All about the Torque

[Sidewinder Jerry]

Tell me if I am right here... it looks like M8... which is what my mounting bolts are... at class 10.9... come in at 26 ft/lbs... or 24 ft/lbs... depending on if they are fine threads or not. I 'think' they are standard pitch... right? So 24 ft/lbs... but then why is the head coming in at 12 ft/lbs when those rods are also M8... right?

EDIT: Hell, those are LUBRACATED numbers... seems 10.9 comes in at 35 fine and 32 standard with non lube...

I believe you on the money with it. Remember this is the max torque for that bolt. If the block is aluminum look up max torque for cast aluminum holes in that size. I'd play it a little safe and go with 20 ft/lbs max.

 

[FrizzleFried]

...but what about my question re: the 12 ft/lbs for the head. Why is that so low vs what is on the chart? I worry about taking the mounting brackets to the 32 ft/lbs ... and it pull out of the block. LOGIC would dictate that if the head is as 12 ft/lbs, I should stick to 12 ft/lbs for anything going in to the chinese block... no?

 

[Sidewinder Jerry]

...but what about my question re: the 12 ft/lbs for the head. Why is that so low vs what is on the chart? I worry about taking the mounting brackets to the 32 ft/lbs ... and it pull out of the block. LOGIC would dictate that if the head is as 12 ft/lbs, I should stick to 12 ft/lbs for anything going in to the chinese block... no?

You're probably right in that the block being cast aluminum couldn't go beyond that.

 

[FrizzleFried]

Found this tidbit online...

As a general rule, 6mm goes to about 60inch/pounds, 8mm goes to 120inch/pounds.

These are guides for the cheap chinese metal though and replacing with better stuff will allow higher values.

60 inch/pounds would be 5 ft/pounds and 8mm is double that... 10 ft/pounds...

I'd guess with the higher quality hardware that 12 ft/lbs is spot on for any M8 hardware going in to the block. M6 hardware (exhaust I believe) ... would be half that (based on logical estimations) ... 6 ft/lbs...

 

[Sidewinder Jerry]

Found this tidbit online...



60 inch/pounds would be 5 ft/pounds and 8mm is double that... 10 ft/pounds...

I'd guess with the higher quality hardware that 12 ft/lbs is spot on for any M8 hardware going in to the block. M6 hardware (exhaust I believe) ... would be half that (based on logical estimations) ... 6 ft/lbs...

Yeah, it isn't like the good old days when most engine stuff was made of steel and/or cast iron lol

 

[FrizzleFried]

I imagine the weight of a cast iron block wouldn't be worth the benefit...

 

[Sidewinder Jerry]

I imagine the weight of a cast iron block wouldn't be worth the benefit...

Steel would probably be nice just expensive.

 

[Wrench]

Basics
Metric ...............USA
Grade 5 = Grade 2
Grade 8.8 = Grade 5
Grade 10.9 = Grade 8
All stainless steel usually = Grade 5 USA

 

[Wrench]

Being (likely) over-careful about these chinese motors... what do you guys torque things on your bike down to? Do you use a torque wrench or just feel it out? I'm a big guy and have the ability to but some serious foot/pounds in to the wrench... which means I have a knack for over-tightening things.

Maybe y'all can give your opinions on these things... I'll put what I've done and see just how "off" I am...

Head bolts: 12 foot/pounds
Axle bolts: I torque them down pretty damn good... but still not nearly my maximum. I am afraid my maximum torque would simply torque off the damn bolts. I've actually broken a friggin VW rim bolt torquing it down... not fun. I'd love to know a good "official" torque to aim for.
Exhaust bolts: Using the smallest driver I have I really do not put a bunch of torque in to these. I'm afraid of breaking off the stud... no good.
Mounting bolts: These are what I'd love to know what people torque their down to. My brother really cranks on his... but I gotta admit, I'm so damn nervous of breaking off a stud I probably don't crank mine down enough. Is there an 'official' torque I can aim for?
Misc bolts: Rim brake bolts... I crank mine down pretty hard. Still not my max (nothing gets my max on the bike, actually). How about disc brake bolts (I don't have `em yet, but soon)... etc... etc..

Did I miss anything? Sometimes it's a pain in the ass being a rather large guy... I tend to be "all thumbs" when it comes to more exact things. Any/all help would be greatly appreciated.

You need an inch lb torque wench for working on your 2 stroke M/B
You would be surprised at how little bit it takes to tighten stuff to 12 ft lbs or 7 ft lbs

 

[Axl Myk]

I use a TW for the head, tightening in an X pattern in 3-4 steps.
Everything else is tightened without.