Whats causing my header to keep snaping???

[cornerspeed]

Hey guys I have a new problenm now. That is for the second time my left header has cracked and snaped clean off during a ride. Both times the bike sore 6th gear (not red line) speeds (140 kph) but was never opened all the way up. I have just had my valve clearances done. On the photo, the weld at the top was the first crack (it had already been welded) and the new crack is under that weld.
Could I have a valve problem ie. sticking/burnt ????? or is it the vibration of the zorst thats causing it????? Could the bike be running to lean? (mecanic took for ride when valves got done (husky dealer))

The bike is a 570 Husky SMR

Thanks guys....

http://i22.photobucket.com/albums/b344/CornerSPeeD/crackinheader.jpg
http://i22.photobucket.com/albums/b344/CornerSPeeD/crackinheader2.jpg

[cornerspeed]

At least I have some new eyes for it now...:)

http://i22.photobucket.com/albums/b344/CornerSPeeD/IMG_1557.jpg

[Wobbly]

Yikes ... that's an unusual one ... shouldn't be anything to do with valves, at least not unless it's shooting large bits of valve out but by then the bike wouldn't be doing much in the running department anyway :) Seriously, any valve problems are normally manifest in other ways, such as excessive backfiring when throttling down from high rpm, poor starting, etc.

Most likely cause is strain on the header and vibration in combination with the expansion & contraction due to heat. How is the exhaust mounted? Anything strike you as strange with the way it's mounted? Is it the stock header? When putting the exhaust on do you feel you need to strain the pipe to get it to mount properly or does it just fit on easily and then bolt up?

[cornerspeed]

The bike does backfire alot from an open to closed throttle (sounds awesome) but nothing massive. Now that I have found the 'magic' way of starting the thing, it kicks over 1st or 2ed go and no valve bits are flying out of the head hehehehehehehehehe.

I was thinking it could be the stress of the zorst pipe, I will look this arvo weather or not it could be using the header as too much of a support. I do think that the pipe itself DOES rely on the header a fair bit to hold it up so I might have to form a way to take the pressure of it a bit.

The actuall header is the standard Husky item with the zorst pipes and muffler being Barrett.

[Wobbly]

Normally the header is self supporting, but the muffler is held in place solidly so that it only really has to support the weight of the header. Where it could come unstuck is if the mounting of the muffler is a bit misaligned and it puts a directional load on the header. But this would be fairly obvious because you'd have to strain to align the muffler with the mounting holes once you slip it on the header.

The other extreme could also be possible, a lack of tightness of fit between the header and muffler?

[cornerspeed]

hmmmmm yes.... Im thinking it ahs got something to do with the load from the zorst. The muffler is held on at the back and apply no pressure to the pipes nor the header. The pipe however is attached to the header via the zorst springs. SO I am thinking of removing the springs in so as to give a little 'play' where the pipe and the header meet.

Its just weird, it only happens on long rides and not commuting to and fro... and only that one side.... the left. Atleast I think your right about the valves though....... (relief)

Thanks mate.

[agent34]

Thats some wierd stuff going on there Corner speed.
although here is my story, bike running fine at the track, header pipe on Lc4 joining form two to one pipe, one of the header pipes keeps coming out of the join. tap back in, back on track, pipe comes out again, this goes on for the rest of the track day. sounds shit house. looked everywhere, well i though i did anyway, the mechanic found that one of the bolts that you cannot see and is attached to the single pipe system under the seat/ air box area has come out and placing different stresses on the system/ header. New bolt re glue with putty and presto !! no probs with header pipe again.

Bought new very shiny Akro full system, on the Lc4's electric starter the pipe must go over the top of the area. when fitting the pipe this area has minimal clearance,to be precise a bees dick ! actually the way i check it is to get a thin piece of cardboard not your woolies box type thinner like a chinese made cheap import tool packet and slid under, if i cannot get it through then the pipe has moved and the titanium is rubbing on motor - not good for pipe.
Subject to this the fit of the akro system is like a fantastic fit and will not sit properly if something is out of alignment.

Moral to the story: make sure the SYSTEM is balanced and sits free as the manufacture intended. If you interupt the balance then your situation may occur. Although it is a very nasty one indeed.
hope this helps in some way to finding the problem and good luck.

[cornerspeed]

Hey thanks for your story agent.... I'm not the only one then. I will be looking very clos at the whole system when fixed (again). Its an after market Barrett system (pipes and muffler). I'm thinking of actually putting the stock system back on and trying that first. I'll keep you all posted.
Thnks again mate.

[dicky]

If you can fit the original muffler on the headers you might to able to check if thing are aligned properly as Agent did.
Otherwise, loosed everything off and give all the pieps and muffler a bit of a whack, see where they settle, and check clearances and fit, then tighen it all up and check again.
If the bike has been down you might have pushed the muffler out of whack and caused stress on the headers without realising it.

dicky.

[Flash]

One last thing to all the above it you are realy concerned onece the pipe is welded get it heat treated, this will relieve all the stress put in the metal after welding. I used to get all the Turbo manifolds heat treated to prevent cracking!! That was why my manifolds didn't crack and others did.
When you weld, the weld shrinks so if you are welding a section of pipe and it shrinks it puts stress on the surounding metal hence a problem. Not saying it will fix it but it is well worth the exercise as the heat treaters will only charge you a six pack! :up:

[cornerspeed]

Thanks for the feed back guys. Okay, update: I pulled out the stock system and found that on the stock pipes there is a join in the lenth of them. That is, as the pipes run down to the muffler they are connected together by two brackets with a bolt through them both. On the Barrett system there is no such jion therefore the header has all the weight of the pipe hanging of it. SO..... I'm going to fit the stock zorst and take for a long fast ride and see if it breaks again. If not I'll paint the pipes black and polish the std muffler.

thanks again fella's

:)

[cornerspeed]

well I put the standard zorst on and went for a massive ride through Mt Nebo/Glorious and the gap. The header (3xre-welded) didnt snap this time. Sooooooo the magic bracket must be the ticket...............
http://i22.photobucket.com/albums/b344/CornerSPeeD/bracket.jpg

http://i22.photobucket.com/albums/b344/CornerSPeeD/stockZorst.jpg

[dicky]

That's a bloody nice looking bike.

dicky.

[Wobbly]

You're not wrong dicky :up:

[agent34]

I'll, Third that !!