1967 CB450 K0 Resuscitation

I will suggest putting the bike back as close to stock with brand new fresh air filters and the correct size of jet whether it is 125 or 130? If you have both and stock is 125 then use that one first. Change those plugs for new, as they are no good now with all that crap on the porcelain. You can clean them and they will work, yet likely soot up easier now since they have been contaminated.
For testing purposes maybe the cleaned plugs will suffice, yet once you get it sorted then put in brand new ones.

All the grungy filters and larger jets are a probably a contributing factor. Plus todays gas formulation is much different than stuff 50 years ago. If anything it can be leaner with the ethanol, yet your not getting that response from the bike.
 
I took the air cleaners off and the bike runs much better...
Flyin900 said:
brand new fresh air filters
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I wish that was a possibility but those air cleaners haven't been available for a very long time. The FSM says to clean them with gasoline. I guess I'll try that. Sounds slightly dangerous. From my reading I guess a lot of people have cut the paper out of the filters and replaced it with either more paper or with foam. If the solvents don't clean them then I'll probably do foam.

Both @wentwest and @Flyin900 suggested getting the carb jets back to original and that was also my thought. However, I think senility may be setting in. With the air cleaners off I managed to take the float bowls off the carbs while the carbs were still mounted on the engine. I removed the main jets and to my surprise they were #125 just like the FSM stated. The #130s from my junk box, that I thought were the original jets, are obviously the larger ones. Duh. I have no idea now when I swapped them out. It must have been several months ago when I first took the carbs apart, long before I got the bike running again... Or who knows, maybe a ghost has been moonlighting wrenching on my bike? Every day, getting old gets just a little harder...

Flyin900 said:
Change those plugs for new, as they are no good now with all that crap on the porcelain. You can clean them and they will work, yet likely soot up easier now since they have been contaminated.
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@jensen said somewhere, maybe even in this thread, not to clean the plugs as they are iridium. I guess if you use a steel wire brush you can contaminate the iridium tip. I don't know, maybe use a nylon brush? I was hoping that the soot would just burn off the plugs if I put them back in...

I've read several places that the 450 DOHC doesn't run well without the original style air cleaners on. Why is that? Why don't pod filters and other things work?
 
Iridium are expensive plugs and those are heavily sooted. A brass wire brush and hand clean them will help the cause. I have used kerosene to soak and clean the paper element on old air filters. Then blown with compressed air once they are thoroughly cleaned and shook out of excess kerosene.
Make sure they are completely dried and not still wet before trying them again.
 
There is also a possibility that those carbs are not clean in the air circuits which will lead to a richer condition if some are partially blocked. These carbs seem to be a nemesis for members who restore these DOHC early bikes for some reason. The member Teebo chased carb issues for quite awhile on his early DOHC BB model.
 
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I understood that the plugs are only sooty, but still function ? I wouldn't bother, these will burn clean. even with my two-stroke, KR1-s these iridium plugs never failed me. A few years ago, I had an issue with the choke lever on my CB450 K0, during a high way ride the choke closed, and my bike didn't pull, and finally it stopped running. After parking the bike alongside the road, I found the issue, fixed it, and after a few minutes I tried to start the bike. First it wouldn't start, but after closing the fuel tab, and kick start the engine WOT (ignition off) trying that this would dry-up the plugs. After a while I didn't smell pure fuel fumes from the exhausts and tried to start the bike. To my surprise, it did run. First on one cylinder but very quickly on both, and I could continue my journey.
 
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KHSE said:
Every day, getting old gets just a little harder...
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Yes it does. And it's even more true when you go away for a week or so and are out of your home comfort zone, adapting to varied circumstances is a bit more difficult when accompanied by the increasing restrictions and needs our lives have as the age numbers rack up. But I'm not going quietly... :giggle:
KHSE said:
I've read several places that the 450 DOHC doesn't run well without the original style air cleaners on. Why is that? Why don't pod filters and other things work?
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Any vintage Honda with CV carbs - which means 350s, 360s and 450s primarily - will not run right using aftermarket air filters without copious rejetting efforts, and even then it's very difficult to get them to run like they did from the factory. Honda didn't just slap on some air filters they had lying around, they knew what they were doing when they designed the intake tract for the proper air flow and intake "draw".
 
ancientdad said:
Honda didn't just slap on some air filters they had lying around, they knew what they were doing when they designed the intake tract for the proper air flow and intake "draw".
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Ya, my thought is that it is the total surface area of the filters. These 450 DOHC bikes having the two filters with the crossover tubes have a lot of surface area per carb. I guess mine currently don't have enough effective surface area :(. I think I'll try the kerosene and if that doesn't work bite the bullet and move onto the foam. I think both @wentwest and @teebo went the foam route.
 
KHSE said:
Ya, my thought is that it is the total surface area of the filters. These 450 DOHC bikes having the two filters with the crossover tubes have a lot of surface area per carb. I guess mine currently don't have enough effective surface area :(. I think I'll try the kerosene and if that doesn't work bite the bullet and move onto the foam. I think both @wentwest and @teebo went the foam route.
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It's as much about the intake restriction as it is the surface area. Pod filters, and even larger, good quality K&N filters, don't provide the same intake air flow resistance that the stock carbs were designed to use for proper function all around.
 
Definitely try cleaning the filters. You seem to have nothing much to lose, even if the paper disintegrates. Filter foam is easy to find and not terribly expensive.

I have remembered and forgotten some things so many times... But this reminded me (again!) that there is much to be gained by clearing the jet that's inside the air intake tube at the lowest point along the edge of the carb intake. The round brass thing at the lowest point of this intake is the end of that tube.

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I used a very thin guitar string and poked around until it slipped through a jet about an inch in. After that my lumpy idle and uneven power complaints disappeared. Worth a try, for sure.

By the way, I "borrowed" this photo from something @jensen posted a while ago.
 
I'm sorry to say, but I run the original air filters on my bomber, clean them with a middle hard brush and blow them out with a cochlea ventilator. If the plugs look that sooty, something else is not right, but a not perfectly clean air filter is not the issue you're looking for.
 
wentwest said:
The round brass thing at the lowest point of this intake is the end of that tube.
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Ya, I had a heck of time cleaning out the right carb air tube. I tried a violin E string but couldn't get it cleared, the string wasn't stiff enough. I noted the air jet size in the FSM and then used an oxy-acetylene torch tip cleaner that was somewhat smaller in diameter and that finally cleaned it out. The thing I can't verify is how clean the internal passageways are. I sprayed carb cleaner through them and the spray flies out other orifices but is that clean enough? The same is true for the rest of the carb. I spray in holes and it comes out other holes. Is that good enough? I also had a heck of time cleaning the slow speed jet. Someone on here said to soak them in gasoline and that finally did it... I see a lot of people use ultra sonic cleaners but what fluid/cleaner do they use for those?
jensen said:
blow them out with a cochlea ventilator
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Gee, that seems elaborate...

I went ahead and used compressed air and a tooth brush, then diesel fuel and a toothbrush, and finally mineral spirits to wash out the diesel fuel. They are drying now. Got a lot of junk out. The diesel fuel and mineral spirits poured pretty easily though the paper so I would suppose air should pass through it pretty easily too...

jensen said:
If the plugs look that sooty, something else is not right, but a not perfectly clean air filter is not the issue you're looking for.
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That's my concern too. Where would you start looking? I doubt it is the slow speed portion of the carb as the engine idles nice and responds to the throttle. The main jet is factory spec #125. Does that mean something is off with the needle? As far as I recollect the needle is not adjustable. Is that true? I have never removed them but they are clean, straight, and the vacuum slides are free, moving easily.

BTW: Small victory, but the latest purchase of foot peg rubbers arrived and the right side one was safely inserted using the windex treatment and a wooden mallet. :)
 
jensen said:
sorry, meant air mixture screw, and what about the air inlet for the mixture screw ?
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For both carbs: A couple of months ago I removed the main jet and the emulsifier tube behind it and cleaned them. The main jet is the original #125. I also removed the pilot jet and the slow jet behind it and cleaned them. They were completely clogged. I cleared out the air jet. Also completely clogged. I sprayed carb cleaner through the air jet, it comes out the main jet. Sprayed carb cleaner in the pilot jet, it comes out the pilot screw (mixture screw?) position and the slow speed orifice in the carb body. So, the jets and emulsifiers are all clean and because carb spray comes out of all the passageways there is continuity through all those passageways. But I can't claim that all the passageways are all squeaky clean because I don't know of any way to test them.

The engine doesn't exactly readily start but I can usually get it going with around 10 kicks on the kickstarter. Once running it idles well. I have it idling at around 1200 rpm. At that rpm I can adjust the pilot screw (mixture screw?) and the engine will stumble if I make it too rich or too lean. However, the left carb seems slightly more sensitive to that than does the right carb.

I was thinking that the carb's slow speed function wasn't causing the sooty plugs because the engine idles well and it responds well to blipping the throttle. I assumed the carbs were going rich during open throttle acceleration during which the slow speed function of the carb is inoperative and the carb's main jet and jet needle are doing all the work and it is at that point where the engine struggles some. It continues to accelerate but not the way it should.
 
The jetting circuits overlap and work continually together throughout the entire operating range. It sounds like you have cleaned the fuel and air circuits from your description of such work performed. The ability to adjust the idle jet circuit shows that system is operating by having effect when adjusted.
Since you have a rich condition there is either too much fuel or too little air being caused by something in the fuel/carburation system. Will the bike operated with the air filters removed and if so can you ride it and check the plugs for colour afterwards.
How is the ignition system functioning? Is it still points and original coils based, or have those items been upgraded to more modern ones.
I would clean those plugs as the system will not burn off the soot if it continues to have issues that are causing that problem.
I have a spark plug called Gunderson Carb Tune that has a clear plexiglass ring that allows you to see the plug firing in operation. Designed to allow you to tune the air or fuel screw circuit to see the colour of the flame front. While it has some use there I also can use it to see what is happening with the ignition system under load vs a spark plug being tested outside the cylinder for a spark test.
 
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Flyin900 said:
The jetting circuits overlap and work continually together throughout the entire operating range.
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Ya, I guess that is true but once the butterfly valve is opened the contribution of the slow jet system is pretty minor compared to the main jet. Probably why people with bunged up slow jets can get their bikes to run but not idle.
Flyin900 said:
there is either too much fuel or too little air being caused by something in the fuel/carburation system. Will the bike operated with the air filters removed
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Yes. With the air cleaners off, the bike ran much better but still not as I would expect it to run. I've cleaned the filters but need to get them back on and try again.
Flyin900 said:
How is the ignition system functioning?
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New coils, capacitors, clean old points, all timed with a timing light. Advancer works properly according to the timing light and tach.
Flyin900 said:
I have a spark plug called Gunderson Carb Tune
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I haven't seen one of those things in years! For fun I looked it up and found that they are called Gunson colour tune now but that they are also currently not available to buy new. There's a couple on ebay for about $70...

My current game plan is to clean the plugs with a nylon brush, test it with the air cleaners off. Then put the air cleaners back on and try it again.
 
Well you doing all the right things, so it will be trying different things until it gets sorted. Gunson colour tune LOL! I bought it 12+ years ago and it was around $50.00 back then I recall.
The other way to look at the ignition is to attach a timing light and look for the beam to break up when the bike is going from idle to higher RPMS. If the light isn't pulsing uniformly steady then there is something off with the ignition part of the system. At least then you can rule out the ignition electrical section and focus on the fuel and carb setup.
 
If the light isn't pulsing uniformly steady then there is something off with the ignition part of the system
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In most cases indeed, but I've also seen an irrigular behavior due to weak detection by the pick-up
 
I'm baaack. So, last you heard from me was about a year ago. Some frustration set in so I let the bike sit so it could contemplate my threat of sending it to the junk yard. I had had it running but not up to snuff. Issues were a hesitation in acceleration, the clutch was causing the bike to seriously lurch when put into first gear, and then, it just wouldn't start. The right plug was always blackening. My diagnosis was that I hadn't cleaned the carburetors quite enough. I don't have an ultrasonic cleaner. So, I took it to a local guy who specializes in vintage Honda restoration. It took quite a while for him to finally get to work on it but now it runs great. Basically he cleaned the carbs and set them up. While he was at it I had him put on new tires. Put on a pair of Metzler Block C tires. They seem OK and look vintage. It definitely accelerates now!! I used to blast around on this thing in my teens and early 20s but at this point, not having ridden bikes for 20 years, and being 74, it's actually a bit scary!! It's also a bit squirrelly. There's a notch in the steering head bearings so I think that is causing the problem or at least I hope it's that and not me...

It starts fairly easily now, maybe even better than it did 50 years ago, and the clutch seems fine now after some adjustment.

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Good to hear it's running well now. The notchy steering is caused by flat spots on the original balls and races in the steering head. Many of us have replaced the original steering bearings with tapered roller bearings, once you do you'll never have to touch them again.
 
KHSE said:
Out of curiosity I wondered if anything ever happened on that other website that is not to be mentioned. I admit I joined it last year. I did a google search for 'Black Bomber seat hinge site:thatothersite.net' and there was a thread there about someone making repop hinges. A source called DJIA? It was from 10-15 years ago and @jensen chimed in about trying to get a couple of sets when they were discussing getting more made. There was a picture of the set and they looked different from the Clauss set. Maybe if @jensen circles around again he'll know what that was all about.
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DJIA is Clauss Studio's eeeBay name
 
Your Bomber looks amazing! Glad to hear it is running at a high level too. 👍

I have bought the complete set of seat hinges through David Silver Spares in the past. Might want to check there if you are still in need?
 
stl360+450 said:
Very cool to hear that it's running better than it did back in the day! It must be quite something to have the experience of riding the same machine after fifty years.
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Ya, it is. I told the story earlier but I'll repeat a bit here: Way back when I took a cute girl for a ride on it on her 18th birthday. A few years later we were married and we've been married now for 53 years...
 
12ozPBR said:
Your Bomber looks amazing! Glad to hear it is running at a high level too. 👍

I have bought the complete set of seat hinges through David Silver Spares in the past. Might want to check there if you are still in need?
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I'm using the ones I got but they still need to be shaved down some more as I can't easily latch the seat.
 
KHSE said:
I'm baaack. So, last you heard from me was about a year ago. Some frustration set in so I let the bike sit so it could contemplate my threat of sending it to the junk yard. I had had it running but not up to snuff. Issues were a hesitation in acceleration, the clutch was causing the bike to seriously lurch when put into first gear, and then, it just wouldn't start. The right plug was always blackening. My diagnosis was that I hadn't cleaned the carburetors quite enough. I don't have an ultrasonic cleaner. So, I took it to a local guy who specializes in vintage Honda restoration. It took quite a while for him to finally get to work on it but now it runs great. Basically he cleaned the carbs and set them up. While he was at it I had him put on new tires. Put on a pair of Metzler Block C tires. They seem OK and look vintage. It definitely accelerates now!! I used to blast around on this thing in my teens and early 20s but at this point, not having ridden bikes for 20 years, and being 74, it's actually a bit scary!! It's also a bit squirrelly. There's a notch in the steering head bearings so I think that is causing the problem or at least I hope it's that and not me...

It starts fairly easily now, maybe even better than it did 50 years ago, and the clutch seems fine now after some adjustment.

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I would use the mufflers hanger bolts to exclude the risk on cracks around that point. I usually make these holes a little larger in the horizontal direction, and put some loctite in the bolts, and not tighten the bolts too much, so the muffler weight can rest on it, but is able to move around in the horizontal direction.
 
jensen said:
I would use the mufflers hanger bolts to exclude the risk on cracks around that point. I usually make these holes a little larger in the horizontal direction, and put some loctite in the bolts, and not tighten the bolts too much, so the muffler weight can rest on it, but is able to move around in the horizontal direction.
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Hey @jensen , nothing escapes your eagle eye... Ya, I need to get back to that. The hanger hole doesn't line up with the bolt hole as you imply but also there's quite a gap between the hanger and the frame. I need to elongate the hanger hole and concoct a support coming off the frame to meet the hanger...
 
KHSE said:
Hey @jensen , nothing escapes your eagle eye... Ya, I need to get back to that. The hanger hole doesn't line up with the bolt hole as you imply but also there's quite a gap between the hanger and the frame. I need to elongate the hanger hole and concoct a support coming off the frame to meet the hanger...
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Are you sure you mounted the mufflers correctly ? The large triangular engine hanger should be places with the stepped part toward the muffler positioning the muffler closer to the frame. Are you sure you didn't switch the headers ? It is very strange that the hole of the small engine hanger doesn't align with the threaded hole in the frame, and that there is a space between the hanger and the frame.

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Both headers are very close to the engine when mounted correctly, I really don't understand how your mufflers are mounted.....
 
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