alan

As designed, the engine breathes through the cam bush into the outer casing. There is a hole behind the clutch cable entry point to get the pressure out, the oil drains back to the sump through the small hole in the inner case. Most people fit a blind bush on the cam to stop breathing into the case and plug the drain hole ( to stop water getting in when streams etc) . The engine then breathes through a hose fitted into he dizzy blanking plug, ideally with a non return valve to create a vaccum in the crank cases.

i have this one, uses the same 50mm dia filter as the morgo version. Cost me £45.00

Were there many at the pre 65 ? . I walked up to manmore on the saturday, there were quite a few electric mountains bikes.

No it is not mine, afraid i dont have pictures of the other side. I believe it is mostly original. It was bought new in october 68 by Hedley Cockshott, and was then traded in against a Bultaco. It now resides in Lancashire.

Unfortunately some so called experts (usually ones that manufacture parts) dont understand the basics of steering geometry. Making the forks looks steeper is assumed to be a good thing. If it is acheived by merely altering the offset of one of the yokes it increases trail. ( Unless you increase the offset of both yokes to compensate - in which case you end up with tiller like steering and the mass of the forks and front wheel acting on a long lever around the steering head bearings). If it is done by altering the rake angle of the frame it decreases trail. If you dont want to cut the frame the simplest options are to put longer shocks on the rear or drop the stanchions through the yokes.

All you have done by fitting parallel yokes is increase the trail, so it takes more effort to turn now.

420 and 428 are the same pitch so the sprockets will be the same diameter. i think you will struggle to find a 520 front sprocket. i have not come across a twin seal casing, is there enough room to space the sprocket out further without the chain rubbing on the back of the primary chain case ?

Yes, those are the dimensions of the offset sprocket . You will have to reduce the OD of the socket to go inside the recess.

Excellent service from trials bits ... http://www.trialsbits.co.uk/product_info.php?cPath=85_86_99&products_id=687

The standard clutch effectively has 4 plates.. The back of the drum acts as plate, adding another set of plates increases theoretical torque capability by 20 % for the same spring load. This should just about compensate for the increased torque due to the reduced engine sprocket. I havent used a four plate clutch so cant say for sure.

Hoover drive belt ?

You can get the 3 plate clutch to work but you need heavy springs and careful setting up. Without some sort of clutch lightener, you will end up with a heavy clutch lever.

no problem.. the issue is that when you compress rubber you don't change its volume just it's shape. The beauty of an o ring is that it just goes oval, the quad ring and tube have to spread out.. so yes i also use an O ring at the bottom, BS022 25.12 x 1.78 . There are a few choices.. you can trim the rubber tube and use just one, or remove the rubber tube and use up to 3. Do the dry build with the O ring on the top to determine the best way to go. Again you are looking to compress the O rings by around 20% of the cross section diameter .. good luck

i use a BS124 O ring which is 31.42mm ID x 2.62 dia. In a static application you are looking for between 15 to 20% compression of the diameter. That means on your dry build without any thing on top of the push rod tube you are ideally looking for a gap of between 2.0 to 2.2mm when you compress the bottom tube. You can trim the tube to achieve this if necessary. Any decent bearing supplier should have them. Simply bearings here in the UK are good for mail order. http://simplybearings.co.uk/shop/advanced_search_result.php?keywords=bs124 viton is the best material for this application, nitrile is OK, but avoid the epdm as it is not oil resistant.