Exhaust studs
 

I tried to take off the exhaust headers today (trying to fix a backfiring on deceleration problem that has come up in the last few days) to check the gaskets. The first one I tried, I got the old 'bending toffee' feeling, and the stud sheared off just below the nut. I didn't use much force, honest. The clamp is still in place and it's not blowing, so I am going to leave the other three until later.

I expect I am going to have to drill it out. Can this be done with the head still on the bike, or would it be better to take it off and do it on the bench? Any information welcome. Is this a common problem? Bike is 14 years old with 22k miles on it.

If the stud has broken off at the clamp, there will be a bit left protruding from the head. Use lots of "penetrating oil" a good 24hrs before attempting next nuts !

You could try mole grips or a stud extractor, but these methods are only 50:50 sucessful usually :( but worth a try.

Best bet is to weld a nut onto the broken stud & try and remove. The welding super heats the stud and can help to release it.

If they shear flush, the head MUST come off and a pillar drill used to get the buggers out. If they are 6mm studs, first drill a 3mm then up to 4mm or 4.5mm and you should be able to clear out the stud bits remaining.

Last resort (best method) is "spark errosion" but it ain't cheap :eek3:

Good luck :thumbup1:

Thanks Pigford. I haven't touched it since (I need the bike to get to work) but I think there will be something to get hold of, as the break is just below the level of the clamp, not flush with the head. Fingers crossed I can get the others out and tackle it. I'll soak it in Plus Gas every night this week!

Any idea where's good for Yamaha spares? In the light of this breakage, I'd like to replace all four studs, and replace the nuts with brass if possible. I had planned to fit a set of Motad s/s headers soon in any case, so I think I will do it all in one go.

Weld a nut to the stud, if you have little to play with.

Before you try to remove it, heat it up with gas (if not recently welded). Bang it maybe 10 times with a hammer, use an extension if you can’t hit it directly. If it does not move with moderate force, stop and heat/bang it again.

Before I removed my rusty headers i soaked the nuts in penetrating oil (wd40) in the days up to the event. They went right of, no trouble. I replaced them with new ones, as they were allready bought, and greased them with coppercrease just to make sure hey would come of again next time.

Its a '03 but with 70k km on it, and its seen a lot of offroad and winterdriving.

hi there i would soak the other studs/nuts in penetrating oil for a few days, when you are ready to have a go at undoing the 3 good ones as seid tap the nuts /studs . then start with a cold engine , start the engine and let it run for 1-2 minites then stop and try to undo the nuts , the alloy head will heat up faster than the studs and with a bit of luck the stud will unwind from the head or the nut will undo as normal . for the snapped stud if possibal weld a nut on let cool down a few seconds then try to undo, if you carnt weld a nut on clamp some molegrips on and heat the head where the stud is then try to unwind . heat is the key here . when you put the new studs in coppergrease them ,i always use stainless steel nuts ,with coppergrease , every few months undo the nuts re coppergrease and nothing will seize . zigzag

for future reference most cases of deceleration backfires are caused by running lean on the idle jets not anything to do with the exhaust having a leaky seal.

I take your point on the idle mixture. However, this started suddenly - popping in the exhaust one day, full-blown Edinburgh Tattoo bang-fest the next. I hadn't touched the carbs in all of that time, so unless someone had been fiddling with the bike while it was parked, I thought that was unlikely.

Add a rusty set of headers, and an increase in external noise from the front of the engine, and you can see why I went for the exhausts first.

I'll have a check of the idle mixture this weekend - thanks for the tip.

Backfiring could be numerous things... Air leak is favourite (exhaust joint or hole), OR could be a split/cracked manifold carb rubber or a bit of sh*te in the fuel thats part blocking the pilot system....... OR.....

Next its on to the electrics :stormy: dirty plug, loose wire.... etc :confused1:

Always a pain the exhaust studs, especially as they are right in line of fire for the spray off the front wheel :frown:

Why can't manufacturers just spend a few more pence and fit s/s studs at least :rolleyes2:

stainless steel with aluminum = oxidation? i wouldn't bet on it :P

Vando :innocent:

THE POINT OF S/S IN ALLOY IS THAT ONCE FITTED TO THE HEAD - THEY SHOULDN'T NEED TO BE REMOVED. IF PLAIN STEEL NUTS ARE USED, THEY WILL STRIP BEFORE THE STUD AND ITS EASIER TO GET THEM OFF, THAN REMOVE A STRIPPED STUD.
The use of Copperslip with s/s & ally has been proved to reduce oxidation to a negligible effect, even if s/s & ally are at opposite ends of the oxidisation "reaction" scale.

Nickle cote
 

Hi all,
As pointed out, you get electrolisis with these different metals. Copper and Aluminium do not go together!!!

Here in Australia, I use Nickle-cote anti-seize, this does not react with Alu/Stainless steel.

Hope this helps.

Cheers from Oz.

Going back a bit, does anyone know a good source of genuine Yam spares? I'll need to replace at least one stud, and I might as well replace all 4 while I'm at it. Or is easily made up from some threaded rod?

KEDO - Performance Products :)

hi there if you have a nut/bolt stockest near to you see if they can match the stud up , threaded rod or studding as it is called is normally low grade steel unless you ask for high tensile studding . if you are going to go for full thread and not a stud , ask for a hex set screw and cut the hex head off. a good one will be 8.8 strenth dont get one lower than this . the next one up is 10.9 then 12.9, very strong , with stainless nuts on and coppergrease no more seizing should happen. any bike shop should be able to match the stud up if they keep them in stock, honda/suzuki/etc or just order the right ones from your local yamaha dealer . good luck zigzag