Topic: 1973 CB350F "Modest Original" build

[iiAtlas]

The notification feature for subscribed posts and PMs has been having issues. The forum recently did some changes -- I believe with the host -- and I think is trying to sort it out.

Fingers crossed!  I relied on that quite heavily...

[grcamna2]

Good to hear from you again Atlas,how's the bike doing ?

[iiAtlas]

Good to hear from you again Atlas,how's the bike doing ?

It is slowly coming along.  I have blocked off a handful of hours tonight with a few friends in an attempt to make meaningful ground...lets see how far we get!  Expect an update tomorrow AM - good to hear from you all too.

[jamesv220820]

There are 2 reasons I wanted a 350F: tiny pistons and 10k redline 

That's what I love about mine.  Many years ago I was on the I405 in Southern California going 100mph @ 10k rpm.  Smooth as a cruise missal.

After I bored mine out to .75 over in the top gear I don't need a speedo cause I checked it with the gps the RPM matches the speed

[iiAtlas]

As promised...progress!

Step 1) I decided to get some inspiration by clicking my engine back into place, it certainly did the trick!!







This thing is going to be awesome!!  Okay so now I knew I had to get that sleeve out and replaced.  My oven was out of the question, and no friends were willing to sacrifice theirs.  I was eager to get the ball rolling so I went to Bed Bath & Beyond and grabbed the biggest toaster oven I could find.

It was...big





After working out how to situate it on my hog, I peddled my way home.



Ta-da!



And she fits like a charm -- sweet!  Or so I thought...I decided to check something I should've checked a long, long time ago...







Yup..nope    The sleeves are the wrong size.  I feel like a real idiot!  We have a new policy in the "shop" (after making this mistake too many times).  Step 1 after receiving a part, CHECK FITMENT!!  These sleeves are far too large.  The sleeves from MoMo appear to be ~60mm, where are my little STD 350F is ~44mm.





I don't blame MoMo for this in the least!  He came to me while my build was in a time of need, and offered me a helping hand.  Much appreciated MoMo.  I place all the blame on myself!  I should've asked more questions and I should've measured immediately once I received them.  Oh well...if anyone needs 60mm sleeves I've got em.  One has a nasty gouge but the other two are good.



After all these I've decided my sleeves are just fine the way they are and it's time to move forward.  The scratch is so fine I can't even catch my fingernail on it.  I'm going to proceed with cleaning up the head and cylinder block, install the new rings, and move on!

Speaking of cleaning....this was the rest of my night.







Damn, this gasket is THE WORST!!!  I'm using a razor blade and a screwdriver.  Sometimes when I got frustrated I would use a torch to try to soften it up, but that didn't seem to do much.  It appears this gasket will take a judicious amount of time and scrapping.  Any tips would be greatly appreciated!

I'm super happy to be moving back along on this project.  Ultimately all I ended up doing last night was scraping away at that gasket....but I'm glad to have all the flim flamming with the sleeves sorted out.  I'm committed to getting the motor finished up this month, baring any major surprises...

Thanks for revitalizing this thread with all the comments lately, it's given me the kick I needed to get back at it!

[calj737]

Do not fall victim to rushing ahead after suffering a setback. At a minimum, have those cylinders honed.

[iiAtlas]

Do not fall victim to rushing ahead after suffering a setback. At a minimum, have those cylinders honed.

Good point, but I don't consider this a set back nor rushing ahead.  I did a bead hone on the cylinders and it came out great.  4/4 cylinders have a nice clean cross hatch, and 3/4 are scratch free.  The one with the scratch is so fine I can only see it in the right light and can't feel it.

I will re-check the numbers on the cylinder ID and piston OD.  If I have room to hone again I will, on that one cylinder.  If not (too close to spec) I will install the new rings and move forward.

[grcamna2]

Good work Atlas  ,i'm glad to see you back at it again.
That was a difficult thing to find out you had the wrong sleeves,after All that,etc...  but I'm glad to see you recovered your positive motivation energy and are putting that stuff in the past.I hope you save those cylinders for someday when you might turn your little engine into a 5 speed CB400F !

[sbeckman7]

Glad to see you getting back to work!  I know how you feel when these things happen, sometimes perfection is not achieved but in the end it's how you feel about your work that counts the most.  I am currently putting off re-tapping about 6 threads in my head, can't wait to do that haha.  Keep going!

[iiAtlas]

Good work Atlas  ,i'm glad to see you back at it again.
That was a difficult thing to find out you had the wrong sleeves,after All that,etc...  but I'm glad to see you recovered your positive motivation energy and are putting that stuff in the past.I hope you save those cylinders for someday when you might turn your little engine into a 5 speed CB400F !

Glad to see you getting back to work!  I know how you feel when these things happen, sometimes perfection is not achieved but in the end it's how you feel about your work that counts the most.  I am currently putting off re-tapping about 6 threads in my head, can't wait to do that haha.  Keep going!

Thanks guys!!  Yes here, rolling, and happy to be.  Saving the cylinders but sent one back to Larry so I'm at 3/4...effectively useless.  Oh well, maybe I'll make 'em into cupholders or something  they'll sit in the shop for now as a reminder to double, triple, and quadruple check!

Sometimes perfection is not achieved - that is a good point.  I'll keep going through this with my head high and trying to do the best work I can, but sometimes when these roadblocks come up we're put at a crossroads.  I want to get this engine done this month and in my budget.  I'm confident with new rings and a solid hone she will be running SWEET!  And if not well Hey, I'll already have had one rebuild under my belt...whats one more! 

[zammykoo]

Hey Atlas, have you tried gasket remover spray? I need to go through this tedious task myself but some people say that helps, also try propane torching to soften it. Maybe not a combination of both cause it could turn into a fireball, ha.

[iiAtlas]

Hey Atlas, have you tried gasket remover spray? I need to go through this tedious task myself but some people say that helps, also try propane torching to soften it. Maybe not a combination of both cause it could turn into a fireball, ha.

Hah! Tried the torch, it works okay at best. Another member suggested rubbing alcohol, I'll give that a shot tonight.

[grcamna2]

Hey Atlas, have you tried gasket remover spray? I need to go through this tedious task myself but some people say that helps, also try propane torching to soften it. Maybe not a combination of both cause it could turn into a fireball, ha.

Hah! Tried the torch, it works okay at best. Another member suggested rubbing alcohol, I'll give that a shot tonight.

Possibly some strong paint remover will soften those gaskets,you might let it sit on there for a good duration and then wash it all off w/ solvent and scrape it very slowly & carefully w/ a wood chisel..

[seanbarney41]

I have had good success with acetone...still takes a couple hours work though.  The acetone evaporates very fast,both a blessing and a curse in this situation...

[MoMo]

Sorry about the sleeves Atlas, didn't know sizes were different-thought it was just the bore.  If you want , I'll buy them back...Larry

[iiAtlas]

Possibly some strong paint remover will soften those gaskets,you might let it sit on there for a good duration and then wash it all off w/ solvent and scrape it very slowly & carefully w/ a wood chisel..

I have had good success with acetone...still takes a couple hours work though.  The acetone evaporates very fast,both a blessing and a curse in this situation...

Definite blessing and a curse! I'll keep working on my technique...made some progress tonight but nothing of note. Still chipping away...

Sorry about the sleeves Atlas, didn't know sizes were different-thought it was just the bore.  If you want , I'll buy them back...Larry

No worries Larry, honest mistake.  If you have a use for the sleeves I'll send them back. At least that way you'd have a complete set?  PM me if you're interested. If not I can keep watch over them until another forum member needs them.  Thanks for reaching out! Hope all is going well with your build and that the one sleeve I sent found you well. Best, Atlas.

[iiAtlas]

Still scraping...that is all.

[grcamna2]

Still scraping...that is all.

The 'good' is once you get all that old gasket off it will never be that tough again as long as you own the bike;the tough part is trying to get every last little bit off w/o removing any aluminum..

[iiAtlas]

Still scraping...that is all.

The 'good' is once you get all that old gasket off it will never be that tough again as long as you own the bike;the tough part is trying to get every last little bit off w/o removing any aluminum..

Woohoo!  Looking forward to that day....

[budman]

I used aerosol paint stripper.  Softens up the old gaskets in minutes.  I used plastic putty knives for scraping.  I bought a bunch of them because the stripper eats up the plastic, but it works.  The stripper will eat engine paint.  Not a problem if you plan on repainting.

[iiAtlas]

I used aerosol paint stripper.  Softens up the old gaskets in minutes.  I used plastic putty knives for scraping.  I bought a bunch of them because the stripper eats up the plastic, but it works.  The stripper will eat engine paint.  Not a problem if you plan on repainting.

Gave that a shot tonight, helped a bit but this gasket reallllly is baked on there.  Heat is really all that worked with any amount of success for me.  Progress after tonight...





Getting there!  I used 150 and 220 grit sandpaper to begin creating a equal plane for the new gasket.  I say one more day and I've got it.

A small plastic ring began peeling from the base of the cylinders.  It eventually snapped out.  Is this replaceable/should I replace it for each of the cylinder bases?





Thanks all!  Looking forward to getting this part over with....

[grcamna2]

Hi Atlas,
Replace those lower cylinder liner rubber sealing o-rings;new ones should be included in a quality gasket set.I would like to caution you against using any kind of sandpaper on the lower cylinder block mating surface,you want to be sure that those machined horizontal surfaces stay as 'true' and square as when they came out of the factory(same idea w/ anyone attempting  put a file to crankcase halves mating surfaces  verboten/warning!) otherwise it could change the pitch of how the cylinders sit on top of the block.. a misalignment would certainly wear your pistons and cylinders out prematurely.I think it's better to just keep slowly and surely peeling away at the black surfaces of old gasket in one spot at a time;keep at it,you'll get there finally. 

[iiAtlas]

Hi Atlas,
Replace those lower cylinder liner rubber sealing o-rings;new ones should be included in a quality gasket set.I would like to caution you against using any kind of sandpaper on the lower cylinder block mating surface,you want to be sure that those machined horizontal surfaces stay as 'true' and square as when they came out of the factory(same idea w/ anyone attempting  put a file to crankcase halves mating surfaces  verboten/warning!) otherwise it could change the pitch of how the cylinders sit on top of the block.. a misalignment would certainly wear your pistons and cylinders out prematurely.I think it's better to just keep slowly and surely peeling away at the black surfaces of old gasket in one spot at a time;keep at it,you'll get there finally. 

D'oh!!  I completely neglected the importance of having this surface remain true.  I thought the sandpaper was a good idea......I will check to ensure I didn't create any high/low spots.  Should I consider having the block trued?  I do have a mill downstairs.....

Sounds like this may have not been the best idea - oops! 

[grcamna2]

Hi Atlas,
Replace those lower cylinder liner rubber sealing o-rings;new ones should be included in a quality gasket set.I would like to caution you against using any kind of sandpaper on the lower cylinder block mating surface,you want to be sure that those machined horizontal surfaces stay as 'true' and square as when they came out of the factory(same idea w/ anyone attempting  put a file to crankcase halves mating surfaces  verboten/warning!) otherwise it could change the pitch of how the cylinders sit on top of the block.. a misalignment would certainly wear your pistons and cylinders out prematurely.I think it's better to just keep slowly and surely peeling away at the black surfaces of old gasket in one spot at a time;keep at it,you'll get there finally. 

D'oh!!  I completely neglected the importance of having this surface remain true.  I thought the sandpaper was a good idea......I will check to ensure I didn't create any high/low spots.  Should I consider having the block trued?  I do have a mill downstairs.....

Sounds like this may have not been the best idea - oops!

I think you'll be ok as long as it wasn't a heavy amount of sanding;you still have the lower area at the bottom of each cylinder liner to keep it 'true',if they were removed it could have had more material removed.. from what i can see you possibly just began this process?

[iiAtlas]

I think you'll be ok as long as it wasn't a heavy amount of sanding;you still have the lower area at the bottom of each cylinder liner to keep it 'true',if they were removed it could have had more material removed.. from what i can see you possibly just began this process?

Yes, minor sanding.  I misinterpreted another members post in regards to sanding off the old gasket, d'oh!  I don't believe I wen't too far and the area directly below the cylinders was untouched.  Thanks for the heads up grcamna2!  I can't promise to not make mistakes...but I can promise to do my best to fix them!