1973 CB350F - Project Build Thread

[silentsvn]

Hey guys,

I wanted to start a build thread for my new project as i'm sure I'll have some questions along the way. I have been working on the bike for a few weeks and have some progress made.

Background:
I picked up this 1973 CB350F in pretty meh condition. The bike is on its 6th owner and it seems to have a mismatch of parts and fixes all of which i'm not sure if they are right safe or not. She would start on 2nd kick and runs solid which is a good sign and exhaust was running clean. Although it was missing some parts, namely master cylinder and new front brake lines since they seemed to be clogged. The steering was a bit "notchy", tires were shredded, petcock needed rebuilding and the tank needed a good inner bath. There are also a lot of not so nice parts on the bike that I need to replace, ex EMGO pods, but the budget can only stretch so far for so long, the bike runs so right now if it ain't broke I ain't fixin it – right now at least.

So all that and it needed a few items to make it road worthy in my opinion and legal.

This made the bike in perfect condition for the plan I had which was to get all the heavy lifting out of the way, paint it, get it on the road and ride he shit out of it over the summer and just enjoy it.

What I want to do:
My plan right now is to tear into the motor over the winter, perhaps swap with a 400F motor, increase the performance and reliability and just have fun with a super light bike. All while keeping the cost down and learning a vintage Honda along the way. I know from my other bikes that it takes a while to get acquainted with an bikes mechanics so there are going to be a few "oh shit" moments along the way.

So all that being said here are a few pictures of where I am at now.

Any tips and tricks would be much appreciated.

Purchased:

Teardown - Part 1
I wanted to get right into the bike and see what was needed and start making a list of items that need replacement and or work.

Teardown - Part 2 - Front End & Polishing
Teardown of the frontend for polishing of the forks, rebuild of the brake brake lines, new front tire and All Balls tapered neck bearings.

Decided to polish the rear drum cover as well.

Fitting New Exhaust
So the exhaust sounded great and I found out why, there was a huge seam that was ripped in the bottom of the left and right pipes that were on the bike, so need to replace. I couldn't find a place local that would weld the pipes back up and re-chrome. Everyone said it would not work and contaminate the tanks on re-chroming. OPtions I had were limited so Mac 4-into 1 will be used. Im having some serious issues fitting the new exhaust since the one I took off had no gaskets. This 4 into 1 is hanging out seriously far to the right and just doesn't look correct.

Paint Time - Part 1
Time to tackle the paint and some of the cosmetic work. Shaved off the Honda badges and filled in the spots on the tank. I tried a few different layouts and found one that I was happy with. I actually kinda liked them all, but one fit the look I was going for.

Paint Time - Part 2
Paint is complete Im pretty happy with it overall. Color is spot on to what I wanted just something classy and clean.

I couldn't resist just to see what it all looked like.

So this is how she sits as of today. Sonreir has made me a wonderful cleaned up new harness to upgrade the wiring. I have a laundry list of misc small tasks to do to get her up and running again.

More soon....

 

[carnivorous chicken]

Looking good.

If you are interested in what it would take to replace the engine with a CB400F, I wrote a pretty lengthy post on the process. I understand the desire to have the extra ccs and gear, and I did it because my 350F engine was shot. If yours is running well, I'd think long and hard about replacing it. Those 350F engines run like tops when they're in good shape -- I've had a mostly stock one for 15 years and it is a blast to ride.

 

[DesertLab]

NICE!

 

[BCBarker]

that paint work is SICK! love a 350F!

 

[silentsvn]

Looking good.

If you are interested in what it would take to replace the engine with a CB400F, I wrote a pretty lengthy post on the process. I understand the desire to have the extra ccs and gear, and I did it because my 350F engine was shot. If yours is running well, I'd think long and hard about replacing it. Those 350F engines run like tops when they're in good shape -- I've had a mostly stock one for 15 years and it is a blast to ride.

Thanks - i'll have to check out your thread. Originally I was thinking just pulling the motor over the winter and porting & polishing the heads to make them flow just a bit better. The guy who I bought this from said the motor was gone through, but I dont really trust that and don't know where down the line that was done. I know the heads are an area or restriction with these motors so a P&P and a possible a better cam might just make its way in there. I do need to upgrade the ignition too.

I understand this isn't a race bike and never will be, way better options for that. Its fun to squeeze out just a bit more with what I got. Or to find a donor 400F and bore it out to 466cc but at that point might as well just find another project to make a speed machine.

If I could just figure out this stupid exhaust I would be so much happier. The hanger on the muffler seems to be 120º from where it needs to be to make the exhaust hang nice with a slight up slope without interfering with the brake lever.

Also a question:
The front axle seems to float laterally about 1/2" that doesn't seem right and taking it all apart I bagged and tagged everything. I checked the diagram and all parts seem to be accounted for. The forks are straight and the disc lines up in the brake. Is there a spacer that is missing or is the play just built in?

 

[carnivorous chicken]

Exhaust seems a bit of a pain, but not a tough fix if you can fab up something to bridge the difference.

As for the front axle, if I remember correctly there is indeed a spacer in there. I can verify when I get home...

 

[carnivorous chicken]

And here's this so you don't have to go searching for it:

I'm finishing up a build with a CB400F engine in a CB350F frame. Yes, they're compatible. I like the CB400F front pegs much better; they're set back about 6 inches. Hate to give this away, but they will also work on 550s and I'm guessing 750s, with some minor mods, for a "semi-rear set" kind of deal. I guess since I'm sitting on 3 sets I'm good for now. The rear pegs, however, I like much better on a CB350F as they are mounted to the frame. On the 400F, they are mounted to the swing arm. WTF. If you switch over to 400F pegs you'll need the shift linkage (obviously) but also the rear brake lever. On the left side, the new shifter with linkage will interfere with the side stand, but not if you cut off the little ring of metal that comes on them; the main part of the stand is fine. On the CB350F, the mount for the brake lever (a small tube welded on to the frame) sticks out about 1 or 1.5 inches more than on the 400F, so if you mount a 400F brake lever on a 350F frame, it will stick out a bit from the engine. I used a grinder with a cutting wheel to cut this off, and stuck some of what I cut off on the brake lever behind the mounting tab (essentially making it more like the CB400F). Takes a little finangling for the brake light switch, if I remember correctly, but nothing major. Tanks fit just fine. Side covers are, obviously, different, but I am not running side covers. Seats are different. Handlebars on a 400F had a rise of about 2 inches, and on a CB350F the rise was about 4-5 inches. As far as I know, there was no stock 4-1 exhaust for the CB350F; the CB400F is recognized as the first stock 4-1 exhaust system (someone correct me if I am wrong here). That being said, a stock CB400F 4-1 exhaust bolts right up to the CB350F engine, although you can't use stock CB350F pegs and need an exhaust mount in the rear. Key is mounted differently (as are idiot lights). The CB400F has a really ugly headlight and front turn signal mount, and the CB350F has cool looking headlight ears and gaiters for the front forks. Forks are same diameter (33mm) and are interchangeable. CB400F has 6 gears. I've found with both that keeping stock exhaust and switching to pods doesn't require rejetting, just tuning, with both bikes. I will let you know what happens with my new bike when it's up and running -- I am running custom 4-4 exhaust and pods. Different front fenders on the CB400F and CB350F, too. Oh yeah, you can turn the headlight off on the CB350F, but not on the CB400F; it's always on when the bike is running. Different horn, too; CB350 is cooler and covered in chrome. I guess that's all I can think of now...

I know a ton of people slag off the CB350F when compared to the CB400F, but I honestly like the CB350F styling better (cooler tank with knee cuts, cooler seat, rear pegs). And I gotta say, I've had a CB350F for about 15 years. Rebuilt the engine back then, and with the occasional carb overhaul and annual tune-ups (and a slightly rattling cam chain...) the thing runs super smooth. I hold 75 easily on the freeway, which isn't too bad, but it'll go faster (I've done the ton on one of my old CB400F bikes, however).

Recent photo here: http://wordsofwezdom.blogspot.com/2012/08/cb350f400f-update.html

 

[scfire]

Nice to see another 350F. Good looking paint. By chance do you still have the seat lock that you removed when detabbing?

 

[silentsvn]

Nice to see another 350F. Good looking paint. By chance do you still have the seat lock that you removed when detabbing?

Unfortunately no, it was removed by one of the previous owners. I had the old seat but sold it and the whole locking mechanism, catch all that was already gone.

 

[silentsvn]

Exhaust seems a bit of a pain, but not a tough fix if you can fab up something to bridge the difference.

As for the front axle, if I remember correctly there is indeed a spacer in there. I can verify when I get home...

That would be great, im thinking that its the case of the spacer is there its just either homemade or just wrong. I have had a few other issues with that like the rear brake lever the previous owner decided to cut his own teeth into the lever making it impossible to remove other than cutting it off.

 

[carnivorous chicken]

yep, spacer. I've got one...

 

[silentsvn]

Ahhh damn. Time to start searching for one I guess.

Good thing when I test drove it it didn't have a front brake so I didn't take it to fast.

 

[Toyotech]

Fantastic looking build, I'm curious as to how the 4-1 works out for you. I too have a 73 350f I'm building, do you still happen to have the old 4-2 exhaust? I might likely be interested if its available.

 

[carnivorous chicken]

Stock CB400F 4-1 works great, with no need to rejet (just have to replace 350F pegs with 400F pegs). Dunno about other systems.

 

[silentsvn]

Fantastic looking build, I'm curious as to how the 4-1 works out for you. I too have a 73 350f I'm building, do you still happen to have the old 4-2 exhaust? I might likely be interested if its available.

Thanks - Its turning out quite well.

I do still have the exhaust. I like the look of the 4-2 into 1 that came with the bike. Problem is there is a rip on the underside of the megaphones that I want to try to find someone to weld up and maybe re-chrome or ceramic coat. I tried to find someone to re-chrome already and they told me no, since it will contaminate their baths.

I'm going to keep them around till I get the bike dialed in and fired up for the first time with the new build.

Might use them or stay with the MAC 4 into 1, I'll let you know.

 

[silentsvn]

So an update:

The bike is pretty much ready to run minus a few items, front brake line and I blew the turn signal relay accidentally. So those are on the way.

Meanwhile....

I want to try to make this bike safer and run better as well as looking cool and one thing that I wanted to tackle was the headlight.

Right now I got a headlight that is a 5 3/4" Sealed Wagner bulb that the PO had in there. The brightness is okay at best (50/35w) and I like the look of the smaller 5 3/4" headlight vs the 7". I was looking around at different conversions and found a 5 3/4" Halo H4 on eBay for $39 that has a Halo LED ring like Audi's.

I think it looks f-ing cool.

http://www.ebay.com/itm/5-3-4-WHITE-HALO-HALOGEN-H4-BULB-HEADLIGHT-ANGEL-EYE-LED-Fits-Harley-Motorcycle-/330761272798?pt=Motorcycles_Parts_Accessories&hash=item4d02e87dde&vxp=mtr

Is there anything that I need to be worried about using the H4 bulb or dropping this in?

My charging system seems to be in good order.

 

[silentsvn]

Update -

Everything is finished enough to finally get her out on the road. Over the July 4th holiday did a few test rides around the neighborhood and then a longer 50 mile maiden.

She is running really nice although there some idling issues.

1. Cold with choke on she fires up 1 kick - great and idles around 2500. A bit high I think (?)

2. Warm idle she is around 1500 - 2000 choke open

3. After a longer ride she idles around 3000 no choke.

I'm going to check the throttle cable and lube it, the others im not sure about. I need to synch the carbs and do a tune up I do know that.

 

[carnivorous chicken]

If it's running well, should idle around 1200 rpm. These can take a little while to warm up -- depending on outside temp, of course. But set the idle when it's warmed up. Carb synch is also a must with these things to get them to run perfectly. The problem likely is not in the cable -- but since you've got clubmans on there always good to see if it's pinching somewhere, or if you turn the bars and the idle goes up.

 

[silentsvn]

Ya I have a Morgan Carbtune on the way, I only have a 2 carb synch from my other bikes (this is my first 4). Hopefully that will get here this week and I can baseline everything.

The other problem I have is I got a mini speedo from DCC and a new speedo cable at over 40mph the needle starts to bounce wildly. Im thinking its the speedo gear on the wheel that is the culprit - are these known to go bad?

I'll check to see if the cable binds anywhere. The other thing that I noticed was there was a bit of a "snap" with the throttle handle like it was pulling on something, hard to describe. That was the reason I thought it was the cable.

I did start it this morning and let it run for a while on the center stand, wheels straight and she purred. I'll start her again tonight and post a video.

Ahh the fun of vintage bikes...

 

[carnivorous chicken]

Ahh the fun of vintage bikes...

That's why I'm here!

Dunno about that particular synch tool, but at least it's not one of those crappy motion pro blue-liquid filled pieces of crap. I've got a mercury one, but I know they can be hard to come by.

Dunno about the speedo. I'd write those folks, though. Have you lubed the cable? Might do the trick.

Looks like you've only got one throttle cable on there. Stock, they came with a push and a pull cable. The spring is good enough on those carbs that you don't really need the second cable.