Hi, I'm told there is a two day pre-65 trial in the lake district during August or September, but can't find any info. Any info / pointers appreaciated.
I had Boyer Bransden black box ignition on my Cub for 10 yrs without fault.
It does rely on good magnetism in the Lucas rotor of course. I fitted a new one at the same time as the old one gave hardley any spark at all.
I just changed to PVL because it was on another Cub I bought.
Does it run any better?
Yes I think it does due to a stronger spark that is probably down to the closer tolerances between the rotor and stator.
Pros and Cons
PVL is lighter overall - not affected by knocks to the primary chaincase that causes the Lucas rotor to rub on the stator and overheat etc.
You can run the engine with the primary cover off to check the timing with a strobe.
Boyer has I suspect a marginally better advance curve.
No need to strip down for expensive engineering (although unusually my PVL is on a bolt on bracket so no engineering to the crankcases was needed).
Cheaper than PVL - almost half the price if you have a good rotor and stator?
You pays your money and you takes your choice!
I've heard good reports about PVL, but found it hard to believe it could be much better than my existing Boyer system. What you say seems to confirm this. I have seen some B40's with a smalley primary chain chase (off a C15?) which narrow the engine significantly, which may be the major advantage. Many thanks. Any more info ??
I ride a bantam that has a 428 chain fitted and have a cub with a 420 fitted. Whilst riding these in trials i have had people comment on 'you don't need a 428 they run better with a 420 and vice versa when running the cub with 420. I only use these sizes as that is what the bike come with.
I am now replacing the Bantam chain and sprockets, is there a noticeable difference n performance or chain/ sprocket life between 420 and 428?
I have no experience of 420, but run 428 on my B40. I replace the chain regularly and have found the sprockets last really well. Some people run 520 on B40's, but no one has ever said there was any advantage to me. The only thing to be carefull of is heavy duty chains fouling the engine cases.
Has anyone fitted Boyer and swapped to PVL ignition ? I am particularly interested if fitted to a B40, but any comparison would be interesting. What are the advantages / disadvantages of each ?
hi,nearly finished building a 4 speed big bore bantam trials bike with pvl ignition and 22mm amal mk 1 carb and could really use some advice on where to start with carb settings ie,slide
I tried the "give it another "for luck" on a bicycle i know that doesent work cost me a new wheel will try the half a turn.
Thanks Telecat !
There's an article about wheel maintenance if you go onto the main page, click the "other " header, Technical article, Ron Milam collection no 9. Havent read it all but should give you some pointers.
Had a KT many years ago, and although I had a lot of fun and did my first trial on it, my main memories are that the front end was never right. The stearing was unpredictable and the forks were also poor. The Kt, when used on the road used to pop and bang on the overrun, and I was advised by the dealer to open the plug gap to 75 thou ! I can also remember on wet days putting my hand on / near the engine and getting sparks jumping several inches. Most riders did away with the two stroke tank and went to pre mix. I'm pretty sure that I still have the original hand book somewhere which I thing was A4 size and fairly comprehensive.
Any help would be appreaciated. Haynes manual says you have to remove clutch, alernator, primary chain tensioner, and engine sprocket simultaniously (probably dropping all 25 beatings in the process) before removeing the cluth back plate to get access to gearbox sprocket. Is this the only way or are there any shortcuts ? Thanks.
will try the half a turn.
Just think yourself lucky you havent got an unmodified cub cos then you have to split the crankcase also 
Info Required On Lake District 2 Day Trial
in Pre-65 Bikes
Posted · Edited by B40RT
Hi, I'm told there is a two day pre-65 trial in the lake district during August or September, but can't find any info. Any info / pointers appreaciated.
Ross