Welding a YZ250 Frame? Any welders?

Thats a bummer! The seller is an idiot & a jackass for drilling a hole like that and NOT disclosing it! EITHER he is too dumb to know NOT to drill holes through the frame and honestly didn’t think its anything to concern about OR he IS a dishonest asshat that knew it would alarm a buyer and covered it up with a frame guard! I would certainly want it repaired as well and sorry that I can’t offer you any assistance other than to say I think you’re correct in your concern and wanting to repair it! I hope one of the legit Vital experts on the subject can get you the right info on how to resolve that correctly & safely! Good luck and I hope it isn’t a bigger nightmare than it looks like right now! 😎 👍❗️

That’s true. Aluminum can get weaker when you weld it. Put a piece of brass on the backside and rosette weld the holes up without getting it super hot. There is a gusset right below the holes. Not saying this would be as strong as new but would be stronger than it is now. 

I could be wrong, but that area looks like a casting or forging ?

Which may be relevant to mention if you are speaking to welders about the job.

If you can't get someone to weld it, I don't know if that is the most stressed part of the frame, it may never crack or break in that area, you just never know.

If he had drilled holes near the steering head or rear shock mounts I would be really concerned, but in that area it may never break, and if it does it may not cause an accident , unlike a frame break at steering head or suspension mount.

I would be checking over the whole bike for more "modifications"

The seller needs his butt kicked for sure. 

I’m not sure if that part is forged or cast, but I think preheating is a good idea. I agree it’s not the worst place to have a break, but it could still be bad. 

I would look for someone parting out a bike and buy another frame. It may be cheaper in the long run. 

Is your son at Embry-Riddle?  Maybe someone there could help. 

"I've searched the web and this forum and the only useful post I found said the Japanese use 7000 series aluminum, so it can be welded with 5356 rod and it will self harden over a 2-3 week period. Any qualified folks on here who might have the actual facts on how to solve this problem? Thanks in advance. "

That's it, in a nutshell. When you look it up, you'll find that most grades of 7000 series are not weldable, but  there Are several grades that are. And the aluminium of that Welded frame, is just that.........

Pre Heating? It's not remotely thick material, so Not needed, unless the welding unit being used had a piddly Amperage capacity, or, they tried to DC weld it - yes, you can DC weld aluminium, but f**k that for a joke. I've seen that done, but Never, Ever done it. 

I'm a TIG welder of over 5 decades of experience. I make frames, both Bicycle and Motorcycles (and now, tubular car chassis, in my half blind, shaky handed dotage).

I'm a bit wary about those holes (what the hell were they thinking?) size and how close they are to the outside plate. Like, it looks like the OD of the hole, might be right up to the inner side, maybe even having the drill scuffing that inside (of the outer section) . I'm on a phone screen, so can't really see it well. And that hole, I'd be worried , has gone through part of the inner Radius of each 'corner'  that is in that casting / forging. Having that radius violated, Is a very real structural insult and stress riser to that section - well, the bloody hole is that, of course. To repeat, WTF were the previous owners thinking?

With a lot of after weld filing / linishing / sanding, and a backing plate (as suggested by a previous poster) you could make the repair undetectable. 

I'd be tempted to have a plate of aluminium inside, that the plug / rosette weld could penetrate to, with a  little weld of the plate to just below the outer edge (of in inner cavity, so to speak), as I tend to be (very) cautious with aluminium repairs. 

Leaving it to age for the couple of weeks is a GOOD (and much preferred) thing. Especially a Frame repair. But, I've had innumerable repairs that have been put back into use, without any time. I don't like that caution being ignored, but, you have little power over what the owner does after they've left your premises. Some repairs, I've refused to do, unless the job was Left With Me for  the required time, after welding. They don't like that proviso? , well they can F.R.O is what I tell them, and sometimes, as rudely as that. 

Since that frame has been in production since 2005 it could be possible to find a bare frame at a reasonable price, worth considering.

Is it possible to put a dowel thru the holes and weld each side after tapering the hole to get a strong weld? Weld outside and inside during the process. Not the cleanest look but strength is the key. 

I just did a quick search on eBay- several YZ250 frames on there. $400-$600 if you decide to go that route.

That's a pretty sound idea cmotodad !

 You'd be able to  make the outer weld 'disappear' with some finishing work, and just do a weld on the outer arc of the dowel.

Though, there's a reason for the large unwebbed portion of the swingarm pivot plates at that area, I'd say.

So that might make it too rigid at that point, bringing on  cracking. But that's  speculation on my part.  Just a couple of beads, or little more than a tack, on the outer arc of the dowel might be safe - to allow a bit of 'give', or a deliberate 'indicator crack' point. 

Find a good steelie frame…. 

I'd be interested in the actual hours, wonder if all of those had this "mod"? Is that area really under that much stress where a repair wouldn't work? 

It does look terrible however, makes you wonder how people come up with these ideas. There have been bolt together frames in the past, lower cradle such as VOR, I would think that area is way more stressed than this area. I imagine the cost of a repair may be close enough to a replacement frame.

I'm still trying to figure out what the hell the holes are for.

Yeah, really bizarre. Another question would be intended use. 

Add to the cost of the repair a baked in risk of future cracking.

I'd also go with a replacement frame.

I tig weld a lot of aluminum. I would not bother filling those holes. The frame is cast aluminum. The downsides to welding that far outweigh the benefits. Thankfully, they are holes. If anything, I would lightly chamfer the holes and put a bolt of the same OD through it. The hole on the right is not clean and I'd want the backside of the hole chamfered. There's a gusset right below the holes. It's plenty strong. I don't see those holes adding much weakness to the frame.

Funny you got 4 downvotes. I never rode one but used to race with a guy and knew another who put modern YZ suspension on a pre 05'  steel frame and both said it was amazing. Thumbs up here  

I would clean up and de-burr those holes as best you can, then just keep an eye on them.  Welding them may be an option, but you will only ever be able to age the material back to T4 hardness without heat treatment (which is still relatively strong).  I can't imagine that you would have an immediate and complete failure of the frame in that area from a one-time load (think casing or overshooting a jump), I think the more likely failure mode would be stress cracks from long term fatigue, which would be detectable if he inspected the frame regularly.  Cleaning up and deburring the holes properly will go a long way in reducing their ability to act as a stress raiser and significantly increase the life of the frame, to the point where it may never actually end up being a problem.  If the frame does begin to show cracks in that area then you know that it's time to replace it.

Regardless, leaving jagged holes like that in any material is a bad idea, if you do nothing else at least properly clean them up both inside and outside of the flange.  Don't just cover the holes with a frame guard and forget about them though, inspection after each ride would be the best insurance for preventing a failure.

cup holder?

Passanger foot peg/floor board.

Or he heard that those frames are super stiff and decided to loosen ol' girl up a bit. 

I d take the bike back to the guy... Ask for your money back if he didn't disclose it. 

That is the 20" inseam mod

He just returned it to "factory"

This. Perfect candidate for a steel conversion - if the engine / swingarm fits the steel. The steel YZ's handle so so so nice

A cage for a disabled rider?

That would be worry free solution, you wouldn't have to further worry about fatigue in that area down the track.

I would strongly caution against welding. The HAZ (heat affected zone - the material next to the weld) of welded aluminium usually is badly affected be welding and has reduced strength and reduced fatigue performance without PWHT (post weld heat treatment). To manage that you need to know the alloy and the temper including its state post manufacturer- e.g. did yamaha heat treat the whole frame post manufacture and if so how?  Contrary to a post above 7000 aluminium is difficult to weld and is dangerous welded without extensive pwht. If used well 7000 series has good fatigue properties (handle bars etc) but welding requires a lot of knowledge and care. 

My tip, replace the frame.
 

IF you are absolutely desperate to ride between now and then, polish the holes and nearby frame carefully to remove the burrs and maximise fatigue life and inspect the holes and nearby frame after every stint on the bike until you get a new frame. As soon as you see a crack start stop riding it. BUT remember doing this still risks the frame breaking during a ride. 
 

The frames are made of 7005 Japanese spec which is 7020 UK spec.

5356 is the rod to use, it will age harder and is the only 7000 series Aluminium to do this, thus you will not get a brittle HAZ, it will get stronger up to around 60 days but it will be fine from 2 weeks in as that is the greatest strength gain.

weld the inside first, allow to cool then grind the weld from the outside and then weld and linish flat, it will be absolutely fine.

Easy, do not weld it. Just deburr the hole.  Even if it’s welded and retempered, it’ll never be the same as when it was raw, welded and tempered from new. 
I work in an industry where we’d scrap it and start again just to mitigate any potential failures. 

You may have found my thread on welding up a 2014 YZ450F frame a few years ago.
I did that weld myself on a subframe mounting tab that ripped off in a hard crash.
The weld held up fine in a location that sees substantial stress.

I'm not a welder and I have zero formal welding training.  (I'm a mechanical engineer who owns a machine shop).
Repairing that part of the frame would concern me unless the repair was done extremely well, perhaps by a pro.

Be careful with the design of any gussets or reinforcement you add.  By adding material, you can create a stress concentration around it's edges which actually results in cracking where it transitions from thick to thin cross-section.

If that were my frame, I would probably carry out the repair with a very clean plug weld, then keep a very, very close eye on the frame.   You can purchase a dye penetrant kit (used to check for cracks in automotive castings, etc).  Check for cracks after each of the first few laps on a track, then after every moto for a while.  Eventually when you're confident the frame is holding up, lessen that inspection frequency to what makes sense to your riding/racing schedule.