1982 CB750F... The resto-not

adventurco

Nick Ol' Eye
DTT BOTM WINNER
If its your first time getting into a bottom end, what I like to do is draw a rough diagram on cardboard of the bottom case from whatever view you're disassembling it from with an arrow toward the front. I'll punch some holes roughly where the bolts are so its comparable then stick the case bolts right through the cardboard so you don't have to screw around trying to remember which bolt goes where.
 

The Jimbonaut

Active Member
Good call mate - I do that with all the side covers, oil pan etc. Dominos boxes are perfect, so that's dinner taken care of too.

Hondabond huh. Best to go with OEM, right? Not an off the shelf product?
 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
Jimbonaut said:
Good call mate - I do that with all the side covers, oil pan etc. Dominos boxes are perfect, so that's dinner taken care of too.

Hondabond huh. Best to go with OEM, right? Not an off the shelf product?
I actually prefer Yamabond its a little cheaper and it stays good for a while. I'm sure you can use something off the shelf but I always just use this stuff. I've had my current tube for a couple years, it hardens up at the end but I just dig it out with a pick and roll on.
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
There's really no difference between Hondabond and Yamabond, chemically. They're both made by ThreeBond. You can also get ThreeBond 1184, 1211 and 1207B.
 

The Jimbonaut

Active Member
Righto, Fortnine (it's a huge website here in Canada) sells ThreeBond 1184 for around $17 CAD so I'll order some of that. Been looking for an excuse to go shopping there for a while as I need (well, want) another set of Biltwell kung fu grips for the KLR, and a new visor for the lane splitter.

Looks like I'm splitting the cases then.

"Never get out of the boat. Absolutely god damn right. Unless you were going all the way."
 

The Jimbonaut

Active Member
Trying to split the cases, everything seemed to be going ok but there's something near the rotor that's putting the serious kibosh on things. Everywhere else seems fine. 4 hours of wrassling with the thing and I'm stumped.

The back is clear -



the rotor, not so much -





When I lift the lower case up, it brings the rotor (and crank) with it. Something's stuck. Any ideas?
 

Nybz

Member
Looks like your getting a good schooling on the 1100f.net forum.
Some of them are a bit cranky, but a few of them know this bike inside and out.

Take the god damn rotor off!

What do your main bearings look like?
If they show copper, they are toast.


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The Jimbonaut

Active Member
Indeed - teachers come in all shapes and sizes Nybz. And it's a fool who thinks otherwise. I took a bit of a beating over there, but I'm totally ok with that. The CB1100f forum is a different beast than DTT but no worse off for it. The guys over there know their onions and no mistake. They've forgotten more about the SuperSport than I'll ever know. Amazing help and resource.

So, a productive few days. Got the newly bored-to-823cc and honed block back, completely with repaired fins, came back mint -



(need to get a photo of the fins, will do today). Someone over on the other forum mentioned S-100 and pressure washers. I have the S-100, and just last week my neighbour offered me his washer whenever I needed it. Penny drop. Balconies could use a good going over too so made that happen -



- then sprayed a load of S-100 and waited 20 mins for it to do it's thing. Kids, I discovered the coolest way to get totally soaked this summer! It's easy - line up your air-cooled cylinder block (the more cylinders the better) on a stool at about knee height. Doesn't matter what engine it comes from, the important take away here is air-cooled. It's all about the fins you see. Stand close - really close - and have at it with the pressure washer. All those fins, nooks and crannies will have you Absolutely Soaked almost immediately. It's great. Fun times.



Dammit if the S-100 didn't work a charm though, especially between the cylinders. Wiped the bores down with some engine oil to prevent flash rust, job done.

After some encouragement and gentle persuasion/peer pressure figured f*ck it let's split the cases. After the drama of the last post, it became very obvious that the rotor really does need to come off when attempting the job. Turns out the rear axle of this bike is a perfect fit into the rotor and assumes admirable chops as the pulling tool. Once I got the rotor bolt out, threaded in the axle and whaled on the thing with a heavy hammer until eventually the rotor popped off -



- and the cases split no pasa nada -



Pulled the main crankshaft bearings, the upper bearings all looked good -



but the backs of them are showing copper -



- does that matter?


The lower bearings look ok but two are showing copper -



In that case, do I need to replace all the lower bearings? Or just the two showing copper? They're about $10 each so on the big scheme of things, doable.

The con rod bearings all look good -






I'm going to replace the two cam chains, some o-rings and oil seals, I'm not sure about the primary chain, and also want to replace the rubber dampers in the primary shaft. Anything else I should be on the look out for?
 

wozza

Member
As your down that far Id replace all the bearings and have the crank done as well..copper on the back is normal (AFAIK) as they only plate the running surface..
Nothing worse than spending all that time rebuilding a motor and have a bearing spin a couple of 100 kays/miles down the road.To my eyes those conrod bearing look pretty worn Id also be looking at the oil pump circuit as well ;)
 

Popeye SXM

Also used for MX
Having gone down the rabbit hole this far... is seems daft (to me at least) not to change all the bearings. All depends of course how long you plan to keep the bike. I do admire your will to make this bike wright, keep up the great work
 

The Jimbonaut

Active Member
Cheers gents - I have it on good authority that there's no need to change all the bearings if they're not worn but I can't help agreeing with you, got this far, may as well. Still, I'd like to learn whether it's a must or not - there are only two lower main bearings that are showing copper, and none of the rod bearings.

Removed the lock bolt on the primary shaft, which involves jamming a flat head screwdriver between the split gear and the crankcase. Busted a small pry bar but eventually loosed the bolt. Involves putting the gear back in the case and tightening up a few case bolts to hold it in place, then do your worst -



With the bolt removed I could then remove a gear and a few washers but came up stuck against the bearing that also needs to be removed. The Clymers is very vague about this, just says to remove the bearing. Heat gun? That thing is jammed on there tight.

 

adventurco

Nick Ol' Eye
DTT BOTM WINNER
You'll want to use a bearing puller if you care to reuse that bearing. If you don't have one, you can try freezing that whole assembly, pulling it out of the freezer once its good and cold and hitting the bearing with a torch and the bearing should slide off.
 

pidjones

Active Member
Not much more help on disassembly, but pretty good on the bearings, here is a link to the Honda FSM chapter for this: http://www.cb1100f.net/Other/CB750FManual/Honda1979thru83CB750ServiceManualChapter12CrankshaftPrimaryShaft.pdf

You might need to join the site, but it is free and has great stuff for F bikes.
 

The Jimbonaut

Active Member
Thanks man, yeah I’m a member of that forum and I already have the FSM - doesn’t really give much info on how to remove the bearing though. The forum’s been acting up a little recently but I’ll post my q in there once it’s back up and running.

I’ll give AdvCo’s suggestion a try - if I apply heat onto the frozen bearing do I run the risk of damaging the bearing in any way? And am I right in guessing that the bearing itself is lubricated by the engine oil, not grease?


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adventurco

Nick Ol' Eye
DTT BOTM WINNER
Jimbonaut said:
I’ll give AdvCo’s suggestion a try - if I apply heat onto the frozen bearing do I run the risk of damaging the bearing in any way? And am I right in guessing that the bearing itself is lubricated by the engine oil, not grease?

Sent from my iPhone using DO THE TON
Nope, think of it like you're starting a bike in frigid temps. Your cylinders and valves will go from icy cold to hot in short order.

Yes, all the bearings in the engine are lubed by oil.
 

The Jimbonaut

Active Member
advCo said:
Nope, think of it like you're starting a bike in frigid temps. Your cylinders and valves will go from icy cold to hot in short order.

Yes, all the bearings in the engine are lubed by oil.
Good point. I don't have a torch per se but the missus has a mini blowtorch she bought for making the sugar go all crispy and fancy on her home made creme brûlées. Unless she makes the things when I'm not around (which would suck), she's never, ever made one and the lighter's sitting on the kitchen shelf unused. That'll do nicely.
 

The Jimbonaut

Active Member
Primary shaft's in the freezer, cozying up to some bison burgers and fish fingers - I'll leave it in there overnight and then hit the bearing with the blowtorch over breakfast. Pretty sure that's what kitchens are for, and if they're not then no doubt I'll find out the hard way. Again.
 
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