The OSSA TR77 250 that I am restoring to ride has an assister spring (expansion type from round bar which protrudes from inner side of swing arm to end of chain tensioner arm) as well as the radial spring on the chain tensioner/rear brake shaft.

I have seen bikes with & without this extra spring so what are you running on your bikes, is the radial spring on its own ok or does it require the other as well, which arrangement works best.

Springs...anyone...?

I always used to run with just the original spring. What's probably happened is that as that has weakened over the years, people may have added helper springs as it wasn't possible to buy a new original type spring.

They're available again now

Hi Woody, the TR77 & I think maybe the MK3 have this additional round bar from the inside of the swing arm which protrudes about 2" and carries the upper end of a straight expander type spring, the lower end of the spring attaches to one of the bolts holding the chain slipper rubber at the end of the tensioner arm.

I have bought a new radial spring for the pivot shaft but the straight spring was missing so I have no idea what the ends were like or how strong the spring was or why they bothered to fit it at all. It is something that can be easily added in the future if deemed necessary though.

I've used a Sherco or Beta Rev3 tensioner spring from the tensioner to the bar on the swing-arm in the past to assist the radial spring, the radial spring also acts as the brake pedal return spring but they're a bit pathetic, Is the end of the bar cross-drilled to take a split-pin? If so, fit the spring, next, a 6mm washer then secure it all with a split-pin, job done!

Yes the end dia. is reduced and drilled at the end for a pin, pin and washer are there but no spring. Thank you all for the info.

I'm not aware of the part of the swingarm you mention, I've got a TR77 swingarm and it looks the same as my MAR swingarm with just the two lug mountings for the chainguard. I've seen one of those mountings used to take an additional spring but I'm not sure there was anything like that as standard. Certainly wouldn't hurt to fit one though.