I have looked at 3 hurricanes recently and all had a crack on the frame in the same place. The crack is on the underside of the main frame rail just in front of the rear motor mount. Any ideas? What do you think causes it? I have stripped one bike down and had the frame welded.

 

picture?

is it a cracked weld or crack in the frame spar?

did you see any dents in the frame near the crack?

what side of the frame are you seeing this at?

are all frames owned by same entity?

i'll go look at both of my frames tonight.

 

i looked on both my frames and i don't see any cracks assuming i'm looking in the same place you are describing. a picture would help.

 

All the bikes were from different owners... the crack is forming on the left side main spar just in front of the guide for the top, rear engine mount. The crack itself extends around the bottom of the spar and it is on the larger of the two frame sections...behind the weld. It looks like a stress crack. There is no obvious damage anywhere else on the frame. The odd part is that the crack has not appeared on the copy I bought new. I aquired two of the bikes very cheap because of the frame damage... I will take a picture and post it so you can see exactly where the crack shows up.

 

this is the repaired frame ... Iwill have to pull the plastic to show the other frame that still has the crack

 

i just looked at my bikes. one of my two '87 frames is cracking in that same spot. its just starting around the outside frame, next to the weld, for the rear engine mount.

 

I have a theory about why they crack and why my original owner bike has not... we all know the high frequency vibration that is transmitted through the bike around 5500 rpm... That engine speed tranlates to 60mph of 100kmh in top gear with stock gearing.My bike has seen redline almost every shift for 20+ years and has not spent a lot of time in that rpm range and the frame is fine... I believe the frames that are cracking are on bikes that have been ridden "gently " and at or near the speed limit and in the high frequency buzz rpm too much. It is just a theory....

 

here is the other frame with the crack visible.

 

second attempt

 

Tripicana, do you know the history of the bike with the crack? Has it been rode hard ... wheelied lots? Babied? Crashed? It would be interesting to know how many other hurricanes have the crack...