Oops I did it again, she played with my heart, Lifan 140cc

[Blender]

Go for stainless steel studs and nuts if you can, it'll make it alot easier down the track to remove your exhaust. If you have trouble with getting and exhaust stud out, just drown in Inox or WD40 , and get 2 nuts on it and lock them against eachother, then undo the first nut you put on against the 2nd one. Hope that makes sense?

 

[Rikchick]

Go for stainless steel studs and nuts if you can, it'll make it alot easier down the track to remove your exhaust. If you have trouble with getting and exhaust stud out, just drown in Inox or WD40 , and get 2 nuts on it and lock them against eachother, then undo the first nut you put on against the 2nd one. Hope that makes sense?

Yep, thanks heaps! yeah pretty much as I have been getting new bits for this bike, I've been replacing the nuts and bolts with stainless, I'm sure I've even got some stainless M6 1mm nuts somewhere.....

The problems we inherit from 2nd hand bikes, but that's why they only cost us $150 to start with eh?!


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[Blender]

Yeah, whenever i replace a bolt, its always replaced with stainless, only problem is it's a bit softer than mild steel..

 

[my67xr]

not really blender
a high tensile steel bolt, grade 8.8 is the same strength as a high tensile stainless steel bolt grade 316 A4-80

 

[IAMTG]

Heres a table of strength for different fasteners. Note the reference to markings on the right column, where 12.9 is the highest tensile we see commonly, 10.9 the next down and 8.8 the next common one then you see Stainless steel. I agree with you Rikchick and would recommend replacing every nut and bolt on any China bike. I had a bolt that came in my Blitz copy marked 8.8 that had threaded itself when screwed into Aluminium. Source all your bolts from a reputable local supplier.
Tensile Strength Comparison Chart | Anzor Australia, Brisbane

Note that while we all tend to refer to tensile strength, for engineering purposes many fasteners are specified by their yield strength....but thats way beyond our needs or concern.

Here's an exert from the below linked reference, its very good info to clarify what the tensile bolt markings mean.
"There are three grades of bolt in common use in Australia. Most bolts which you will come across will only deviate slightly from these three grades. The lowest grade is 4.6, commonly known as commercial grade. Next comes grade 8.8, known as structural grade, and finally, the highest grade is 12.9, known as high tensile bolts. The first number represents the ultimate tensile strength of the bolt, 400 MPa, 800 MPa or 1200 MPa respectively. The second number represents the point at which the bolt will permanently stretch. (Officially, the 0.2% proof load stress). A 4.6 bolt permanently stretches at 60% of its ultimate, an 8.8 at 80% and a 12.9 at 90 %."

Read the full reference here, if your into technical stuff.
Grades of Bolts

 

[Blender]

not really blender
a high tensile steel bolt, grade 8.8 is the same strength as a high tensile stainless steel bolt grade 316 A4-80

So what about standard stainless against standard mild steel? Would it be the same ?

 

[IAMTG]

According to the table and the exert, standard steel bolts are 4.6, 400MPA. Standard stainless is the 304 or 316 grade which is 520MPA so standard stainless is better than the basic steel bolts. No reson not to replace every bolt with stainless, except where High tensile is used i..e frame /engine/swingarm/axle and fork bolts. My son even snapped a couple of stainless over tightening the fork holders on the tripple clamps.

 

[Blender]

So stainless steel is actually better than standard steel? Never would of thought that! Cheers IAMTG !

 

[my67xr]

most of the china bolts aren't even as good as a 4.6 Grade bolt
when a bolt is made, a 'Standard Bolt' is meant to shear under pressure at the beginning of the threads.
a lot of the broken china bolts that i find have sheared the heads off

 

[stoozo]

most of the china bolts aren't even as good as a 4.6 Grade bolt
when a bolt is made, a 'Standard Bolt' is meant to shear under pressure at the beginning of the threads.
a lot of the broken china bolts that i find have sheared the heads off

I've seen them shear half way,at the top, threaded heads stripped thread half way down...I think the only time ive not replaced stuff with new actual 8.8 or better is when ive only needed 1 bolt and can't be bothered driving 5mins to the auto shop to buy a pack for $4....bolts are super cheap. My local car shop sells stainless marine grade packs too but they're $7ish!

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[Rikchick]

Ok guys, is there anywhere in Australia that I can get stainless steel studs for the exhaust? I want to replace the studs that are on my cylinder head at the moment, as they both came out when I was replacing the gasket anyway.... But can only find 1 seller on eBay that has stainless ones and they're in England.... Any help?


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[Rikchick]

Or can I just get an m6 stainless bolt with a head already attached and blot the exhaust straight into the cylinder head?


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[my67xr]

you could, but might need to use some spring washers to get it to do up tight.

 

[Rikchick]

you could, but might need to use some spring washers to get it to do up tight.

Do u reckon try putting a spring washer either side of the flange?


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[my67xr]

nah just on the outside of the flange, under the bolt head.
but you may need to add a couple if the bolt is too long, or cut the bolt down a bit

 

[Rikchick]

Ok, so I tried a few things today, was trying to put the new copper gasket on, and when I put it on, the flange won't sit flush against the head, the bolt and spring washer seems to work ok without the copper gasket, but as soon as I try to add the gasket it doesn't sit right, any ideas... ??

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[my67xr]

not really sure what you mean there.
is the spring washer sitting into the bolt hole on the flange plate and making it sit at an angle ?

if so, can you run a bigger diameter flat washer and a spring washer?

 

[Rikchick]

No, it's not because of the spring washer and bolt, it's because the copper gasket is pushing the flange out from the head, so it's not creating a tight seal.....

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[my67xr]

the copper washer gets crushed into the recess of the head by the pipe

 

[Rikchick]

Yeah it's not crushing enough.... Maybe I just have to screw down tighter??

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