Topic: Noobie sayin' howdy! and CB400F frame repair question

[rtbxr]

Hello to everyone

I just signed up because I'm starting into a restoration of a '75 CB400F. I've had a look around here and it looks like a great site with a great bunch of folks. Hopefully I can find a place to fit in and contribute some bits here and there .

This 400 might turn out to be a bit more than I want to bite off right now, but I figure I'll start small and see how it goes. I keep going back and forth between selling it and buying one that's ready to go riding or sticking out the restoration.

Today I managed to get it to sputter a couple of times and it definately wants to run. The floats were stuck so more gas was running out the bottom than making it into the cylinders! Once I get the carbs back on, I think it'll fire right up. Definately an encouraging first step

The biggest part of this restore will be dealing with a nasty gouge in the frame where the sidestand used to mount. I searched the sites as best I could, but only managed to find a couple of mentions of the same problem, no fixes. I don't really relish the idea of riding on a welded frame, but I'm a pretty fair welder so it appears to be an easy fix on the surface. Anyone ever try it or am I better off finding a good frame? I do have a sidestand and the associated frame section (came with the bike).

Anyway, thanks to the folks who run this place. I'm sure it's not an easy job, but you've put together a wonderful resource here. Thank you.

BTW, I live in West Grove, PA. Just down the road from you, Glenn. We should get together for a ride.

Happy Holidays to all,
Chris Herring

[jotor]

Welcome aboard, matey.  What part of Penna is that?

Water gets in the frame and collects at the low point, then rusts out.  I bought a 400F at Mid Ohio that was completely eaten away in that area.

I fixed one years ago by welding in a piece of frame tube and sidestand from another bike--don't remember what it was anymore.  I cut "half-laps" in the tubes to get more welding area.  Wasn't a restoration by any means, but it held the bike up.

Go ahead and try it.  If it doesn't work out you aren't out much and if it does--you're golden.

Joe 

[rtbxr]

Thanks for the tips, Joe. I think that I may well try the repair for the short term, lapping the pieces sounds like the way to go.

I'm in south-east PA, right where DE,MD, and PA all come together. Thanks for the welcome

Regards,
Chris

[Henry Dorset Case]

Hi ya

I'm another 400F owner (in New Zealand) and you are right this is a great site, with friendly people.

I cant help you with your problem, sorry, but welding does sound like an option:  presumably you have the engine out of the frame, or can somehow get your welder in between the motor and frame?  Just looking at mine and there doesnt appear to be a lot of clearance in there.

good luck with it...

[oldbiker]

RTBXR, on a couple of frames that I built some years ago, I was advised to Braze (or bronze weld) any joints or repairs as this was plenty strong enough and did not get the metal hot enough to cause any brittleness. I also remember that when I worked in the drawing office of Triumph Motor-Cycles all frame building was done by brazing. Even though you are competent at welding I think it is worth considering the above.

[rtbxr]

Thanks oldbiker.
 I had thought about putting the frame on a jig and sleeving a heavy wall pipe into both sides of the cut away section, then brazing them tight. Then I would just have to weld or braze the sidestand section in place for function and cosmetics.

In this case, I think you're right. The brazed joint, with good flow, will actually be stronger than a weld and even stronger than the frame metal itself. This is a problematic fix, but done right I think it may work out ok.

Thanks for the help,
Chris