2001 Honda CR250 Frame Crack - downtube off steering stem

[dbf498]

Well...it took some time to happen, five years, but if finally happened...my frame cracked.

Here's a little history with it.

In 2007 I was racing my '01 Honda CR250 and wrecked it...4th gear pinned. Well, as the bike went down it jammed the lower triple tree to the right, crushed the throttle cable, embedding the cable into the upper down tube.

For a number of years the damage from the cable was visible but no cracks formed from the damage. Well...fast forward to today and while looking over the bike and noticed a cracked that formed over the damage and must have happened from the last ride.

To make a long store even longer has anyone successfully repaired a Honda CR Frame? Does anyone know what series aluminum it is? I've seen lots of threads on the aluminum framed Honda's, especially the CR500AF, but no one really going into any details in what the base metal is or which filler rod was used.

Here are two pictures of the crack; the lighting isn't all that great but it should give a good idea of the crack. These down tubes appear to be of a real thin wall thickness; around 0.032 inches.

[factoryX]

Weld that sucker, doesn't look to bad. This is the problem with aluminum frames, they don't age well due to rigidity.

[dbf498]

Well...that's the gist of the whole thing...what filler rod? A4XXX, A5XXX, A6XXX or A7XXX?

[SachsGS]

It's been my experience that steel frames crack from the outside in and aluminum frames from the inside out so you may just be seeing the "Tip of the ice berg" so to speak. That crash created a stress riser that has hastened the demise of your frame. You may have reached the fatigue limit of your frame, I wouldn't personally trust it anymore, and it may be time for a new one.

[riffraff]

First thing I would do is stop drill the ends of the crack then I would weld it up or even rivet on a doubler and inspect before and after each ride, but that's just me 

[dbf498]

First thing I would do is stop drill the ends of the crack then I would weld it up or even rivet on a doubler and inspect before and after each ride, but that's just me 

As mentioned before...before I weld it up I need to know what aluminum alloy this frame is made of? Knowing this would help me decide which alloy to use as my filler metal which, in theory, would help reduce the likelihood of inducing any more fatigue in this area.

As far as the repairs, I've been kicking around a few ideas on how I'm going to repair it. I've got a buddy who can NDT it to check where the crack begins and ends so that's not a problem. One idea is to groove it out and weld it up or stop drill it, groove it out, weld it up, and weld a doubler over the crack. Either way, it'll need to be looked at after each ride just to make sure the crack doesn't reform.

Then again, SachsGS makes a good point...it may be time to cut my loses on the frame and just replace it.

[factoryX]

http://www.ehow.com/facts_7912444_kind-aluminum-honda-motorcycles-made.html

Ditto on drilling holes on each end of the crack.

[Stusmoke]

I would have a crack (<---- Hehehehe! See what I did there ) at either taking it to an experienced aluminium welder and seeing if he can determine the base metal. Or you could just send honda an email. But they probably wont tell you cos its a two stroke.

[dbf498]

WTFactoryX thanks for the link. Well, armed with the link WTFactoryX provided, it's likely to be 6061-T6, we may be able to perform an eddy current inspection, http://www.ndt-ed.org/EducationResources/CommunityCollege/EddyCurrents/cc_ec_index.htm, on the frame to validate it is 6061-T6 and we're off to the races; so to speak.

Or you could just send honda an email. But they probably wont tell you cos its a two stroke.

You're probably right; they might try to sell me one of their "upgrades"...of which I'll pass...I like my ring-dings.

[SachsGS]

From what I understand the Honda frame is made from a 7000 series self hardening aluminum alloy. In the event that it is 6061 T6 the frame will have to be annealed after repairs and then re heat treated to get the T6 strength back. In light of the fact that the damage is in the steering head area it is essential that the repairs are done correctly. Having the front end snap off and your melon driven into terra firma at 50 mph usually has dire consequences.

[dbf498]

From what I understand the Honda frame is made from a 7000 series self hardening aluminum alloy. In the event that it is 6061 T6 the frame will have to be annealed after repairs and then re heat treated to get the T6 strength back. In light of the fact that the damage is in the steering head area it is essential that the repairs are done correctly. Having the front end snap off and your melon driven into terra firma at 50 mph usually has dire consequences.

I couldn't agree more with the past part of your statement. I know all my safety gear will do it's job but if I can avoid doing a real world test I'd like to avoid that...besides...the older we get the longer it takes to heal. I remember a debate on this site and was hoping Bearoso would chime in but he hasn't so far. We'll still do an eddy current and see what the results are. I got a replacement frame but I'd really like to see if the original one can be repaired with decent results.