Rear Mudguard (Chrome Section)

[Martin6]

Hi,

I have a UK version CB750K6. Owned just over 2 years. Initially a non-runner, it's currently running nicely after resolving some top end, fuelling and ignition issues. While the engine was out, I sent the frame etc. for a strip and powder-coat. Luckily, the Antares Red parts are fine. Since then, over the last 2 years I've been replacing fixings and cheaper cosmetic parts, to get it looking really nice. Not concours, but nice.

One part I could do with sorting out is the chrome rear mudguard. It had a 1" square rust hole on the left side, just behind the edge of the saddle. I had to trim it back, fill and silver paint it, as a temporary fix. But, the surrounding metal was fragile and I'm sure the repair won't last.

The mudguard for a UK model is part 80100-300-600XW. I've been Google searching for 2 years without luck. On ebay, I can see re-made mudguards, part no. 80100-341-000, which is a K6 part, listed for US, Canada and 'general export' markets. This is made/sold by a firm called 'Motorcycle Seat Factory TD', in Ho Chi Min City, Vietnam.

Does anyone know what the difference might be between the UK model part and the US (etc.) one and whether I could use it?
Has anyone had any experience buying from these people?

Thanks, Martin

[McCabe-Thiele (Ted)]

In my brief experience of old Honda's it's usually the holes for the rear number plate bracket that tend to be different for different markets. That can also mean a different tail light. That's probably stating the obvious.

[Martin6]

Yes, think you're right Ted, as the indicator stalks are on the grabrail bolt and that's the same part no. for all markets.

The rear light / plate holder on mine at least, are black items, whereas the US are chrome. But don't know about hole spacings. Wonder how different the holes are and whether it can work?

[McCabe-Thiele (Ted)]

I believe on some models the Vietnamese manufactures make different fenders for various markets. It might be worth messaging the seller.
It might be worth checking the photos on the CSML site to see how many bolts the number plate brackets have e.g. 3 or 4.
The bolt centre holes  for the rear light might be different.
I would have thought some members here with imported models will have your answers.

[Martin6]

The front part of the fender (the black plastic section) is the same part for the US and UK. The light / no. plate fitting is a different part no. So, that must be it, different fitting holes as well as different finish (chrome vs. black), even though the shape looks quite similar.

They also sell the mudguard with the rear light bracket and lense, for another £50. I'm not made of money, which is why I've been nibbling away at the restoration. However, it's niggling me, so that's probably the route I will go, take the risk and get the chrome light fitting with it. I suppose I could always rough the tail light section up and paint it, or get it powder-coated,  if I don't like the shiny version. I'm not after concours, just a good rider, nicely presented.

If anyone is able to confirm that's the only difference, that would help. Thanks.

[Laverda Dave]

If the Vietnamese made part is for a USA model you could always ask them to send you one without the chrome finish applied. Once you receive it in the UK you could re-drill the holes to UK spec and fill the other holes in with a bit of plating or brazing and then get the guard chrome plated (and it will be less expensive than replating an old UK guard because the plating company only has to give your 'newly modified Vietnamese guard' a polish and chrome).
This is what I had to do with the front a rear guards for my 400/4. The PO had drilled huge holes in both guards to fit a tombstone tail light and some kind of chopper style shopping trolley rail on the front. I found a blacksmith who filled the holes and now they are plated you wouldn't know the holes had ever been there.

[honda-san]

For exactly the same reason I have a US spec k2-K6 rear mudguard fitted to a 1970 UK CB750 - and the original black painted UK rear light bracket bolted straight on (the spacing of the four bracket mounting holes is the same). The bracket does appear to sit very slightly further up the mudguard such that the number plate is now slightly angled. The US rear mudguard also has an extra single hole at the rear for a rubber bump stop which (I think) is supposed to support the bottom edge of the US license plate (number plate). Pictures attached - the one with wet patio is the bike as bought with rotten original UK rear mudguard, the other with the US spec K6 mudguard fitted. Maybe it helps?

[Martin6]

Thank you. Those photos are really helpful. Id be happy with that rear tail set up. I'm likely to go for the US one. Also, one of our members is not too far from me and has offered to show me his US version K6.

Thank you for your help. 👍

[honda-san]

Curiosity got the better of me today, so I went searching out my spare rear CB750 mudguards.
Found three of them in a box. One is a plastic repro. One is a US style K6 mudguard in good solid condition, albeit with some marks / dents.
The other one is actually a UK spec (80100-300-600XW) in nice solid presentable condition. Shame someone has drilled it at the rear lower edge in a couple of places (for a mudflap possibly); also a couple of extra holes as if a different rear light bracket was fitted at some time. I guess the holes could be welded by those skilled at such things, and then re-chromed - though perhaps just cheaper to buy a US spec repro.

[Martin6]

So that's what I've done. Of everything that bolts to the mudguard, the UK tail light looks to be the only difference in the parts book. I've ordered a US repro, with the tail light included. Hopefully it fits without further drilling. May need some work on the light's wiring, I'm hoping not, but shouldn't be too difficult.

Delivery is quite a date range, early June to early July. I will feed back on quality and fit, once it arrives.

Thanks for your advice. 👍

[McCabe-Thiele (Ted)]

I'm assuming Martin that you have ordered one from Vietnam, although this source has been discussed before I am not aware of any feedback from a member who has actually bought one.

I hope it meets or exceeds your expectations, it will be interesting to read how it turns out, best of luck.

[Bryanj]

Wiring is same but the light unit might be the huge type as on F1 and the mounting bolt holes are at a different spacing

[Martin6]

I'm assuming Martin that you have ordered one from Vietnam, although this source has been discussed before I am not aware of any feedback from a member who has actually bought one.

I hope it meets or exceeds your expectations, it will be interesting to read how it turns out, best of luck.

The mudguard and rear light assembly arrived this morning. I started on the swap at 2pm and finished at 8.30! ...There were problems.

First the good:
-The mudguard looks identical to the original, even made up the same way, with the pieces welded together as per stock. It even has an identical metal protector the rear light wires run through.
- The correct holes have their captive nuts.
- The guides are in the right place for the indicator wires.
- The hole spacings were difficult to measure, but are the same as my original, so it accepts the black UK version light assembly and number plate bracket.
- The chrome plate is fine, minor imperfections, but not anywhere visible and not significant.
- All the threads to the captive nuts are the same as stock.

The bad:
- The holes for the rear light wiring were in the right place, but they were smaller, so the 2 grommets would not fit.
- The whole mudguard was about 1/4" too wide for the gap between rear frame rails (between the indicator stalks) and the profile side to side is a fraction shallower. It's like the whole thing didn't quite get bent round enough. Looking at it side on, it looks right. It just doesn't quite have a deep enough curve looking at it from back to front view. I think that is why it was not fitting between the frame.

I retired for a cup of tea and a think.

I decided to give it a go. I was able to force the sides together sufficiently to slide it between the frame rails. It took ages to line the indicator bolts up and catch the thread in the captive nuts, but I got there. Even with these loose, there was no way the two bolts would go through the top frame cross member and catch the captive nuts in the top front of the mudguard. The standard bolts were at least 1/4" too short.

Another cup of tea.

I matched the thread to some longer bolts (screws) and was able to get them both started. I've tightened all four mounting bolts now. The top two are tight, but there is a 1/4" gap between the top of the mudguard and the top hat washers of the plastic front fender.

So that's how I've left it. I'm hoping the mudguard may steadily relax into the right profile under the tension of the fixing bolts, so that I can tighten the top screws further, over time. I would like to get to the point I can use the original bolts in there, but I'll give it more time before I try to swap them. Of course, I am running the risk that I'm introducing too much stress into the mudguard or its chrome plate. I'll not force it any more, just check to see if it can easily be tightened further, after a week or so. If not, I'll make a short spacer, to go on the two top bolts between the rear and front mudguard, so everything is vibration free.

Conclusion: The new mudguard looks very nice on the bike. It is definitely not a simple switch, as there are quality issues with the profile of the mudguard. Time will tell if worst case, that causes a terminal fail, or  best case, it relaxes and conforms to the right shape. For now, it looks right. The old mudguard I removed is pretty nasty, beyond repair.

Sorry this was a bit waffly. 👍

[McCabe-Thiele (Ted)]

Very informative write up, are you going to put a photo up of the final fitting?

The DS replica front mudguard was a bit of a pig on my 500 K1, the main problem was with the two stays not fitting correctly on the bottom of the forks as its a larger hole with a steel/rubber insert to make up the differeance. Lots of time spent loosening the stay to fender bolts, gentle beding etc.

Likewise the aftermarket plain steel rear mudguard on my 400NA was a pig to fit. I used some longer bolts to make it all fit by tightening thus pulling it into place, I think I actually ended up putting a washer between that and the plastic rear section to make it line up.

[Laverda Dave]

Congratulations on getting a reasonable fit. The pattern 400/4 rear mudguard I fitted a few years ago had similar issues with the side profile preventing a proper line up. I did the same as you did, slightly bend the sides in to get it to fit into the frame.
It could have been far worse, it may have been labelled as a 'universal fit' you know, it fits nothing without major work!