Topic: From Sh*tty to Shiny: Sbeckman7's CB350F Cafe Resto

[grcamna2]

You could tighten the top-end back down and seal up all the ports,etc. and take it to a spot that has a high pressure water supply and then get you a thick bristle brush to get between the fins and spend a good hr. de-gunking it w/ some strong(foamy) engine cleaner,hopefully in a warm place.. then disassemble it;as far as the head goes,was it you that said you have a contact who's selling you a rebuilt cylinder head?

[sbeckman7]

You could tighten the top-end back down and seal up all the ports,etc. and take it to a spot that has a high pressure water supply and then get you a thick bristle brush to get between the fins and spend a good hr. de-gunking it w/ some strong(foamy) engine cleaner,hopefully in a warm place.. then disassemble it;as far as the head goes,was it you that said you have a contact who's selling you a rebuilt cylinder head?

Do you think some plastic caps will sufficiently seal the ports?  That's my only concern: blasting wanter inside the cylinders.  But I have some wire brushes and degreaser so maybe its time for a nice bath   I am indeed the one who will be (confirmed now) purchasing a rebuilt cylinder head from Old Scrambler.

My opinion is to remove the piston and ring and at least re-home the cylinders. With that standing water history, now is the time to discover and correct and problems in the bore.

Can I re-hone the bores myself using a kit from an auto store, or do I need to take it somewhere to have that done?  Have some experience with hooning, but never honed before!

After that would a stock size ring kit be the way to go?

And also am I supposed to be able to just pull the cylinders right off now or are there some hidden bolts in the bottom end keeping it together?

[sbeckman7]

Many folks hone their own blocks using a Flex Hone stone. Ring changes are only necessitated if the bore diameter has changed. That can only be accurately determined with micrometers. You could remove the block and carry it to a shop and have them measure the bores and pistons to determine if a re-bore is needed.

Ok. In your opinion, do you think that would be overkill on this little guy or a worthwhile expense?

[grcamna2]

You could tighten the top-end back down and seal up all the ports,etc. and take it to a spot that has a high pressure water supply and then get you a thick bristle brush to get between the fins and spend a good hr. de-gunking it w/ some strong(foamy) engine cleaner,hopefully in a warm place.. then disassemble it;as far as the head goes,was it you that said you have a contact who's selling you a rebuilt cylinder head?

Do you think some plastic caps will sufficiently seal the ports?  That's my only concern: blasting wanter inside the cylinders.  But I have some wire brushes and degreaser so maybe its time for a nice bath   I am indeed the one who will be (confirmed now) purchasing a rebuilt cylinder head from Old Scrambler.

My opinion is to remove the piston and ring and at least re-home the cylinders. With that standing water history, now is the time to discover and correct and problems in the bore.

Can I re-hone the bores myself using a kit from an auto store, or do I need to take it somewhere to have that done?  Have some experience with hooning, but never honed before!

After that would a stock size ring kit be the way to go?

And also am I supposed to be able to just pull the cylinders right off now or are there some hidden bolts in the bottom end keeping it together?

To the first question I would spray a bit of WD40 into each port and then,using a flat blade screwdriver stuff each port w/ a plastic bag tightly and seal-up all the other openings on the head and block to wash it,remove the bags later after you're done washing it and then finish disassembly w/ clean hands 
Make sure to follow the advice to take the cylinders w/ each original piston in it's original bore/cylinder to the machine shop after cleaning those pistons up real good;keep each piston number to the hole it came out of.I would clean the cylinder bores from excess carbon too.

[MoMo]

A Flex Hone is the way to go, as it removes very little but yields a beautiful cross hatch pattern that will help the rings seat

[sbeckman7]

Guys, I'd like to order the Flex-hone ASAP but not sure which option to select.  I watched the video explaining to order the next largest bore-size if your exact bore isn't offered, so I know I need the 48mm version.  I just don't know what material to select: Abrasive, Silicon Carbide, Aluminum Oxide, Boron Carbide, Tungsten Carbide, etc.  What's the grit preference?Thanks for the advice!

I'll be sure to label each piston with its corresponding cylinder when I do so.  I could start the cleaning tomorrow if I have time.  Again just to clarify, the cylinders are supposed to lift off of the crankcase after removing the head bolts?  Or am I missing something?

[MoMo]

You'll most likely want to get 320 grit as it will be the least abrasive.

[grcamna2]

A good,careful machine shop will measure the bores and see if they are still round also..

[sbeckman7]

Thanks guys, I will order the 48mm 320 grit Silicon Carbide flex-hone today   Tonight I'll try my luck with removal of the cylinder head with my new torch!

[iiAtlas]

Ow ow!!  Look at this beauty   

Starting from the top down.  Looks good so far:


Then the head came off.  I think it could have been worse, but there was definitely sitting water in this thing:



The cam lobe journals had a good amount of wear it seemed.  Is this normal for a bike with 24k miles or does it suggest an oiling problem?


They're just so cute    But jeez talk about room for boring!! This block could have been a good 2" narrower if it was purpose cast. Oh well, scaled production architecture does that...


The bores looked good as I rotated the assembly a few times.  Definitely some cleaning to do though.  Should I pull it apart even more?


And lastly, the reason this all started: looks like the stripped thread didn't go all the way, but it only has ⅓ of the grip length it used to have.



So, oh wise community, what next?  Do I need to go further?  I want to clean it up a bit (exterior as well as pistons and sealing surfaces) but I'm assuming it's best to do the outside with the engine either fully disassembled or fully assembled.  Any advice?

Thanks as always!

Great writeup! This will be a big help when I crack my engine open.  Looks like you're getting some great advice!  I can advocate for the flex hone, works sweet!

[sbeckman7]

Only advice I have to add is: make sure you remove the nuts from inside the little crevices of the engine head! I couldn't figure out why mine wasn't loose until I saw them, completely covered in about 40 years of gunk!

[grcamna2]

Thanks guys, I will order the 48mm 320 grit Silicon Carbide flex-hone today   Tonight I'll try my luck with removal of the cylinder head with my new torch!

Have you had any experience w/ using a 'ball' type flex hone to hone a 'cross-hatch' pattern in your cylinders so they are ready for fresh piston rings? I prefer the type of hone that has flat,rigid stones on it...

[sbeckman7]

Thanks guys, I will order the 48mm 320 grit Silicon Carbide flex-hone today   Tonight I'll try my luck with removal of the cylinder head with my new torch!

Have you had any experience w/ using a 'ball' type flex hone to hone a 'cross-hatch' pattern in your cylinders so they are ready for fresh piston rings? I prefer the type of hone that has flat,rigid stones on it...

I can't say that I have. Is it somewhat superior technically or is it just a personal preference? Starting to wonder if I should just take it to machine shop! 

[grcamna2]

Thanks guys, I will order the 48mm 320 grit Silicon Carbide flex-hone today   Tonight I'll try my luck with removal of the cylinder head with my new torch!

Have you had any experience w/ using a 'ball' type flex hone to hone a 'cross-hatch' pattern in your cylinders so they are ready for fresh piston rings? I prefer the type of hone that has flat,rigid stones on it...

I can't say that I have. Is it somewhat superior technically or is it just a personal preference? Starting to wonder if I should just take it to machine shop! 

The machine shop can hone them for you using a Sunnen 4-stone precision hone that will make quick work of each cylinder,as long as they are with-in 'Spec'  see my Edit below:

as mentioned earlier it would be Best to know exactly what the inside diameter is inside each of the 4 cylinders,A decent machinist will carefully check the bores all the way around and the entire depth from top to bottom of each hole.The cylinders will sometimes wear unevenly(oval shape  )and if that is the case it's better to bore out the cylinders to the next biggest size pistons to get an exact 'Round' hole for better ring sealing and even wear for many strong running miles and years.A better seal equals more consistent compression and that means more horse power 

[sbeckman7]

You can decide whether to hone at home or have a shop hone them but really you should have a shop determine if the bores and pistons are still within spec, and are suitable for just honing. If there is too much wear, then its possible new pistons, rings and a re-bore are necessary.

I personally don't recommend DIY rigid hones unless you have a drill press. Its pretty critical to keep the alignment perfectly co-linear to the bore to avoid warping or ovation the bore with a rigid bore. A Flex hone is far more forgiving and a really suitable type for DIY and a handheld drill. (Even better in a press  )

Thanks for that info Cal.  I don't know why I didn't think of it before, but my friend has a solid drill press I could use (as well as an entire machine shop...).  I'm gonna check with him to see what could be done at his place   What type of rigid bore would be best for this cylinder set then?

[sbeckman7]

HOLY MOLY another beauty for you guys to feast your eyes on!!!  This time it's the speedo

The speedo that came with my bike is the only item that showed signs of a possible crash, with a shaved down portion of the left side of the bezel.  Fairly sure I would be replacing it anyways, I decided to take it apart to practice before I mess up a nicer set of gauges.  I pried the metal clip up and eventually off by working a pair of needle nose pliers around the circumference, and presto.

This is right about when I decided to definitely source another speedo:


I don't usually share selfies, but having found my new dinner I was too excited not to.

[MoMo]

Ugly.......................................................................................the speedo not you .   Never have I seen any gauge that bad

[SOHC4 Cafe Racer Fan]

Toast!

[grcamna2]

Are you sure you didn't put that speedo in the freezer before taking it apart and snapping the pics? lol 

[sbeckman7]

It was completely full of rust! I've never seen anything like that before 

[Davez134]

Thanks guys, I will order the 48mm 320 grit Silicon Carbide flex-hone today   Tonight I'll try my luck with removal of the cylinder head with my new torch!

Have you had any experience w/ using a 'ball' type flex hone to hone a 'cross-hatch' pattern in your cylinders so they are ready for fresh piston rings? I prefer the type of hone that has flat,rigid stones on it...

I can't say that I have. Is it somewhat superior technically or is it just a personal preference? Starting to wonder if I should just take it to machine shop! 

I used that flex hone on my 750K2 with great results. More "forgiving" than the stones and easy to use.

[sbeckman7]

I used that flex hone on my 750K2 with great results. More "forgiving" than the stones and easy to use.

Good to know Dave.  Love your bike(s) by the way! (black one w/ gold wheels and yoshi exhaust particularly)

[sbeckman7]

Ha! Right you are Cal, don't know why I'm was so lazy and dropped 15 bucks on a nice quality speedo when I could have instead spent the next week cleaning the old one 

Guys, anyone familiar with TTR400 (Kevin)?  I emailed him asking about pricing on his gorgeous billet CB400F top triple but not sure if he is around to respond to emails or on some crazy enduro ride.

[grcamna2]

It was completely full of rust! I've never seen anything like that before 

if we had a 'wall of shame' here on the forum we could post that speedo pic up there explaining just how ruinous it is to store your vintage Honda outside for years.. 

[sbeckman7]

Cylinders are off!  It was pretty easy, I applied a little heat with the torch (although I honestly don't think it was enough to do anything), tapped around the base of the cylinders with my rubber mallet/wood block combo for a few minutes, and presto!  The hardest part was sliding it off of the #1 piston (the one that had standing water at some point).  All the rings on this one are seized into the piston itself, but the other 3 are ok.  I mean, not great... Couldn't see any cross-hatching on the bores so I am hoping they're not too worn, but I guess I will find out once I take it to a machine shop.

Other parts that arrived: my handlebars which look good, and the carb rebuild gasket kit, which means I have to do the other three now 




Open to suggestions/recommendations on engine parts repair or replacement here..