Stripped Exhaust Threads

I have a 75 Z1B with the bolt holes in the head stripped. What would be the best thing to do with this? I have tried to tap with the same thread but it was a no go. Only a few bolt holes are stripped. I have now had 2 bolts fall out going down the road. The first time I noticed because I could here an exhaust leak. This time the seal is holding up and no leak. Should I take it to a machine shop and have them look at a solution or is this something an average mechanic can do at home?

What I thought would be my next option is to drill out threads tap for a different size and use a bigger bolt but I do not know if the aluminum head can take that. Could this be a possibility (seems like an easy task for me to do...)?

I'd call around at machine shops and get some prices for Heli-Coils or Time-Serts: www.timesert.com/html/mtrcsert.html

Ask at the bike shops who they trust for this kind of work.

let me save you time and money bro!

i bought the time sert kit
first kit was wrong i needed
the big serts for my exhaust studs
as they had been heli coiled 19 yrs earlier
and lost their thread again. :dry:



i spent $80 bucks on each kit
and as i was drilling the first hole i chipped out half the side, :blush: sat down had a beer!

in the end after good advise from fellow members
i took the motor out, :S

and had 2 holes welded up and re tapped by a welder
cost me $200 for the guy to do it and unless you looked real close you could never tell,

on the plus side i had motor pressure washed and blasted
while it was out, all ready for a fresh coat of paint.

its the only way to go get it welded up and re tapped..

I do not know how I forgot about helicoils. My school has a set and so does my dad. I guess I will probably do that because lets face it $200 is a lot. I will probably do something different like kano said when I rebuild the engine. I just do not want to be out of service that long. I just need it to last till this years winter or next years winter. That is when I plan to rebuild my engine on this bike and another bike.

Or another question. Should I worry about an exhaust leak if it does occur? I mean it is just an unwanted noise or is it more than that?

Fresh exhaust crush gaskets will end your worry. www.z1enterprises.com can get the Suzuki ones that are a little thicker than the Kawasaki's.

Z1~KZ900 used 6mm exhaust studs.
1977 KZ1000 changed to 8mm exhaust studs, which then continued as the norm.

Perhaps there's enough metal to re-tap for the larger 8mm studs.

Z1E carries both sizes.
Click here for link to > 8mm exhaust studs from Z1E

It would be okay to keep using the 6mm studs that aren't stripped.

Good Luck!

Edit -- with any re-threading, be careful about the depth so as not to penetrate an oil passage. Just go same depth as oem hole, and no deeper.

O I forgot to mention it is not a stock exhaust. There are no studs. It is a 4 into 1 but I have no idea what one it is. I just use 6mm screws. Should I put studs back into it?

Am thinking MaKaw used studs (not bolts) for good reason.

Seems that steel bolt being frequently torqued into and out of aluminum threads adds more risk toward stripping soft aluminum threads.

Whereas a semi-permanent steel stud implanted in an aluminum base thereafter involves a steel nut on a steel stud without much stress on the aluminum base.

Same reason for cylinder studs and head nuts instead of long bolts through head and cylinders into aluminum cases. It's with steel bolts screwing into aluminum where problems often occur, such as cam cap bolts so readily stripping the aluminum head threads.

Imo, using bolts (instead of studs) to attach the headers is asking for trouble, some of which is now being experienced. :pinch:

Good Luck!

I'm with Patton on this. In fact, some PO of my bike had used bolts in place of studs, and I ended up with a couple of stripped holes. By replacing the bolts with studs I was able to screw them all the way into the head in the stripped holes and avoid any repairs to the threads at all. That might work for you too.

can try one more thing...

The z1 and kz900 exhaust studs are 6mm... Yours is stripped.
Tap the holes for 8mm studs and replace...

RedLine Cycle has the studs just for this... Hell, you ccan probably get some grade 8 studs at any automotive parts store for that matter or ACE hardware..

Just a thought...

OMR

redlinecycle.com/flanges2.html

you may be able to do one of the above fixes by either a longer threaded stud or trying to insert a coil......i am another member who wasted time=$...and a good chunk of real $....by spemding ten on this and 18 on this and 23 on that and 5 on this ...ect.....ect...
in the end it all sucked way hard.....i decided to pull the motor....1 hr.....and threw it in a wheelbarrel and sprayed gunk-engine brite and a lot of pressure washing...it was the ticket...then threw it on a big towel in my beater civic,,,,took it to a local welder with references...he used to have 500 triple turns out.....he welded the holes closed and re-set my studs......1 hr to drop the motor in and now i can tighten my header sweet,,,,,,imo....this is the only way.....everything else is a shot at best....100$ is what my guy got for it.....plus i now have a good welder dude to go to....good luck.....let us know like kano and i did when repaired....thanks craig

p.s i don't miss the welders 100 one bit...i was however stressing for two weeks back then though....100 was easy compared to having no bikey to rickey

Z1Enterprises.com has exhaust studs.