October 5, 200916 yr Hey, what size of sprockets should be on the primary drive of a b 40 for trials use (it's the wd gearbox)? on my bsa the chain is verry loose and the chain tensioner is fully in so i guess the chain is to long or the sprocket is to small? can you get the chains in different sizes? or can you just take a link out the chain? regards bob
October 6, 200916 yr According to Rupert Ratio WD B40 clutch 52t, engine sprocket 23t which dosn't sound right. Have a look at http://www.trialsbits.co.uk/index.php?cPath=85_182_257 for more info, or e.mail them.
October 7, 200916 yr The normal engine sprocket for trials use is 18 teeth and yes you can remove some links if the chain is too long. If you don't have the device for breaking chains then you can grind back the rivetted end of the pins on one link and knock them out with a punch. If your current chain is does not have a joining link then you will need to buy one.
October 7, 200916 yr Author tnx for that info! any adress where i can get a joining link? regards bob
October 26, 200916 yr I find C & D Autos can supply all I ever need for my B40 Wd GB engined iron horse! Tel 01564 795000. I had the same issue when I bought mine, they recommended and supplied a sprocket/duplex primary chain that fitted perfectly with no cutting. Good luck. Mark
October 27, 200916 yr Check out Ebay 10658ken for some quality duplex chain for your unit BSA Trials Bikes and cheap
October 28, 200916 yr Hi Bob, If you take my advice , fit a new primary chain. It will be a lot less expensive than the wreckage you could expect from a primary chain that breaks that has been shortened. Pat.
October 28, 200916 yr Standard set up for the B40 would have been as mentioned earlier 52T clutchwheel- 23 front sprocket and 70 link duplex chain The trails dropped it to 52T - 18 and a 68 link duplex chain The b44/50 with more grunt went the other way and had 52T - 28 and a 72 link chain At the moment I am machining a compromise front sprocket of 26 teeth for road use as the 23 still low and limited. I think then I will be at the limits of the adjustment of the 72 link chain which fits the 28. As pat says with chain available for 20 or so it pays to replace it. I have a stator and rotor that look as if the chain snap at some stage broke either the crankpin or the gearshaft on the primary side.
October 30, 200916 yr Author hey i found a new chain and links near my home (industrial chain suplier) regards and tnx for the advise bob
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