missing bolt on muffler tao tao with pic  By  brandon667 (Read 9,098 times)

Thats your Exhaust Stud, A Nut goes on it is 6mm
They Love to Vibrate loose, Most Likely Leaking Exhaust now.
Be Careful Not to Over tighten as you Will Break the Fragile Undersized Stud.
A Lock-Nut will Work Beter than a Nut with a Washer and Lock Washer.

You Use a 10MM Wrench or Socket ,That Has Nothing to Do with The Stud/Thread Size. In Any language.
You Contradicted yourself there. as in What Wrench you use then it doesn't matter? huh?
If he goes to the "Nut Store" and Buys a 10MM Nut it will be Too Big.
He needs to get a 6mm Nut and Appropriate Lock/Washers.
This is Sold By the BAG for the GY-6 in E-bay

I have Seen some 8mm Stud Up-Grades because this is a Weak Link. But OE should be 6mm

I have plenty of heads, no 6mm bolt fits them... Unless I am misunderstanding you you are saying 6mm threads work with the exhaust threads, but the stud themselves have 8m threads when checking them at lowes. They do not fit past the first turn on the 6mm slot and even then it strips part of the stud getting it in there...

Either way the best thing for  brandon667 to do is go back to lowe's, bring the extra nut he has, fit them to the measurement plaque thing, and buy new nuts and a couple crusher rings like that come stock. Maybe his are different, what works for % of people may not work for 100% of people... 

they are 6mm, here is a kit I put together it sells great.

John

ON MEASURING NUTS AND BOLTS:

Just to clarify, because all of this talk of measuring and carpenter's tools is confusing me, and I assume it will confuse others, and since I've done a a little work with threads, I'll lay it out for the layman. This is useful because you can't always take a bolt with you to the store.

That is a machinist's tool called a caliper, or calipers. Its not just for machinists but it's a standard machinist's tool and can measure inside, outside, depth, and step measurements on 8 different surfaces.

Threads are measured by two things, diameter and "pitch" or the distance between the threads. (There's more to threads but this is all you need to buy most bolts and nuts.) A 6mm x 1.0 means 6mm outside diameter, and 1.0 mm between threads.

Obviously a 6mm x 1.0 bolt won't fit with a 6mm 0.75 nut. Because it would be difficult to measure the difference between a 0.75 and a 1.0 thread directly, it's easier to measure several threads and divide that measurement by the number of threads. i.e. count 10 threads, measure that distance, then divide the measurement by 10. If the disatance between the tops of ten threads is 10mm, then you have a 10/10=1.0mm pitch. If it were a 0.75 pitch, ten threads would measure 7.5mm.

To measure a nut, use a bolt that works in it and figure the size and pitch of that bolt, or use a thread gauge, or do it manually as above, which is generally difficult to do, but can be done in a pinch. I think standard sizes for a 6mm are 1.0 and 0.75, and for an 8mm bolt the standard sizes are 1.0 and 1.25. The good news is that the size of the hole in the nut will be approximately the diameter of the bolt - the pitch, so a 6mm x 1.0 nut should have an inside diameter of about 5mm.

The reason measuring is useful is because sometimes you can't take a bolt with you, or because the nut or bolt threads are damaged and won't fit the correct bolt or nut they belong with. If you force them into the gauges at the stores you could damage the gauge or the fastener you have.

If anyone would like for me to do a write up on it and post it somewhere I'll be glad to, along with diagrams and pictures. It makes figuring out the sizes easy and also is good for tapping and dieing threads. I may have even done one already, I don't recall. I'll also cover inch size nuts and bolts as well.

The Above is Correct. ALL 50-150 will be 6mm, The Upgrade for the Problem is 8mm, Many 150 Big Valve Heads come With 8mm Studs. pic is coming
Here is a Fake Hot Rod Head with 8mm Studs.

Yeppers, my stock 125cc came with 6mm, the big valve head upgrade came with 8mm.