Topic: SON OF A...

[borzwazie]

So, here's my fun for the day.

I just got the motor back in this thing. Damn, the 750 is a pig!



I have been turning it over every now and then to keep it free. Today, after I successfully wrestled this fat #$%* back into the frame by myself, I put the kickstarter on so I could turn it and squirt some engine oil down the plug holes.

STUCK.

!!@#$@!#!!!!

I threw some marvel mystery oil down in there to try to free it up. Could I have put the left side cover back together wrong? Maybe the starter gear?

[fastbroshi]

What all did you do to it while it was out?

[andy750]

That is one good  looking bike! I cant wait to see more pics of  it. What bars do you have on there? I really like the black/chrome combo!

good luck getting it moving again
Andy

[borzwazie]

I had pulled the old sidecovers off as they had ugly paint and jbweld (cracked) all over them. I put on a less-crappy set that I polished up a bit.

That's pretty much it.

[KRONUS0100]

how were you turning it over before you put it back in the frame?

[Gordon]

I had pulled the old sidecovers off as they had ugly paint and jbweld (cracked) all over them. I put on a less-crappy set that I polished up a bit.

That's pretty much it.

By side cover do you mean the gear selector cover or the stator cover?  If the stator cover it's possible to assemble it incorrectly (or loosely) which could cause the rotor to hit the stator when trying to turn the engine. 

[borzwazie]

how were you turning it over before you put it back in the frame?

Kickstarter, pulling it by hand.

[Deltarider]

Today, after I successfully wrestled this fat #$%* back into the frame by myself,

Is it still in neutral after all your wrestling?

[borzwazie]

yeah, I put the chain on it and it's stuck hard. 

[69modelj]

take the covers off one a at time and see if it frees up as you remove each one. that'll tell if its something you did.

[borzwazie]

Well, the good news is that after re-pulling the alternator cover yet again, the motor isn't stuck, just the kicker. I put a wrench on the rotor and the motor turned just fine. Yay for not pulling that fat bastard out again!

Pulled the old plugs while I was at it - they look pretty good, actually! I've never heard this thing run (bought it in a basket). I think it was running a little rich for the PO, maybe, but no oil fouling at all.

[madmtnmotors]

Did you change the clutch cover with one from a different motor? I'm talking about the aluminum case cover, not the chrome tin outer cover. I used an aluminum case cover from an earlier model CB750 and realized one significant difference (other than those earliest ones that had an extra bolt). Seems that some of the earlier case covers had a deeper screw boss where one of the three screws attach the outer tin cover to the aluminum case cover. This one deeper casting extends in deep enough to bind the clutch hub on later engines with a taller clutch stack. The one screw boss is the one closest to the kicker shaft I think. I took the dremel to mine and shaved about a 1/4" off this one screw boss till it was even with the rest. The cover was chromed and looked better than the one I took off so I really wanted to use it. I had simply replaced the friction plates in mine, had this chromed cover laying around, so I bolted it on. The extended screw boss effectively "Pinned" the clutch in place and the kickstarter would not move. I liked to never figured out what was wrong except for the gouges on the clutch hub (I jumped on the kicker pretty hard) and now all is well.

[madmtnmotors]

This would also apply if a "Clutch Upgrade" were performed on an earlier engine that had the type of aluminum case cover described in previous post. The earlier clutches can be upgraded to the thicker clutch pack that was in the later engines (I think my 78' has seven friction plates while earlier engines had six) which would produce the same results that I experienced. Good luck, and keep us posted.

[Gonzowerke]

The Honda rice boys swear by ATF. They also claim filling the cylinders with it overnight frees stuck, carboned up rings.

try putting it in gear and putting a wrench on the sprocket shaft. Be careful! you don't want to snap the bolt, just see if it turns. If not, try it in neutral to verify it's the engine section and not the trans section.

[borzwazie]

madmtnmotors, that's exactly what I did!

I have a '78 motor, pulled the sidecovers off another motor, I think it's a '73. They look mostly the same, and fit right on, so I thought they were the same.

I'll pull that clutch cover back off tomorrow. awesome tip!

[madmtnmotors]

Mine is also a 78'. If I hadn't done it myself I would not have believed it. The covers look identical and bolt right up. The fix was easy, and proved to be a valuable lesson learned. Fortunately for me, the only work I had performed was replacement of the friction plates so diagnosis was focused on the clutch assembly instead of a wide range of possibilities that comes with a complete engine teardown/reassembly. I didn't even feel like waiting for a new gasket so I cut my own from sheet gasket so I could keep riding. Your symtoms sounded identical to those that I experienced, especially after you verified that the engine moved freely. Glad I could help.

[borzwazie]

just an update - madmtnmotors was exactly correct. The '78 has the bottom of the screw boss already milled off - the earlier clutch cover screw boss is rounded. I ground it down a bit, and my kicker works again.

thanks!

[madmtnmotors]

Glad I could help. The subtlety of the problem still blows me away.