fisambard1 Posted November 16, 2015 Report Share Posted November 16, 2015 Hi Guy's. Just an update,in 2015. The best carb to use on a trials Cub is a VM 22 Mikuni, as used on a pit bike,( and "Mini Otter") and they are cheap compared with the rest of the outlay thrown at the humble Triumph Cub, now-a-days. Regards Charlie. Hello Charlie What pilot jet, main jet, slide, needle and needle jet are you using please. My Vm22 has an awful flat spot when the throttle is cracked wide open from near standstill. Would appreciate any ideas to sort this out please. cheers Quote Link to comment Share on other sites More sharing options...
charlie prescott Posted November 18, 2015 Report Share Posted November 18, 2015 Hi Guy's. Hi F1. Look just a thought before you even touch the jets. By the way mine are all standard as came with the carb. On main jet R95. W on the holder. 15 on the pilot jet. Right I don't know what manifold you have your carb fixed too? But look at the carb from the back, you have two bolt fixing holes, right. In the middle of these two holes at the bottom is an airway hole. Now this hole must NOT be covered by the manifold you fix the carb too, I learnt the hard way until it dawned on me that perhaps this should be kept uncovered. I drilled an hole through the manifold larger than the vent in the carb,and tapered the back for air flow, fitted the carb back onto the "Top Cat" Cub, and the problem was solved and the little bike ran like a watch. Hope this is your problem,as it was an easy fix. Regards Charlie. 1 Quote Link to comment Share on other sites More sharing options...
laird387 Posted November 18, 2015 Report Share Posted November 18, 2015 Hi, Just as a point of interest - the works Tiger Cubs were fitted with the motor internals from the 'Sports' Cub, coupled to the 'box of the 'Trials' version - and the resultant performance was far more likely to be successful in the 'modern' classic sections. Quote Link to comment Share on other sites More sharing options...
fisambard1 Posted November 18, 2015 Report Share Posted November 18, 2015 Hi Guy's. Hi F1. Look just a thought before you even touch the jets. By the way mine are all standard as came with the carb. On main jet R95. W on the holder. 15 on the pilot jet. Right I don't know what manifold you have your carb fixed too? But look at the carb from the back, you have two bolt fixing holes, right. In the middle of these two holes at the bottom is an airway hole. Now this hole must NOT be covered by the manifold you fix the carb too, I learnt the hard way until it dawned on me that perhaps this should be kept uncovered. I drilled an hole through the manifold larger than the vent in the carb,and tapered the back for air flow, fitted the carb back onto the "Top Cat" Cub, and the problem was solved and the little bike ran like a watch. Hope this is your problem,as it was an easy fix. Regards Charlie. Wow, I will look first thing tomorrow, sounds interesting, cheers. Quote Link to comment Share on other sites More sharing options...
fisambard1 Posted November 20, 2015 Report Share Posted November 20, 2015 Wow, I will look first thing tomorrow, sounds interesting, cheers. I looked, there is no air way hole at all between the stud holes, have I been sold a chinese copy Mikuni? Quote Link to comment Share on other sites More sharing options...
stickinthemud Posted November 25, 2015 Report Share Posted November 25, 2015 Just thought that Cub riders based in the north of England might like to know that the Yorkshire Classic MCC voted at it's AGM last week to no longer allow the use of 'foreign' carbs on Cubs from 2017 on. This means that we are now in line with the Pre65 Scottish, Sammy Miller Series and the Northern British Series. Basically this means that only Amal Monobloc and Concentric Mk1, Mk1.5, Villiers plus other original fitment carbs can be used. The change brings all classes into line with the exception of the specials class that will continue to allow the use of foreign carbs. 2 Quote Link to comment Share on other sites More sharing options...
charlie prescott Posted November 26, 2015 Report Share Posted November 26, 2015 Hi Guy's. What they should have banned was the use E10-15 fuel because in a concentric mono block Carb this fuel containing Ethanol causes more problems and expense, than being politically correct by fitting these carbs rather than a cheap carb made in Japan that tends to overcome this problem. Have you seen the price of ultrasonic cleaners? well you need to add this expense on as well if you are going to insist on the use of Amal carbs. Then there is the matter of striping them down and rebuilding them with a new repair kit every time. Do we actually think now-a-days? or do we just go along with the flow, of being conned ? Regards Charlie. 1 Quote Link to comment Share on other sites More sharing options...
davetom Posted November 26, 2015 Report Share Posted November 26, 2015 Surely everyone with Monobloc/ Concentric should be suffering , not just Cub owners? I always use Premium Unleaded ( no special brand) and my Concentric is 3 yrs old without any problems Quote Link to comment Share on other sites More sharing options...
japes1275 Posted November 26, 2015 Report Share Posted November 26, 2015 Cubs in the 60's ran fine on Amals but then aparently in the 80's they just couldn't be made to run properly on them so foreign carbs were the only answer. For some reason the tables have turned and Cubs are once again able to use Amal carbs. A strange phenomenon that didn't seem to affect other bikes. 1 Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted November 26, 2015 Report Share Posted November 26, 2015 My understanding of the Cub carb issue is that the overbored motors 230, 250 and the like run well on the Amal concentric but due to the choke sizes available the 199 which is what aTriumph Cub is did not. Burlen I believe have now introduced a 20mm choke concentric so maybe that will be ok, problem is though those who ride a 199cc Cub which is what was available back in the day are the very people affected by a costly enforced change that will add nothing to the sport. 1 Quote Link to comment Share on other sites More sharing options...
woody Posted November 26, 2015 Report Share Posted November 26, 2015 Really, I can't see the point of initially allowing riders to spend money on a foreign carb and spend time getting their bikes set up to run well with it, then revoking the rule so that they have to spend another £150 on another new carb and spend more time trying to get the bike to run exactly as it did before. Just causes unnecessary time and expense for riders It's ok to have a Cub that looks nothing like period and bears absolutely no resemblance whatsoever to a 1964 machine in terms of appearance in either overall silhouette or individual components - which is contrary to the overall desire of maintaining period appearance - but you can't have a foreign carb because it doesn't look period. What is the point really after all this time using foreign carbs? Bring them into line with the Scottish? Why? If clubs want to run events for bikes using only genuine Pre65 parts and of Pre65 appearance why don't they just do that and put everything else in the specials class 2 Quote Link to comment Share on other sites More sharing options...
alan Posted November 26, 2015 Report Share Posted November 26, 2015 As i understand it the aim was not to bring the rules in line with scotland, that is just a consequence. The aim was to bring cubs in line with the club rules that apply to all other 4 stroke machine classes. yorkshire classic were the only pre 65 club to allow cubs to use foreign carbs, the regs for the northern british rounds, the manx the scottish etc do not make any exception for cubs. A years grace was given to allow anyone who has recently invested in a dellorto to at least get some use out of it . The point was made that cub riders in scotland do not seem to suffer from poor running issues .. And that includes dave thorpe on his 199 2 Quote Link to comment Share on other sites More sharing options...
charlie prescott Posted November 26, 2015 Report Share Posted November 26, 2015 Hi Guy's. So what difference putting a Concentric back onto this bike , is going to change the overall appearance ? Regards Charlie. 1 Quote Link to comment Share on other sites More sharing options...
japes1275 Posted November 27, 2015 Report Share Posted November 27, 2015 No, it's still going to look like a 'modern' Pre 65. But if a Cub is allowed to use a Mikuni why can't a B40 or AJS etc? Where does it all end? My rear shocks don't seem to work properly so unfortunately the only thing I can do is convert it mono shock etc etc etc..... Quote Link to comment Share on other sites More sharing options...
trialsrfun Posted November 27, 2015 Report Share Posted November 27, 2015 (edited) No you are missing the whole point here, there has always been some riders on Triumph Cubs that ran very well (usually ridden by the better riders) many Cubs ran with symptoms of cat flu until more recent times when fitted with PVL, Electrex or similar ignitions so anything that helped improve things was readily taken up. The Amal Concentric carb was launched in 1967 so NO Pre 65 bike ever had one fitted as standard anyway. To make a Cub run well on a concentric engineering types have reduced the choke diameter by placing a sleeve through the carb choke, a costly job. At the recent Stafford Show Burlen had the Concentric Premier carb in 20mm so maybe now they can supply a suitably sized model for the 199cc cub? Where does this leave Duckwizard probably confused like most of the rest of us? Edited November 27, 2015 by trialsrfun 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.