I have had a lot of what I thought was top end rattle on my B31. I used the tried and trusted method of holding a screwdriver to my ear and trying to identify metallic noises from every part of the engine. Nothing apart from a definite metallic sound from the magneto pinion area at the top of the timing case. I slackened the magneto straps just a little and I think it may have made a difference. I might have overtightened it. I also read somewhere that sometimes shims or metal spacers can be used if front of and under the the magneto to line it up correctly.
Could anyone advise me please on the best way to position the magneto.
Thanks
David
Quick and dirty answer...Take the timing cover off and rotate the engine with a piece of paper between the magneto and idler pinions. If it tears you need to add shims under the magneto to give you clearance between the pinions. The straps need to be tight when testing and after final assembly.
If you have no clearance between the pinions you may well hear a whining noise and it will stress the magneto bearings.
Worth remembering. I've always thought that the clamped mag is a poor design when compared to the mags on the twins.
My magneto was way off as well , all I did was add a tiny amount of tig weld to the pins on the barrel side and filed the weld with the safe edge of the file facing the alloy mag in the end it took very little to make it on centre, I also added a shim across the points end .Cheers
Great advice thanks you
David