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1972 CB450 -- Slight Build

JustinF25

Well-known Member
Joined
Aug 2, 2022
Total Posts
90
Total likes
38
Location
herkimer, NY, USA
I have a 1972 CB450 that I purchased recently. The bike has 5300 miles on it, sat in a barn from the mid 80s till 2014. The PO rebuilt the front brakes and got running (roughly though). I spent time learning and wrenching on what I felt comfortable tackling (i.e.: oil change, allen head motor hardware, new clutch, clutch cable, throttle cable, regulator/rectifier combo, condenser, new turnsignals, petcock, starter solenoid, cleaned the tank, spark plugs, fork oil, clutch adjuster and adjuster spring).

Now the bike is at a shop having the carbs cleaned and adjusted...Im just not familiar with carbs and havent watched enough youtube videos yet to feel confident doing them myself.

Anyways, Id like to make a few changes going forward but not many because I like the look of the bike now. I have a 2 into 1 exhaust that I will be cleaning up and installing. I assume Ill have to re-jet the carbs and that will be my "intro carbs 101".

Id also like to put lower bars on from a 400.

The last big change Im trying to decide upon is doing a front end swap to a USD modern bike, or, keep the original front end and purchase a wider front rim to accommodate a wider front tire? These are both for aesthetic purposes really....
I have a BMW F900R to ride when I really want to crank through the local gorge/twisties. Any thoughts on my plans..one way or the other... ? Thanks Guys
 

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Your bike looks really nice (if only it had a front fender, even a CL fender). Looks like the return spring is missing for the rear brake pedal, or it is unusually bent, it's sitting quite low in the pic above. You may get away without any rejetting if the pipes aren't overly loud. I'd put the pipes on and ride it first, then if it seems to run well in all ranges I'd do a plug chop at higher rpm, wide open throttle, and see what they look like.

4into1 has the CB400F bars for a good price, I have them on my 450 - https://4into1.com/chrome-handlebars-53100-377-000-honda-cb400f-1975-1976/
 
Thanks, I feel like this was a relatively "easy" bike to start off my first vintage bike build. I actually do have the original front fender, it will be a tight fit with the 100/90/19 Metzler on the front. The bike came with the fender off.
Also, I did address the rear brake lever issue already, (MAN- you notice details! LOL), the PO was using a zip tie attached to the spring to allow him to adjust the lever down beyond stock. I took the zip-tie off and re-adjusted the spring so it is now normal.
Hopefully, the bike will run fine with the 2 into 1 exhaust, it does have a baffle in it. Lastly, thats a great price for the CB400 bars! thanks for the link.
 
I'll say that going to a wider front tire will slow the steering response, you might make a few runs with the +1 oversize front tire you have now before opting to go wider.
 
Thanks for the tip. I guess there’s no real hurry to do anything, so it’s probably wise for me to get a few rides in before deciding.
 
Thanks for the tip. I guess there’s no real hurry to do anything, so it’s probably wise for me to get a few rides in before deciding.

Absolutely, consider a few rides before starting work as a shakedown to get a feel for what the bike might need as well as how it handles prior to any mods. As far as details are concerned, that brake pedal was easy - I didn't even have to enlarge the picture, but then again I've been in the mechanical field for most of my life too so I better notice stuff!

BTW, the 450 is only "easy" if you don't have to go into the engine as a first vintage build... not that they're tricky, but the top end of the engine is pretty unique and they can be challenging for those unfamiliar. Which brings me to this below - I hope you saw it in my Welcome Package of links, but in case you didn't I'll put it here

https://www.vintagehondatwins.com/f...mportant-DOHC-450-and-500T-warmup-information
 
coil/cap testing ['76 cb500t]

My CB500T wouldn't fire, even though a plug tester showed spark (maybe weak and/or intermittent?) on both sides. I had already replaced the condenser and plugs, but not plug caps. I bought a set of cheap "universal" coils off of eBay and the bike now runs, but the coils aren't wired right, don't fit the OEM bracket, and I don't feel like trying to make them work. The only actual replacements I've seen are from 4into1 and run about $70 for the pair, which I'd really rather not spend if I don't have to. I wanted to try replacing the caps first, but I can't find any (I don't think the caps on the coils I bought are meant to be removable/replaceable and I want to get my money back on them). What caps, preferably 120* degree angle and non-resistor, can I get? What is the proper way to test the coils with the caps removed? I see a bunch of references to testing them, but I couldn't find the actual procedure spelled out anywhere.
 
Correct plug caps would be VBF or VZF as an alternative
V= 120 degree, B= 14mm plug thread, F= terminal end, Z= 10, 12 or 14mm plug thread Kind of a one size fits everything
VBF caps aren't sold in the US. Here's a source https://www.gpwholesale.com.au/prod...g-finder/1PVBF--ngk-plug-cap-vbf-non-resistor or http://www.nowramotorcycles.com.au/part/honda/VBF Both in Australia

Secondary coil resistance is checked by negative probe connected to the grounded mounting lug, positive probe inserted into the wire making good contact with the core.
 
...
VBF caps aren't sold in the US.
...

Well now I feel better about not being able to find them. :lol: Thanks for spelling all that out, I appreciate it. I got almost exactly 10K ohms resistance (I think it was K, I forget now which range I had my meter on at the time) on both coils and really weird numbers on the caps by themselves, so I ended up doing surgery on my cheapie set to put those caps on my old coils and then the bike started and ran fine.
 
Well now I feel better about not being able to find them. :lol: Thanks for spelling all that out, I appreciate it. I got almost exactly 10K ohms resistance (I think it was K, I forget now which range I had my meter on at the time) on both coils and really weird numbers on the caps by themselves, so I ended up doing surgery on my cheapie set to put those caps on my old coils and then the bike started and ran fine.
Yeah, with NGK replacing B8ES with the BR's this is a problem. Took a few days of searching to find the LBF caps in France but they don't handle the VBF. You could email them and see if they could supply them https://www.motodak.com/
 
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Take a look at the caps. They may have removable inserts that you can disassemble to remove the resistors.

How to modify resistor plug caps

That was helpful, thanks. One of my bikes (I think the 350) has a slotted plug connectors that unscrew to get to the resistor, but I didn't know the 500 caps could be disassembled from the other end. One of them was completely missing the spring and the resistor was all corroded and jammed down into the cap, so that was probably the problem. The other one was in decent shape, so I'm going to try and rebuild them both without resistors and see if they work.
 
Update: I got a #10 3/4" brass screw from the hardware store, and after cutting the head off of it it's a perfect replacement for the 5k resistor in the cap and only has about 1 ohm resistance. I also got a #1 spring and cut it match the length of the remaining spring I had in the other cap (I didn't measure it, but maybe 5/16" long or so?). After reassembling the cap I got about 10 ohms of resistance from one end of the cap to the other and it's running like a top now. Unfortunately I'm not getting any continuity in the other original cap after doing the same thing on it, is there anything obvious that I'm missing, or is it well and truly dead? I've got the plug end, spring, screw, and threaded end, I'm wondering if I'm missing something in between the plug end and the spring, or if it's deteriorated/broken.
 
take the spark wire off and test it for continuity. You may need a new wire. Or maybe clip off an inch off the wire and reconnect to the cap.
 
take the spark wire off and test it for continuity. You may need a new wire. Or maybe clip off an inch off the wire and reconnect to the cap.

Sorry, I meant this is with the cap removed from the coil. I'm testing from the threaded bit to the plug connector.
 
Hey Guys,

currently installing a new set of carbs along with the 2 into 1 exhaust shown above. Going with a pair of Mikuni carbs. Once I get this all dialed in, Id like to get the stock seat shaved down for a slimmer look.
Also now contemplating a electronics tray to hide everything. Any one who can point me to other builds or posts about the electronics tray and relocation of everything would be appreciated....Thanks
 
Hey Guys,

currently installing a new set of carbs along with the 2 into 1 exhaust shown above. Going with a pair of Mikuni carbs. Once I get this all dialed in, Id like to get the stock seat shaved down for a slimmer look.
Also now contemplating a electronics tray to hide everything. Any one who can point me to other builds or posts about the electronics tray and relocation of everything would be appreciated....Thanks

Any progress since we last saw you almost a year ago? I mean, this is a build thread...
 
No progress other than what I just posted. Spent my fall/winter/spring working as normal and playing in an adult hockey league. Since the weather has warmed up, it’s time to get the bike up and running 100%.
 
Good, glad we didn't miss anything. I know life gets in the way of our addiction, so be sure to update as you have time to get more done. (y)
 
Hey Guys,

currently installing a new set of carbs along with the 2 into 1 exhaust shown above. Going with a pair of Mikuni carbs. Once I get this all dialed in, Id like to get the stock seat shaved down for a slimmer look.
Also now contemplating a electronics tray to hide everything. Any one who can point me to other builds or posts about the electronics tray and relocation of everything would be appreciated....Thanks

No personal tips on hide the goodies or a tray but you may want to check out Texavina seats for lots of ideas or to avoid the unknown shaving a stock one. There are others here who have done mods and might chime in if you post your plans.
 
I'm a pretty firm believer in getting it running as it was originally built (or as close as you can get without spending stupid money) before you start messing around to try and extract more ... something. I think I'm not alone in that idea.
 
Update on my bike:
Mukini VM32 were installed and jetted to match the vintage 2 into 1 exhaust that was found on eBay.
The mechanical advancer and points plate were removed and a digital Ignition was installed, this alleviated the random high idle and has given great throttle response so far. I had a great mechanic that worked to get everything dialed in. So far the bike is running great. Now I’m more confident that this bike is worth moving forward with.

Ignition info:
Digital Ignition Systems
ELEKTRONIKI
SACHSE
www.elektronik-sachse.de
 
Firstly, glad you have a skilled mechanic to integrate all those mods.

Those SACHSE ignitions are interesting from the advancer standpoint. Some, I've heard relocate to the crank from the camshaft for more accuracy. Due to the cost, not many go that route, but will love to hear your further comments on it.
 
I will report on how the ignition works out over time. Right now it starts right up, pulls hard through the gears, and sounds great too. Honestly, I was surprised I havent read more about the ignition on this site prior to buying it...seems like Charlies place, Pamco and Tytronic get all the attention.
The neighbors may not like the new exhaust, but its not completely obnoxious.
Currently the side covers are off due to the pods, so this weekend I want to install the pods I purchased from Common motors, which are supposed to fit. We will see...
 
I had forgotten about that ignition, though I had heard of it. It's been long enough that I did not remember it had electronic advance, which is what I want so the stock advancer can go away along with the wear issues that come with it. It's pricey though at about $415 US, about double what you can get some of the stock advancer-based units for.

I would be interested to hear how it performs.
 
This is the instruction pamphlet and the parts the mechanic removed inorder to install the ignition. The springs on the mechanic advancer were very weak. I read through the instructions quickly yesterday, but will definitely familiarize myself with them more moving forward. I originally was planning to go with Charlies place, but Im glad (so far) that this was the route the mechanic preferred.

ignition.jpg
 
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Any suggestions on a pod that will fit behind the factory side covers when running VM32 mukini carbs?….my side covers are mint and I’d like to use them. Thanks
 
There are pods available (4-into-1) for the stock carbs that come with a couple of PVC tube spacers and washers to mount the covers without the airboxes. I could post a picture if you like.

The diameter of the vm32 carbs is different than the stock carbs as I recall, so make sure you get the right size pods. You could screw the mounting shafts into the battery box without the air boxes and then measure the free space behind the carbs. That will tell you how much length you can handle with the pods.

Addendum: I have the kit and I have vm32 on hand as well, so I just took some measurements.
  • The outer diameter of the vm32 air side is 58mm.
  • The pods in the kit I mentioned are about 165mm long and the diameter of the filter section is roughly 70mm.
  • The PVC spacers are 65mm long and the pipe has an ID of 7mm and an OD of 14mm. The thick wall makes for better support with the washers.

krzFoeD.jpg


 
Remember that the kit was intended for stock carbs, so the filters provided will not mount onto the vm32 carbs. I would suggest making your own spacers from stuff at a hardware store and using the measurements to select an appropriately sized pod.
 
With the kit, do the covers still press into the two mounting tab holes at the top? It seems like the center bolt and the spacers wouldn’t be enough support.

Right now the front of the pod “cone” hits the side of the cover….not far from the carbs.

I could certainly make the spacers…thanks to your measurements. Thanks again
 
They do press in. If you get something of similar dimensions to what is in the kit, but large enough at the throat to mount on the vm32 I think it will fit, but, obviously, I can't be sure.

The purpose of the spacers is to make sure the threaded mounts are under tension, so they won't back out due to vibration. It should be enough support for the covers when combined with the two tabs up top. And you can eyeball the size of the washers, so I would definitely make the kit yourself.
 
I took the bike out for another rip around town and local highway last night. She revved well through the gears and dropped down to idle at the stop lights, as it should. I think Im going to use the measurements Stl360 supplied to make the spacer kit. Then Im going to modify a pair of ebay sidecovers so they clear the existing pod filters. With the small amount of room between the carbs and the side covers, itll be very diffcult to find pods to fit behind the covers (unless they are the pancake ones). My plan is to enlarge the "curved" area on the leading edge of the side cover around the pod shape. Below is a pic with the new exhaust, carbs and pods.

bike 2023.jpg
 
Can someone verify what color my bike is? CNdy garnet brown, maybe? …I have modified the side covers I purchased off eBay, to fit around the pod filters. However now I need to paint them to match…I also need to find the rubber grommet piece that is usually on the large hole in the cover…any help Honda pros?
 
Hey everyone, I spent some time in the garage over the past week. I modified a set of side covers I purchased on ebay, sand blasted/ primed/ painted them. The color is nighthawk black pearl, which shows more blue pearl than I anticipated. I thought it would be too difficult to match the 51 year old brown color. Its was duplicolor paint with a K2 clear over top. I also installed new coils, which seemed to help really steady the idle. So far the Elektronik Sachse ignition has been performing great.
 

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I recently purchased coils from 4into1.com for my 72 cb450. They were approximately $56 or so. Would these have the resistors built into the caps?

I went to their site to ask, but they mention that they don’t answer technical questions.
 
The easiest way to find out for sure would be to measure the resistance of the cap with a meter. I see that 4-into-1 is still showing some tune-up kits that come with B8ES plugs and, presumably, resistor caps, so it could go either way.

Feel free to ask questions like this in your build thread. It will still be seen and get answered without shifting the focus on an existing thread.
 
Based on the fact that 4into1 sells replacement parts based on OEM specs or intent, I'd believe the plug caps that come with the set of coils would be resistor and as Brody mentioned above, the fact that B8ES non-resistor plugs come with the set should confirm. Of course, at some point the B8ES plug supply of theirs will run out and they will likely ship BR8ES so the change could happen any time and they might not change their listing on the website accordingly right away.
 
Thanks for the replies. Sorry for posting here and not my build thread, still figuring out what works best on this site. The coils on my bike were original and I was running a resistor plug. I replaced the coils with the ones from 4 into 1 and ran the same plugs, then fouled the plugs with in a short distance. Is it reasonable to think that, the spark is now different with a resistor plug and resistor cap....and cause the fouling?....I do still have the original caps. So I could swap just the caps and see if that does the trick or find non-resistor plugs...or take the resistor out of the new cap. A few options I guess.
 
Thanks for the replies. Sorry for posting here and not my build thread, still figuring out what works best on this site. The coils on my bike were original and I was running a resistor plug. I replaced the coils with the ones from 4 into 1 and ran the same plugs, then fouled the plugs with in a short distance. Is it reasonable to think that, the spark is now different with a resistor plug and resistor cap....and cause the fouling?....I do still have the original caps. So I could swap just the caps and see if that does the trick or find non-resistor plugs...or take the resistor out of the new cap. A few options I guess.

If the old caps were original to the bike they should be resistor caps as well. If you have a multimeter, I would start by finding out exactly what caps you have. If you only have resistor caps, then I would either source non-resistor caps or non-resistor plugs. One option in the post B8ES era is the Nippon Denso W24ES-U. I am running them in my CB450 right now.

Maybe this portion of the discussion should be moved to Justin's build thread?
 
Thanks for the replies. Sorry for posting here and not my build thread, still figuring out what works best on this site.

Remember, there are no absentee admins here, and we can do whatever we need to do when it needs to be done (well, except in the middle of the night US time, LOL).

I merged your electrical thread with your build thread, all right here now.
 
I’ve been putting miles on my bike running the original exhaust, the new coils from 4into1, and the correct non-resistor plugs. I also changed the main jet from 185 to 165 after doing plug chops….and adjusted the clip on the needle, which fixed my fouling issue. But, me being curious by nature…I put the 2 into 1 exhaust back on after removing half of the baffle, hoping to make it less restrictive. The bike is running alittle rich again. IM running a 6dh4 needle in the mikunis…I’m considering change the needle to a h7. Any thoughts ? Bike starts and idles great.
 
Is it fouling the plugs with the 2-1 exhaust? Is that the indication of rich you're using? Or additional plug chops? Or something else?

The mixture can change a lot based on the throttle position and it could be lean in some positions and rich in others. That's why there are so many different points of adjustment involved in tuning a carb.

What clip position is the needle in now? Before putting in a fatter needle you could try lowering the needle (raising the clip) one slot at a time. Or is the needle as low as it can go already?
 
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Thanks for the interest guys. The plugs were getting very sooty with the 2 into 1 exhaust and the original setting of the carbs. I installed the stock exhaust and moved the clip up one position to the #1 spot (top of the 6dh4 needle).
This made a night and day difference. The plug was no longer sooty at all after a normal ride, which included cruising around between 1/2 -3/4 throttle and some wide open short bursts.
So, since I like the look and sound of the 2 into 1 exhaust, I took the baffle out, cut it down and re-installed it. The plugs after the same ride ( now with the 2 into 1 exhaust and clip at #1 position), are now alittle more sooty...but not as bad as before.
Since Im now at the top of the 6dh4 needle, Im thinking of trying a different needle to give me more room for adjustment in the 1/2-3/4 settings.
 
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