Topic: '73 cb350f siezed barn find!

[Mark1976]

    It's always hard to use a picture to determine overall conditions, but everything looks as it should. Don't disassemble the rockershaft cover right away, leave it until later or until you have some time to spare. It needs to be cleaned and reassembled in the order it is in, no mixing of rockers on shafts or different locations on the shafts.
   Time to take pic's and bag and tag every assembly. Remove  the cam chain tensioner, loosen the cam sprocket fasteners and then remove the cam sprocket, then carefully slide the camshaft out. You can clean as you go, then re-oil and bag it. That's how I do it, your build your choice.
   Your going to have 2 different acorn fasteners on the head, as well as 2 different types of washers. There are, i believe 4 (maybe 2, its been  a while) washers that have a rubber type seal on them, take note of their locations, if ya don't the head will leak oil after its reassembled. Note the 2 long nuts and their locations as well, they're for securing the rockershaft cover, and don't miss the 2 nuts in the open recesses on the exhaust side.
   Once all the fasteners are removed you'll need to TAP the head with a block of wood and a mallet to loosen it. Once the head is off note the locations of the dowels that align the head to the cylinders as well the 2 small oil metering jets in the cylinder oil passages. Once that's done the cylinders will need a tap as well, be careful its real easy to damage a cooling  fin doing this. Easy peasy...

[574hondarider]

Pistons!!

Finally got her down to the pistons.  Found this stuck exhaust valve which was causing my compression issue on 4.  Next steps is to clean everything and assess the damage.  If everything checks out, what would be a good course of action on an engine with 16k that is 47 years old, just a slight hone, or rings, clips, pins, or bore up?

Also, the little copper washers under the cylinder head acorn nuts, are these re usable or should I buy new ones?  Thanks for all the help!

[Mark1976]

   First, congrats on getting down to where you are, vey good. Now finish getting it all cleaned up and bagged and tagged, pistons rings clips and all then just set the bottom half aside.
   Second, how you proceed will be based on you tool and skill set. You obviously  have the skills to move on but do you have the tools (micrometers or hole gauges) to do the measurements needed to move forward from here, if not, find a GOOD machine shop. This particular engine is a fairly unforgiving type if the tolerances aren't followed, so yeah its more than likely your going to need to move up to the next oversize in pistons and while you at it let them disassemble and look at the head as well. The valve guides need a good close inspection
to make sure they're within tolerances, if ya got a stuck valve or two your more than likely to need guides for those as well. I like to do everything except the boring, I let the machine shop do that.
   How dirty and how much do you really wanna learn and spend is up to you, its a process and regardless of whether you do it or the machine shop does it will take some time and money, tools and a bit of perseverance to make it happen. The end result is well worth the investment from a personal perspective.
Keep up the good work...

[574hondarider]

   First, congrats on getting down to where you are, vey good. Now finish getting it all cleaned up and bagged and tagged, pistons rings clips and all then just set the bottom half aside.
   Second, how you proceed will be based on you tool and skill set. You obviously  have the skills to move on but do you have the tools (micrometers or hole gauges) to do the measurements needed to move forward from here, if not, find a GOOD machine shop. This particular engine is a fairly unforgiving type if the tolerances aren't followed, so yeah its more than likely your going to need to move up to the next oversize in pistons and while you at it let them disassemble and look at the head as well. The valve guides need a good close inspection
to make sure they're within tolerances, if ya got a stuck valve or two your more than likely to need guides for those as well. I like to do everything except the boring, I let the machine shop do that.
   How dirty and how much do you really wanna learn and spend is up to you, its a process and regardless of whether you do it or the machine shop does it will take some time and money, tools and a bit of perseverance to make it happen. The end result is well worth the investment from a personal perspective.
Keep up the good work...

Thank you for the suggestions!  There is a place about 30 minutes away that builds bikes for the world's top amatuer motorcross guys and for Team Honda.  A small shop but he does have some impressive machinery in there.  I may hit him up when it's past my expertise!

[574hondarider]

Can this fork ear be straightened, or does anyone have a straight left hear I could buy from them?

I have the motor apart for cleaning/inspection, and have taken the front end of the bike apart.  It's about 85% taken down now.  When I get it down to just the frame, is there a good tutorial to figure out of the frame is bent?

[Stev-o]

Personally, I wouldnt bother trying to straighten, looks pretty rusty.

Try posting a thread in the parts wanted area for a good used one.

[574hondarider]

Personally, I wouldnt bother trying to straighten, looks pretty rusty.

Try posting a thread in the parts wanted area for a good used one.

Thanks, I picked one up on fleabay.  Another $50 into the project lol.

[574hondarider]

Got her down to the frame!  Swingarm bushings are very tight and seam fine, but since I got this far and plan to powdercoat everything, I guess the next step is to remove them before sending to pc.  I will be getting the bronze bushings as replacements.  Is there any brand better than others to buy?

[Mark1976]

Make sure to send the airbox, centerstand and anything else you want black to the power coaters. My powder coater takes off the vin tag on the steering head as well.

[HondaMan]

Wow, that's a nice one! It looks better than mine...

[574hondarider]

Wow, that's a nice one! It looks better than mine...

Thanks!!  If only I had your level of skill!!!  :-)

[574hondarider]

Removed valve guide springs and cleaned.  First with brakecleen, then scrubbed in simple green solution (for aluminum) and then soda blasted and rinsed again in hot water and simple green.

Exhaust valve #4 and valve guide are bent, so having a local motorcross machine shop install a new guide.

Next up is valve lapping and swingarm bushing removal so that can go to PC.

Should I completely disassemble the cylinder head cover, or just simple green clean and re oil?  Should I replace the springs on the shafts?  I ordered some but not sure if they are heavy wear items.

[HondaMan]

Got her down to the frame!  Swingarm bushings are very tight and seam fine, but since I got this far and plan to powdercoat everything, I guess the next step is to remove them before sending to pc.  I will be getting the bronze bushings as replacements.  Is there any brand better than others to buy?

There are no swingarm bushings to fit this arm correctly. I'd recommend either leaving the stock ones in place and cleaning everything well, followed by liberal regreasing and reassembly, or send it to me for a proper bearing build.

[574hondarider]

Got her down to the frame!  Swingarm bushings are very tight and seam fine, but since I got this far and plan to powdercoat everything, I guess the next step is to remove them before sending to pc.  I will be getting the bronze bushings as replacements.  Is there any brand better than others to buy?

There are no swingarm bushings to fit this arm correctly. I'd recommend either leaving the stock ones in place and cleaning everything well, followed by liberal regreasing and reassembly, or send it to me for a proper bearing build.

I ordered some NOS ones from David Silver Spares, of course not copper.  Will these work properly?  If not, is it ok to leave them in during powdercoat?  I appreciate your advice!!

[574hondarider]

A new guide requires the seat to be recut. Might as well do all of them while you’re at it (recut the seats).

I might just do that, thanks for the advice!!

[Mark1976]

   +1 on touching up all the seats, its the right thing to do, while your at it give them the valves as well, nothing like fresh seats and faces.
   I don't know a powder coater who leaves the bushings in, I'm assuming these are plastic, they'll need a good clean swing arm for powder coating and to get the grease and other contaminants out, ya remove the bushings.
   The rockershafts and cover can stay as they are, the picture posted earlier shows a pretty clean cover. Just wipe it down well and relube it before reassembling it to the head. The rocker shaft springs are fine,

[574hondarider]

Got her down to the frame!  Swingarm bushings are very tight and seam fine, but since I got this far and plan to powdercoat everything, I guess the next step is to remove them before sending to pc.  I will be getting the bronze bushings as replacements.  Is there any brand better than others to buy?

There are no swingarm bushings to fit this arm correctly. I'd recommend either leaving the stock ones in place and cleaning everything well, followed by liberal regreasing and reassembly, or send it to me for a proper bearing build.

Well, I probably should have taken your advice and left them in.  I was able to get the bushings out, but to my surprise they were brass!!  Everywhere I have looked says the stock ones are either plastic or steel.  This was a 1 owner barn find and the widowed PO told me her late husband bought it new in '73 and didn't ride it since the early 80's.  No JIS bolt or any other evidence of anything ever been taken off this bike, so it has me wondering how these got here.  More importantly, did they make any swingarm adjustments to get these to fit correctly??  I have stock ones coming from David Silver, hoping they still fit!!

[574hondarider]

Well, I was able to get the gasket off the bottom and top of the cylinder, cleaned up the oil pan and oil filter housing, and....reassembled the carbs!  The carbs took me around 20 hours to complete, but I'm sure I could do it in half the time the next time around!

One question,  I set the floats all to 21mm as they were measured barely touching the needles as I used all old original brass (also used honda o ring kits).  I tested float seats and height with gas with the bowls off as in this video and they all shut off fine with no leaks.

I then put the bowls back on and filled them with gas from an aux tank.  All carbs initially leaked out of the overflows at the bottom, but then stopped leaking.  I moved them around and knocked on them a little and filled the aux tank again, this time they all tested fine with no leaks.  Do you think I should be concerned with this or is the initial peeing from the overflow to be expected on freshly cleaned carbs that havent seen gas in 40 years?

[574hondarider]

It was leaking because the float seats were dehydrated. Should be fine now.

awesome, thanks!!  makes me feel better knowing that.  next up is front suspension and wheels....and getting the head over to the machinest...the fun never ends!!

[seanbarney41]

basically, any time the carbs are disturbed, you will most likely see some initial overflow

[574hondarider]

Christmas came early for me....my neighbor who paints for a dealorship collision center brought my tank and parts by today....the pics definitely don't do it justice, but here is a peak at what she's gonna look like!  It's hard to see the strip with the poor lighting, will take better pics once i get emblems on.

[jgger]

Love that color,  always have. They look excellent!

[574hondarider]

Love that color,  always have. They look excellent!

Thanks! It's my favorite colors too.  I had him take the paint codes from my tacoma and match it....it will look pretty awesome being trailered to Deals Gap with my truck!!

[574hondarider]

Debating between using stock 350f bars or trying out the 400f bars, I understand they are a little straighter and lower.  I really like the looks of the 400 bars over the 350, my only concern is comfort.  I am 42 years old, 5' 10", 170lbs and not looking to build a cafe racer, but something a little more sporty would certainly be nice.  While this isn't 100% an oem restore, I do like keeping most things stock.  Suggestions??

[574hondarider]

Just a quick update:

I was able to score some gauges with 400 original miles on them!  A guy I know bought a cb350f from a friend in '76 who bought the bike new and dropped it, then had insurance buy him a new set of gauges and a new tank.  When my friend purchased the bike from this guy in '76, he gave him the dented tank and scratched gauges too.  They've sat in my friend's barn in a box since then.  I bartered with him for this so he didn't give me a crazy deal, but they will look good on the bike!  Just trying to decide if I should paint them or leave them as is for a little patina.

Also, a shout out to restocycle for quickly shipping my Ikon shocks!!  Getting excited to put this all together!  Going in for powdercoat next week and final engine machine work then I can start building her back up!!