Broken / Frozen Exhaust Flange Bolts

[buickyouth]

At Least I think that's what they're called.
(the double threaded bolts that attach the exhaust headers to the engine block)
I'm putting a stock exhaust back on my bike and all these bolts are corroded horribly.
I tried to remove the nuts to release the exhaust headers this afternoon.
Most of the nuts were frozen to the bolts and pulled the bolts out of the engine block or snapped the bolts.
Out of the 6 I had 4 still stuck in the block.
I got one out by putting 2 nuts on the stem tightening them together to get enough torque to break the bolt loose and pull it out. For the remaining three the threads that are left are too damaged to repeat the double bolt pull.

My questions are:
1. Does anyone have any tricks to removing these damaged bolts from the engine block?

2. Does anyone know the specs on or know where to get replacement bolts and the hex nuts that were used with the stock exhaust flanges?

Any help would be greatly appreciated.

Thanks a lot.

Ian

[buickyouth]

Here are a couple pictures of the troublesome bolts prior to me attempting to remove them.

[Bubba1954]

You can try to use a set of Visegrips to unscrew the studs, once you can get a grip on each one. It would be best to first heet up the cylinder heads around the studs to loosen them so that they can be unscrewed from the head. You may need to saw off the pipes just to access the studs with the Visegrip.

You can probably find new studs, nuts and gaskets at PowersportsPro (Partsfich) or at Bike Bandit. I bought new set of gaskets from them.

http://www.powersportspro.com/

http://www.bikebandit.com/partsbandit/Default.asp

Bubba

[randy]

Before you go and order the same old steel studs, think about stainless hardware. For a few dollars more, you can replace them all with hardware that will never rust.

The studs are M8 x 12 mm long. The nuts are M8. Don't forget to use lockwashers.








HTH

[TopCatGr58]

Hey Randy,

I was wondering about your length statement, don't you mean that the part that sticks out of the engine is 12mm long, and that the overall length should be around 25-30mm??

Checked Bike Bandit, looks like it's an M-8 and only 15mm long!

15: BOLT, STUD
(M8-15L#02749~)

Also, Buick, apply liberal amounts of penetrating oil around them, and bang on the ends with a hammer to shock the studs, allows the oil to possibly penetrate better, along with then heating up the head around the stud. You could also try a Dremmel grinding bit to grind a couple of opposing flat edges/surfaces into the studs to allow wrench, vice grips, pipe wrench a better grip than just the round surface.

If you have access to a welder, you could tack a nut onto the ends of the studs?? Many options to try! Good Luck!
T.C.

[buickyouth]

Bolt Stud Specs

The one bolt that I was able to remove that came out clean and without the nut looked factory to me. It was one with very little corrosion and I have determined the following specs.

• M8
• 1.25 pitch
• 45mm overall length
• 3 increments of 15mm

like this --> //////====//////

Materials: I have decided that the bolts should either be stainless or chromed for the aforementioned weather protection.

My options are to either have these exact bolts machined somewhere, or lop the heads off of a few bolts that meet most of the specs above.

The one thing that I'd lose would be the threadless 15mm section in the center of the bolt. I'm not sure how much of a big deal this is. The only thing I could see being a factor is that the header flanges might not be able to move as freely and might get hung up on some of the center threads. Which might compromise the seal or the integrity of the bolt. How much of an issue does everyone think this is?

Topping it off, I was thinking of using acorn nuts instead of regular ones. I think this would help keep the elements out of this area. Chrome ones too might be the way to go for the same weather resistant properties.

[randy]

T.C.

The 12mm I got from Yamaha fiche, you're right, thinking it through the part # describes the length of the threaded end, so Buickyouth got it right. Sorry about that.

IIRC, the specials and the standards have different lengths? I seem to recall a thread here about that.

And, I did use the acorn nuts on mine if you look close, they look pretty good.

They are also known as CROWN nuts from some suppliers.

[randy]

Here's a twist for you, on the Yammie fiche the flange studs are listed as:

78E - 25mm

79F- 25mm AND 15mm ?? - what's up with that?

79SF - 15mm

80 and up - no length listed in the part#

So go figure, pull one and measure is the only way!

[chevy45412001]

bolts

What about just a regular bolt. No stud? i'm also thinking stainless is the way to go. Even chrome will eventualy go bad XSpecally near that much heat and road crud.

[skids]

Re: bolts

I have one xs11 that has knurled nuts with allen-type centers. They are trouble where you can't get straight-in clearance for an allen socket. I also have two xs11's that have (or had) a regular bolt instead of a stud for the header behind the number 3 pipe, if I remember the location correctly. It makes it real handy to get a wrench on it from the sides. Therefore, Yes...you can use a bolt. I use "never sieze" when I install plugs, and I used it for head studs also, but I don't really know if it cooks away or not.

Originally posted by chevy45412001
What about just a regular bolt. No stud? i'm also thinking stainless is the way to go. Even chrome will eventualy go bad XSpecally near that much heat and road crud.

[TopCatGr58]

Hey BuickYouth, and Chevy,

With it threaded the whole way, from removing and then refitting attaching nuts later on, the nuts could get hung/stuck on the threaded shafts, and then cause you to overtighten the shafts further into the engine more than they would go with the NON threaded section. This could possibly cause damage to the head.

As for using just bolts, removing and then retightening them could cause more wear on the threads in the head, and they are softer aluminum. And again concern that you could keep tightening the bolts further into the head than desired!?

So...Buick, you may want to apply some stud thread lock when putting new ones in especially if they are fully threaded, to prevent them from getting tightened further into the head beyond their seat/stop point!

[fredintoon]

dead studs

Hi Ian,
judging by the photos, those studs are toast. They need removal and binning. The hard part is getting them out without wrecking the threads in the cylinder head. Can you get a nut splitter onto those nuts? You don't want those particular nuts any more, you just want them gone so you can remove the pipes to get a vise-grip onto the studs to remove them also. Once the old rusted studs are gone, fit new ones. Using acorn nuts not only looks nice, they also stop the threaded end of the stud from going rusty and jamming the nut on there.
Fred Hill, S'toon.

[buickyouth]

The pipes are off.
All but three studs remain in the block.
I'm at my dad's borrowing a dremmel tool to grind flat spots on the bolts remaining to give the vise grips better purchase on them. Man, I hope the dude I bought the bike from didn't use the red thread lock.

As for the replacement hardware...
I've got all the studs. (NAPA had em) They're grade five steel. Wish I could find stainless, but they'll do for now. And a bottle of BLUE thread lock. Its a removable kind that is more of an anti-vibration thing.

The acorns and lock washers are stainless and I got them.

All I'm waiting and hoping for is the removal of the last three studs.

More on this story as it unfolds.

[rneal55555]

If you wanna take a trip to one of my favorite places take a look at these.
Of course you could just go and get a really nice pair of vice grips

http://www.sears.com/sr/javasr/produ...id=00904458000

or

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=00 946338000

[Bubba1954]

Damn,

Thats a tool worth its weight in Gold!

My Craftsman Roll Around Tool Chest is saying; Feed me!

Bubba