Topic: 1973 CB350F "Modest Original" build

[iiAtlas]

Took a quick break from the bike but I'm back in biz and ready to get rocking!  Tonights project was that cylinder hone I've been waiting to get at.  But first, I couldn't get over how beautiful these OEM piston ring boxes were.







It's almost a shame to open them!  Anyways...down to business.





I used a variable speed drill and some 20W-50 (what I had on hand) motor oil.  I kept the drill spinning as it entered and exited the cylinder wall.  I aimed to have a distinct 45° cross hatch on the walls.  Here they were just before honing.



And after



And after a warm water soapy wash



Wow!  Great stuff.  I think they honed up really nice!













For the most part, really good.  However I noticed something not so good...



A distinct score on cylinder 1.







Definitely noticeable.  I can feel it bite in with my finger nail.  I doubt this happened during the honing process, as the line is so perfectly horizontal.  Had it been the hone, I'd imagine it'd be at an angle as the thing is always spinning and moving up and down.  (Someone please correct me if I'm wrong about this).  What do you all think could've caused something like this?  Whats my best course of action?  I assuming this could lead to ring-seating issues once I have the engine back together.  Any other potential outcomes you can think of?  Apart from that, they look good and I'm happy to be back working on the bike!









More soon

[grcamna2]

The hone job looks good. 
That long vertical scratch in your cylinder not so good.I would now measure the cylinder bores and install one of those NOS top piston rings into the cylinder and measure the ring end-gap w/ a feeler gauge.
You did measure your pistons o.d. and the cylinders i.d.'s and recorded them,right? Well,now you can see how much tolerance is there after using the 'bead hone' and possibly use the hone as much as is needed to try to clean-up that long scratch in the one cylinder and just keep honing and measuring while checking clearances.I would check the Honda FSM and see what the recommended clearance 'variance' is on a fresh top-end job;you don't want to go too big and nowhere near the 'service limit';the 'good' is that a 'bead hone' will be very gentle on your cylinders and won't remove too much metal,it takes a while for that hone to remove much material.
I would get some special honing oil so you keep your stones clean;I mix 50/50 kerosene and motor oil and it works well to keep the stones free from metal particles.
I would definitely be concerned w/ that long scratch,as long as it doesn't catch your fingernail even though you might still see 'traces' of it then it can pass;I hope it's not too deep..

[iiAtlas]

Hey thanks for all the great info! Cylinder ID measurements pre-hone are a few pages back. I will measure again to check if I am still within spec, and depending on how much have a go at inching back that scratch on cylinder one. I don't know how deep so I'm not sure what results I'll have, but definitely a concern either way. Was a disappointing surprise, but I'll take it in stride and see what I can do!  Thanks for the list of next steps, will get started on all that Friday. Good to be back!

[grcamna2]

Depending on how deep the scratch is.. you could possibly replace/source just the one cast iron liner in your cylinder block w/ one that's STD size and good shape as long as it measures good clearance for that piston.

[calj737]

The vertical scratch is from a piston ring snagging the wall, or some piece of metal trapped during rotation of the crank. You must eliminate it before considering engine assembly. I doubt it will hone out, so I'd replace that one sleeve.

If you attempt to hone it out, you will undoubtedly "oversize" that bore and have compression issues and leaking oil in that sleeve. I say this because it is still readily apparent after a thorough hone.  A few 0.00s matter greatly on piston/bore clearance.

I would also suggest you clean the head completely before honing in the future. Once honed, you want to wipe with oil the cylinders to prevent any flash rust or damage occurring to them from cleaning products used elsewhere.

So if you do opt to replace the sleeve, turn the jugs upside down in the oven, about 1/2" spaced from a sheet pan. Only provide room for the damaged sleeve to "slide out" when hot. Bake them until that sleeve slips out (use great care because the other sleeves will be loose too). To install the new sleeve, jugs upright, and place the new sleeve in the freezer. It should drop in due to thermal contraction.

[iiAtlas]

Depending on how deep the scratch is.. you could possibly replace/source just the one cast iron liner in your cylinder block w/ one that's STD size and good shape as long as it measures good clearance for that piston.

The vertical scratch is from a piston ring snagging the wall, or some piece of metal trapped during rotation of the crank. You must eliminate it before considering engine assembly. I doubt it will hone out, so I'd replace that one sleeve.

If you attempt to hone it out, you will undoubtedly "oversize" that bore and have compression issues and leaking oil in that sleeve. I say this because it is still readily apparent after a thorough hone.  A few 0.00s matter greatly on piston/bore clearance.

I would also suggest you clean the head completely before honing in the future. Once honed, you want to wipe with oil the cylinders to prevent any flash rust or damage occurring to them from cleaning products used elsewhere.

So if you do opt to replace the sleeve, turn the jugs upside down in the oven, about 1/2" spaced from a sheet pan. Only provide room for the damaged sleeve to "slide out" when hot. Bake them until that sleeve slips out (use great care because the other sleeves will be loose too). To install the new sleeve, jugs upright, and place the new sleeve in the freezer. It should drop in due to thermal contraction.

Good ideas guys!  This morning I was thinking, if I oversize the cylinders with the flex hone I'd probably just be doing more harm than good.  More chance for an ill fit.  I wiped the cylinders down before honing to make sure there wasn't any debris, and I had the head soaking a few days back.  EvapoRust and the pine-sol mixture.  Should I clean them even more in the future?  I've coated the cylinders with a thin film of oil to prevent flash rust as mentioned.  Thanks for the tips on sleeve removal/install.  I'd be happy to replace that one if I could track down a CB350F STD sleeve.  Any thoughts on where to find one?

[grcamna2]

I hope someone here on this forum has a good spare for you otherwise get the part# online and do a search..

[iiAtlas]

I hope someone here on this forum has a good spare for you otherwise get the part# online and do a search..

I can't find the part number anywhere on this fiche...I'll keep looking!

[grcamna2]

I looked also and it seems they won't sell the cylinder sleeve separately,you may have to get a good,used one that hasn't ever been bored/honed-out or get a new one from a sleeve company like 'LA Sleeve'. I hope someone will offer a good used one to you.

[iiAtlas]

I looked also and it seems they won't sell the cylinder sleeve separately,you may have to get a good,used one that hasn't ever been bored/honed-out or get a new one from a sleeve company like 'LA Sleeve'. I hope someone will offer a good used one to you.

Okay good so I'm not crazy!  Looks like LA Sleeve doesn't carry anything that small.  Fingers crossed for a donor!

[calj737]

Might be cheaper/easier to overbore all four cylinders and get new pistons/rings?

You could send a PM to Bill Benton and see if he's a set of jugs lying about and buy those. Also, on another thread, there was mention of a Parts Salvage guy in South Carolina who likely has a set of jugs in his heap. Get a set, clean them all, hone them, and mic them. Take the best one and swap it back into your jugs.

Here's the link to that Salvage guy:
http://www.motorcycle-recycle-center.com

[iiAtlas]

Might be cheaper/easier to overbore all four cylinders and get new pistons/rings?

You could send a PM to Bill Benton and see if he's a set of jugs lying about and buy those. Also, on another thread, there was mention of a Parts Salvage guy in South Carolina who likely has a set of jugs in his heap. Get a set, clean them all, hone them, and mic them. Take the best one and swap it back into your jugs.

Here's the link to that Salvage guy:
http://www.motorcycle-recycle-center.com

Wow great link!  I've sent that guy a message, and will see about contacting Bill.  I'd prefer to keep this at the standard bore, especially after I spent so much on this STD piston rings.  I could relist, but would rather not have to.

[iiAtlas]

Found this set.  Thoughts?

http://www.ebay.com/itm/72-73-74-HONDA-CB350F-CYLINDER-JUGS-/280830712540?_trksid=p2141725.m3641.l6368

[calj737]

Snag them.

[grcamna2]

I'd be careful on ebay as sometimes you can buy something that has a high claim but unless you can get the seller to precisely measure the bores they may be worse than what you have.. That seller only has a 99.3% feedback score & for what you're looking for(a cylinder liner in excellent cond. w/ a clean STD bore measuring similar i.d. dimensions as you already have)I would want 100% feedback score.I wonder who makes new liners for the CB350F ?
Have any other sohc4 members been in touch w/ you about a good liner? Someone may have already needed to 'borrow' one cyl. liner from a nice set of four and now they're stuck with just three.. just hoping for you. 

[iiAtlas]

I'd be careful on ebay as sometimes you can buy something that has a high claim but unless you can get the seller to precisely measure the bores they may be worse than what you have.. That seller only has a 99.3% feedback score & for what you're looking for(a cylinder liner in excellent cond. w/ a clean STD bore measuring similar i.d. dimensions as you already have)I would want 100% feedback score.I wonder who makes new liners for the CB350F ?
Have any other sohc4 members been in touch w/ you about a good liner? Someone may have already needed to 'borrow' one cyl. liner from a nice set of four and now they're stuck with just three.. just hoping for you. 

Thanks grcamna, appreciate the hopes!  I agree with you on the eBay concerns. At a glance the four cylinders I have would look great, and it's only upon further inspection that their true conditions reveal themselves. There's a chance one or two out of those listed four are salvageable, but I think I'll leave that as a last resort. I've reached out to two sleeve manufacturers, Advanced Sleeve and LA Sleeve. Patiently awaiting their response! Would love to know roughly the cost of a custom order like this. You know...I do have a lathe and mill....maybe I'll look into making my own....we'll see

[iiAtlas]

All,

Thoughts on this strategy for cleaning my valves?  Chucked in a drill (with something to protect the stem), then gently rub down with lubricated scotchbrite red while she spins.  I'm thinking of doing a 30 min chem-dip soak to loosen up the major bulk then finishing them off with this drill + scotchbrite method - unless of course one of you talks me out of it...thanks

[grcamna2]

I hope you score a cylinder liner sleeve soon 

[iiAtlas]

I hope you score a cylinder liner sleeve soon 

Maybe this will help...

[grcamna2]

I hope you score a cylinder liner sleeve soon 

Maybe this will help...

That should help;I think you should add 'STD size bore i.d.' to the thread.

[iiAtlas]

I hope you score a cylinder liner sleeve soon 

Maybe this will help...

That should help;I think you should add 'STD size bore i.d.' to the thread.

Fixed

Thoughts on the valve cleaning procedure I posted above?

[grcamna2]

I like that youtube video,learned something new 

[iiAtlas]

I like that youtube video,learned something new 

That's todays project!  Will report back results shortly.

[iiAtlas]

Ugh...not the best day in the shop.

It all started off well.  I separated the valves, labeled them, and soaked for 30 minutes in the chem-dip.



After removing the valves from the chem-dip I placed them in cups labeled 1, 2, 3, and 4.  From here I went on to chuck them in the drill (with cardboard to protect the stems).  I lubricated both the scotchbrite red and valve itself with WD-40 then let the drill fly.  Easy peasy.  I slowly applied pressure to where the carbon had built up.  With enough persistence and re-soaking I think you could achieve some pretty good results.  Here were the intakes after...



The exhaust before soak


After soak


After clean in drill




Some more time in the chem-dip, fresh scotchbrite, and another round in the drill and I think these would clean up nicely. 

Now for the bad news.  I am absolutely petrified that I've switched intake valve 4 and 2.  The cups were labeled 1, 2, 3, 4 and placed in order, but when I went to clean up they were sitting 1, 4, 3, 2.  Instinct tells me I must've placed the right valve in the right cup after removing from the soak, and that the mixup occurred while I was chucking the valves in the drill - but it's impossible to say either way for certain.  I'm so frustrated and disappointed at this point  the chem-dip must've got to my head and caused a momentary lack of concentration    Discouraged, I packed the valves back up and went upstairs.  I really don't know at this point if I've switched 2 and 4.  I'm hoping I didn't and that I matched the tape label up with the cup label, but who knows for sure.  Ugh!!

On top of that I've noticed some decent pitting on the intake valves.  Bleh.  Bad day, would like to write this one off and move on   Baking a cake to take my mind elsewhere.... 

[grcamna2]

The valve faces look better,you may have to do a bit more careful scraping on the stubborn carbon.
You may want to consider getting the valves ground or at least spend lots of time w/ using a suction handle(it's better not to use a drill) and lapping them in by hand to get past the corrosion;any pics of the heavy corrosion on the valve seats ?