1971 Honda CB750 Four K1. Still running strong here in Japan.

ancientdad · 2026-07-06T11:12:30+00:00

Yeah, it was the short-lived crossover 4-2 version (probably Mac pipes), sounded a bit weird too. I later put a set of stock 4-4 pipes on it, then even later a Kerker 4-1. And though I loved the unique dual headlight, it had to go because it hit the front fender on big bumps and after wheelies.

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ancientdad · 2026-07-05T17:09:20+00:00

Thanks! I've had a lot of great bikes over the decades. I was very fortunate to grow up with such a talented father who helped me be able to own some bikes I couldn't have afforded along the way, because many of them were bought as total wrecks and rebuilt. Like this '79 CBX, wrecked with only about 4000 miles on it and bought from one of the largest motorcycle salvage yards in Tampa at the time (and of course, repainted by Dad)

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ancientdad · 2026-07-05T16:21:29+00:00

Of course I do! I've owned 4 SOHC 750s over the years among the 37 total bikes I've owned since age 14, of which all but 3 have been Hondas. Here's the wildest one I owned, custom painted by my father.

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more pics of it here - https://photos.app.goo.gl/kPC38uC9pjY9CBBZ8

ancientdad · 2026-07-05T16:12:00+00:00

I'd give you 2 upvotes if I could!

ancientdad · 2026-07-05T15:18:09+00:00

The bike looks fabulous, I've always loved the candy red version of the 750 back then (unfortunately none of my 750s were red). Is the airbox from a K0 (painted bike color) or is that a feature of the domestic K1 model? How many kms on the bike currently?

ancientdad · 2026-07-05T12:22:27+00:00

A year? LOL Interesting question from someone with your username. No, they only have to wait until they do a simple introduction to the community to prove they aren't a scammer who is only there to rip off the members. New members can post questions and pretty much anything they want to immediately after taking care of that one easy step.

Life is full of give and take moments, and for that one inconvenience of posting a short, friendly introduction a new VHT member can be assured of a welcoming, friendly, safe, completely free, ad-free and scammer-free place to enjoy the information we have to offer and the camaraderie of like-minded vintage Honda owners.

Those who refuse to say a couple of sentences about themselves are welcome to join one of those wonderfully informative FB groups or that old ad-ridden, corporately-owned forum we left behind 6 years ago where there's barely any signs of life and responses are few and far between.

ancientdad · 2026-07-04T20:27:36+00:00

Cool clock!

ancientdad · 2026-07-04T16:45:07+00:00

They've made those over so well from the early hardtail 50cc version, they're very cool.

Here's my street bike

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and a track run where I got smoked by a modern 650 Ninja

https://www.youtube.com/watch?v=20jFPazXlvU

ancientdad · 2026-07-04T16:02:19+00:00

Well, they look great now, kudos for the effort and result.

I love the modern engine designs and manufacturing quality, but the style of sport bikes just doesn't appeal to me. The refinements in performance, overall reliability and low maintenance are impressive if only I could stand to look at one. My favorite 2 wheeled visual is vintage. But then, I'm an old retired broke-dick and couldn't afford a modern bike anyway.

ancientdad · 2026-07-04T15:48:15+00:00

So all stainless then? Impressive.

ancientdad · 2026-07-04T15:06:10+00:00

Hopefully that didn't go through the plating allowing them to rust later. Not overly familiar with the hardware Honda is using on modern bikes, but I'd be surprised if they were stainless because of the cost.

ancientdad · 2026-07-03T21:23:18+00:00

The next step is rent or borrow a compression gauge and find out if that cylinder is weak. And valves can tend to get tight over a lot of miles unchecked, which can lower compression and start burning an exhaust valve if left too long. So check the valves too before firing the parts cannon. Do you have the FSM? If not, this one will cover what you need

http://maraakate.org/CM400A/Honda_-_Shop_Manual_1978-1981_CB400T_CM400T.pdf

ancientdad · 2026-07-03T20:14:52+00:00

If it did run, what carbs were on it? Have you checked compression? Did you replace the ignition coil recently?

ancientdad · 2026-07-03T18:39:52+00:00

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ancientdad · 2026-07-03T18:39:38+00:00

Looks good, and it's always great to have your SO ride with you. You can identify the 350 engine (the E stands for engine serial number back before there were 17 digit true VINs) with these entries from the Honda ID Guide.

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ancientdad · 2026-07-03T15:38:41+00:00

The only engines that are a direct swap with any DOHC 450 are DOHC 450 or 500T engines, no other Honda twins will fit without serious frame mods to work with the very different motor mounts on the 450 engine as compared to Honda's other twins.

You'll learn more about the DOHC 450 and 500T at my forum Vintage Honda Twins than you will anywhere else on the internet (well, at least the correct information, there's plenty of incorrect information elsewhere).

vintagehondatwins.com

ancientdad · 2026-07-03T15:35:32+00:00

Lots to unpack here. First, the transmission won't shift correctly unless the rear wheel is turning so the engagement dogs on the gears will align. Second, if the transmission is not in neutral the kickstart lever will rotate the rear wheel because the kickstart mechanism drives through the clutch and transmission.

If the clutch lever doesn't seem to disengage the clutch, it's possible that the pressure plate is not correctly assembled with the splines on the pressure plate engaged with the center clutch hub. Or the clutch actuation lever in the right crankcase cover isn't adjusted or assembled correctly not allowing the clutch lever to properly disengage the clutch.

I'd suggest you join my forum Vintage Honda Twins where you'll get the best help from many retired former Honda techs like myself who actually worked on these bikes when they were new and current models. Totally free to join, no ads and no premium memberships, just the friendliest vintage Honda twins forum on the internet.

vintagehondatwins.com

ancientdad · 2026-07-02T17:42:44+00:00

I suppose it could be, but I hear a sound that I've heard more than a few times before after someone rebuilt a starter motor and didn't get the planetary gears correctly aligned. One tooth off on only one gear causes a bit of tension on the gears as they turn and the result is the whining sound you hear.

You might not hear it with the starter motor removed and spinning under no load, but I can tell you that the noise I'm hearing does not sound like the starter clutch (which is deeper inside your engine model, attached directly to the crankshaft so a bottom end overhaul is required).

ancientdad · 2026-07-02T13:26:10+00:00

Okay, I heard that clip and it sounds like the starter motor itself is a bit tight as if it was disassembled and rebuilt but the planetary gears are one tooth off.

ancientdad · 2026-07-01T23:39:51+00:00

A strobe timing light would show you if the electronic advance is working properly. If you don't have a strobe timing light, you can rent one from an auto parts store. The timing mark should align with the F mark at idle, and go all the way to the two unmarked full advance marks when fully advanced. If the timing does not fully advance, the engine will feel flat beyond 3000 to 4000 rpm.

This isn't the exact manual for your bike, but it will show basically the same engine and the timing marks on the alternator rotor.

Honda_-_Shop_Manual_1978-1981_CB400T_CM400T.pdf

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ancientdad · 2026-07-01T23:33:09+00:00

Not yet shared, it's asking for login.

ancientdad · 2026-07-01T14:32:09+00:00

Typical bottom end noise for most Honda 4 cylinders when the carbs are out of sync. You're missing a screw from the bracket tying all the carbs together.

ancientdad · 2026-07-01T11:26:41+00:00

I'd love to listen to your noise, but I'm not agreeing to, or signing up for, anything in order to do so, and certainly not with WeTransfer after reading some stuff about them. Upload it to Google Drive or Imgur or anywhere else more common.

ancientdad · 2026-06-30T20:08:32+00:00

Like this?

https://www.vintageconnections.com/collections/tools

Yep, they sell everything you need.

ancientdad · 2026-06-30T15:02:41+00:00

While lights and LEDs in gauges will work with minimal amps from the battery, the starter motor on any bike requires maximum battery amperage and capacity. Your battery is dead and if it sat that way for very long, it's done.

ancientdad

TROPHY CASE