Exhaust rear header pipes issue

Hi all

I'm a VFR800 Fi X owner in the UK. I've had this bike just over a year now and love it!

However, over the last few weeks the bike has started backfiring when decelerating and coming down the gears, usually ending in a loud bang in 2nd. On the advice of another rider I checked the exhaust pipes for a leak. The original pipes have been replaced with a stainless system at some point in the past, which is in good condition, and the silencer is a genuine Honda part (HM MBG E1) - no problems there. However, on closer inspection I found that all 4 nuts that should be holding the rear header pipes to the head are missing, leaving the collars rattling around freely!!! The studs are still in place. I don't know whether the nuts have worked loose, one by one over time, or whether the last guy who serviced the bike forgot to replace them after work!

My question is, will it be sufficient to just resecure the pipes with new nuts, or is it likely that, after several hundred miles of riding recently, the vibration and free movement of the header pipes may have damaged the copper gaskets to the point where they should really be replaced? If so, presumably I will need to replace the front gaskets too and all the seals between joints in the exhaust system, with something like this: http://www.ebay.co.uk/itm/HONDA-VFR800-EXHAUST-GASKET-SET-COMPLETE-VFR-800-98-99-/380932273883

Is there a chance that this could also be the cause of another problem I've been getting over the last few months where the engine starts sounding more like a twin when riding in the rain?! I thought it might be an electrical fault, maybe HT coils/leads, but now I wonder if this is all tied in with the exhaust issue.

Thanks for any advice you can offer!

 

The exhaust gaskets are designed to crush and conform to the angles between the headers and the heads. If the headers have been rattling around, then they have lost their ability to conform. Gaskets are cheap, but a lot of work to replace, especially rear two. Make sure pipes are properly aligned, snug them down a little at a time before final tightening.

 

+1 for the above. Might be an idea to get a friend to help because it's hard to do with just two hands! While you're replacing the gaskets and the nuts, consider replacing the studs themselves - as long as they come out - with stainless steel good quality ones. Careful though, it's not unknown for them to snap halfway in or halfway out, and then you'll know the true meaning of the word nightmare! Good luck with it.

PS. Whereabouts in the UK are you?

 

I don't know about your year, but I needed an assortment of extensions and swivel adapters to get a good angle on the rear nuts on my '83. Definitely requires take rear wheel off. Frustrating job.

 

Thanks for the help guys. I've decided to go the whole hog and replace the gaskets, seals and studs. I've removed the rear wheel, hugger, silencer and fairings this evening and ordered the parts. Will update on progress! Cheers

(BTW - yellow99, I'm near Southampton)