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I just put my full Yoshi system on. First time I've ever installed a major modification on any kind of vehicle, so I am pretty proud of myself. :) One question though...

The instructions say to torque the header nuts "according to manufacturer specifications" .. too loose is obviously bad, too tight might ruin the gaskets I'm guessing?

I've tightened all 4 nuts pretty tight and made sure they are all about the same torque, although it's just an estimation on my part. How important is it to have the bolts at an exact torque? Should I be worried about this?
 

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Id say its a big deal if you are not very skilled in this area. I know a guy who can look at a bolt and tell you what size and thread it is. He can also tell you how hard he torque it. the biggest part is the to tight.
 

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I've been turning wrenches for years, but today I bought a torque wrench at sears. Its a dial indicated one that goes from 0 to 175 ft. lbs. and only cost me 25 bucks. I just want to keep everything within manufacture settings to not void the warrenty ( I got the extended one).
 

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I think I'll go grab one tomorrow and redo the bolts if they are that cheap! On that note, does anyone actually know Kawasaki's specifications on this? Still waiting on that service manual from eBay. :(
 

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Exhaust Pipe Holder Nuts: 12 N-m, 106 in-lb (8.8 ft-lb)
Exhaust Pipe Mounting Bolt: 20 N-m, 15 ft-lb

That's pretty light. Some torque wrenches won't even go that low.
 

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I just put my full Yoshi system on. First time I've ever installed a major modification on any kind of vehicle, so I am pretty proud of myself. :) One question though...

The instructions say to torque the header nuts "according to manufacturer specifications" .. too loose is obviously bad, too tight might ruin the gaskets I'm guessing?

I've tightened all 4 nuts pretty tight and made sure they are all about the same torque, although it's just an estimation on my part. How important is it to have the bolts at an exact torque? Should I be worried about this?
Pics please, I have one of these systems coming and would love to see some on bike photos. Just to tide me over till mine gets here....:eek:
 

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Discussion Starter #8
Thanks for all the useful info everyone! I loosened the nuts and will hit 'em again tomorrow with the right tool. Here's some crappy cell phone pics! :D
 

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A couple good torque wrenches is always an invaluable tool if you are going to be doing your own wrenching. I would recommend a click type torque wrench instead of a dial torque wrench. With the click type you set the specified torque and then just apply even tightening pressure till the wrench "clicks." That's it. Most dial types require you to tighten and monitor the gauge at the same time to ensure you aren't over torquing and doing both can be a pain in the ass sometimes. The click micrometer type though generally costs more but is much easier to use and more fool-proof.

The pipes look awesome and congrats on the upgrade.
 

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For that level of torque, and for 6mm bolts, I just use a T handle or socket wrench and hold it with the point of rotation in my hand, then a firm snug. 2 finger on either side of the P.O.R.

You shouldn't be able to over tighten it like that, unless you really set your mind to it and concentrate! :eek:
 

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Love that yoshi system / me next!

For that level of torque, and for 6mm bolts, I just use a T handle or socket wrench and hold it with the point of rotation in my hand, then a firm snug. 2 finger on either side of the P.O.R.

You shouldn't be able to over tighten it like that, unless you really set your mind to it and concentrate! :eek:
He's right, the bolts/studs are 6 mm, so the nuts should be tightened with either a 10 mm wrench or 3/8" drive with 10 mm 6-point socket on the end. You've already snugged them down, ride it and then see if you can snug them any more, sometimes they'll turn another 1/4 rotation; then you shouldn't have to check very often. I checked mine on my 300 when new and again at 200 miles, at which point they took 1/8-1/4 turn.
 

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He's right, the bolts/studs are 6 mm, so the nuts should be tightened with either a 10 mm wrench or 3/8" drive with 10 mm 6-point socket on the end. You've already snugged them down, ride it and then see if you can snug them any more, sometimes they'll turn another 1/4 rotation; then you shouldn't have to check very often. I checked mine on my 300 when new and again at 200 miles, at which point they took 1/8-1/4 turn.
Some times even if it'll turn some more, doesn't mean you should turn it. I have been using torque wrenches for years as an aircraft crew chief and will not torque something with a set described torque setting without using a calibrated torque wrench. There have been many cases where I torqued something down with a torque wrench and still felt I could still go further if I wanted to. That little bit extra "give" quarter turn could be you crushing a frame tube or gutting a nut plate.

If I were you I would find someone with a torque wrench in the needed ranges and break those bolts and re-tighten them to proper spec. You may not have damaged anything short term, but over torquing that nut could have long term structural ramifications later on. There is a chance nothing bad could happen, but why take a chance if you don't have to? If you torque the bolt properly every time you wont have to worry about hardware failure down the line.
 

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Discussion Starter #15
Great info, thanks guys! :)

I picked up the dial-type torque wrench today and redid all the header bolts. I studied the needle carefully and made sure they were all as accurate as I could get 'em... which really isn't tight at all, as Delta pointed out already. I'd be a little worried, but I remember the bolts actually weren't very tight originally when I removed them.. I will at least make sure they are snug next time I get through riding it.
 

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Great info, thanks guys! :)

I picked up the dial-type torque wrench today and redid all the header bolts. I studied the needle carefully and made sure they were all as accurate as I could get 'em... which really isn't tight at all, as Delta pointed out already. I'd be a little worried, but I remember the bolts actually weren't very tight originally when I removed them.. I will at least make sure they are snug next time I get through riding it.
Remember, when you recheck torque on a nut or bolt, you cannot just throw the torque wrench on there and check. You gotta break torque then re-torque to spec. Many repeated checks without breaking torque has the effect of slowly over torquing the nut/bolt over time.
 

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It's good practice to torque back to spec. For most bolts, "nice and tight" is probably good enough. The only place I think you can get into trouble is if you over torque a bolt that goes into something soft like aluminum. If you are doing something like internal engine work, proper torque is a must.
 
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