CB125K5 was avalaible in Europe, CB175 in USA. CB125K5 was avalaible with and without starter. CB125S is bike with single cylinder.Though pictures don't always convey the proper colors perfectly, I don't see a brown switch - I see an electric start button on one of them and a High/Low switch on both, and one has the obvious red kill switch. Something tells me you might not have the right switch for the bike. Also, I don't see a CB125K5 in my Honda Identification Guide book either, just CB125S0 starting in '73 and going to S2, then CB125S'76 to CB125S'85 models and I don't think any of the singles had electric start as well. What year is it?
CB125 K5 was also Twin, except smaller ccm cam chain is located outside cylinder (175 has it between cylinder).A CB175 in the US is a twin cylinder engine bike, not a single. Would have helped to know it was a European bike, I wouldn't have bothered to look in my US Honda Identification Guide. That's why putting your location in your member information is important to getting correct information
Might add your location to your profile, it helps at times when sorting out problemsYes, it's a cb125 K5 1975 from France, where I'm located. I believe you're right that in the US it's the cb175 K5 model. I found out that it's indeed not the right part for my model, so it's good that I have another one which does fit.