Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Otis on August 20, 2026, 12:08:09 PM
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In the recent thread about main fuse blowing I explained that after finding the broken wire I had to dismantle the air filter housing for access.
I was meticulous in photographing the components before hand and put everything in the air filter housing for safe keeping. Upon reassembly I now have a bolt without a home. I have spent half an hour looking to see where it might go but to no avail. Would anybody have any idea where this little bot and washer should be because for the life of me I can't see it.
Thank you
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Is it the one inside the filter housing right at the bottom?
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Is it the one inside the filter housing right at the bottom?
OMG, thank you so much, I've been worried sick about it
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Is it the one inside the filter housing right at the bottom?
Notwithstanding my initial excitement I'm not sure that is correct. There is a hole at the bottom but smaller diameter plus there is a 4 inch void beneath so not sure what any bolt would achieve. Hmmm!
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For some unknown reason I am getting a message saying that I am not allowed to access these photos. 1st one OK but next two no good
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Have you thought of looking at an exploded diagram of the area? Such an image you'll get on the CMSL site.
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Looking at the size of that washer, could it be one of those bolts that have a rubber cushion beneath, and do you remember how many of those you fitted back?
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Is it the one inside the filter housing right at the bottom?
Notwithstanding my initial excitement I'm not sure that is correct. There is a hole at the bottom but smaller diameter plus there is a 4 inch void beneath so not sure what any bolt would achieve. Hmmm!
I might be confusing it with the 500.
There are similar bolts & washers in the steel frame for the battery box. Did you remove one of those perhaps?
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There's two like that that holds the voltage regulator to the battery box
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Looking at the size of that washer, could it be one of those bolts that have a rubber cushion beneath, and do you remember how many of those you fitted back?
That's a really useful diagram and thanks for sharing. I can confirm that all appears to be present and correct so I guess I will just have to wait and see if something goes array at some stage. It's a small bolt so I guess nothing structural.
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There's two like that that holds the voltage regulator to the battery box
I will double check that because I did remove the regulator; thanks
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The hole in the bottom of the air filter housing is for a self tapping Phillips screw that holds the plastic oil separator from the crankcase breather.
The only other mounting for the battery box is under the battery but that is a captive bolt on the engine mounting bracket so only takes a nut and washer.
It's got me stumped.
Regards
Dave
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Are you sure this bolt didn't come out of your pocket at some point, that would be me all over! ;D
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The only other mounting for the battery box is under the battery but that is a captive bolt on the engine mounting bracket so only takes a nut and washer.
Regards
Dave
Could that captive bolt have been changed to a nut & bolt for ease of removal in the past?
Do you have a spare nut as well?
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I can't believe how much of your kind and helpful time I have taken from you very generous gentlemen.
These forums are just fantastic and so often it is the simplest of tips and ideas that produce results. You have all been incredibly helpful but this will perhaps have to remain a mystery for the time being. I would love to admit that this bolt was just lurking in my pocket but sadly not. It also doesn't have an associated nut. The regulator is only held with a single nut but remains robust in its position.
When something drops off or fails I promise to eat humble pie and advise you of my findings.
Thank you all.
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The regulator has 2 bolts holding it onto the plate, both are M6 x 16mm. Measure the bolt and that will mean we can tell you exactly where it's come from.
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I'm pretty sure my regulator has two bolts securing it.
One at the top, one at the bottom.
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Just add the bolt to your jam jar of other surplus fasteners. One day it will come in handy.
Regards
Dave
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Looking at the size of that washer, could it be one of those bolts that have a rubber cushion beneath, and do you remember how many of those you fitted back?
If you go an inch up from number 21 and go right you will see a hooked bracket that holds the regulator. There is no second fixing for the regulator on my bike
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Looking at the size of that washer, could it be one of those bolts that have a rubber cushion beneath, and do you remember how many of those you fitted back?
If you go an inch up from number 21 and go right you will see a hooked bracket that holds the regulator. There is no second fixing for the regulator on my bike
Are you sure you aren't responding to Oddjob? ;)
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I am sure the regulator should be on two bolts, the rubber will be solenoid or flasher relay
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It's a long shot, when you say your regulator is held on with one bolt, you do mean the regulator, not the rectifier?
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It's a long shot, when you say your regulator is held on with one bolt, you do mean the regulator, not the rectifier?
I don't believe there is a seperate rectifier? Aren't the regulatorss and the rectifiers combined?
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Looking at the pictured posted, it looks like a combined reg rec unit so the fixing won't be standard unless there's an adapter bracket.
Regards
Dave
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Here is the original regulator, bolted to the air filter box.[attachimg=1]
Regards
Dave
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Ah ha. Looks like someone has relocated the OEM rectifier. That lump with fins looked like an aftermarket combined unit. I can see the original regulator in the most recent image.
The original rectifier on the 400 was on the other side
[attachimg=1]
Regards
Dave
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It might not be an issue, I thought the rectifier was mounted where it was originally to aid air flow/cooling.
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Here is the original regulator, bolted to the air filter box. (Attachment Link)
Regards
Dave
OK, mystery solved.
I'm a bit confused about regulators, rectifiers and combined units but if the unit with the white strip containing green and black rectangles is the original regulator then that is what I have and the bolt fitted the upper fixing. It was concealed behind a part of the harness so I missed it. I must have started to remove this unit and then realised it didn't need to come out.
Anyway, thanks to all for the help and guidance which as always, is educational.
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Here is the original regulator, bolted to the air filter box. (Attachment Link)
Regards
Dave
OK, mystery solved.
I'm a bit confused about regulators, rectifiers and combined units but if the unit with the white strip containing green and black rectangles is the original regulator then that is what I have and the bolt fitted the upper fixing. It was concealed behind a part of the harness so I missed it. I must have started to remove this unit and then realised it didn't need to come out.
Anyway, thanks to all for the help and guidance which as always, is educational.
If a combined unit has been fitted, the one part replaces the original Rectifier and Regulator.
Yours has what looks like the original Regulator, it's held in place by the top and bottom bolts via rubber mounts fitted to the regulator.
The Rectifier is the unit with the alloy fins in your photo.
It might be worth checking if you have the lug on the right side of your frame where the original Rectifier is bolted in place by one bolt.
Seems unusual that yours is fitted where it is, makes me wonder if the wiring lead is too short to mount it in the correct place. Might be worth investigating a possible move to a cooler position on the right side of the frame.