Topic: Frame-up cb350f restoration, hunk o' junk transformation

[markreimer]

Pistons back on after giving the wrist pins and rods a nice layer of assembly lube. Gasket surfaces are clean, ring gaps are spaced at 120 degrees apart and facing away from the wrist pins. Circlips are all in, and I'm ready for final assembly.


One question. My gasket kit came with these two seals. They look like the supports for the hard oil lines that run parallel to the camshaft on top of the head, but they're about five times bigger than they should be. I'm thinking they're not meant for a 350F. Anyone recognize these?




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[markreimer]

After test fitting my head gasket I'm unsure about these seals. The originals fit the head gasket much nicer than the new ones. The originals seems pretty soft and aren't chewed up at all. What do you guys think - re use these?



And the new ones:




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[Remcod]

Find a set oem nos ones on eBay: they are for sale but make sure they have the Honda packaging or they are just aftermarket still. My rebuild leaked after 200 and after 1200 km severely after resurfacing and with nos aftermarket ones. Now rebuild with oem seals and with copper gasket, bone dry for 500km and just retorqued but winter now. Hope this does not slow down the build but it's worth it. No idea where those big seals are supposed to go.

[Remcod]

I can add to that that when I compared the two the aftermarket ones appeared shrunken by heat causing the leak.

[markreimer]

I can add to that that when I compared the two the aftermarket ones appeared shrunken by heat causing the leak.

Thanks. What is strange is that these seals came in a Honda gasket kit, and looking at the parts fiche (checked all years) it seems this is what the seal looks like too. Very odd. So the non-lip seals I have are Honda seals, yet not the same as what came in the engine...

Sorry to hear about your leak. So it leaked once, then you resurfaced the head and it leaked again? Man, bummer! I'm using a Honda head gasket and copper coat, hopefully it helps. I've read a ton of leaky top end rebuilds on the forum here, only ones I could find that held had some kind of copper or other sealant added, so I'll give it a try. It's winter now though so I'll have to wait a long time to find out


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[markreimer]

Here is the seal in question, no lip...

 http://www.cmsnl.com/honda-cb350f1-four-1974-usa_model434/gasket-orifice_12910333000/#.WGloUGnOeEd


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[markreimer]

Some poking around brought me to this thread:

http://forums.sohc4.net/index.php/topic,111517.25.html

Quite a few people with leaking top end rebuilds using a variety of gasket brands and seals. The one guy who seems to have good luck used Honda gaskets and seals - including the oil orifice seal without a lip. Sent him a PM for more info and an update two years after his rebuild. If it's been holding, I'm going to copy that approach and use the replacement seals that came in my kit.

[DH]

Pistons back on after giving the wrist pins and rods a nice layer of assembly lube. Gasket surfaces are clean, ring gaps are spaced at 120 degrees apart and facing away from the wrist pins. Circlips are all in, and I'm ready for final assembly.


One question. My gasket kit came with these two seals. They look like the supports for the hard oil lines that run parallel to the camshaft on top of the head, but they're about five times bigger than they should be. I'm thinking they're not meant for a 350F. Anyone recognize these?




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Balance tubes for 4/4 exhaust mufflers?....(guessing)

[markreimer]

Pistons back on after giving the wrist pins and rods a nice layer of assembly lube. Gasket surfaces are clean, ring gaps are spaced at 120 degrees apart and facing away from the wrist pins. Circlips are all in, and I'm ready for final assembly.


One question. My gasket kit came with these two seals. They look like the supports for the hard oil lines that run parallel to the camshaft on top of the head, but they're about five times bigger than they should be. I'm thinking they're not meant for a 350F. Anyone recognize these?




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Balance tubes for 4/4 exhaust mufflers?....(guessing)

Wow, right you are! No wonder I couldn't find a spot for them.




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[markreimer]

Top end is nearly back together now!

Last night I slide the cylinders on and torqued the head down.

I put the new base gasket on, making sure the oil return galleys were clean and clear of debris. I used a very think film of Hondabond around the high pressure oil line and the oil return lines, above and below the gasket. I've always done that on my 750 builds and it's worked well.

Slide the block on with no issues. New o ring seals on the bottom of the jugs and knock pins in place. It's nice having that taper on the bottom of the cylinders. Makes it real easy. A thin film of oil on the jugs makes it all come together nicely. No compressor needed, just my fingers and going slow.



Then comes the head gasket and orifices. I used hondabond on the seals around the orifices like the link earlier showed. I made sure nothing got in or near the actual oil passage though. Don't want to toast this build off the bat. The head gasket got three thin coats of permatex copper coat. Knock pins in place with new seals and it was time to drop the head on





The head fit without issue and I started torquing the 12 stud nut and one 10mm bolt down. I went in three stages and brought it up to max torque. I'm going to leave it for a day or two and then come check it again. I was planning on just putting the torque wrench on at final spec. Some people back the nuts off half a turn and tighten again. Any advice? That sounds like it might break the copper bond to me.

One more session in the shop and I can fire it up! Then it's on to addressing my really leaky fuel tank. The new petcock is leaking like a sieve.


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[calj737]

After a day or two, best to release the nuts in reverse sequence (as you would to remove the head) then re-tighten to final torque. This prevents any distortion of the head. If you simply went through each nut and torqued again without loosening, you may find just a couple of nuts are not "tight". That means you have not tightened the head uniformly to begin with, and thus run the risk of distortion later.

As for disturbing the bond of the copper, without heat cycles, you'll be just fine.

[markreimer]

Any advice as to whether I should do one bolt at a time (loosen 1/2 turn, then bring back to torque spec, move on to the next bolt) or loosen all the bolts 1/2 turn (in reverse sequence compared to instal) and then bring them all back up to spec?

[MoMo]

Any advice as to whether I should do one bolt at a time (loosen 1/2 turn, then bring back to torque spec, move on to the next bolt) or loosen all the bolts 1/2 turn (in reverse sequence compared to instal) and then bring them all back up to spec?

loosen all bolts in reverse criss-cross as Cal mentioned then retorque...Larry

[MoMo]

Any advice as to whether I should do one bolt at a time (loosen 1/2 turn, then bring back to torque spec, move on to the next bolt) or loosen all the bolts 1/2 turn (in reverse sequence compared to instal) and then bring them all back up to spec?

loosen all bolts in reverse criss-cross as Cal mentioned then retorque...Larry

  edit:  from outside to inside-same as removal

[markreimer]

Any advice as to whether I should do one bolt at a time (loosen 1/2 turn, then bring back to torque spec, move on to the next bolt) or loosen all the bolts 1/2 turn (in reverse sequence compared to instal) and then bring them all back up to spec?

loosen all bolts in reverse criss-cross as Cal mentioned then retorque...Larry

  edit:  from outside to inside-same as removal

Right, opposite of install than, which starts from the middle and works outward. I'll give it a day and check the torque.


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[grcamna2]

Nice work Mark 

[RAFster122s]

Yes, when removing you do it a bit at a time, reverse of install.  Bringing it down slowly in same way you are slowly tightening the head evenly.  Removing in the opposite order you tighten the head.

Just as Cal and MoMo have said.  Cal has plenty of experience and has never mentioned having a leak.

I don't recall, did you have your head and cylinders skim cut to ensure they were flat?

David

[markreimer]

Yes, when removing you do it a bit at a time, reverse of install.  Bringing it down slowly in same way you are slowly tightening the head evenly.  Removing in the opposite order you tighten the head.

Just as Cal and MoMo have said.  Cal has plenty of experience and has never mentioned having a leak.

I don't recall, did you have your head and cylinders skim cut to ensure they were flat?

David

Thanks Dave, I did have the head skimmed as it was around 5/1000th out toward the center. They didn't touch the cylinders though


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[grcamna2]

Any advice as to whether I should do one bolt at a time (loosen 1/2 turn, then bring back to torque spec, move on to the next bolt) or loosen all the bolts 1/2 turn (in reverse sequence compared to instal) and then bring them all back up to spec?

loosen all bolts in reverse criss-cross as Cal mentioned then retorque...Larry

  edit:  from outside to inside-same as removal

Right, opposite of install than, which starts from the middle and works outward. I'll give it a day and check the torque.


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I install and start tightening in the middle and work my way out toward each end of the the head in 'X' patterns alternating sometimes to double-check.When I loosen the head I start from the outside ends first w/ 'X' patterns and loosen/work my way toward the middle;all of this sequential tightening and loosening in steps to keep the head from warping.I make sure the threads are clean on the studs and nuts first and use a thread chaser if necessary(not a tap or die)on either and then I use a small bit of Anti-seeze on each studs threads and washers and test-run each nut down on the studs to evenly distribute the Anti-seeze;this is because I like to be sure I am getting a 'true' torque reading on each set of threads.
I use the same 'Anti-seeze' process on my wheel spokes.

[calj737]

...I use a small bit of Anti-seeze on each studs threads and washers and test-run each nut down on the studs to evenly distribute the Anti-seeze;this is because I like to be sure I am getting a 'true' torque reading on each set of threads.

This would not be advisable for studs into cylinders. Better to use LocTite than AntiSieze. You actually want the stud to be chemically "connected" to prevent it from spinning out when you loosen the nut.

[markreimer]

...I use a small bit of Anti-seeze on each studs threads and washers and test-run each nut down on the studs to evenly distribute the Anti-seeze;this is because I like to be sure I am getting a 'true' torque reading on each set of threads.

This would not be advisable for studs into cylinders. Better to use LocTite than AntiSieze. You actually want the stud to be chemically "connected" to prevent it from spinning out when you loosen the nut.

I think he meant antiseaze on the upper stud threads where the nuts go. The lower threads going into the engine case would benefit from loctite.


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[grcamna2]

...I use a small bit of Anti-seeze on each studs threads and washers and test-run each nut down on the studs to evenly distribute the Anti-seeze;this is because I like to be sure I am getting a 'true' torque reading on each set of threads.

This would not be advisable for studs into cylinders. Better to use LocTite than AntiSieze. You actually want the stud to be chemically "connected" to prevent it from spinning out when you loosen the nut.

I think he meant antiseaze on the upper stud threads where the nuts go. The lower threads going into the engine case would benefit from loctite.


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Yes,thanks for making it clear;I don't want the studs to loosen once I tighten them down into the cases.

[markreimer]

I had a few spare hours tonight and made some progress.

I followed the advice shared earlier and backed off all the stud bolts in the opposite order. I noticed my manual called for a light dose of motor oil on the threads, so I did that and proceeded to torque them all down. Seems like it pulled it a bit tighter than last time.



Next was installing the camshaft, tensioner and oil lines. I gave the camshaft journals a layer of assembly lube and finessed the cam chain sliders into place. That's when I realized my cam chain tensioner mechanism was seized. No wonder it was so noisy. A bit of penetrating oil and alternating pressure on the slider and the tensioner mechanism I got it to break free. It's nice and snappy now!



I timed the valves/camshaft, gave everything a little bath of oil then installed the cover. Set the valve clearance and the motor is ready to go!



I need to add oil (do NOT forget that...) drop in the carbs and exhaust, then fix my leaking petcock. Maybe 2-3 hours and I can fire it up


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[MoMo]

Thumbs up....Larry

[RAFster122s]

Nice progress, hope the carbs are quicker to install on the 350...the 550 takes a few tricks and holding your tongue just right.

It is a good habit to always check the oil everytime before starting and do a walk around after starting to check lights & signals while gearing up.

I've actually sat the bottle of oil on the seat if I left it without oil.