing which would not …

Hi Guys, Does anyone know the weight of a Drayton Bantam ready to ride with fuel etc. Thanks, Prelit.

Anyone point me to an extended inlet manifold to fit a C15?

Anyone know if and where you can purchase longer than standard Stantions with springs ?

Jeezzzzzz it’s a steep learning curve with these things. Ok folks, current issue is what, is the gearing of choice for trials. This Cub is said to have a Serco gearbox in it according to paperwork history that came with the bike. That could be BS, but there is a receipt from Serco for other work done. How would you identify a gear selection of theirs.? The duplex Drive is a 16 tooth, the high gear a 27, it had believe it or not a 9 tooth front sprocket that had been welded on and a 46 rear. Now from the research I’ve done it appears that 13 or 14 is what’s used on the front. But would a Serco gearbox have completely different number of gear teeth to an orig…

I'd be grateful if anyone could advise on rear shock absorber choice and length for a 1960 C15 trials bike, previously it had a strange rear subframe concoction but I've fitted a new rear subframe from Progressive Classic Products which is far more trials orientated and has also now allowed the exhaust to run inside the subframe without fouling the tyre. Any advice much appreciated, thanks. Pete.

Guys, Got a centre casing on my Cub that’s past it’s sell buy date. Im looking for a replacement, the replacement I’ve found has the same E4087 number as mine , but mine is stamped underneath that as AM 1, the replacement is AM 2. They look identical but that’s from a comparison of photos , not in person. Will the casings be the same, I’m assuming the AM number is probably a casting batch and the part number is the E4087. Thanks.

Hi, I am rebuilding my cub engine at the moment - I have fitted the bearing and oil seal for the gearbox but when I slide the drive sprocket onto the high gear it binds up and is very tight to turn, but when it is not on it turns with ease (as you would expect from a new bearing)! I’m assuming the sprocket is going tight due to friction from the oil seal, even when lubed with oil it is tight! I have the lip seal facing towards the bearing I wasn’t sure if this was correct or not but assumed it was the best orientation? Any help would be appreciated! Henry.

Hi, I've just acquired a B40 that isn't a trials bike but has been modified a bit for green laning. I'm intending to have a go at a few trials even though I know the geometry, frame, footrests etc. won't be ideal but it's just for fun right. Anyway it really needs a rebore but is already on plus .060. The head is also not very good so I am looking for a complete top end if anyone knows of one that may be for sale. Ideally one that I could just put on and go but beggers can't be choosers so anything considered if it wasn't going to cost the earth to put right. It is a late B40G engine. Thanks, Keith.

Does anyone know the thread types/sizes on the Cub engine? I'm particularly interested in the fasteners that attach the gearbox casing to the crankcase. On my engine I've dispensed with the outer cover, meaning I've got 10 2BA screws of various lengths, plus two larger diameter screws at either end of the casing. These are the two I need sizes for. Many thanks.

can anyone tell me the tolerances for the camshaft shaft diameters and internal measurement of the bushes

hi I am new be to trials central I have points in side engine in bit and early bush distributor in bit all mixed up so don't know what gears belongs to what are they all the same inter change if anybody put right thank you

Here's the problem, I have a what appears to be a feked off part-widened and lengthen swing arm and a 4x18 tyre on my rear wheel, to get the chain to run straight and clear the shock (already spaced slightly out) by a millimetre, the tyre has to be moved on to the left giving very limited clearance on that side and the wheel does not sit centrally in the swingarm. This does not seem right to me but I have nothing to compare it against. To me it seems that the swingarm is not wide enough, and maybe the sub frame is to narrow causing the shock interference. Has anyone else experienced these issue, am I just missing something?

Further to my post regarding the Cub oil return mod, I have now started stripping the engine to find a cause for the smoking. The engine was built from bits and pieces and put in my spare frame for my Son to ride. It starts and runs ok. He entered its first trial and almost completed the first lap with no issues. It then started smoking badly on tickover so we retired the bike. I carried out a number of the usual mods when I built it including adding a blind camshaft bush and putting a large breather in the unused distributor hole, Alpha big end, etc etc. I also fitted a new (later type) oil pump. I measured the clutch and gearbox oil when I removed it …

I continue to be plagued by oil leaks on both my Armac Cub and my old 'bitza' Cub. Most of the oil seems to leak around the rocker covers and push rod tube. Both bikes have had various mods done to the breather system. My Armac Cub has a 230cc conversion and modern piston but I now thinking about fitting that to my old Cub and fitting a Max Heys 250cc barrel conversion to the Armac which I believe uses a modified oil return. I'm aware this mod returns the oil from the rocker area down the barrel studs rather than down the 2 small holes in the top of the barrel. I'm wondering if will help with my problem as I think this area is flooding with my current set up.…

Does the Triumph Tiger Cub have different valve springs for the standard cam and R cam, if so how do you identify which springs are for which cam. Same for the cam followers or are they the same for both types.

Have recently replaced the Amal pancake air filter on my Cub with a new foam cylindrical type which I sprayed with Castrol filter spray. Now having ridden the bike I think it is running rich and very badly at lower rpm. I removed the filter which seemed to improve things but need more riding time before I will know properly. Do all foam filters need spraying or have I made a problem by doing so, anyone else had running issues after spraying a foam filter?

Hi guys, Please see images of my Cub casings.Just split the engine. The first casing shows an area milled out and a plate inserted with four Allen screws inserted. Is this the mod to allow access to the oil pump. You lads who know there stuff will probably recognise the model of engine but it’s a 1961 year model. The second casing, well, I’ll wait for some ideas, is it to allow the gearbox sprocket to be removed without having to break the motor. It’s a really poor fit. Thanks.

Bought a T20 cub, want to optimise it, but it should still be a pre 65, not a Twin shock with old engine.... What are youre experiences with the fork, oil, springs, modified interials ? Rear shocks in which lenght ?