Hi , I have had my magdyno off , to fit a seal that wasn't in there , and need to replace cam and crank seals as well , so I ordered the correct seals ! ? , and I have found the new seal is 19mm OD and the old seal 17mm , my cover has the seal that goes into it , I just wondered why that size wasn't listed ?cheers
The B31/33 has the steel quill (approx 3/4" long) pressed into the timing cover and that goes down inside the hole of the crank.
The camshafts have the plain rubber seals and the magdyno should have conventional lipped seal with spring etc.
Has your timing cover and crankshaft been converted to the later Gold Star type with seal in the case and an extended nose on the crank.
If that is the situation you will need a later GS type seal.
Can you post a pic of your timing cover innards and the crank nose?
Hi Neil thanks , I think your right , yes my crank has a small spigot and the seal is fitted to the cover can you tell me what year to look up for that seal , it is odd sizing 9 mm I'd 17mm od and 5 mm wide . Cheers
If it is a Gold Star timing cover and crank nose the BSA part number is 65-2505 (according to my DBD 34 parts book.
Afraid I've not got one of those stripped at the moment so I can't help with dimensions.
According to https://degroot-bsa.nl/product/oil-seal-kickstarter-shaft-bsa-b40-44-50-kopie/ it is 19 x 9 x 6mm lipped seal.
So looks like you were sent the correct size for stock part, so it would appear your timing cover has been modded (as suspected).