markg Posted February 10, 2016 Report Share Posted February 10, 2016 Hi all, Looking for the fork oil quantity for a '83 Jumbo with 38mm Betor forks. Thanks,, Quote Link to comment Share on other sites More sharing options...
bezaboy Posted February 10, 2016 Report Share Posted February 10, 2016 Your best bet is to message Martin at www.motoswm.com he will be able to help with anything SWM Quote Link to comment Share on other sites More sharing options...
woody Posted February 10, 2016 Report Share Posted February 10, 2016 Start with 200cc per leg, recommended is around 220. Which weight to use is personal preference but maybe SAE10 where you are due to it being a bit hotter than here The recommended quantity in manuals is usually the maximum which can give a stiffer action, you can generally use less than recommended. If you start at 200 you can add a bit at a time if you find them too soft Quote Link to comment Share on other sites More sharing options...
markg Posted February 14, 2016 Author Report Share Posted February 14, 2016 Thanks I'll try your recommendations. Am I right in thinking the vents on the caps should let air out on compression and suck in when released? Quote Link to comment Share on other sites More sharing options...
woody Posted February 14, 2016 Report Share Posted February 14, 2016 I've never really understood the purpose of those vents or how they're supposed to work. All I've ever had from them on most bikes with Betor forks is a squirt of oil in the face when the forks compress. I've always closed them off with a blob of araldite, so can't help you with this one. Quote Link to comment Share on other sites More sharing options...
metisse Posted February 15, 2016 Report Share Posted February 15, 2016 The vents on one of the fork tubes on my bike has venting issues, a very audible one when the forks are working. Even after a robust soak and clean its made no difference. Its either the araldite route or.. speaking to the Magical's man in Spain before Christmas, I was led to believe some new ones may soon be available as replacements with a valve you can fiddle with..... Quote Link to comment Share on other sites More sharing options...
markg Posted February 15, 2016 Author Report Share Posted February 15, 2016 Both caps on mine were letting air in and out which is different to my Bultaco. I pulled them apart and cleaned. It seemed someone had tightened nuts down onto spring forcing small sealing washer to not seal. I backed the nut off leaving room for spring to work and let sealing washer open and close. Works great now, only vents on full compression and let's air in on the up stroke. Think this is how it should work........ 2 Quote Link to comment Share on other sites More sharing options...
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