old trials fanatic Posted January 15, 2008 Report Share Posted January 15, 2008 I've noticed quite a few MAR Ossas have had a weld repair to the ignition cover which seems to run diagonaly from near the rear top scrw down to just above the rear brake pedal. Mine has also. Why is this? Is it a weak point? Can you do anything? Dont seem to remember a problem in the early 70's Also seem to remember everybody cut them back as much as possible to help with cleaning and chain maintenance. So why do so many show signs of being welded? Quote Link to comment Share on other sites More sharing options...
tony283 Posted January 15, 2008 Report Share Posted January 15, 2008 OTF, From my experiences the rear spindle was prone to bending, along with a lot of other soft Spanish steel of the period, and this could cause the chain to jump the sprocket and whip forward causing the damage. There was a BIG chain guide as well as the tensioner but that used to bend as well. Without the cut backs the chain can be difficult to put on, not imposs, but very annoying if you have watch makers fingers! Tony Quote Link to comment Share on other sites More sharing options...
woody Posted January 15, 2008 Report Share Posted January 15, 2008 Also worth doing OTF is to check that the threads for the screws that hold the ignition cover on are in good nick. If they aren't there is the chance that they won't hold and will strip when you pull in the clutch lever, meaning you will lever the ignition cover off instead of pushing the clutch push rod. I've come accross quite a few that are in a mess Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted January 15, 2008 Author Report Share Posted January 15, 2008 (edited) Also worth doing OTF is to check that the threads for the screws that hold the ignition cover on are in good nick. If they aren't there is the chance that they won't hold and will strip when you pull in the clutch lever, meaning you will lever the ignition cover off instead of pushing the clutch push rod.I've come accross quite a few that are in a mess Thanks for the tip Woody. Will check it over at the weekend. That would probably be a better indication as to why the crack is there on some of them i've looked at. Simple enough job to just pop a helicoil insert in so never understand why people bodge threads. The crack would be along a stress line. Nice one. Must say all this about the rear wheel spindle bending is a new one on me. I ran MAR's for 3 years in the early 70's and never had a problem, thats basically why i've been after one for a while Nostalga it aint what it used to be , with the spindles. Actually never had a problem with them at all they were the most reliable of all the bikes i had. Edited January 15, 2008 by Old trials fanatic Quote Link to comment Share on other sites More sharing options...
woody Posted January 15, 2008 Report Share Posted January 15, 2008 The crack in the case is generally as Tony283 has said, chain jumps off for whatever reason, wraps itself around the sprocket and takes out some of the casing with it. I only managed to ever bend one spindle in all the time I had Ossas back then and like you, I found them very reliable, just dodgy ignitions sometimes. Most problems these days are due to some ham fisted owners home-brewed methods of maintenance over the last 30-odd years, overtightening of threads or ill fitting fastners stripping threads, barrells and flywheels removed with malletts and tyre levers, crankcases prised apart with screwdrivers etc. The actual engineering in the bikes I'd say was pretty good. Still the nicest looking trials bike ever... Quote Link to comment Share on other sites More sharing options...
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