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beardy2000

B40gb

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Hi I have a problem with my B40 trials, I went to fit a pvl ignition and found the primary chain had been rubbing the crank seal. Is this common and how can I sort it?

I also need to get more ground clearance from a c15 frame b40 engine . Been having problems with getting hung up all the time. Are there any common mods that were done?

Also how easy is it to replace the conical hub with a cub hub, I have b50 front forks four studs

Any help would be much appreciated

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Hi

distance of drive gear from crank bearing (and hence the timing gear from the seal)is controlled by a spacer behind the gear which can be replaced by smaller/larger to allow alignment of the timing chain on the drive sprocket and clutch drum. This spacer provides the surface which the oil seal runs on. If the two cogs are not in line, which can be measured with the edge of a steel ruler, and the drive gear too close to engine a larger spacer is needed. If they are in line and the chain is still rubbing you may have to correct the end float of the mainshaft to bring the clutch out further and then match up the drive gear. I am not 100% if the B40 mainshaft has a nut on the timing side to stop end float, but if it has not then the thrust washer in the middle of the shaft will need replacing. Hope this helps

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Thank you very much for the reply, I didnt realise that different size spacers are available. I have another B40 with a distributor and it has done the same thing, The spacers are they different thicknesses or do you get them made as you need? The chain has done a lot of damage to the engine casing but I dont really want to strip it right done and get it welded, but it is what it needs really.

Cheers for your help I will have a measure up tomorrow, really want to get it running again!

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Hi Beardy

sizes used to be available a b and c at different thicknesses. It is probably as easy to gather what shims will fit and try various combinations of them. Ta Nigel

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