1978 Honda CB400A Hondamatic moves under its own power after 35 years. Kinda...

This is my 1978 Honda CB400A Hondamatic that I’ve been rebuilding since October of 2016. It’s been completely taken apart, powder coated, polished, repaired, parts replaced, cleaned, and now I’m trying to figure out the stutter at anything more than part throttle.
When I rebuilt the carbs I mistakenly messed up the idle jet that I couldn’t remove and I think that’s what is causing the issue. Luckily I have a spare set I’ve also rebuilt, correctly this time, from the 79 CM400A that you also see in the garage toward the end of the video.
Yes, I have 2 gold wagons. One is a 95 Honda Accord LX which is my son’s daily and one is my daily, the 2015 BMW 328 xDrive.

[@viciouscycle8890]

Just got one of these with 12,225 miles on it, they're out there!

[@stevedotworld]

I put almost 5K miles on mine from last April through this April. Fun little bike to commute on.

[@tysoncott7402]

clean the carbs on that old girl!!!

[@stevedotworld]

It was a damaged jet.

[@roverchap]

Sounds like it's running on one cylinder, which would explain the poor acceleration. Have you checked whether one exhaust pipe is cooler than the other? Probably needs carbs stripping and cleaning but also worth checking the spark on the dead cylinder.

[@stevedotworld]

It was one of the carbs. I swapped to the other set and I’ve put 1000 miles on it since. Thanks for the comment.

[@dhtsoaedsdhtnadi9575]

PLEASE tell me where you find parts for this age bike? I have this exact year and model that came to me as a titled basketcase. Some of the parts are too worn to reuse, and others are missing. A timing chain tensioner is one of the criticals I can't find replacement for.

[@stevedotworld]

There are lots of parts online that are either NOS or used. eBay and FB vintage Japanese motorcycle groups are your friend. The timing chain tensioner you would have to find used.

[@dhtsoaedsdhtnadi9575]

@@stevedotworld Thanks. I was afraid of that about the tensioner, and so far the ones I find are ridiculously trashed. Unless there's a way to refurb? The metal is good, the slip shoe is still serviceable, but the pin on one side burned up and crumbled. I may have to try to get some Stanyl and make a new shoe and pin. Funny how google couldn't answer my question 4 years ago when I searched "timing chain tensioner material", yet today it finds a forum thread from 2011. With that I should be able to put this basketcase back on the road.

[@tylerarblaster2431]

@@dhtsoaedsdhtnadi9575 did you find the parts you need because I have some sites I found ... I just started work on my own of the same year make and model as well

[@dhtsoaedsdhtnadi9575]

@@tylerarblaster2431 I haven't had much of a chance to do much in the past month. Really before I do much more I need to see if I can even split the case. Flywheel is ON there.

[@davidwilliamson9162]

Replaced tank!….sounds like carb blocked on one cylinder?

[@stevedotworld]

Replaced the carbs with another set and we are off to the races.

[@davidwilliamson9162]

@@stevedotworld cool nice bike by the way ,never seen or been on one!

[@davidwilliamson9162]

It’s probably a partial blockage on main jet!

[@stevedotworld]

@@davidwilliamson9162 that’s what it was a few times after swapping the carbs for the other set. I’ve cleaned the jets out a ton of times. I have a small in-line filter on there now. I actually ride this motorcycle to work 45 miles round trip when it’s not raining. Even at 75-80 mph it’s fine for a 400.

[@davidwilliamson9162]

@@stevedotworld try some tank cleaner with some old nuts n bolts or any small metal objects they will get everywhere in the tank remove from bike n shake it about so u can dislodge all the rust n crap out ov it!

[@ShogunAutoworks]

Jets or air intake/filter

[@stevedotworld]

It was one of the carbs. It had a bad rebuild and one of the idle jets was damaged along with that carb body.

[@lesn9125]

I used to have an orange manual speed Would you be interested in selling it

[@stevedotworld]

Sorry, I'm not going to sell this one. It took my son and I 5 years to finish it and be able to ride it.