Broken exhaust stud - Buddy 150

theralchico · Post by **theralchico** » Fri Sep 06, 2019 1:14 pm

I broke one of the mounting studs for the exhaust where it connects to the engine. Anyone ever replace that before? What size tap do I need and where I can get a replacement stud? I tried looking through all the threads but couldn't find one that discusses this repair

Stanza · Post by **Stanza** » Fri Sep 06, 2019 3:14 pm

If memory serves, it's an M6 stud, and you can either get one from the hardware store (some carry automotive studs), or you can just use a bolt in place of the stud/nut.

babblefish · Post by **babblefish** » Sun Sep 08, 2019 2:44 am

Stanza is correct, it is a 6mm stud/nut. You can find them on eBay for next to nothing by searching for "gy6 exhaust studs".

Is it broken off leaving a piece of the stud in the head or did it loosen up and fall off? If broken off flush to the head then you'll probably need a screw extractor. If broken off leaving a short portion sticking out of the head then you might be able to grab it with pliers and unscrew it. I've gotten broken studs out that were flush with the surface by using a sharp punch and a hammer to slowly rotate the stud around enough to grab it with pliers. I've also used a Dremel tool with a cut-off wheel to cut a slot on the end of a broken off screw so that I can use a blade type screwdriver to remove the broken piece. You'll end up cutting into the head a little bit but that shouldn't hurt anything as long as you don't go too deep.

PNWbuddy · Post by **PNWbuddy** » Sun Sep 08, 2019 4:35 am

Be sure to measure the studs yourself. My Buddy 125 has 8mm exhaust studs as does the NCY big valve head that I just got. There are lots of sources including Amazon.

babblefish · Post by **babblefish** » Sun Sep 08, 2019 9:34 am

Not saying you're wrong but the only 8mm exhaust studs I've seen are for performance heads such as NCY and Taida. You must have a very unusual engine.

PNWbuddy · Post by **PNWbuddy** » Sun Sep 08, 2019 2:59 pm

Have you measured the exhaust stud on your Buddy or are you going on that generic GY6 Ebay listing? There is a lot of GY6 variety among various scooter brands.

tenders · Post by **tenders** » Sun Sep 08, 2019 3:46 pm

Presumably the stud broke because it is corroded and frozen into the head. The more you rub the lamp with improvised attempts to exert force where the original design failed, the less likely that genie stub is to pop out. I am not one to walk away from most DIY projects but in this case I would get pro tooling and expertise on that stub early before anything else is drilled, cut, or snapped off in vain.

To elaborate on what that picture shows: upper left, tall acorn-style nuts holding the exhaust onto the studs. Middle right, obviously, the studs, all threads of which should be liberally coated with antiseize before installation to try to prevent this situation in the future. Lower left, the chintzy o-shaped version of the exhaust gasket. Better gaskets than this exist which are held in place by the exhaust studs.

(As an aside, my Buddy 50 also has 6mm exhaust studs, but my Vespa 150 has 7mm studs. Apparently the Piaggio engineers were on vacation when all the other engineers in the world got together and decided never to use 7mm fasteners, because they are almost unheard of. They donâ€™t seem to shear very often, but neither do the Buddy 6mm studs.)

PNWbuddy · Post by **PNWbuddy** » Sun Sep 08, 2019 6:51 pm

Edgar Allan Poe:
"Believe Nothing You Hear, and Only One Half That You See"

Check yours before ordering one.

I'm not convinced that I have some unique cylinder head. Although possible, it seems unlikely that the prior owner had the head drilled and tapped for larger studs (he had all service done professionally and I have all of the old receipts).

I gave mine a second look and indeed both the stock 125 head as well as the new NCY big valve head have 8mm exhaust studs.

Here are a couple pictures with the nut removed from the stock head stud (12mm socket, M8 nut) and put on 8mm stud of NCY head.

OP: I'm curious where your stud broke off, it would make a difference in how it could be removed. if you want attach a picture to your post.

babblefish · Post by **babblefish** » Tue Sep 10, 2019 3:57 am

OK, just for accuracy (on my part) I decided to check the exhaust studs on my Buddy and Blur. PNWbuddy is absolutely correct, they are 8mm. I stand corrected. That's the last time I trust eBay...lol
I'm guessing the 6mm studs are used in 50cc engines or really cheap China made scooters.

Stanza · Post by **Stanza** » Tue Sep 10, 2019 1:18 pm

Stanza wrote:If memory serves, it's an M6 stud, and you can either get one from the hardware store (some carry automotive studs), or you can just use a bolt in place of the stud/nut.

Memory did NOT serve! Ha, I also stand corrected.