Topic: Didn't want to see this...

[gdgreen56]

At some point in this bike's previous life it looks like the chain came off violently enough to dig grooves into the engine casing just ahead of the front sprocket. After splitting the cases it looks like the damage extends all the way through the lower case with a couple of cracks.

The question at this point is - Can this be repaired, and if so, what is the best way?

[mystic_1]

Yes, it can be welded.

That's the only "real" fix.


Many many people have just slathered the cracks with epoxy, JB Weld, etc to keep the oil in.

mystic_1

[Retro Rocket]

Yes, seek someone out that knows how to weld old aluminum, it needs to be heated to purge the oil in it, then tig welded up.. You are lucky, most of the time, that whole section is either missing or bodged up with epoxy or JB weld, in comparison, yours is a much easier fix...

[setdog]

From what I've read in these forums this is definitely repairable.  I also think you caught this just in time because you still have all the original aluminum. 

Best tip I can think of is to make sure you qualify that your welder has significant experience with aluminum.  And find a really good fine file, swiss pattern, , to make case edges nice and flat and smooth at the repair site

[thep1pe]

Here in the UK we have a product called Belzona. It's a bit like bondo for aluminum. I have used it many times to repair aluminium auto engine's and gearboxes. It's fully machinable and vibration and oil proof. I think it is expensive though I have also used it to repair porous metal and cracked casings.

[Don R]

 Check for an engine shop used to repairing drag race engines. Where lots of aluminum and frequent carnage are normal sightings.


 The next question, is it a nice original numbers match bike now? If you're building a custom or if it's already a bitsa bike just find another engine. It's probably cheaper and easier.

[gdgreen56]

Thanks to everyone for the information on this. I was concerned that I'd have to go find another engine...

The bike had only 23K miles on it when I bought it and outside of this one issue the rest of the engine internals are in excellent shape. I like Don R's suggestion to find a shop in the area that does repair work on aluminium racing engines.  If anyone knows of a shop in the Dallas area and wouldn't mind suggesting, I'd appreciate it.

[calj737]

If you struggle to find a shop, simply seek a qualified welder with Aluminum TIG experience. It's not that tricky a repair since it's just cracks. But getting the cases clean, degreased, and cleaned some more is something you can do while you search.

Welding aluminum generates enormous heat, and any impurities at all absorbed into the metal will leech out. This spoils a TIG weld and creates air bubbles in the bead. That's why it needs to be degreased so heavily,

[gdgreen56]

 In this type of repair are there concerns about warping the case due to the heat from welding or is it localized enough that it shouldn't be a problem?.

[calj737]

If performed by a competent and experienced welder, warpage won't be a factor. Any time you weld, the longer and more sustained the heat is applied in a single area distortion occurs. Weld, move, weld, move, weld, move... You don't want to run a continuous bead from start to finish for a repair like this.

[gdgreen56]

I've talked to a couple of shops in my area and I'm not confident that they have the experience to do this type to repair.

I'd be really interested to hear from others in the forum who may have a recommendation for a know competent shop to do this. I don't mind shipping the case off to get the work done. I just want to get it done right...

[calj737]

If it were me, I'd invest the money into having the cases vapor blasted first. That way, they are about as clean as possible and in perfect condition for welding.

The "crack" would want to be ground open a bit for new weld to infiltrate from the interior, then also on the exterior of the case. Whether the mating surface would need to be machined flat, that would only be determined after welding.

Do you think you want to have the "gouge" filled and filed back to the same surface level as stock? If so, you are rapidly approaching a many hundred dollar repair, and its possibly much less expensive to simply buy new cases halves. Member Bill Benton probably has some cases he could ship you that are free from damage and readily usable.

[NobleHops]

My ace welder wanted both halves of a set of cases I had him fix, which he bolted together before he made his repairs, to prevent any possibility of twist or warpage.

[Don R]

 I know Texas is a big place, these guys are in Sherman TX and if they can't help they will know who can.
http://sunsetperformanceengines.com/

[Kingmambo]

A talented oxy/acet welder can repair this; using a small torch will put way less heat into it, mitigating the concerns of warpage and the boiling of the aluminum causing impurity issues.  That is the route I would go though I would find an old-timer or very experienced welder.  There are many situations where oxy/acet welding is preferable for aluminum but not many welders have much experience with it.

[gdgreen56]

Got the lower case back from the welder today. The repair looks good, so hopefully no leaking once I get it put back together. I'll have to file the parting line area and may need to smooth off a couple of spots inside the case, but otherwise it looks like a workable repair.

I ended up finding a motorcylce restoration shop in Lewisville,TX close to where I live and got a lead on the shop that does all of their cast aluminium repairs.

[calj737]

You need to carefully examine the mating surface. In the second picture, the weld appears to have been built up above the surface and this will be a permanent problem for you. Not the prettiest weld, but it should hold 

[754]

 Do you know how to drawfile ?,, take your time...