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Throttle Body Discoloration

6K views 22 replies 12 participants last post by  808Bonneville 
#1 · (Edited)
Not worth a new thread. Son mentioned yesterday that one of his "carbs" had a bit of discoloration. He said that he was going to take some Nevr-Dull home with him but didn't believe it was simply "dirty". Whatever the case, if it doesn't clean up easily, he'll get that throttle body swapped out.
Anyone else with a Thruxton-R notice anything like this?
As several folks followed up with comments that they too were seeing this problem and I am as well - I do want a new thread on it as specific, helpful answers may come through.

What metal are the made from? The little bit of riding I did when it was still raining seemed to leave them coated with a light film of what looked like oxidation and they were spottily discolored. The few products I used in small test-areas did not make them look like new - maybe someone here will know what will?
 
#2 ·
Haven't noticed an 'oxidisation' look as yet - but will keep an eye on them over the next few months. Maybe somebody will know what the underlying material is and what surface finish might have been applied - I'd be nervous of attacking the surface with the 'wrong' cleaning product(s).
 
#3 ·
Based on what I see and having tried a small amount of metal polish on a test area (do not recommend doing this), I believe the TB had a bead blasted finish. Yes, there is some variations in finish on my bike as well.
 
#4 ·
Update: I decided to take the plunge and go ahead and try and polish the outer throttle body area with the mottled and discolored look. Removed the silver medallion covers on the outside (3 screws) as well as the brushed stainless cover to the back of the TB (1 small 3mm hex at the top and then pull straight out). I then taped any silver painted parts of the upper and lower TB housing with painters tape before using some Wenol metal polish on the TB. Using a paper shop towel, I used small amounts of polish to polish the outer TB area visible to the eye. I would then wipe the excess polish residue away and clean with some naphtha solvent on another clean paper towel. To get a more uniform look, I used a small piece of 1000 grit wet sand paper soaked in water. Could also use 1500. Lightly brushed the TB outer housing with the wet sand paper and water and wiped away excess with naphtha solvent on a paper towel. I then lightly polished the surface again with metal polish. Use the polish sparingly. You end up with a uniform finish that looks much like pewter. Reinstall TB medallions and rear covers.
 
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#5 ·
You end up with a uniform finish that looks much like pewter. Reinstall TB medallions and rear covers.
Looks like an 865 now? :)

Seems like a lot of work. If you have a decent digicam, (not a phone), any chance of a snap?
 
#9 ·
I think you could use some 000 or 0000 steel wool but I would be careful to tape off the opening to the TB if you remove the medallion covers. I would not want steel wool dust getting in there. Main reason I stayed away from steel wool here.
 
#11 ·
This makes the bike look so much better. It's the small things, I polished mine and could not be happier. Right when I picked my bike up at the dealer I noticed the casting glaze. It drives me nuts on my air cooled thruxton but a lot easier to address on the R. Brought mine up to high polish, might do whole throttle body this winter.
 

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#14 ·
Flatgod - Looks nice. You spent a lot more time getting yours to a high polish finish. I preferred more of a brushed finish on mine just trying to even out the texture and appearance of the finish overall. Nice work though.
 
#17 ·
My bike is 6 months old and looks ok. They changed from 'new' to a little bit 'worrisome' within a few weeks, but then did not continue to get worse. I think it's just a nature of the metal they're made of, but like I said they still look fine - just not brand new.
 
#19 ·
Well here's the thing, I don't want to be doing stuff on a new bike. I am very lucky to have an old Austin Healey which I am restoring and so my garage time goes on that. For sure I accept that I need to maintain the bike by doing jobs like lubricating the chain but not polishing bits that shouldn't be corroding.

Feeling a bit of a prick but I will mention it to the dealer when I see them later on this morning (collecting bobbins to use a stand to maintain the chain = the limit)
 
#20 ·
Mine corroded after first wash. Was pretty cheesed about it. They should be finished better than this. I ended up with a tooth brush and hot soapy water. Then dried it with the air compressor. Anyone know of a clear that won't discolour with heat?
 
#22 ·
Wow. You guys have wayyy too much time on your hands. After perusing this post went out and looked. Yes, the cover has a different finish but I like it. Sort of ruff but I like it. Won't be wasting riding time on this. To each his own. Wait, hummm maybe I'll have it powder coated in red to match the stitching on the seat. Naaaaaa, Maybe.
 
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