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Discussion Starter · #1 ·
I'm about to tighten the nuts holding the exhaust down pipe to the cylinder head on my 2002 RD07A. My Haynes manual tells me that the torque setting should be 27nm (or 20 lbft), which strikes me as a bit high considering that I've just done the same job on my CB1300 and the torque setting there was 9 lbft. I'm happy to take Haynes word for it, but before I do, does any forum member have access to an official Honda workshop manual to confirm (or deny!) that 27nm is in fact the correct torque value?

Much obliged for any advice.
 

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Gut feeling says 27 Nm is too high. I've always tightened these flange nuts by 'feel' rather than torque (not unlike installing an oil filter hand tight)
since you are crushing a gasket of variable strength in the process.
I would tighten them evenly until you think you've got a good seal and leave it at that.
Start up the bike and check for leaks.
 

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Hi eddie19.
Just checked my official Honda manual for my RD07A - also quotes 27Nm. I would go with learned member TheSheep above and go with "feel", but would recommend rechecking after, say, 200 miles. Good luck.
 

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Discussion Starter · #4 ·
Have just torqued the downpipe nuts to 27nm. I take the point about "feel", but if I'd done them up to the same feel as my CB1300, they'd have been loose. Only Honda knows why there's a difference, presumably it's something to do with the construction of the exhaust gasket in both cases. Anyway, I have a torque wrench,so I might as well use it. Thanks for the advice.
 

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Have just torqued the downpipe nuts to 27nm. I take the point about "feel", but if I'd done them up to the same feel as my CB1300, they'd have been loose. Only Honda knows why there's a difference, presumably it's something to do with the construction of the exhaust gasket in both cases. Anyway, I have a torque wrench,so I might as well use it. Thanks for the advice.
Hi Eddie19
I think your last statement is unfortunately what I meant by going by "feel" not torque. Several times I've relied on a torque wrench only to see studs pulled out of alloy.
These exhaust studs are in the alloy head - ideally they need to be tightened in the head with more torque than the fixing nuts - or they might unscrew on the next occasion.
Threadlock can help with the studs. These M8 nuts they will in theory take the 27 Nm, question is will your particular bike ?
I normally put copper grease on these nuts as they are prone to rusting - this requires a different torque ...

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Just put the headers back on my RD07a. As stated above, personal choice is not to use a torque wrench for this particular job.
I found access to the nuts restricted with the left nut on the front cylinder being the worst - header and main frame are in the way.
Getting the nut started was hard enough but then to tighten the only solution I found was to drive a socket through a knuckle joint
and a 30 cm extension bar (3/8" drive). Had to turn the nut 1/6 turn at a time and reset socket. There's no way I'd trust a torque setting through such
and indirect drive set-up.
Perhaps the Original Poster or Honda manual can enlighten us all?:toothy8:
 

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Discussion Starter · #9 ·
I persevered with my header nuts and used a (long) 1/4 inch extension on an adapter to fit my 3/8 inch drive torque wrench to get at all the nuts. As you rightly say the left hand front cylinder nut was very awkward and the only way to get direct access was to remove the right hand engine mounting plate. On the plus side, I was able to lightly grease the mounting plate bolts before I replaced them! Each exhaust nut needed a different combination of extension(s) and angle of attack though.
 

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Good to hear I wasn't the only one struggling. I too thought about removing the engine mounting plate but chose to
persevere with my less than optimal solution. Glad you got the job done anyway :thumbup:

All this got me thinking about how the bikes were assembled in the factory? Maybe using your solution ...

Current state of play on my RD07a resto ...

IMG_2243.jpg
 

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Discussion Starter · #11 ·
I've just come in from my garage: my RD07a looks just like yours, right down to the blue restraining straps and the red (invaluable) Clarke(?) hydraulic bench! I'm slightly ahead as I have a silencer fitted.
 

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I persevered with my header nuts and used a (long) 1/4 inch extension on an adapter to fit my 3/8 inch drive torque wrench to get at all the nuts. As you rightly say the left hand front cylinder nut was very awkward and the only way to get direct access was to remove the right hand engine mounting plate. On the plus side, I was able to lightly grease the mounting plate bolts before I replaced them! Each exhaust nut needed a different combination of extension(s) and angle of attack though.
That was exactly my method too - not the easiest of jobs i agree.
 

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I had this issue too when I replaced my OE headers with Arrow headers. Likewise, I removed the RH engine mounting plate and used a long 3/8" wobble bar to remove the nut. I've since found out that the nut can also be removed from the LH side with an angled ring spanner after moving the oil cooler & adjacent rad hose out of the way.
 
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