Tidying up my new to me CB450K5

spideypop

spideypop

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Joined
Jul 13, 2025
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Location
Lexington, North Carolina
Since I'm still recovering from rotator cuff surgery I'm starting to go through some basic maintenance before working on making it mine. Tentative future plans:

Electronic ignition
Trying to find a luggage rack/backrest that doesn't look ugly.
Other TBD

Today I adjusted the drive chain and rear brake pedal free play. I noticed the front brake is dragging quite a bit (yes I missed that :sneaky:) I suspect caliper piston might be sticking. Gonna do some research before I tear into it.

Nothing too exiting so far.
 
Be sure to take lots of pictures from different angles as your working, I really wish I had. Have you got a copy of the FSM and the parts manual? If not then reach out to one of the admins. Also I think LDR has a really good checklist for a new to you bike. Looking forward to following this thread.
 
RobMan said:
Be sure to take lots of pictures from different angles as your working, I really wish I had. Have you got a copy of the FSM and the parts manual? If not then reach out to one of the admins. Also I think LDR has a really good checklist for a new to you bike. Looking forward to following this thread.
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Already sent a PM for FSM, gotta send another for parts manual...didn't think about that. Forgive my ignorance, what is LDR?
 
Today I pulled the caliper assembly apart. The caliper holder and pivot pin were pretty corroded not rotating freely. I was able to knock it out, clean it up, lube it and now it rotates freely.
IMG_1366.JPG

Still not sure why the caliper is binding, I haven't pulled the pads from the calipers yet but I think the active side is sticking. Does the orientation of the disk to the calipers look odd? From the pictures I've seen, it looks like the caliper holder should be oriented on the left edge of the disk.
IMG_1369.JPG
 
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Might also be the master cylinder check/release valve is plugged so it just stays tight. Sometimes just bleeding won't clear it and it needs dis-assembled and cleaned out good. Take good pics and clean it very good.
 
ballbearian said:
Might also be the master cylinder check/release valve is plugged so it just stays tight. Sometimes just bleeding won't clear it and it needs dis-assembled and cleaned out good. Take good pics and clean it very good.
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The little orifice in the bottom of the master cylinder does show fluid movement. Would that indicate the check/release valve to be unplugged?
 
spideypop said:
The little orifice in the bottom of the master cylinder does show fluid movement. Would that indicate the check/release valve to be unplugged?
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The smaller of the two holes, yes. You can use the master to pump the piston out of the caliper, very slowly. If you haven't done one yet, it is very messy. Do it over a bucket.
You can simply try to bleed it, if that works, first.
 
ballbearian said:
The smaller of the two holes, yes. You can use the master to pump the piston out of the caliper, very slowly. If you haven't done one yet, it is very messy. Do it over a bucket.
You can simply try to bleed it, if that works, first.
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I've partially pushed it out and see a lot of crud on the side surface. I'm just gonna pull it all apart and inspect it. Thanks BB
 
Considering you are are already seeing a lot of corrosion I would recommend rebuilding both the master cylinder and caliper. Also do a careful inspection of the hoses, metal line and brake light switch to make sure there is no deterioration of the hoses or crud blocking anything. You really want the brakes to work when Mr oblivious pulls out in front of you. :oops:
 
RobMan said:
Considering you are are already seeing a lot of corrosion I would recommend rebuilding both the master cylinder and caliper. Also do a careful inspection of the hoses, metal line and brake light switch to make sure there is no deterioration of the hoses or crud blocking anything. You really want the brakes to work when Mr oblivious pulls out in front of you. :oops:
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All the lines look new and the brake light works fine so I think I'm good there.

Pulled the Caliper apart and this what I found. This is the caliper before cleaning.
IMG_1377.JPG
IMG_1376.JPG

I got all the gunk out and it still doesn't look pretty but it's a whole lot better.
IMG_1378.JPG


The piston has some pits. The piston seal inner edges still feel sharp although it is a little loose around the piston.
IMG_1373.JPG
IMG_1374.JPG

Before and after of the brake pad.
IMG_1372.JPGIMG_1379.JPG



What do you think fellas? Should I reassemble what I have or should I purchase a new caliper? Where do y'all purchase your parts from?
 
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Be sure to get the square o-ring groove completely clean before reassembling it, if the o-ring (piston seal) doesn't sit completely flat and fully into the groove it will affect the slight return of the piston when braking pressure is removed. And those pits in the piston will likely cause leaks down the road.
 
ancientdad said:
Be sure to get the square o-ring groove completely clean before reassembling it, if the o-ring (piston seal) doesn't sit completely flat and fully into the groove it will affect the slight return of the piston when braking pressure is removed. And those pits in the piston will likely cause leaks down the road.
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I think it's already leaking. I suspect the gunk buildup on the pad and inside the housing is dried up brake fluid. I'm gonna purchase a new seal and piston. I hate doing things more than once, and as RobMan says: "You really want the brakes to work when Mr oblivious pulls out in front of you."

Where do y'all purchase your parts? I see those guys in Houston as one source, are there others? I'm sure the Honda dealerships are have outrageous prices, if they even carry this stuff any more. Thanks (y)
 
Don’t discount your dealer but they will be limited on parts. I found an nos main jet set for my 73 MT250 from the dealer. There are better options than those guys in Houston. 4into1, David silver spares plus others that some other members will mention.
 
spideypop said:
Where do y'all purchase your parts? I see those guys in Houston as one source, are there others? I'm sure the Honda dealerships are have outrageous prices, if they even carry this stuff any more. Thanks (y)
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There are several sponsoring vendors you should look at when searching for parts at this link here, https://www.vintagehondatwins.com/forums/categories/sponsoring-vendors.80/

Some of the others I have used in my search for parts is 4into1, Partzilla, Northeast Vintage Cycle, David Silver Spares, VintageCB750 and CMSNL to name a few as well as EBay. Price shopping while considering the different companies shipping makes it fun as well. I ended up getting most of my front brake parts from 4into1 myself.
 
spideypop said:
Where do y'all purchase your parts?
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You're 27 posts into your time at VHT, please tell me you didn't overlook this...


Particularly the one about identifying and locating parts....
spideypop said:
I see those guys in Houston as one source, are there others?
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Only for those who are on a budget, like maybe most of us :ROFLMAO:
spideypop said:
I'm sure the Honda dealerships are have outrageous prices, if they even carry this stuff any more.
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And for the most part, they don't - simple little things like o-rings, nuts, bolts and screws cross over to many other bikes but the bike-specific parts, not likely
 
ancientdad said:
You're 27 posts into your time at VHT, please tell me you didn't overlook this...


Particularly the one about identifying and locating parts....

Only for those who are on a budget, like maybe most of us :ROFLMAO:

And for the most part, they don't - simple little things like o-rings, nuts, bolts and screws cross over to many other bikes but the bike-specific parts, not likely
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I repent ;)...yes I did go through the welcome package.
 
RobMan said:
Be sure to take lots of pictures from different angles as your working, I really wish I had. Have you got a copy of the FSM and the parts manual? If not then reach out to one of the admins. Also I think LDR has a really good checklist for a new to you bike. Looking forward to following this thread.
Click to expand...
I know I copied down LDR's checklist a month or so after I bought my CB 350. It's a good list. And.. as I do the tasks, I write down the details of my bike so I have one place to look for all information the next time I do it. Like gaps, torques, and part #'s and brands for replacement items. That list is helping me be a more organized Maint. dude.
 
For $126 the completed kit is a deal with 10% off. Your starting with all new pieces and not dealing with 50:year old parts. Your budget and wallet will dictate if this is an option for you.
BTW your original caliper was still not clean enough and the pitted piston could be an issue too, hence the leaking from the rebuild.
The seal groove must be pristine inside with no evidence of any dried up gunk or the new seal will bind on the piston or leak. The bore needs to be much cleaner than what you are showing in your pics.
 
$81 US dollars with discount, but + for shipping. Flyin900 is right, that would be best for sure. Just a piston and seal would be more than half that.
 
I got the front brakes back together and they work as they should now. Happy I replaced with all new components.

All pretty and shiny.
IMG_0560.JPG



I used a mighty vac to do the majority of the bleeding, then finished off the old fashioned way.
IMG_0561.JPG


Finished product...now just need to wait till my shoulder heals to take it for a test ride. Gotta trailer it to HP Thursday so they can do a VIN search, because it came from out of state. Not sure why, never had to do it with other vehicles I've purchased out of state???
IMG_0562.JPG
 
spideypop said:
I used a mighty vac to do the majority of the bleeding, then finished off the old fashioned way.
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Remember to put the 6mm lock nut back on the adjuster screw and snug it down to retain the adjustment.
spideypop said:
Gotta trailer it to HP Thursday so they can do a VIN search, because it came from out of state. Not sure why, never had to do it with other vehicles I've purchased out of state???
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It's a great question, maybe the others were cars with all modern VINs?
 
ancientdad said:
Remember to put the 6mm lock nut back on the adjuster screw and snug it down to retain the adjustment.

It's a great question, maybe the others were cars with all modern VINs?
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Got the lock nut back on.

Apparently in NC anything purchased out of state and reregistered here that is older than 1981 needs to go through a VIN search. The reason they say is because it has fewer than 17 numbers in the VIN
 
I noticed something a couple weeks ago that seemed a little odd. I had run the engine for a little while (not riding it), just getting to know the bike better. I shut it off and closed the petcock, I could see residual gas in the clear line going to the right carb. When I came out the next day there was no gas in the line. (I had previously checked the oil level when I got it home and it read right to the top line)

After I got the front brakes fixed, I took it for a little ride, brakes worked great, everything seems to run smoothly. Put it away and closed the petcock. Again there was residual fuel in the line. Came out today...no fuel in the line. Checked the oil again and this time it read quite a bit above the top line. Took and sniff and noticed the faint smell of gas.

I Changed the oil, definite smell of gas in the oil. I drained the carbs and pulled the bottoym of the float chamber off and I saw nothing out of the ordinary. The floats moved freely and I didn't see any obvious signs of damage/cracks. The float valve looked like it moved freely (no sticking). I checked the petcock and it is not leaking.

At this point I need to re-educate myself, but it seems that something in the carbs is allowing gas to run into the cylinders after the bike is shut off.

While I'm figuring out what is the cause of this mystery, I'd like to ride it around a little bit. Would I be doing any damage if after a ride I shut off the petcock to drain the carbs before shutting off the bike?

Thanks fella's
Mike
 
spideypop said:
I noticed something a couple weeks ago that seemed a little odd. I had run the engine for a little while (not riding it), just getting to know the bike better. I shut it off and closed the petcock, I could see residual gas in the clear line going to the right carb. When I came out the next day there was no gas in the line. (I had previously checked the oil level when I got it home and it read right to the top line)

After I got the front brakes fixed, I took it for a little ride, brakes worked great, everything seems to run smoothly. Put it away and closed the petcock. Again there was residual fuel in the line. Came out today...no fuel in the line. Checked the oil again and this time it read quite a bit above the top line. Took and sniff and noticed the faint smell of gas.

I Changed the oil, definite smell of gas in the oil. I drained the carbs and pulled the bottoym of the float chamber off and I saw nothing out of the ordinary. The floats moved freely and I didn't see any obvious signs of damage/cracks. The float valve looked like it moved freely (no sticking). I checked the petcock and it is not leaking.
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Smart to pay attention to it, and glad you changed the oil right away. Petcock not leaking, but does it completely shut off when in the off position? And, if it's an aftermarket petcock it might be marked backward - reserve and off may be opposite the markings, we've seen it before.
 
ancientdad said:
Smart to pay attention to it, and glad you changed the oil right away. Petcock not leaking, but does it completely shut off when in the off position? And, if it's an aftermarket petcock it might be marked backward - reserve and off may be opposite the markings, we've seen it before.
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I'm assuming it's not original. Not sure if it's aftermarket or not. With the fuel line disconnected, the closed position has no fuel coming out. Both the on and res positions have fuel coming out. Closed faces forward, on faces down, res faces backward. Pic below is a box with an old petcock in it that came with the bike.

IMG_1424.JPG
 
Sounds like you may have two problems, the shutoff valve may be leaking but the main one is the needle and seat is not closing properly on the right carb allowing fuel to overflow in the carb and then run into the engine. This could be caused by a bad needle, seat, float not adjusted correctly, float leaking or the float hanging on something. Examine the needle and seat and see if you see any defects, if the needle has a rubber tip see if there is a indentation mark around the tip where it rests in the seat this can cause leakage. Also beware of aftermarket carb kits.
 
RobMan said:
Sounds like you may have two problems, the shutoff valve may be leaking but the main one is the needle and seat is not closing properly on the right carb allowing fuel to overflow in the carb and then run into the engine. This could be caused by a bad needle, seat, float not adjusted correctly, float leaking or the float hanging on something. Examine the needle and seat and see if you see any defects, if the needle has a rubber tip see if there is a indentation mark around the tip where it rests in the seat this can cause leakage. Also beware of aftermarket carb kits.
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I don't think the shutoff valve is leaking. I pulled the bottom of the float housing off both carbs this morning and there was no evidence of fuel. (after draining them yesterday). Also, if it were leaking and there were no other issues with the carb internals, wouldn't I see evidence of leaking fuel out the overflow lines? (I checked yesterday and they are clear)

As far as checking the internals of the carbs, that's on my ever expanding todo list. I'll no doubt do a rebuild eventually so I have known good parts. I'm curious why you singled out the right carb in your comments? Is it because it has a shorter fuel line from the shutoff valve?

Right now I'm just going to run the carbs dry after each ride. I'm still getting used to being back on a bike after 40 years.
 
spideypop said:
I could see residual gas in the clear line going to the right carb. When I came out the next day there was no gas in the line.
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Your comment here is why the right carb is more suspect to me, if the needle valve was holding properly the line would still be holding fuel overnight. Good check on shutoff valve, I was concerned a very slow seep was allowing fuel past the shut off valve and then past a defective needle valve overnight adding to the oil level. BTW are you seeing any fuel come out of the overflow lines at the bottom of the carbs?
 
spideypop said:
I don't think the shutoff valve is leaking. I pulled the bottom of the float housing off both carbs this morning and there was no evidence of fuel. (after draining them yesterday). Also, if it were leaking and there were no other issues with the carb internals, wouldn't I see evidence of leaking fuel out the overflow lines?
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On most other Hondas, or when a carb is truly flooding, then yes - but the 450 carbs are odd in that respect, they can slowly seep fuel past the float needles, up into the venturis and down past an open intake valve, then past the rings and into the bottom end. That's why it's so important to know that the petcock fully shuts off, and to always remember to shut it off when you turn off the key.
spideypop said:
Right now I'm just going to run the carbs dry after each ride. I'm still getting used to being back on a bike after 40 years.
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Good way to avoid until you go back into the carbs.
 
ancientdad said:
On most other Hondas, or when a carb is truly flooding, then yes - but the 450 carbs are odd in that respect, they can slowly seep fuel past the float needles, up into the venturis and down past an open intake valve, then past the rings and into the bottom end.
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Thank you for the explanation because I was also curious why fuel was getting into the bottom end without making a mess out of the overflow tube first.
 
RobMan said:
Thank you for the explanation because I was also curious why fuel was getting into the bottom end without making a mess out of the overflow tube first.
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I'm not sure why, but it seems like the 450 has been susceptible to the problem more easily over the years than the others. I remember the first graphic example of it I saw in 1972 when I worked at Honda Village (where your bike came from). A top end rebuild was done on a CL450 and it got parked in the back of the service area. Mechanic forgot to turn off the petcock and the customer didn't come pick it up for a month or two. When he did and someone went to get it for him, they fired it up and the engine started blowing fuel/oil mix out of the breather tube in a hurry.
 
Just picked up a set of JIS screw drivers from O'Reilly's for $26. Not sure how good they are but at half the price of everywhere else plus a lifetime warranty, I thought I'd take my chances.

IMG_1429.JPG
 
spideypop said:
Just picked up a set of JIS screw drivers from O'Reilly's for $26. Not sure how good they are but at half the price of everywhere else plus a lifetime warranty, I thought I'd take my chances.
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I'm sure they're fine for screws that aren't too tight to get loose with just the screwdriver handle leverage, but when you need a little bit of extra force then a T-handle is the way to go. Or the Vessel Megadora Impacta series screwdrivers which include an impact-driver mechanism in them as well.
 
So I'm starting to go through the "new to me checklist" (BTW thank you for that excellent document) and I have a question...is that a "living document"? If so, can I suggest adding to the Front fork and steering section, to check the rubber cushions connecting the handle bars to the triple-tree? During my last ride, my steering felt just a little sloppy. So I tightened up the connecting bolts and now it's even more sloppy. I'll be ordering a set of them today.

The tidy-up continues
 
spideypop said:
So I'm starting to go through the "new to me checklist" (BTW thank you for that excellent document) and I have a question...is that a "living document"? If so, can I suggest adding to the Front fork and steering section, to check the rubber cushions connecting the handle bars to the triple-tree? During my last ride, my steering felt just a little sloppy. So I tightened up the connecting bolts and now it's even more sloppy. I'll be ordering a set of them today.

The tidy-up continues
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I've up dated the checklist, thanks for the suggestion.(y)
 
In retrospect I probably should have named this thread something else. A lot of little interesting issues, still no regrets.

I finally got the handlebar dampers installed, definitely a difference. The old ones I assume were original and had seen better days. One of the lower handlebar holder's threaded end was bent, which makes me wonder how on earth that would happen??? I don't see any other obvious signs of damage elsewhere. But it makes the lower rubber cushion not seat straight so I temporarily have compensated that with a half washer spacer to correct for the bend to allow it to seat straight. Not sure where or if I can source a new set, I'm sure this is a NLA part.
IMG_1485.JPG

After R/R of the of the front brake slave cylinder, the master cylinder started to leak (or maybe it was and I never noticed before). So after some self deliberation I decided to just replace the entire master cylinder with a brand new instead of chancing rebuilding the old one. So now the entire front brake system, including lines are new.
IMG_1486.JPG

Another interesting finding...I could never get the left rear view mirror to adjust to be able to see properly behind me. I pulled the clutch mechanism off and noticed there's a pin that locates it to the handlebar. I'm assuming the handlebar is not original and whoever drilled the hole to locate the pin did it wrong, so the assembly was positioned too far down. I drilled another hole to position it up more and viola now I can see behind me :rolleyes:.

I've decided to name the bike Frank...short for Frankenstein. The frame is 1972, the engine is 1974. When I finally got through the convoluted process of registering it here is NC, DMV here says it's a 1973 according to their computer??? The Tenn pink said it's a 1972...go figure :sneaky:

Hoping to get to timing chain/points/valve adjustment today.
 
The frame number would tell the story of which K series it is since back then new bikes were titled the year sold, which probably explains why what should be a K5 was titled '73.
 
I see a couple of positives aside from the EI, the index mark on the usually-covered exhaust valve adjuster shaft is pointing the right way, and the visible JIS screw in the cam bearing cover (points base) looks to have been unmolested. On the down side, Tytronic EIs are not known for their longevity, at least in the examples we've seen discussed here. Hopefully yours works and lasts.
 
ancientdad said:
On the down side, Tytronic EIs are not known for their longevity, at least in the examples we've seen discussed here. Hopefully yours works and lasts.
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I don't know if it indicative of its longevity, but the gentleman who I purchased it from Owned the bike for 8 years. I Just talked to him and he said he purchased it like that.
 
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spideypop said:
I don't know if it indicative of its longevity, but the gentleman who I purchased it from Owned the bike for 8 years.
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Yeah, it looks pretty fresh so I'm guessing it isn't 8 years old. But, ride it until it doesn't work anymore and get that free value from it for sure.
 
Well I'm not sure what I did wrong but after adjusting the cam chain there is a definite clatter that wasn't there before.

I followed the FSM exactly (with Bill Lane's annotations). I did not follow the "common" instructions on the inter webs. The engine was cold and there was definite compression in the left cylinder when I aligned the LT timing mark.

I rotated the crank a number of times to feel for compression before loosening the adjusting screw. There was no audible clunk. When tightening the adjusting screw back in, I only screwed it in by hand until I felt resistance, then tightened the lock nut.

It was a challenge to keep the crank in proper location, it wanted to slip past TDC. I also noticed after the adjustment, with the exhaust valve cover and rotating the crank, the chain did not have a consistent tightness throughout it's rotation.

When I started the engine, I didn't rev it and could here a tone change when oil was pumping to the top.

There is one note I don't understand in the FSM...N O T E : (l) lt should be noted that the tensioner pushrod should not be pushed in with finger and the cam chain should not be tightened excessively. This shortens the chain service life and lessens the guide roller durability.

Should I do the procedure over...and yes I will wait until I get someone's input. Thank you all in advance for helping me with my lack.
 
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spideypop said:
When tightening the adjusting screw back in, I only screwed it in by hand until I felt resistance, then tightened the lock nut.
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This is the problem. Logically, if you had to use a wrench to loosen the lock bolt, you can't finger tighten the lock bolt afterwards. While the overall instructions might not be spelled out exactly, the lock bolt is intended to lock down the tensioner push bar AFTER adjustment. If you only finger-tighten it, then lock it at THAT position with the lock nut, you've effectively left it with a lock bolt not locking it in position. The load on the cam chain to rotate the cams while opening valves causes the chain to push back against the tensioner roller and therefore the tensioner push bar, and the tensioner is being pushed backwards while the engine is running, effectively creating slack in the chain which is what you're hearing.

So, re-do the adjustment and tighten the lock bolt this time before you tighten the lock nut.
 
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