Honda NT650 "Deauville" - Stainless Steel Exhaust Pipe Renovation

This page shows you how to renovate a used stainless steel component, in this case a complete aftermarket exhaust system.

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Tools : Steel polishing kit comprising (all wheels and mops size 4" x 1/2") ; 2 wire wheels; 1 sisal polishing mop; 1 colour stitch polishing mop; Tapered mandrel; Vienna lime (not esential as detergent will do); Polishing compounds (black and pink); eye protection; plus ... plenty of time!

 Words and Pictures : Posi. Web editor : Rob Davis

I decided to buy a very mucky Predator stainless steel exhaust on Ebay, which was a few years old, as I could not afford the system new at £451.	http://predatormotorsport.co.uk/Honda-NT650-Deauville-Predator-s-s-system-new/ These are the ebay pics:
The seller, at my request, cleaned a small part to show that there was a gem hidden beneath the corrosion, discolouration and melted plastic. This gave me sufficient optimism to bid and I got it for £50.
METHOD First task was to get back to the bare metal and I tried a solution supposed to have magical restorative effects on stainless steel. This is a product called Optiglanz. It didn't do a thing. So it is now in my arsenal of cleaning kit for later when the pipes have a more ordinary level of discolouration. So I hunted round the internet for tips on polishing. I mainly found YouTube clips featuring the polishing of things like car tail pipes and forum suggestions. These were mostly American and referred to products not available in the UK. But there was one nugget of good information in a long forum article on restoring an old exhaust manifold header so I used that as my guide http://crxcommunity.com/viewtopic.php?t=29848 I tried to find a 'brass' wire wheel drill attachment without any luck. I went to all the tool shops in town and checked a lot of internet sites all without luck. There are a lot wire wheels out there with a brass finish to steel wire. I was trying to avoid that simply because brass being a softer metal would be less likely to damage stainless steel. I gave up on this and spoke to a specialist polishing supplies place who promised to send me a sample of a Satin finishing wheel which should be the most appropriate tool. It never arrived so back to the internet and I found http://www.metalpolishingsupplies.co.uk/. I bought one of their kits for £25. This contained a lot more stuff than I was to find I actually needed. You can build your own kit just including the list above and it will be a lot cheaper. Don't get the grinding stone parts. I tried using these on a deeply pitted area and they went through it but left a surface which was as difficlt to reduce as the original pitting would have been. You may need some of the smaller shaped mops to get into recesses.
While waiting for the kit to arrive I got impatient and started on the front downpipe, which was in the least bad condition, using various abrasives like wire wool, scouring pad (not kitchen scourer) etc. These got the pipe smoothish but still very stained and no bright metal showing as this picture shows.
When the polishing kit arrived I went at it again with a wire wheel (brass coloured/covered steel wire). within an hour it was bright metal all over. The front pipe was now my test piece to learn the polishing method outlined in the pamphlet accompanying the kit. Next step was to twist the sisal polishing mop onto the tapered mandrel and apply black compound. I worked small areas in a sideways motion which leaves a line of wax which marks the extent of the area you have covered. Moved down to the new area moving the line of compound down. Overlapped if in the slightest doubt an area had been covered. Stubborn marks obviously need more work and it helps to keep the mop on that area to heat it up. Cleaning the small area I had done using the vienna lime powder included in the kit, was a revelation. The area now had a smooth satin finish of bright metal. I then used the same method using the colour stitch mop and the pink compound. After cleaning that off I was stunned with the result. The steel was as bright and shiny as if it had just been chromed. But there were imperfections calling for a second dose of the method. But now I had a good idea how fast to move the mops (slowly) to get the different levels of 'stain' or pittng down. Over the next day I gradually went over the remaining parts of the exhaust with the wire wheel. Melted plastic on the other downpipe and significant amounts of rust came off fairly easy but at times I had to use the edge of a kitchen knife to scrape the worst back. The wire wheel was reduced to a stub by the end but no worries as the kit contained two of them. This pic shows the system all reduced to bare, but in places, pretty scuffed bright metal. Regrettably the manufacturers label located under the rear of the silencer, with the various certifications, disappeared at this stage. I had hoped it was more deeply etched but no such luck.
Now it was just graft to go over the whole thing slowly with one mop and black compound, then clean all the black off. This was the most time consuming stage as some of the pitting was difficult to reduce. Surprising that a wheel made of sisal was not damaged whereas the wire wheel was. Then it was time to go over it all with the sisal stitch mop and pink compound. This was comparatively easy where the previous stage had been done properly. But it showed up areas that needed another go with the black stuff. When I was finished at the end of each mopping I washed down with washing up detergent and tap water because I would have used up the small amount of vienna lime supplied, then inspected for areas that needed more work. When I was satisfied I used the lime again and had to dig some of the compound out of the joints in the welds. A lot of time was saved by not bothering to finish those parts that would be hidden. The result was exactly what I wanted and far exceeded my expectations.
FITTING On the NT650V4 it was neither necessary to remove the radiator or the right hand fairing. However I did remove the 4 easy to remove right hand fairing bolts located at the knuckle deflector, beside fuel tank, under the right hand engine protector and by the right hand by the exhaust pipe. This was so that the fairing could be moved slightly. This enabled me to get a socket on the rear pipe front nut, and an open ended spanner on the rear nut. Separating the front pipes from the silencer was facilitated, after undoing all fastenings, and by the use of a four pound club hammer with a peice of wood to protect anything that could be re-used. It was also necessary to prise up the silencer pipe joints a little to break the seal between them and the front pipes. I managed to free the rear pipe this way and removed the silencer and front pipe still attached. The rear manifold pipe comes out sideways with a bit of judicious wiggling. Putting the Predator on was fairly straight forward. When replacing both copper gaskets a word of caution. I went to David Silver's to get them. Only one size (after market part) was available so I ordered two. Big mistake. The rear gasket is a slightly smaller diameter so next time it will be Wemoto as they do both sizes. Ensure each pipe is properly located in the cylinder head and the clamps equally adjusted, but not tight. You will need a bit of movement to fit the silencer. The new pipes have a different depth manifold fitting so I did not have to re-use the heavily corroded front clamp sleeve. Access to replace the rear downpipe nut was so restricted I had to remove the fuel tank. Five minutes work so no big problem. The silencer to front pipe connection is a bit awkward as both pipes have to be pushed on straight without being able to twist them, but you can locate one before the other and then tap the end of the silencer to located them. Put a straight edge across the join if you are unsure whether they are in properly. I used the club hammer and wood against the rear of the silencer to move the silencer up the pipes until the silencer mounting flange lined up with the frame bolt hole.
Result saving £370 ish. Perhaps the most satisfying renovation I have ever done. PREDATOR REVIEW This system is I think a bit lighter in weight than the original as it does not have the large cast lump in the middle. The front pipes discoloured to a light bronze immediately the engine was warm. If it gets bad I believe the Optiglanz should clean it up Preadator tell me they do two versions. A straight through for performance/track and street legal. You can see the difference by simply looking in the rear of the silencer to spot that the pipe enters at an angle. The sound is barely different from the original. But it is different, giving a much more satisfying burble that brings a smile on. Slightly louder but nothing to disturb the neighbours. Also it feels like the bike has more power - probably just sounds it though. At slow speeds, without earplugs, its a more joyful experience to ride and the engine no longer sounds like a bucket of bolts - it thumps. At speeds over 70 with earplugs its really difficult to discern any drone without bending forward below the screen to hear it. Cruising at 80 seemed more relaxing but that is pretty subjective and indicative of the pleasure it is giving me. There is the merest suggestion of a single backfire on throttle closure occasionally. I don't think there is an issue with ground clearance, as I believe there is with the £150 cheaper Motad exhaust, but I can't be sure.