Topic: 1973 CB350F "Modest Original" build

[iiAtlas]

+1  I also like to use 'Berkebile 2+2 instant gum cutter' which is good and strong too;wear skin and eye protection !   

Ordered!

There probably is even finer than red, the acetone keeps the scratching down and dissolves the carbon and varnish...red seems to be ok for just about everything so I keep lots around

Picked up red and gray while I was at it, should do the trick.

[calj737]

Leave the springs on while cleaning. This keeps the valve fully seated under tension and protects the seat. Then, remove the springs and extract the valves and deal with them separately, keeping them ordered and arranged by their original location if you plan to re-use.

Green, Red then Grey ScotchBrite for coarseness (Rough to Fine)

[iiAtlas]

Leave the springs on while cleaning. This keeps the valve fully seated under tension and protects the seat. Then, remove the springs and extract the valves and deal with them separately, keeping them ordered and arranged by their original location if you plan to re-use.

Green, Red then Grey ScotchBrite for coarseness (Rough to Fine)

Will do!  Green, red, gray - I've got it all.  Thanks Cal!  Keeping things ordered and arranged is something I can handle

[iiAtlas]

Finally received my measuring instruments (dial bore gauge, outside mic set) and found time to get the cylinder inner diameters checked out.  I ordered from Fowler as it's all my budget allowed for.  The 0-4" Mic set (amazon, fowler) states an accuracy of +/- 0.0002" with graduations of +/- 0.0001" - sufficient.  The dial bore guage (amazon, fowler) has graduations of 0.0005" the accuracy is a little more confusing, it's listed as being accurate to +/- 0.0005" but the spec sheet included in the box throws around some different numbers. 



Total error of +/- 0.0009" ?  Either way under 0.001" so I believe these should be sufficient.  They were easy to use and worked well for my use.  Anyways, here is how I measured the cylinder inner diameters. 



First, I wiped down cylinder walls with mineral spirits to remove any residue.  Then I grabbed the 1-2" mic and checked it with the 2" anvil.  Great, zero'd.  I set the mic to the target cylinder wall ID I grabbed from the CB350F service manual listed here on the site.  1.8504" was my target.  Service limit was 1.8543".  I set my 1-2 mic to 1.8504, then zeroed the dial bore indicator within that.  Now I went cylinder to cylinder measuring front to back and left to right at three depths, and three times per measurment.  72 measurements in total.  I drew this picture to keep track of everything.



A short while later...



All set!  The dial bore indicator made short work of this.  Once I learnt how to use the tools and wrapped my head around everything I was able to get consistent measurements in a relatively short amount of time.  Here are the results in an easier to read format.



From my untrained eye, everything looks to be within service limit and without dramatic taper or egg shaping.  I've never done this before and really have no baseline of what "a lot" or "a little" is.  Any input reading these would be greatly appreciated.  I read taper as being dramatically different along either axis from top to bottom or bottom to top.  I read egg shaping as being dramatically different numbers at each plane (top middle bottom) and across the two axis' (X, and Y). 

One question I have, how do I account for any error in my equipment?  I understand my measurements are only as accurate as my least accurate tool - that being the dial bore gauge.  I'm still unsure if the error in the is +/- 0.0009" or +/- 0.0005".  What do I do with this number once I have it?

Thanks all!  Hoping to get the piston OD measurements tomorrow, then ring end gaps then too.

[sbeckman7]

Very cool man - that looks like a lot of work!  I may not have a popular opinion here, but I honestly think this approach may be overkill on a 40+ year-old 34hp engine.  You are correct in your understanding of the measurement definitions of tapered and out-of-round (egg shaped) but I wouldn't be worrying about less than .001 when the OEM tolerances are .004".  How much did those tools cost?  I checked the links but they don't appear to be working.

A hone - on the other hand - is a very good idea when reinstalling everything (although keep in mind it will also change all the numbers you just went to the effort of measuring  ) 

[grcamna2]

You're on the correct precision 'track' iiAtlas  Good job. Tools are always a good investment especially precision tools for measuring the cylinder bore,etc. on a 40 year old motorcycle;for what it's worth,those numbers look good.
I want to hear from others feedback here about the numbers you posted as i'm more of a 'do it while it's right in front of me' kind of man rather than the computer.. I'm still learning quite a bit on how best to transfer information/words to rightly describe what is meant. I will wait until someone here on the forum who has more machinist experience can give you good & precise feedback. That way i'll learn too 

[seanbarney41]

Very cool man - that looks like a lot of work!  I may not have a popular opinion here, but I honestly think this approach may be overkill on a 40+ year-old 34hp engine.

A hone - on the other hand - is a very good idea when reinstalling everything (although keep in mind it will also change all the numbers you just went to the effort of measuring  ) 

that depends on whether or not you want your engine to burn more oil than it would of if you just left the poor old old thing alone

[iiAtlas]

Very cool man - that looks like a lot of work!  I may not have a popular opinion here, but I honestly think this approach may be overkill on a 40+ year-old 34hp engine.  You are correct in your understanding of the measurement definitions of tapered and out-of-round (egg shaped) but I wouldn't be worrying about less than .001 when the OEM tolerances are .004".  How much did those tools cost?  I checked the links but they don't appear to be working.

A hone - on the other hand - is a very good idea when reinstalling everything (although keep in mind it will also change all the numbers you just went to the effort of measuring  ) 

Hey thanks for the support!  I was so embarrassed by my slightly lax approach to the piston tops that I wanted to do this job right, overkill as it may be.  I have a 1979 Chevy LUV truck engine waiting to be redone so I thought best to teach myself these precision measuring skills now.  I actually am a bit of a hobbyist machinist myself so I was familiar with the use of the micrometers.  The dial bore gauge was an absolute treat to use, it made short work of these ID measurements and gave me quick, repeatable results.  I fixed the links above.  Each set was about $100.  You'll need both as the dial bore gauge only measures change so you'll need the mics as your reference point.  The fowler set is good for the money, and should give you all the accuracy you need for the engine. 

You're on the correct precision 'track' iiAtlas  Good job. Tools are always a good investment especially precision tools for measuring the cylinder bore,etc. on a 40 year old motorcycle;for what it's worth,those numbers look good.
I want to hear from others feedback here about the numbers you posted as i'm more of a 'do it while it's right in front of me' kind of man rather than the computer.. I'm still learning quite a bit on how best to transfer information/words to rightly describe what is meant. I will wait until someone here on the forum who has more machinist experience can give you good & precise feedback. That way i'll learn too 

Thanks for the support!! The job was actually surprisingly fun once I got my head around it.  Planning and prep are key, setting that sheet of paper up for my measurements really helped.  Silly as it is it took a few attempts at coming up with a way to keep track of the measurements, I'm happy with what I ended up with.  Glad I got your preliminary sign of approval!  Eager to here what other minds have to say as well.

that depends on whether or not you want your engine to burn more oil than it would of if you just left the poor old old thing alone

Huh, thats the first bad thing I've heard about a hone!  Would you recommend I leave it all be?


Good news - my Steel Dragon intake came!  Absolutely BEAUTIFUL piece of machinery.  I love the way it looks, feels, the craftsmanship behind it.  It's a unique piece of kit and I couldn't be happier.  Some pictures...

[sbeckman7]

Mine came today as well    They were definitely in the same order (maybe the only two!).  With regard to honing, I believe seanbarney41 was referring to my comment on mic'ing the bores and checking for roundness, not honing itself.  He stated - with good reason - that the engine may burn more oil if the mic'ing process is skipped (a personal choice of mine) as the cylinders may be out of round and the owner wouldn't know.  It's just one more unknown in the build process.

Spence

[iiAtlas]

Mine came today as well    They were definitely in the same order (maybe the only two!).  With regard to honing, I believe seanbarney41 was referring to my comment on mic'ing the bores and checking for roundness, not honing itself.  He stated - with good reason - that the engine may burn more oil if the mic'ing process is skipped (a personal choice of mine) as the cylinders may be out of round and the owner wouldn't know.  It's just one more unknown in the build process.

Spence

Ahh - makes sense.  I chose to go the whole nine yards to educate myself on how to use these instruments and to be sure I was putting time and money into a good motor.  I had other indications of it performing well throughout its service life and probably could've gotten away without it, but it was a fun exercise and I feel that much wiser!  If your budget and timeline allows for it I say go for it.  If not, hey, so be it.  I'm glad I did and I'm happy with my results!  Will hone the cylinders once I can source a set of rings - having a REALLY tough time.  Also struggling to find a ring squaring tool which accepts such a small (1.8") bore.  Is there any way around using one of these?  If not I may turn to the machinery and attempt to make one myself...

[seanbarney41]

Atlas guy, I was not criticizing your intention to hone, after accurately measuring clearances...I was criticizing Beckman's poo pooing of your accuracy.  Those who just assume that "a hone will clean it up" are often rewarded with some smoky exhaust here in sohc4 land.

Please save your baseline measurements and compare after you have honed.  I would be curious to see ho much material a diy hone job removes.

[grcamna2]

I located a few pr. of STD oem Honda CB350F rings last week on Ebay and mentioned the listings to another member;you could look up the oem part# and then search Ebay,they will be found. 

[iiAtlas]

Atlas guy, I was not criticizing your intention to hone, after accurately measuring clearances...I was criticizing Beckman's poo pooing of your accuracy.  Those who just assume that "a hone will clean it up" are often rewarded with some smoky exhaust here in sohc4 land.

Please save your baseline measurements and compare after you have honed.  I would be curious to see ho much material a diy hone job removes.

Will be nice to have a reference between pre and post hone.  Sorry for the misunderstanding.

I located a few pr. of STD oem Honda CB350F rings last week on Ebay and mentioned the listings to another member;you could look up the oem part# and then search Ebay,they will be found. 

My ebay-foo was lacking!  Here are my options...would love some advice

• Complete set of OEM piston rings for all four cylinders: $300 - YIKES!! Link
• Single OEM ring set, good for the one batch of piston rings I broke.  This will involve me reusing the existing 3 sets of rings. $50 Link
• Set of for el-cheapo aftermarket rings.  $40.  This will involve replacing three OEM honda ones with four aftermarket el-cheapos.  Link

[grcamna2]

The NOS oem Honda STD rings I found on ebay last week were around $40 a set;I can keep an eye open for you if you like;don't reuse old rings.. Fresh man. 

[iiAtlas]

The NOS oem Honda STD rings I found on ebay last week were around $40 a set;I can keep an eye open for you if you like;don't reuse old rings.. Fresh man. 

$40 per piston or $40 for a set of four?  The latter would of course be better!!  Would the aftermarket rings be an unforgivable sin?  I'm assuming yes...thanks for the help - appreciate it! 

[grcamna2]

The NOS oem Honda STD rings I found on ebay last week were around $40 a set;I can keep an eye open for you if you like;don't reuse old rings.. Fresh man. 

$40 per piston or $40 for a set of four?  The latter would of course be better!!  Would the aftermarket rings be an unforgivable sin?  I'm assuming yes...thanks for the help - appreciate it! 

$40 for each, set but we might find'em cheaper.. You can't beat OEM Honda rings! anything else wouldn't last,seal or perform as well..

[iiAtlas]

The NOS oem Honda STD rings I found on ebay last week were around $40 a set;I can keep an eye open for you if you like;don't reuse old rings.. Fresh man. 

$40 per piston or $40 for a set of four?  The latter would of course be better!!  Would the aftermarket rings be an unforgivable sin?  I'm assuming yes...thanks for the help - appreciate it! 

$40 for each, set but we might find'em cheaper.. You can't beat OEM Honda rings! anything else wouldn't last,seal or perform as well..

Gotcha, sounds like I'm out a pretty penny but I suppose thats the cost of an engine rebuild.  Better to do it right than be sorry later.  I've contacted this seller to see if he has 4 sets available.  Would you recommend new piston pins while I'm at it?  Mine, for reference.  $9/pin on BikeBandit.

[grcamna2]

I would. The pistons just look dirty but don't look too worn so that's good.

[grcamna2]

I just looked on ebay for 4) sets of part# 13011-333-005 STD oem Honda rings and the ones I found are in the high $40's which includes shipping..,better to get all 4 sets from the same dealer.I know you can find them for less if you keep looking online;get the ones w/ the 3-piece oil scraper rings rather than the 1-piece oil ring.

[Camrector]

Looks great! How long did you wait for your airbox? I ordered mine beginning of Jan. Still waiting.

[iiAtlas]

I would. The pistons just look dirty but don't look too worn so that's good.

Whats another $40

I just looked on ebay for 4) sets of part# 13011-333-005 STD oem Honda rings and the ones I found are in the high $40's which includes shipping..,better to get all 4 sets from the same dealer.I know you can find them for less if you keep looking online;get the ones w/ the 3-piece oil scraper rings rather than the 1-piece oil ring.

I reached out to the seller I believe you were talking about and he only has one set...damn.  Will continue the hunt!  There is a set of 4 listed for $300...yikes.

Looks great! How long did you wait for your airbox? I ordered mine beginning of Jan. Still waiting.

Hi Cam!  I actually ordered my box in DECEMBER!  The guys at Steel Dragon warned me they were swamped.  I'd expect yours to be out to you in a week or two, but you can always email Mike and Cody.  They were happy to field my progress report requests.

[iiAtlas]

Valve time!  Decided it was time to start scraping some of that buildup away.  I used mainly what was mentioned above.  Berkabile 2+2 gum cutter, and scotch brite (green, red, gray).  After one tedious hour, here is where I am.







Slow process, thats for sure.  The exhaust valves are noticeably worse than the intake, but I suppose thats to be expected due to the closer proximity to exhaust gasses.  Much more carbon buildup, so much so that its hard to even see (what I'm guessing will eventually be) the conical shape. 

Just a short update.  Will keep on trucking with this!  Any tips would be greatly appreciated.  I'd like to remove the carb intake boots and soak the valve portion of the head for a while to relieve some of this buildup but they're pretty stuck on there.  Hard to get a good whack with my hand impact with the head off the bike.

[grcamna2]

You may want to keep the plugs in and fill-up each combustion chamber w/ acetone and let it soak for a while.. I would remove the carb. rubber manifolds first w/ that impact and a helper holding the head down.You can remove the valves(are you going to do your own valve work? otherwise the machine shop can remove the carbon)later to clean them up along w/ the ports and valve seats..

[iiAtlas]

You may want to keep the plugs in and fill-up each combustion chamber w/ acetone and let it soak for a while.. I would remove the carb. rubber manifolds first w/ that impact and a helper holding the head down.You can remove the valves(are you going to do your own valve work? otherwise the machine shop can remove the carbon)later to clean them up along w/ the ports and valve seats..

One man + 5000 forum member show here!  I'll be doing the valves.  Plugs are in.  I didn't want to soak until I removed the carb intake boots.  Need to find a helper to hold the head down while I work on them with them with the impact.  Thanks for the tips!

[sbeckman7]

You may want to keep the plugs in and fill-up each combustion chamber w/ acetone and let it soak for a while.. I would remove the carb. rubber manifolds first w/ that impact and a helper holding the head down.You can remove the valves(are you going to do your own valve work? otherwise the machine shop can remove the carbon)later to clean them up along w/ the ports and valve seats..

One man + 5000 forum member show here!  I'll be doing the valves.  Plugs are in.  I didn't want to soak until I removed the carb intake boots.  Need to find a helper to hold the head down while I work on them with them with the impact.  Thanks for the tips!

If I were nearby I'd be happy to help, but those carb boots... I'm glad I "had to" buy a new head or many more curses would have exited my mouth    Do you plan on reusing the boots?  If not, a torch is a very good idea.