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Author Topic: My '78 CB750F project - Reassembly!  (Read 10513 times)

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Offline cmonSTART

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My '78 CB750F project - Reassembly!
« on: January 04, 2012, 03:35:08 PM »
Hello folks!  I purchased a mostly complete and very neglected 750 Super Sport this week for my next project.  (see photo below!)  The bike has sat since the 80s and the engine is stuck.  The bike needs a ton of work.  I'm pretty sure this is going to be a complete frame up rebuild into a cafe racer which I will try to document here as time allows. 

Thus far I have removed the luggage and fairing from the bike and began removing as much as I can so it will roll into the shop more easily.  The seat and tank are gone.  I did find the original owner's manual and warranty manual (with emissions certificate) in the glove box.  Also inside was a complete new points plate assembly as well as an older one, and four new plugs!  The rear brake is frozen and will no doubt need a rebuild.  The front brakes somewhat work.  I had to add a bit of fluid and clean out the relief hole, and the right side caliper sticks just a bit. 

I tried removing the carburetors but being very very cold outside now the intake boots are too stiff.  I'll have to get it inside for that. 
« Last Edit: March 02, 2012, 05:26:37 PM by cmonSTART »
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1981 GL1100 Interstate
1978 CB750F Project

Offline wedoo2

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Re: My '78 CB750F ratbag project
« Reply #1 on: January 04, 2012, 06:04:34 PM »
Well, you are at the right place.  You're gonna see that your bike is not the worst start that people have had.  Poke around here for a while and look at the project threads and get your ideas together.  Manuals here for the taking as well.

That thing looks like a tourer that carried a rider with a flatulence disorder.  Blew it right out!  ;D
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Some days the sun is too loud.

Offline Steven.Burns

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Re: My '78 CB750F ratbag project
« Reply #2 on: January 04, 2012, 07:57:35 PM »
Welcome to the F club!!  8)  Can't wait to see what you got going with that big old cruiser you got there.
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1978 CB750F3 -Scrambler/ tracker or something of the sort  http://forums.sohc4.net/index.php?topic=97025.msg1083788#msg1083788

Offline Terry in Australia

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Re: My '78 CB750F ratbag project
« Reply #3 on: January 05, 2012, 03:09:25 AM »
The "F" club? Is that like "F Troop"?  ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline wedoo2

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Re: My '78 CB750F ratbag project
« Reply #4 on: January 05, 2012, 03:38:58 AM »
Ah, Melody Patterson
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Some days the sun is too loud.

Offline wedoo2

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Re: My '78 CB750F ratbag project
« Reply #5 on: January 05, 2012, 03:44:09 AM »
Sorry for the hijack, but Terry started it.



Back to your regularly scheduled thread.
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Some days the sun is too loud.

Offline Terry in Australia

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Re: My '78 CB750F ratbag project
« Reply #6 on: January 05, 2012, 04:31:45 AM »
Fark! I'd forgotten about her, she's much prettier than Corporal Agarn........... ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline Toxic

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Re: My '78 CB750F ratbag project
« Reply #7 on: January 05, 2012, 04:34:04 AM »
F Troop .... man you guys are showing your age. LOL  Sadly so am I.

BTW great bike
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Offline sopo400f

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Re: My '78 CB750F ratbag project
« Reply #8 on: January 05, 2012, 05:23:39 AM »
Hey comnstart, was that the one listed on CL recently?
Have a blast taking that beast apart.
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1975 cb400f blue

Offline cmonSTART

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Re: My '78 CB750F ratbag project
« Reply #9 on: January 05, 2012, 01:27:15 PM »
Sopo, yes it is.   

I stripped a bunch more stuff off of it this afternoon when I had a free bit of time to kill.  I ended up removing the handlebars too so it would fit through my shop door.  All in all things came apart pretty easily.  Usually the bikes I find with stuck motors are in much worse shape.  The electrical system is pretty clean and most of the nuts and bolts came off easily.  I did snap one spark plug off in the head, though. 

Oh, and the carburetors came off easily today after a little lube. 

Good stuff so far!  Now that it's in the shop the fun work begins!
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1981 GL1100 Interstate
1978 CB750F Project

Offline sopo400f

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Re: My '78 CB750F ratbag project
« Reply #10 on: January 05, 2012, 04:38:35 PM »
Awesome progress, specially  for working in the cold.
Good news on the clean electrical.
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1975 cb400f blue

Offline knowsnothing

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Re: My '78 CB750F ratbag project
« Reply #11 on: January 05, 2012, 09:48:54 PM »
Cold AND windy.  Pretty much miserable.  Keep up the good work!
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1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline dhall57

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Re: My '78 CB750F ratbag project
« Reply #12 on: January 06, 2012, 03:00:58 AM »
Quote from: wedoo2 on January 05, 2012, 03:38:58 AM
Ah, Melody Patterson
Wedoo, She needs to be added to the TV stars you were in love with growing up thread!! Don't know how we missed her.
« Last Edit: January 06, 2012, 03:10:24 AM by dhall57 »
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1970 CB750KO
1971 CB500KO-project bike
1973 CB350G- project bike
1974 CB750K4-project bike
1974 CB750K4
1976 CB750K6
1977 GL1000
1997 Harley Wideglide

Offline dhall57

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Re: My '78 CB750F ratbag project
« Reply #13 on: January 06, 2012, 03:06:40 AM »
Have fun with your 750F project. You'll have a nice one when done ;)  Are you going to sell the Windjammer and bags?
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1970 CB750KO
1971 CB500KO-project bike
1973 CB350G- project bike
1974 CB750K4-project bike
1974 CB750K4
1976 CB750K6
1977 GL1000
1997 Harley Wideglide

Offline cmonSTART

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Re: My '78 CB750F ratbag project
« Reply #14 on: January 06, 2012, 01:30:52 PM »
dhall, yes I will probably try to sell the bags and fairing.  They're pretty nasty and in need of a bit of TLC, though. 

I finished up today's work and made some more progress on the bike.  I got the engine out which went better than I expected.  It is a game of millimeters though.  My Craftsman motorcycle jack under the engine with a couple blocks of wood raised it up pretty easily and a couple pry bars helped pop it out. 

I broke the top end down and it really doesn't look bad all in all.  I will certainly need some new oversized pistons/rings but everything looks pretty good other than that!
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1981 GL1100 Interstate
1978 CB750F Project

Offline cmonSTART

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Re: My '78 CB750F project - Carburetor horror show!
« Reply #15 on: January 07, 2012, 01:48:45 PM »
I was able to finish disassembly today and take the bike right down to the bare frame.  I found a bit of rust right on the lower cross member at the rear of the engine and while it is pitted a bit, it's still solid.  I guess I'm going to sandblast and paint the frame/swingarm next. 

I did get to open the carburetors, too, which as expected were an absolute horror show!  I guess that's what happens when it sits for 20+ years with gasoline in it.  Check out this varnish!
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1981 GL1100 Interstate
1978 CB750F Project

Offline cmonSTART

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Re: My '78 CB750F project - Carburetor horror show!
« Reply #16 on: January 09, 2012, 05:46:43 PM »
The past couple days I've just picked and poked at things, trying to get my head around what needs to be done to this to get it where I want it.  Here is my plan of attack thus far:

1.  Rolling Chassis - Get the frame sandblasted and painted and the front and rear suspension/wheels bolted back on. 

2.  Engine - Rebuild the engine (836 kit, head work, clean it up and figure out a paint scheme for it.)  Get the engine back into the frame

3.  Carburetors and other stuff needed to make it run and drive.

4.  Tank, seat, signals, electrics, odd essential stuff. 

I may or may not rewire the bike.  I'm trying to cut as much weight as possible.  We will see. 
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1981 GL1100 Interstate
1978 CB750F Project

BrockSamson

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Re: My '78 CB750F project - Carburetor horror show!
« Reply #17 on: January 09, 2012, 06:38:48 PM »
Ha!  Those carbs are disgusting.  I opened up the carbs that came with my bike and they were spotless, dumb luck.  Although I doubt even though they weren't on the bike that they had sat unused for very long. 

Best of luck with your build!
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Offline greenjeans

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Re: My '78 CB750F project - Carburetor horror show!
« Reply #18 on: January 10, 2012, 10:27:25 AM »
The only good thing about carbs that look that nasty is:  they can be cleaned and most times the varnish acts like a protective film  ;)
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Yep, I'm the kid that figured out how to put things back together...eventually.

Offline cmonSTART

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Re: My '78 CB750F project - Carburetor horror show!
« Reply #19 on: January 10, 2012, 03:42:09 PM »
Well, the bowls have cleaned up pretty darn well after 24 hours in carb dip.  I think another 24 and the bowls should be spotless!
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1981 GL1100 Interstate
1978 CB750F Project

Offline hapakev

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Re: My '78 CB750F project - Carburetor horror show!
« Reply #20 on: January 10, 2012, 06:49:37 PM »
Man, Dhall beat me to it.  I was gonna ask about the bags and rack, put me in line I guess. BTW I have a 77/78F airbox if you need one, I noticed it was missing in earlier pics.
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1978 CB750F(ish)

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Offline cmonSTART

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Re: My '78 CB750F project - Carburetor horror show!
« Reply #21 on: January 10, 2012, 07:24:03 PM »
No thank on the airbox.  I'm probably going to go with pods. 

Really, if either of you guys are really interested in the bags or Windjammer or whatever PM me.  They need quite a bit of restoration.
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1981 GL1100 Interstate
1978 CB750F Project

Offline cmonSTART

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Re: My '78 CB750F project - Nice Bottom!
« Reply #22 on: January 11, 2012, 01:55:34 PM »
Considering the amount of engine work I have ahead of me I decided to put my mind at ease and inspect the bottom of the motor.  Ok, inspect is a bit inaccurate, but I did split the cases and take a peak at the bearing surfaces and gearsets etc.  Everything looks pretty good.  In most cases the machining marks are still there.  Nothing is broken or missing.  There is a small amount of debris in the oil pan/oil screen, but nothing abnormal and very little of it was magnetic.  I did find one wrist pin clip but I think that is the one I dropped when disassembling the top end.  I may or may not replace the crank and big end bearing surfaces.  We'll see. 
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1981 GL1100 Interstate
1978 CB750F Project

Offline cmonSTART

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Re: My '78 CB750F project - Nice Jugs!
« Reply #23 on: January 14, 2012, 05:30:51 PM »
This afternoon, after I had finished my business stuff for the day I decided to take a closer look at the pistons and jugs in the motor.  The motor is the original and I figured I at least owed it to the bike and collectors everywhere to rehab what I could and NOT hack up a motor if I didn't have to.  The engine was stuck when I got it, having sat for 20+ years.  I have the pistons soaking right now and the top rings are loosening up.  I ran my hone through the cylinders and really they're not THAT bad after clean-up.  I might poke at these pistons/rings a bit more and see if I can save them (they are hard to find.)  If I don't have to drop $500 on an 836 kit right now that will make me happy. 
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1981 GL1100 Interstate
1978 CB750F Project

Offline cheapride

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Re: My '78 CB750F project - Nice Jugs!
« Reply #24 on: January 15, 2012, 04:12:16 AM »
I have a new set of rings that I was going to use.  I ended up going the 836 route.  Let me know if you want them.  Nice progress.
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1978 cb750f Supersport
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