steve+cub Posted January 5, 2006 Report Share Posted January 5, 2006 Hello folks, I have just arrived on this forum, I recently bought a '63 trials cub and I am looking for advice on the best way to get the front forks set up, or should I just replace them with a set of Cerianis I have ? Quote Link to comment Share on other sites More sharing options...
totalshell Posted January 5, 2006 Report Share Posted January 5, 2006 If your forks are halfway original ( on the outside at least) stick wth them heavy weight cub forks are as almost as rare as hens teeth, if the ones on the bike are already 'not of british manufacture' and useless bin them and try the ceranis. difficult to give specific advice without knowing exactly what they are externally and internally the best advice would be to ride them , a fair bit, and decide for your self what more you would want them to do. Quote Link to comment Share on other sites More sharing options...
steve+cub Posted January 5, 2006 Author Report Share Posted January 5, 2006 are these heavyweight forks? Quote Link to comment Share on other sites More sharing options...
rogerroger Posted January 6, 2006 Report Share Posted January 6, 2006 Heavyweight forks have stanchions that are 33mm diameter and are fairly useless for trials (I have found) I fitted internals from Fantic 200 forks as follows: 1. Turn the outer tubes down to the internal diameter of the heavyweight fork's outer tube internal diameter (cannot remenber what it is - 1.25" or so) so that that they are a push fit into the originals 2. Part off at the bottom end then the top end to be left with something that looks like it could be passed from runner to runner in a relay race 3. Smear with locktite and insert (tricky this as you only get one go - you will never get it out again ) 4. Buy some 42x35mm (I think) oil seals 5. Turn the seal holders to accept these (this depends on the type of seal holder - later ones are bigger I think) 6. Bore the damper rod bolt hole in the bottom of the original outer tube to accept the 8mm bolt of the fantic forks 7. Bore the bottom yoke to 35mm to accept 35mm stanchions 8. Bore the top yoke to 35mm, but not all the way through - leave 1/8th of an inch to provide a shoulder to pull the stanchion up against via the top nut. The stanchion should be a heavy push fit into the top yoke to keep things stiff 9. Assemble and enjoy! An alternative is to use the seal holder part of the Fantic outer tube to hold the seals by leaving it attached during step 2 so that when fitted, it sticks out of the original outer tube. This is easier, but doesn't look as original. If you get hold of a set of suitable forks, I belive Martin Adams at Serco will do the mods for you (for a small fee and a slight delay - he is usually very busy!) Quote Link to comment Share on other sites More sharing options...
steve+cub Posted January 12, 2006 Author Report Share Posted January 12, 2006 that sounds like a good conversion, i had hoped that i could make the original fork perform better, maybe with progressive springs - if they are available if i stick with standard heavy weight forks which have not been modified what can be done to improve them, short of machineing them out as above? Quote Link to comment Share on other sites More sharing options...
triton Posted January 12, 2006 Report Share Posted January 12, 2006 I use standard heavyweight forks on my cub,(they have won the Scottish in the past with them fitted, not mine I hasten to add) The joy of riding a cub is to clean a section when the previous gasbetasherco has failed. Keep them original as possible and enjoy Triton Quote Link to comment Share on other sites More sharing options...
steve+cub Posted January 12, 2006 Author Report Share Posted January 12, 2006 i suppose thats why i got rid of my gas gas and bought the cub- wanted to see how good the rider was! am i right in thinking that heavy weight forks are the same as 3ta forks? Quote Link to comment Share on other sites More sharing options...
rogerroger Posted January 16, 2006 Report Share Posted January 16, 2006 I think heavyweight forks were fitted to everything at one point, from 3TAs to Bonnevilles. But I could be wrong. Quote Link to comment Share on other sites More sharing options...
steve+cub Posted January 16, 2006 Author Report Share Posted January 16, 2006 I think you might be right RR I took the cub to its first, and my first (ever) trial yesterday, must admit i was struggling, took a 5, a 2 and then a 5 again on the first three sections, found it hard keeping the motor from stalling trickling round the trees at Ardersier. Malcolm the one of the organisers took pity on us, i was in a group with a 1956 BSA Goldie, my mate Colin on my 1976 Cota 247 and his son on a 1978 Bultaco 250T, we were trying the intermediate course. In the afternoon Malcolm set up some Pre 65 sections which we spent the rest of the day practicing on, only moving on to the next after we had each cleared the course. There was a bloke with a well sorted Cub there for a wee while and i tried it out , he had "special" front forks and they are a big improvement on the heavy weight Cub ones, but I also checked out Malcolms roadholders on his ex-works James and they were every bit as nice! So maybe i should put some work into the standard ones and see how good I can get them for the next trial at Elgin. I will also need to do a bit to the carb and the cable runs to see if that stops the stalling. And spend some time in the Gym Quote Link to comment Share on other sites More sharing options...
rogerroger Posted January 16, 2006 Report Share Posted January 16, 2006 If you haven't already, change the primary drive sprocket for a small one (can't remember how many teeth) available from Serco, Sammy Miller etc - they are made by Talon and will help with the trickling round trees. Quote Link to comment Share on other sites More sharing options...
triton Posted January 17, 2006 Report Share Posted January 17, 2006 Steve, stick with it,if you have an Amal concentric carb give it an overhaul check the slide is not worn if so fit brass one. Fit some Venhill cables teflon lined, too clutch and carb. Set carb tick over and mixture correct plus ignition timing, it should pull away from tickover smoothly without touching the clutch the engine has good torque for its size. Fit Miller type fork stays they prevent the forks twisting as the stays per your pic may do. See cub pic in Miller catalogue. www.trialsbits.co.uk in Swindon are a good company for pre 65 spares. Ray Small has a business only manufacturing Cub mods, very helpful with loads of info (no web site) tel 023 8069 3183. rgds Triton Quote Link to comment Share on other sites More sharing options...
steve+cub Posted January 18, 2006 Author Report Share Posted January 18, 2006 I just had a look at the trials bits site some good stuff there. I picked up a Haynes manual for the Cub - now I am very confused, the heavy weightforks in the manual have external springs the ones fitted to my bike are 33mm but have internal springs? Not sure what type I have now. Had a chat with Surrey Cycles today about the carb, i'm running a 24mm Amal Concentric, i've been told i'd be better with a 22mm so I ordered on today - hopefully that will sort out the slow running. Is there a way of changing the gearbox drive sprocket without splitting the cases? so many questions Quote Link to comment Share on other sites More sharing options...
triton Posted January 18, 2006 Report Share Posted January 18, 2006 Steve, I run a 22mm Amal, this should improve your slow running, you can always e-bay your 24mm one.Some cubs have the Mikuni carb from the honda tl trials bike fitted about 20mm I think, they go quick on e-bay. Ray Small modifies the crankcase half, by cutting a larger hole to gain access to the G/box sprocket nut with the clutch off, then a small circular plate is bolted back over. However to initially accomplish this you have to remove the case half. This can be done on later splitdown the middle type crankcases without taking the engine out the frame,head, barrel, clutch off then remove left case. I run a 16t gearbox and 58t rear wheel. The later type heavyweight forks did have external springs you have the same as I have earlier type. www.tigercubspares.co.uk have a good supply of new and used bits, I got my new fork seal holders from them, not cheap!! Rgds Triton Quote Link to comment Share on other sites More sharing options...
steve+cub Posted January 18, 2006 Author Report Share Posted January 18, 2006 carb hasn't arrived yet, but i'll check the jets when it get here. I asked them to set it up for best tune for a trials cub motor. i was looking at the 35mm forks off my BSA B50 today, it is stripped for a full restoration, the yoke stem is the same diameter and thread as the Cub one, so i may try them while i rebuild the original ones, they are about 2" longer than the Cub forks and a lot better travel and action. i was planning fitting a Triumph T140 disc braked front to my B50 anyway. At least they are British Quote Link to comment Share on other sites More sharing options...
rogerroger Posted January 20, 2006 Report Share Posted January 20, 2006 22mm Amal you say, what jet set-up? Do you run with a pilot jet or bushed?Big John <{POST_SNAPBACK}> Excuse my ignorance, but what is bushed (apart from having a bush shoved somewhere )? RR Quote Link to comment Share on other sites More sharing options...
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