B40 forks, thoughts?

[highboy_coupe]

Hi all, my forks have been rebuilt a while back and not used. I put 1/3pint of oil in with an mind to get up and down the road for a test ride. I can lean over the handlebars whilst standing and fully compress the forks 'til they bottom out. The next oldest bike I own is a 1980 Yamaha XS650, and I thought that had soft forks, it doves but does not bottom out.

There is a feeling of damping, and I can hear oil squirting about if I pull up on the forks.

Should I just use thicker oil or is something wrong?

Thanks

[rhyatt]

there's not a lot of damping, they're pretty squidgy and by the time you have been up and down the road, and the forks up and down, then all the oil will be in the right places - my SS80 is pretty soft.

I think the right grade of oil is SAE 20 - what grade did you use?

[DAVE BRADY]

Hi,

I would think that any fork springs that can be 'bottomed out' just by pushing them down are just about knackered. The damping of the oil will help a bit but over bumps with the momentum of the bike it could prove to be very uncomfortable and perhaps even dangerous.

Dave.

[highboy_coupe]

Thanks, I'll have a look at some new springs... I am over 16 st and putting my weight directly over the bars and giving it a shove with the brake on to bottom them out.

I used 15w40 mineral oil.

Thanks again. The bike had done 12k when the forks where rebuilt

[chaz]

too much clearance on the bushes? correct tubes?
any extra clearance will let the oil flow with less resistance.

[highboy_coupe]

Maybe I'm being stupid, but I can't see any springs in the stanchions at all, I took the top caps off and looked down with a torch, and fished a wire hook down there and there's nothing!  Where are my springs?!

[highboy_coupe]

I am stupid... It's a 1965 so I thought it would have internal springs.... I guess it's got external springs hidden under the shrouds. So does that mean I can put internal springs in? Are they older, or perhaps c15 forks?

[DAVE BRADY]

Hi,

The B40 has much heavier springs than the C15 and has external springs under the shrouds.  New ones will certainly help but I think that A10 springs will fit and as they are for a heavier bike they may be more suitable for your individual requirements.

Dave.

[highboy_coupe]

Thanks Dave, very tactful way of putting it... I'll look like a Gorilla on a bicycle when I finally get to ride it!

[highboy_coupe]

Can anyone confirm if A10 springs fit?  I noticed Draganfly stock sidecar springs for the b40 that say 'heavy duty", might they help with my weight problem?😂