Author Topic: Just another 71 CB750 K1 (After over a year, I finally got some 4 into 4 pipes!)  (Read 92012 times)

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Offline edhaeuser

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #225 on: May 01, 2013, 06:16:39 PM »
OK, more questions for you engine gurus.  What do you make of these crankshaft bearings?  It sure seems like there are a lot of imperfections in them (looks like a lot of it was there from the factory).  I have no experience with Honda stuff, so I don't know if this would be somewhat normal. If they measure out per spec, would you run them or order new ones?  I have not plasti-gauged them yet....I have to go get some.  $100.00 to replace them all from Service Honda.  Yes they are all labelled with permanent marker on the back side.

 This one hase quite a scratch in it but it almost looks like it was there when it was put together new. 



This pair has the worst visual wear.



All together.


« Last Edit: May 01, 2013, 06:19:08 PM by edhaeuser »

Offline pixlgeek

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #226 on: May 01, 2013, 07:14:25 PM »
Please keep up this thread. I am just about ready to start doing this exact same rebuild and your details and fantastic photos are really motivating me to get on this.

Thank you!

Offline mwvachon

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #227 on: May 01, 2013, 08:04:58 PM »
Plasti-guage is cheap enough - I would measure them all, as-is, just to start with. Just make sure your cases are REALLY clean before doing so... Then go from there.
M.W.Vachon
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1971 CB750-K1 (Candy Gold)
1971 CB750-K1 (Candy Red)
Project link: http://forums.sohc4.net/index.php?topic=108498.0]
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Offline iron_worker

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #228 on: May 02, 2013, 07:28:50 AM »
I would be hesitant to run that first pair. Mine had some markings on them like yours but not nearly as much. Plastigauge would definitely be a good check though.

Another good check is ... how do they feel? Can you feel the imperfections with your finger nail? If so, it's probably too much.

IW

Offline edhaeuser

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #229 on: May 02, 2013, 07:56:28 AM »
I would be hesitant to run that first pair. Mine had some markings on them like yours but not nearly as much. Plastigauge would definitely be a good check though.

Another good check is ... how do they feel? Can you feel the imperfections with your finger nail? If so, it's probably too much.

IW

I was thinking the same, IW.  Even if the first pair measures out, I was planning on changing them out.  That is the set that is closest to the primary drive chain. 

I can feel the big scratch, and there are high spots on either side of it.

Ed

Offline edhaeuser

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #230 on: May 02, 2013, 09:00:53 PM »
Last weekend it was 80 degrees here in Wisconsin.  Of course, I was away at work then.  Now that I am home the weather has turned to crap.  I woke up to rain, ice pellets, and snow this morning.  I was out on my driveway in this wonderful weather trying to clean up my cases so that I can get them welded.  I did not get finished because my soda blaster blew a hole in the hose that leads to the nozzle.

Since my soda blaster quit working I plastigaged the rod and main bearings.  I had to grind down a socket to get a good fit on the connecting rod bolts.



I checked the connecting rod big ends first.  They are not too bad.  Just on the upper limit of factory standard specs.  The book I have says .0008 to .0018 inches.  Mine all come in between .0016 and .0018.  Not too bad

The main bearings are not so good.  I believe the factory specs are the same as the big end bearings at  .0008 to .0018 inches with a recommended replacement at .0032 in.  Here is how mine measured up.

1-.0031 2-.0025 3-.0030 4-.0020 5-.0019

I'm not real happy with these numbers.  I will probably replace at least the first three.  Does anybody see any problem with replacing just a few as opposed to all of them?



Here are some photos of the plastigage process.  I know that many of you are well versed in this, but here is a short explanation for those that have never done it. 

I AM NOT AN EXPERT! so if I am doing or expaining something wrong, please post the error.  I don't want to lead someone down the wrong path.

Basically, you place your crankshaft journal in the bearings, lay a piece of plastigage between the journal and the bearing, and then torque your bolts to the recommended foot lbs.



then disassemble the bearing and use the little gauge to measure how much you flattened the plastigage strip.  This one comes in right around .002 in.



 

Offline edhaeuser

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #231 on: May 21, 2013, 07:19:11 PM »
Here comes a long post with a lot of pictures.  It's been quite a while since I posted anything due to lack of progress and to much work.  Where to begin......  I soda blasted the cases in preparation to have them welded up.  Right now, the cases are welded and have been transferred over to the machinist to have the case halves mated and one of the case bolt holes re-drilled and tapped.  I don't have any pictures of the welds because I have not seen the cases since they have been welded.  So far I have $30.00 and three six pack invested in the welding.  Friends of Swan from this forum are doing the welding and machining work. 

My high tech soda blasting setup.



Ready to go to Pat the welder.



I pretty much finished up the rear wheel.  This should have been finished a long time ago but the after market rim from David Silvers would not work.  To their credit, Davis Silver Spares refunded my money and told me not to send the rim back.  I noticed they no longer sell these particular rims either.  I assume they pulled them from the inventory because of problems with the rims.  I know that IW from SOHC had the same issues.

First, I reassembled the rear brakes with new shoes.



When I had removed my bearing retainer on the drive side,  I ruined the threads on the retainer, so I had to buy a new one from Service Honda.  I had drilled out the punch marks, but the threads in the hub were messed up in another area which in turn ruined the retainer.



I had read somewhere on this forum about using a tap to work out the thread imperfections on the hubs so I tried it.  It worked really well, and by the time I was done, I could thread the retainer all the way in by hand.  I ended up clamping the tap in my vice and working the threads by holding the hub in both hands.  This seemed to be the only way I could get enough force and still maintain control of what I was doing.



Got that done.



I'm getting better at installing the Tubles Kits from Outex Japan



My new seat cover arrived today from EBay seller gumtwo.  It seems to be a nice cover.  I worked on that this afternoon and pretty much got it done.









AND, with the rear wheel done, I have a roller!!!!!







« Last Edit: May 21, 2013, 07:54:10 PM by edhaeuser »

Offline Stev-o

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #232 on: May 21, 2013, 07:25:37 PM »
Nice work and write up, Ed.  You got a deal on the welding!
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline edhaeuser

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #233 on: May 21, 2013, 07:52:06 PM »
Nice work and write up, Ed.  You got a deal on the welding!

Yes,  I lucked out on the welding.  I think the machining will be very reasonable as well

Offline cheftuskey121

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #234 on: May 21, 2013, 08:15:11 PM »
great work Ed, I am drooling over your pictures. wish we weren't 1000 miles apart, would love to have a beer and talk bikes. keep it up we are all watching closely

Offline lwahples

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #235 on: May 22, 2013, 03:21:10 AM »
The bike is really looking good.Great detail!

Offline edhaeuser

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #236 on: May 22, 2013, 05:18:20 AM »
 
great work Ed, I am drooling over your pictures. wish we weren't 1000 miles apart, would love to have a beer and talk bikes. keep it up we are all watching closely
great work Ed, I am drooling over your pictures. wish we weren't 1000 miles apart, would love to have a beer and talk bikes. keep it up we are all watching closely

Hey Justin,  Savannah might be a bit of a stretch.  I used to go there for work years ago, but not any more.  Maybe we can meet half way on the bikes sometime :-)  I agree that talking bikes over beer would be good! 

Offline Garystratos201

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #237 on: May 22, 2013, 06:30:38 AM »
Nice progress Ed. I agree a beer sit down meet and great would be sweet. Justin and i arent but a few hours apart.............Gary
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Offline MoMo

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #238 on: May 22, 2013, 07:56:30 AM »
nice roller, a K1 is definitely worth putting the time in to do a top notch resto.  Keep it up...Larry

Offline edhaeuser

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #239 on: May 22, 2013, 08:23:13 PM »
Nice progress Ed. I agree a beer sit down meet and great would be sweet. Justin and i arent but a few hours apart.............Gary

It would be great if we could all work that out sometime!  I have free air travel anywhere :-)   I'd be missing my bikes though!

nice roller, a K1 is definitely worth putting the time in to do a top notch resto.  Keep it up...Larry

Thanks MoMo.  This bike and I have a lot of history together.

Just a random thought......those non stock rear shocks are beginning to annoy me.

Offline cheftuskey121

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Re: Just another 71 CB750 K1 (Damn the torpedos.....Full speed ahead!)
« Reply #240 on: May 22, 2013, 08:37:31 PM »
Ed that would be cool. fly on into atlanta! I can ride on up and Gary is already there. I think Gary mentioned something about margaritas ;)

I agree with you about those shocks. I LOVE the look of the stock shielded shocks, I couldnt fathom getting anything else on mine. at least for a resto look.

Offline edhaeuser

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Well, progress has slowed again, but I am plugging away from several directions.  Mostly, I am concentrating on engine stuff now.

When I left off, the cases were off getting some welding and machining.  That is done, and although not perfect, it will be functional.  I do not believe there will be any leaks.  The machinist said if he were to do it again, he would have liked to get the cases first, and machine out a perfectly square area, and replace with new metal that was machined to fit.  As it was, the cases went to the welder first and he patched the area up the best he could, using what was left of the damage.  There were a few spots that were about 4 thousands low.  Skip, the machinist said he could send the cases back to the welder to have a little more built up on the mating face, but recommended that I just use a small amount of metalset epoxy to bring that area up.  The reason he thought the epoxy would be better is that he has worried about another heat cycle warping the cases more than they already are.  I elected on the epoxy and it worked out fine.  when I bolt up the cases, everything pulls right together.  It's not like there is a lot of warpage.....maybe about 4 thousands or so over about a six inch span.





The hole to the left had to be re-drilled and tapped



What does one do on a rainy day?  Why, plate some nuts and bolts of course.

When I sent off all my parts to the plater, I was not expecting to rebuild the engine.  So.....what to do with the crusty engine hardware.  I checked online with Service Honda to check out prices and availability of various nuts and bolts.  Some are available and others are not.  And some are available and just too expensive to buy (at least for my cheap ###).  So I decided to plate all the top case bolts, as well as the crankshaft bearing bolts.  I decided to purchase new bottom case bolts since they were not too expensive, if they do not have the proper markings, no one will see them anyway.  New washers are on the way also......I get really annoyed with prepping washers for plating.

My prep process for plating is:

1. Thorough degreasing with acetone or lacquer thinner
2. Bead blast old plating and rust off
3. buff up the part on a wire wheel
4. degrease again in a hot soapy solution
5. rinse and plate

From left to right.  Degreased, bead blasted, and buffed



Plating with my Caswell Copy Cad kit.  Degreasing on the left, plating on the right



Finished Parts







Next up is to try and figure out Honda's convoluted bearing selection process.  I elected to replace all the main bearings, as they were marginal.  Why not, it's already apart.  Honda has four different thickness bearing shells just for "standard" size journals.  One has to figure out which "color" shell to order depending on the case bore size and the crankshaft journal diameter for each of the five bearings.  They supply this chart to help figure it out.



I used the letter markings from the case to get the case bore sizes.  I'm hoping that they are still valid as I did not have easy access to a bore gauge.  The crankshaft has letters stamped in it too, but four of the five journals had worn down one letter size.

The photo shows what I came up with for measurements on the crankshaft as compared to how it measured at the factory.  Using these numbers and letters, I was able to figure out which bearings to order.  I hope I did not mess it up.  Hopefully, when the bearings come, everything will measure right on spec.



Next up is a few photos of the engine painting process.

I had to set up my "easy up" paint booth because it was threatening to rain.  I put one side on to block the wind.

 I really dislike painting with a rattle can...there is no control over pattern and amount of paint.  I was going to just bleed off the pressure from the can,  and drain the paint into my paint gun for painting.  Alas...it was not to be as my regulator decided to crap out on me.  Oh well, rattle can it is.



A couple of before pictures





After the deed is done :-)  Painted with Duplicolor 1615 ceramic engine enamel.







A close up of the repaired area



I have a question.  Do all 750 cases have this rough texture on the bottom??????



I managed to get two of the side covers polished up this morning.  I still have a little work to do on them, but I just had to turn the engine on its side, and lay the covers on there!!! Yeah!!

« Last Edit: June 06, 2013, 01:42:55 PM by edhaeuser »

Offline edhaeuser

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Ugh....I just realized I am past my target date of finishing the bike by June 1st with no end in sight.

sigh.......

Offline edhaeuser

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Another question for you engine guys.  Would you go ahead and change out the cam chain on a rebuild with an engine that has 35,000 miles?  If so, what kind of chain and where to buy?  I see Z1 sells cam chains for $30.00 but they are the kind with a master link.  I am leery of a non solid chain.  Any experience with that type of chain?  I am also in the market for can tensioner rollers.  It looks like Honda still sells them.  Are the other, cheaper options as good? ie...Z1 again

Thanks,

Offline Retro Rocket

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In my experience, cheaper is rarely good, I only use Camellia heavy duty timing chains, and yes, i would change the chain...

CycleX has the heavy duty chain for $39 ... Half way down the page on the left....

http://www.cyclexchange.net/Engine%20Parts%20Valve%20Trane.htm
« Last Edit: June 06, 2013, 11:07:45 PM by Retro Rocket »
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
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Offline jerry h

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Hi Ed, Nice progress!

I'll second RR's last post 
Quote
In my experience, cheaper is rarely good, I only use Camilla heavy duty timing chains, and yes, i would change the chain...

That's what you want to use...tsubaki camellia HD timing chain and new Honda tensioners.  (I'd replace the primary chains (Honda as well) and associated tensioner while you have it apart).   

Use the best possible parts inside the engine you can find.... then you can put it together and forget about it. 

Your plating looks really nice!
"It is not the critic who counts, the credit belongs to the man who is actually in the arena, whose hands are covered with grease and oil."

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Offline edhaeuser

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Hi Ed, Nice progress!

I'll second RR's last post 
Quote
In my experience, cheaper is rarely good, I only use Camilla heavy duty timing chains, and yes, i would change the chain...

That's what you want to use...tsubaki camellia HD timing chain and new Honda tensioners.  (I'd replace the primary chains (Honda as well) and associated tensioner while you have it apart).   

Use the best possible parts inside the engine you can find.... then you can put it together and forget about it. 

Your plating looks really nice!


Thanks Retro and Jerry.  I guess it is going to be another call to Cycle X to supplement the gaskets, seals, and rings I ordered from there last week.

Offline MrGardman

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Looking great. Keep up the good work.

Offline edhaeuser

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Some more progress pics.

Just a little story about issues that I had that may or my not help another newbie like myself.

I started the engine reassembly process with some trepidation.  This is my first Honda rebuild.  I got a couple of manuals from a friend, the factory manual online, and the Hondaman book.  I read the steps in the different manuals.  It surprised me that there are different approaches to assembling the cases.  Haynes says to set the upper case over the lower, Clymer, Hondaman, and the Honda manual I have says to set the lower case on top of the upper.  Well, on my first try, I set the lower case onto the upper case.  Everything slipped together nicely.  I installed all the lower bolts, including the crankshaft bolts, and torqued everthing down.  Then I flipped the cases over and saw that oil had  spilled out of the lower countershaft area and contaminated the mating surface.  So, I put a few of the top case bolts in, flipped the engine over, took out all the bottom bolts, flipped the engine again. removed the top bolts and separated the cases again.  Now I had the lower case sitting on the table with all the internal parts sitting in place, except for the final drive shaft, which remained in the top case.  I recleaned the mating surfaces with lacquer thinner and a rag, making sure I got all the oil off for another go at it.

I got it together the second time with no contamination.  It was much more difficult to deal with the fitting the timing chain and connecting rods through the upper case,  all while trying to lower the case and try to keep everything clean.  My son helped to guide everything through.



Here are a few photos of the process if anyone is interested.

Countershaft, shift drum. and shift arms installed in the lower case.



It took a little head scratching to figure out how the shift mechanism went back together.  A visit to the parts diagram on the Service Honda site was a great help









Pretty much everything in the upper case for assembly the first time around.



Lower case to be dropped over the upper



And as it sits now....after the second try.



Cylinders painted and honed.  They measured out within new specs so a hone was all they needed.



Oh, a huge thanks to Swan (member here) for coming up with a bearing retainer at the last minute so that I could get this thing buttoned up this weekend!!!!  I lost it somewhere in my garage.

I am waiting for new piston circlips and valves from Cycle Exchange so that I can keep going.

Offline iron_worker

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Great progress Ed.  ;D I love watching the engine build sections. That's the most exciting part for me.

I would agree with others that for the for cost of the part and how deep you are now you really might as well replace that cam chain!

IW