I have a 2001 Sportster 883 with a 1200 conversion done. When the conversion was done it was done at the local dealer with screaming eagle heads, carb, and a fairly large cam about 7000 miles ago. The bike, and the stock header pipe, had about 11000 miles at the time of the break. I rode from Fort Riley to Oklahoma and back in one day about 500 miles, the high temp for the day was about 80. I was wearing earplugs the whole trip so I don't know exactely when it broke, but when I stopped to fuel up just before my house I left the ear plugs out for the last few miles and the bike was louder than normal. I got home and saw that the header pipe on the rear jug was broken in two places and the only thing holding it together was the hose clamps on the heat shield. It might have been cracked before I left, it was under the heat shield so I probably wouldn't have noticed a small crack but it was definately not broken when I left. I ordered a set of Vance and Hines pipes for it now, it finally gave me an excuse to get the ones I've been wanting but didn't want to spend the money on them. Has anyone ever heard of this happening? The bike does run a little hotter now since the conversion and I'm guessing it runs hotter than a stock 1200, but it doesn't seem to be any hotter than my dad's 07 night train, and it's definately cooler than my 110 on my SE Springer. The bike's never sat out over night, dried after every rain and has only been ridden in the cold (below 30) a few times. Any ideas what caused this, or maybe I just had a bad weld that finally let go?

 

OMG, that's a big one. I haven't seen anything like that, did you check the rear spark plug? It could be running lean and the head pipe turned red. It could also be a small crack and extended time after time. Just my thought.....

 

No I haven't checked the plug. Never even thought about that. If it's lean it'll be white, running good should be a tan color, right? I've pulled in at night after a long ride before and the pipe's never glowed red though.

 

As you know metal heating and cooling, heating a cooling, expanding and contracting, expanding and contracting, sooner or later wears it out. And the welds are often surely the easiest place for fatigue failure.

Bike pipes get hotter than auto headers, so they are subject to greater stresses. They could have also been cheaper headers to boot, with thinner pipe metal, thus making them easier to wear out and fail. It also looks like it broke at a bent area of the pipe, which is usually thinner than straighter areas, and thus weaker.

Do you drive a lot of short trips? this type of driving will wear pipes out faster as well, as the metal heats and cools, expands and contracts more.

 

Not too many really short trips, but quite a few in the 40-60 mile range in the summer, just a short cruise after work if I get home early enough.

 

BTW, that crossover area also probably gets hotter there, seeing how the gasses are somewhat impeded from flowing as smooth through that area. I know that crossovers produce greaterback pressure, and this would mean they impede the movement of gasses, thus leaving the heat trapped in that area longer and able to build up more heatin that area.

 

I'd say it was a stress/heat related crack...

Right there at the cross-over pipe I would think would be as likely place as any...

You have to remember there is a lot of vibration going on...

I personally never heard of it being a problem... but then again I'm sure it happened to more than just you...

Now get those V&H on and clean that dam_ engine...

Charlie D.