'Weak point' on 1980 XS11 Frame??

[renniks73]

I've heard from a few people that the XS11's had a weak point on the frame. Anyone know if there is one (or more) where is it? From what I can see, my guess is...

...up and behind the airbox where the frame under the seat meets the frame that surrounds the engine.

Let me know...

[Ken Talbot]

- Rockjok talks about his broken frame in this thread

- Lloydo had a problem with a cracked frome in this thread

- Czekus21 had a problem with rusting at the bottom of his frame in this thread

The search button will probably find you a couple more.

[Pat Kelly]

Here's the weakest spot I see on our bikes:



Grey lines show the lines of our frames (back half).
Blue arrow shows where the weight of the drivers goes, supported by triangulation of the frame.
When you get rearward of the shock mounts everythin is just hanging there unsupported.
Weight of a passenger (red arrow) flexes the frame downward. Add a trunk with a load in it (other red arrow) and you can see the unsupported torque on the frame past the shock mounts.
I have read a few posts on here of frames cracking in this area and I think this is why.
On my E I plan to run a support from the unserside of the rack/trunk to the mounting plates of my hard saddlebags.

[Brian_D]

definitely agree with Pat. my project F came with a bad re-weld job on the frame just rear of the seat retainer tab - but i'll be cutting that section off anyway.

also, you can see in Pat's picture how the simple addition of the red arrows causes the rear tire to lose air pressure

[motoman]

Any excuse just to show off that clean MNS Pat.

[motoman]

That's special airing for a Wing type ride Brian.

[Pat Kelly]

I should have used lighter arrows.

[mason79]

your rear tire pressure appears low pat

[xschop]

weak point

the real weak point is the flex between the two halves of the frame that happen when you throttle it. To fix this, you can weld a flat steele plate between the rear down tubes in front of the battery... My 2cntz

[Incubus]

Hey Chop, do you have a picture illustrating where this plate would be welded?

Patrick

[xschop]

pic

I welded mine in conjunction with the monoshock point. Pg. 11 of Beggining new mod thread..

[Incubus]

Ah, I see. Good idea. I also now, for the first time, understand the meaning of the title of that string. I read through it all the way trying figure out what you were begging for....

Patrick

[xschop]

ice-ice baby

I see U live in austin.My best friend lives in austin. He said the ice storm has stopped everything there....

[Incubus]

Frozen solid since Monday. Nothing is moving. Or, if it is moving, it's not stopping. We don't get snow here, but every couple of years we get one of these ice storms. It's even too cold to mess with my bike.

Patrick

[xschop]

haha

now that's cold....