Here we go! Restoring 576/748

[markb]

More soaking and I'll bet they come out.  I agree you're better off not pushing too far.  (I should talk).   I even squirted mine after heating hoping that it was creating just the tiniest bit more gap.  Even the ones that came out hard were wet so I know it was getting in there.  Good luck. 

[Wayne]

Still can't get those last 2 head studs out.   I decided to split the cases and get everything packaged up for cleaning later. Once the cases are stripped it looks like there is open access to the stud bosses from the inside. Hopefully heating directly on the boss will free up the remaining studs. Also have the same problem Mark did with the roll pin for the kickstart shaft. It's frozen! Have it soaking in some miracle juice. I'll give it another try tomorrow.

When I split my cases I found that someone had left some markings in both the top and bottom case. Q - 17 marked on both halves. Anyone know what the meaning might be? My first though was, why is there English markings in a Japanese assembled motor? Just as a last footnote, bearings are standard on the mains but I couldn't see any color on the shells, even under magnification. So much for my Dot theory.  



And again:

[markb]

Nice to see it coming apart, Wayne.  I sure wish mine was that clean!  Yes you can get to the bosses that the studs go into.  Too bad they don't tap through so you could soak them from the bottom too but at least you can concentrate heat on them.  Interesting on the Q17.  Have the cases ever been apart?  I remember there was some kind of writing on the inside of my K0 cases.  I'll have to look through my photos and see if I can find it.  I know I was the first one to split the case.  If you can get your hands on a dent puller I'd recommend that.  If I were to do it again I would just try clamping the pin with a vice grip onto the screw on the puller.  With the slit in the pin is should collapse enough to clamp on the pin.  Good luck.

[Wayne]

Mark, to my knowledge this engine has never been down. I watched carefully as I took it apart for any telltale signs. I didn't see anything. The recalls were done for the case guard, throttle cables etc. The Q 17 is a mystery to me. Perhaps there was a non Japanese employee in the plant leaving his mark???

Thanks for the tip on the roll pin. If it doesn't slide out for me I'll go grab a dent puller from my friends body shop.

[Steve Swan]

These markings using English alphabet are not uncommon.  Why they are in English or who put them there, we'll probably never know.  I feel pretty confident saying there were no "round eyes" at Honda making alphabet markings of any kind in English on the inside of the cases. The Japanese used, from the beginning, English alphabet STAMPED markings on the back crank case walls for denoting matched crank case halves.  Also, the Japanese used English alphabet letters for crank shaft bearing sizing, as noted in the 3/12/70, #14 Service Bulletin.  These ink markings are inside E4540's and E254's cases.  Unfortunately i did not document them.  The inside of the unstamped cases i recently sold have markings inside the upper case, i can barely make out what appears to be a "25" -and- there appears to be some sort of marking before the numbers, guessing it might possibly be a letter of the English alphabet.  The lower case is pretty much wiped clean of any possible marking that could have been there at one time.  Since i am so damn computer challenged, i will send Wayne a picture of the upper crankcase, he can share as he sees fit.  I will hazard to guess, the ink markings denoting a machined/matched crank case set were made BEFORE the case matching stamps were made on the back wall of the case.  Quite a number of these case had hand corrections made to them at some point in time, before being assembled as an engine.  Perhaps these marking were used to denote some sort of correction had been completed on the case set, if not denoting a matched/machined case set.

[Wayne]

Here is the case that Steve Swan sent along. You cab see pretty clearly the "25" as part of a series of characters. Looks like we have another mystery to go along with the "Dots". 

[Wayne]

What a difference a day makes!  I got the head stud out finally! It was some stubborn! As a last resort I used a propane torch and lightly heated the boss and around the stud. I then melted some candle wax at the stud base and let it cool. Put the Vice Grips on, the wrench and said a few silent words.  I'll be darned if it didn't crack loose! Felt lucky as the stud was getting pretty ratted from the Vice Grips.

Now, onto the roll pin for the kick start shaft. I just warmed it up a bit as well, snapped my Vice Grips on and tapped on the Vice Grips at the lever pin where I could get some upward momentum. Some squirts of Liquid Wrench, some more tapping and out she came! 

So I guess this is the "turning point" for my project. Cleaning, painting, assembling, deciding what parts to replace etc.

Now there are SO many questions to be answered. I guess we tackle them as they come along. It does feel good to be at this juncture in the road though. 

[Steve Swan]

Wayne, the only parts i would feel compelled to replace (barring signs of gross wear - unlikely) would be the tensioner assembly for the primary chains, bearings and seals.  The primary chains don't stretch enough to have to be replaced.  And, as i recall your bike does not have many miles on it.  I would like to hear from Chris on his 5298 with 140,000 miles, if or when he replaced the chains.  Likely the bearings are fine, but as inexpensive as bearing are, might as well.

2157, the tensioner rollers are soft, are going to keep them in use along with original chains.

[Wayne]

Thanks Steve. The cam tensioner rollers look a bit chewed up to me on the roller faces. As well, the cam chain guide is damaged so a new one is on the must have list. I have read that it is good insurance to replace both the cam and primary chains. Some guys are even buying aftermarket heavy duty units. Are they necessary??? I'll look for feedback from the group here. Bottom line is, I only want to go through this motor once.

At first blush the main bearings look good. I haven't mic'd the crank yet however the bearings are not galled. I have seen a lot of people re-use the crank and rod bearings when they rebuild these units. This goes against everything I was taught and practiced all my life. I have never re-used main journal or rod bearings in a motor.

I did pack mine in proper order, just in case. The mains are clearly marked "STD". I haven't checked the rods yet. In my mind, if the crank measures within standard limits I should be able to order up a new set of 'STD" bearings and have just a bit more peace of mind with my final product. I'm assuming that either Bearing A, B , C , or D in the parts manual is "STD". For some reason I didn't think the shells would have the conventional markings like STD. - .001 etc.

I think it's only wise to replace all of the roller bearings as well unless someone gives me a heck of a good reason not to.

All new seals are on my list as well as a Yamiya gasket set in order to get the right oil pan gasket. (thanks for that tip Mark)

I think a new kick start spring is just safe insurance while I have it apart.

There are lot's of little items but I want get going with the bottom end. Get it prepped, painted and assembled. Hopefully while I'm plugging away at that we can get my sidestand issue sorted out and then the frame work can move forward as well. And so goes the plan! 

[markb]

Glad to hear you got your pins and studs out. 

My main bearings look OK on 97 but I haven't checked them yet.  After I get the cases cleaned I'm going to Plastigage them and if they check out I'm planning on reusing them.  I've done this before and never had an issue.  Just my opinion.

I was pleased with the quality of the Yamiya gasket set but it's a little spendy.  You might be able to find a cheaper set and buy the oil pan gasket separately but I went for the convenience on that one.  I also didn't use the head gasket that came with it.  I bought the one recommended in service bulletin #42 to do everything I could to prevent oil leaks.

By the way, I have the engine out of 1553 and will finish stripping down the frame this weekend.

[hondasan]

For what its worth, #5298 is currently at 116,000 miles and still running well.

The only engine work was at 32,000 when the headgasket was replaced, and at the same time I replaced the cam chain, primary chains, tensioners for both, plus of course ALL seals / gaskets. The output shaft bearings were also replaced as I found some pitting of the races. All other bearings, shells, piston rings, valves, etc, were put back in. 84,000 miles on , there is no primary or cam chain rattle at all.

As to what should be replaced during a re-build, I would simply say anything which has any signs of wear / corrosion, and anything made of rubber (inculding cam tensioner and primary tensioner components) which may have hardened and therefore could deteriorate if / when next used. Mileage is perhaps also a factor to consider, but my experience suggests any motor with modest mileage which is clean looking will likely be good to go again.

Cheers - Chris R.

[Wayne]

Thanks so far everyone. After careful review of the manual and my engine markings I think I have my head around the bearing shell size thing. The only part that eludes me somewhat is the markings on the bearings themselves. Would a green or whatever color bearing still be marked as "STD"? My cases are marked BAABA yet all of my main bearing shells are:

AP220
D9D-A
STD

Does that mean they are all "A" bearing shells? If so, that should not be in my mind. 

Lastly, is this a typical marking on the rods? I usually only see marks there on rebuilt engines. Perhaps Honda marked them from the factory?

[Riccardo]

Waine,

i've had the same problems!

It's a real ROMPICAPO (head-distroyer)!!!!!!!

Some signs are not easy to discover on the parts of the engine anf when you've discovered them the way it not easy to retrieve the color or the exact size of bearing.

Moreover, some size of bearings are not still available from Honda.

At end, i've used all STD bearings when i did my 2 rebuilt engines.

This is the suggestion can you read also on the "shop manual".

The best test after assembled the rods is the hand test: see if the rods turns easy or hard or if they have tollerances under your hands.

Be quiet, i dont think that you will go to run the 200 miles of Daytona, but i think that you will go to make walks in the days of sun.

[ashimotok0]

See service bulletins below and posting on this site

http://data.sohc4.net/SB750/750_31.pdf
http://data.sohc4.net/SB750/750_14.pdf

http://cb750sandcastonly.com/smf_forum/index.php?topic=225.0

Cheers

Ash

[Wayne]

OK, things are getting clearer. On the other side of my conrods they are all stamped "2" on the top and bottom half. I'll take it from that they are "2" rods. No visible markings on my crankshaft though so I'll have to measure it and do the math. We'll used plastigauge before final assembly. Thanks!