Topic: Guidance needed: Engine seized up, third piston stuck, heavy wear on the crank.

[jacquesleclochard]

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[jacquesleclochard]

Figured it out! I wonder if I can pair rods with an F weight mark with ones without? The service manual doesn't mention how close the rods have to be without an F mark.

Well, never you mind. I decided I am going to use a matching pair and order the proper bearings tomorrow; the case told me all B. The crankshaft gave me ABABA, and four 4's for the rods. The rods that I will use all have F2. That puts all the bearings on green.

Next to the service bulletin Bryan mentioned I used Hondamans' book and this thread as reference: http://forums.sohc4.net/index.php?topic=55330

Quite an expensive job, this revision. I ordered new primary chains and clutch plates today. Tomorrow I'll bite in and order the bearings, then install them as soon as they come in.

I decided on using a nicely bead blasted engine, also all B's. This because the cylinder with the overbore came from this case. I'll just transfer all the parts over to the new case, after properly cleaning it, and painting the insides of the casing to get rid of the stray beads. Anything I should look out for? You can still talk me out of it.

Heck, I might even wake up tomorrow and rethink this whole thing over.

[Jerry Rxman Griffin aka MuthaF'er]

Are you talking about an "F" on the big end side opposite the "4"s? If so and 2 rods don't have a weight letter then simply weigh them all.

[jacquesleclochard]

Done. They match up, so I ordered shells, chains, and three shift forks that are within specs. Today ill clean out the bead blasted case.

I have seen some rebuilds where people paint the inside of The case. What sort of paint is that?

[Terry in Australia]

Don't paint the insides of your cases mate, you don't want hot oil washing the paint off and turning it into glue to block all your oilways. Cheers, Terry.

[jacquesleclochard]

Allright, it does sound like a silly idea.

In other news, the last stud didnt come out and decided to snap at the thread. !@#
 
Tried heating, hitting, begging and wedding another bolt to its remains, no avail. What now?...

[jacquesleclochard]

I'll have to take this to a machine shop. Drenching it in oil at the moment, but I gave all that I found on the search function a go, then looked over at the bead blasted case.

Spend five hours degreasing, high pressure hosing, air cleaning it.

All the parts came in today as well. I'll start the rebuild tomorrow. Exciting. I'm going to take my time.

I saw a guy put grease on the roller bearings in this rebuild video made by a member of this forum. Good idea?

CB750 SOHC Gear Shift/Drum Stopper Installation.

[jacquesleclochard]

Don't paint the insides of your cases mate, you don't want hot oil washing the paint off and turning it into glue to block all your oilways. Cheers, Terry.

Read on the comments on the video up here that the red stuff is called Glyptal. Makes oil flow faster or something?

[Terry in Australia]

Yeah, I really don't think it's that important that you paint the insides of your cases mate, as long as your pump is in good condition, your main bearings don't have too much slop and your oil jets are all clear, you won't have this problem again. You're lucky you only broke one stud, last time I tried to remove some I broke three! Cheers, Terry.

[jacquesleclochard]

Inner oil pump rotor damage. Is this a culprit? The big one took a lot of scarring. The small one significantly less.

[bjbuchanan]

That oil pump is probably fine actually, the pumps are overbuilt as stock. Polish up any burrs, check clearances if you have the tools for it

Glyptol is pointless unless you are a max effort kinda guy. In a stock motor, even a tame 836 setup it isn't worth the expense. It helps with oil return to the sump. In drag cars or racing cars of any type it is useful at max effort because it reduces windage in the sump and the most amount of oil is available at the bottom of the sump.

[jacquesleclochard]

That oil pump is probably fine actually, the pumps are overbuilt as stock. Polish up any burrs, check clearances if you have the tools for it

Still, replaced the worn one with a less worn one.

Rebuild started! So excited. Installed new clutch plates, new shift fork fingers that are well within specs, replaced the kickstarter gear and rebuild and primed the oil pump. Lots of fun. More tomorrow.

[HondaMan]

That oil pump is probably fine actually, the pumps are overbuilt as stock. Polish up any burrs, check clearances if you have the tools for it

Still, replaced the worn one with a less worn one.

Rebuild started! So excited. Installed new clutch plates, new shift fork fingers that are well within specs, replaced the kickstarter gear and rebuild and primed the oil pump. Lots of fun. More tomorrow.

Do you mean, with a less worn pump? The rotors are matched to their bodies when the pumps are made (that was the state of Tech in those days), and replacing rotors often ends up making less oil flow in a given pump (if it doesn't just bind up the pump).

Scarring on the rotors is common. You can try Plastigaging the rotors to the sides of the pump, or just measure it all. The clearances are in the manual(s), and Honda was generous: I think their wear limit is .013", or something huge like that. The pumps made 25% more flow than needed when new.

Even with scarring, replacing the shaft seal inside the body does a LOT for increasing oil flow on pumps that sat for a long time.

[brandEn]

That oil pump is probably fine actually, the pumps are overbuilt as stock. Polish up any burrs, check clearances if you have the tools for it

Still, replaced the worn one with a less worn one.

Rebuild started! So excited. Installed new clutch plates, new shift fork fingers that are well within specs, replaced the kickstarter gear and rebuild and primed the oil pump. Lots of fun. More tomorrow.

Do you mean, with a less worn pump? The rotors are matched to their bodies when the pumps are made (that was the state of Tech in those days), and replacing rotors often ends up making less oil flow in a given pump (if it doesn't just bind up the pump).

Scarring on the rotors is common. You can try Plastigaging the rotors to the sides of the pump, or just measure it all. The clearances are in the manual(s), and Honda was generous: I think their wear limit is .013", or something huge like that. The pumps made 25% more flow than needed when new.

Even with scarring, replacing the shaft seal inside the body does a LOT for increasing oil flow on pumps that sat for a long time.

Are you saying that if I replace the rotors in a pump there is a great chance the pump will seize or fail? I just replaced the rotors in my pump for my engine rebuild...

[Terry in Australia]

You're screwed Branden, you better just cut your losses and send me that bike...........

[brandEn]

Haha!

[jacquesleclochard]

That oil pump is probably fine actually, the pumps are overbuilt as stock. Polish up any burrs, check clearances if you have the tools for it

Still, replaced the worn one with a less worn one.

Rebuild started! So excited. Installed new clutch plates, new shift fork fingers that are well within specs, replaced the kickstarter gear and rebuild and primed the oil pump. Lots of fun. More tomorrow.

Do you mean, with a less worn pump? The rotors are matched to their bodies when the pumps are made (that was the state of Tech in those days), and replacing rotors often ends up making less oil flow in a given pump (if it doesn't just bind up the pump).

Scarring on the rotors is common. You can try Plastigaging the rotors to the sides of the pump, or just measure it all. The clearances are in the manual(s), and Honda was generous: I think their wear limit is .013", or something huge like that. The pumps made 25% more flow than needed when new.

Even with scarring, replacing the shaft seal inside the body does a LOT for increasing oil flow on pumps that sat for a long time.

Ill look into it. Thanks for The heads up! Something else... The clutch friction plates, one of them has a wider set of teeth... Does this one go in first, or last? And why is it shaped like this?

[jacquesleclochard]

I ask silly questions. Here is where I am now.

[Terry in Australia]

Looking good mate, Honda used at least 2 different types of clutch plates during the life of the CB750, and there was also an "anti-rattle" plate used in the later engines. Just use the best ones that you have, and yes, from memory, that plate goes in first. Cheers, Terry.

[HondaMan]

That oil pump is probably fine actually, the pumps are overbuilt as stock. Polish up any burrs, check clearances if you have the tools for it

Still, replaced the worn one with a less worn one.

Rebuild started! So excited. Installed new clutch plates, new shift fork fingers that are well within specs, replaced the kickstarter gear and rebuild and primed the oil pump. Lots of fun. More tomorrow.

Do you mean, with a less worn pump? The rotors are matched to their bodies when the pumps are made (that was the state of Tech in those days), and replacing rotors often ends up making less oil flow in a given pump (if it doesn't just bind up the pump).

Scarring on the rotors is common. You can try Plastigaging the rotors to the sides of the pump, or just measure it all. The clearances are in the manual(s), and Honda was generous: I think their wear limit is .013", or something huge like that. The pumps made 25% more flow than needed when new.

Even with scarring, replacing the shaft seal inside the body does a LOT for increasing oil flow on pumps that sat for a long time.

Ill look into it. Thanks for The heads up! Something else... The clutch friction plates, one of them has a wider set of teeth... Does this one go in first, or last? And why is it shaped like this?

Take a close look at the clutch hub: if yours has wider slots to hold the very top plate, and if those on that odd plate have the wider tangs to fit, it is one of the post-1977 clutch setups. Those have a different plate on the top of the stack (last one to go in) and they also have a double-steel plate (2 plates riveted together with little flat springs in between them) that goes in as the 2nd or 3rd steel plate from the inside of the stack.

Many of these later ones had either larger square-cut cork blocks on them (which were GL1000 plates from the Honda recall of 1978 for the clutch rattle issues) or else have slant-cut corks. Be sure those slants point AWAY from the direction of rotation, or it will induce extra slip during takeoff.

[HondaMan]

That oil pump is probably fine actually, the pumps are overbuilt as stock. Polish up any burrs, check clearances if you have the tools for it

Still, replaced the worn one with a less worn one.

Rebuild started! So excited. Installed new clutch plates, new shift fork fingers that are well within specs, replaced the kickstarter gear and rebuild and primed the oil pump. Lots of fun. More tomorrow.

Do you mean, with a less worn pump? The rotors are matched to their bodies when the pumps are made (that was the state of Tech in those days), and replacing rotors often ends up making less oil flow in a given pump (if it doesn't just bind up the pump).

Scarring on the rotors is common. You can try Plastigaging the rotors to the sides of the pump, or just measure it all. The clearances are in the manual(s), and Honda was generous: I think their wear limit is .013", or something huge like that. The pumps made 25% more flow than needed when new.

Even with scarring, replacing the shaft seal inside the body does a LOT for increasing oil flow on pumps that sat for a long time.

Are you saying that if I replace the rotors in a pump there is a great chance the pump will seize or fail? I just replaced the rotors in my pump for my engine rebuild...

No, they don't seize in operation: rather, they won't spin at all when you screw the covers down tight. You'll notice those right away, though!

The only ones that don't seem to do this are the '77-'78 pumps, maybe because by then they were coming from the Gold Wing production equipment. This new stuff was much more precision-like stuff than the "old" SOHC4 lines before them, which were largely made of people crawling over each other, making motorcycle parts as best they could.

If you look closely at the earlier rotors, you can see where they were lapped in to their final fit with lapping compounds, emery paper, and stuff like that. If you install them "out of sequence", they stick and jam when turning: you then have to take it apart, jump one "cog" over on one or both rotors, and repeat until the 2 rotors (hi and low PSI sides) match up again. Then it suddenly spins smoothly and pumps much better.

[Terry in Australia]

Geez Mark, don't give all that info away for free, tell 'em to buy your book! (Yeah I know, I haven't bought a copy yet, I'm so poor I'm waiting for a well thumbed used copy to come up on eBay..........)

[jacquesleclochard]

Thats interesting, Mark! There are also small indents on the inner rotor. Oil holes? Do these face out or in?

The circlip that goes behind the nut before The clutch pack is installed, how does it go in? Do I install it behind the teeth, as seen in the back the photo?

Is this even the right circlip?

[jacquesleclochard]

Geez Mark, don't give all that info away for free, tell 'em to buy your book! (Yeah I know, I haven't bought a copy yet, I'm so poor I'm waiting for a well thumbed used copy to come up on eBay..........)

I doubt someone'll ever sell it. ITS THAT GOOD! :p

[Terry in Australia]

Geez Mark, don't give all that info away for free, tell 'em to buy your book! (Yeah I know, I haven't bought a copy yet, I'm so poor I'm waiting for a well thumbed used copy to come up on eBay..........)

I doubt someone'll ever sell it. ITS THAT GOOD! :p

Well if it's THAT GOOD, what are you doing asking questions? READ THE BOOK!