So, I put the bike(2006 GasGas TXT280 Pro) up on the lift to change the oil and tend to a few other minor maintenance things, and spotted this:

...hmmm...and the other side:

Aside from the obvious failure - which I would normally just weld up and clean up and paint, etc. - the real concern for me was how far it looked that the separation had crept apart, and that it appeared to be permanent(meaning, the original radius at the intact aft end of the tab is separated from the spacer/bushing welded to it; this indicating that the whole frame had elongated or otherwise yielded). It wasn't like this cracked, the ear of the tab got pulled away due to one heavy flexing movement, and then everything sprung back into place. It appears that aside from the fatigue and separation, there is some pretty large displacement of the lower mount bolt FORWARD relative to the original location of the tabs and welded-on spacers inboard of the tabs.

I have a LOT of other experience with bent frames of all sorts - trucks, buggies, motorcycles, bicycles - and what's funny about this one is that nothing else seems bent. ANYWHERE. I will be tearing it down tonight and we'll see what springs apart, if anything...if it does, I'll know I bent the entire frame but as of right now, the alloy cylinder stay and all other engine mounts and all other welds on the frame look intact, and I can't find any indication that anything else has bent either during this failure or in the aftermath of it.

Reports back later...I see one other thread: hhttp://www.trialscentral.com/forums/topic/32783-gas-gas-2007-lwr-engine-mount/ here that alludes to the same failure, but no pictures posted.

This bike has not had the easiest life: I am the second owner, and niether the prior owner or I have ever slammed it onto the bashplate hard enough to create such a failure...and I have never bottomed it hard enough to do this, to my knowledge. I only weigh ~165lbs with all my gear on, and while I'm not shy about aggression, this seems really strange.

Will report back with more pics and solution.

Are all of the engine mounts (including this one) tight? and I mean really tight

Take the bash plate off and see if the crack narrows, a bent plate might be part of the problem. Hopefully.

just found a simlar crack on sons 2008 250, crack/break is across wheight saving hole and same as hilslamer appears to have pulled apart,but cant see how cos swingarm spindle thro fame and cases good. could it be that the frame flex that has caused crack has pushed broken parts to edgeof bolt hole?

Mine had the same problem. All fixed now though. Rewelded the crack up with some 'super steel' filler rods and my trusty oxy/acetylene torch. I had some 3mm 4130 chromoly plate in stock from my car racing days so I reinforced the mount at the same time before re powder coating the frame.

The mount goes from being some 30 odd mm wide to about 10mm due to 'weight reduction holes'. It seems a common failiure on gassers of year 'X'. The combination of constantly knocking the bash guard, stresses from accelerating and bouncing the rear suspension and engine vibration soon fatigues the original chromoly mount which over time is sadly not upto the task.

Edited May 15, 201214 yr by tankygsy

Same thing happened to my 2010 and 2011. It is a weakness.

Thanks for the replies, all! Good to know I'm not alone...already stitched mine up as well. No pics right now...maybe later.