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Author Topic: 1977 CB 750K tune up..  (Read 7134 times)

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Offline toytuff

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1977 CB 750K tune up..
« on: March 05, 2013, 05:57:02 AM »
Put the 750 up on the lift for a little TLC. I have put 800 miles on it since getting her back on the road. Usual stuff, oil change, valve adjustment, set the dwell. sync carburetors etc.

I was wondering if anyone here has found something that works a little better then factory spec. I know on the CBX everyone said to shim the valves at .005 mm straight across. Factory spec is .003 to .005 mm on the CBX. The 750 shows a bigger spread between IN and EX.

Book states:

Valve adjustment IN .005 EX .008 (mm)
Dwell at 49 degress plus or minus 2 degrees
Plug NGK D8 EA

Thanks in advance.

tt
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Offline flybox1

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Re: 1977 CB 750K tune up..
« Reply #1 on: March 06, 2013, 09:21:46 AM »
nice work!!! 8)
good looking gauge setup as well.
« Last Edit: March 06, 2013, 09:24:25 AM by flybox1 »
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #2 on: March 06, 2013, 09:27:12 AM »
Quote from: flybox1 on March 06, 2013, 09:21:46 AM
nice work!!! 8)
good looking gauge setup as well.

Thank you!

I have another set that I never used. Thinking about selling. Thinking.

tt
« Last Edit: March 06, 2013, 09:28:47 AM by toytuff »
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Offline iron_worker

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Re: 1977 CB 750K tune up..
« Reply #3 on: March 06, 2013, 10:33:36 AM »
That is a sharp looking set.

I don't think the clutch should be that loud. Are you sure it's not the cam chain whipping around? Try adjusting the cam chain tension and making sure your carb sync is spot on. This should help with cam chain noise and probably clutch noise too if you have any.

IW
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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #4 on: March 06, 2013, 12:19:37 PM »
That's been done per post above.

When on the center stand it always made a lot of noise but when everything is good and hot it disappers. Or at least I think so.

tt
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Offline lucky

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Re: 1977 CB 750K tune up..
« Reply #5 on: March 08, 2013, 06:39:32 AM »
Quote from: toytuff on March 05, 2013, 05:57:02 AM
Put the 750 up on the lift for a little TLC. I have put 800 miles on it since getting her back on the road. Usual stuff, oil change, valve adjustment, set the dwell. sync carburetors etc.

I was wondering if anyone here has found something that works a little better then factory spec. I know on the CBX everyone said to shim the valves at .005 mm straight across. Factory spec is .003 to .005 mm on the CBX. The 750 shows a bigger spread between IN and EX.

Book states:

Valve adjustment IN .005 EX .008 (mm)
Dwell at 49 degress plus or minus 2 degrees
Plug NGK D8 EA

Thanks in advance.

tt

Dwell has to be in spec at the SAME time the points gap must be in spec.
I would just set the valves at what the book says.
BUT.... Check them. Make sure that if the valve is set at .003 thousands that a .004 will not fit in.

Many owners do not check. They think they are setting it correctly but it is not right.
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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #6 on: March 13, 2013, 04:05:26 PM »
What's the secret?

Trying to remove my transmission cover and stator cover. After 30 years those screws do not want to back out!

I tried heat, brute force and who knows what else. Rounded one so here comes the drill out.  >:(

Arghh!!!

tt
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Offline Vinhead1957

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Re: 1977 CB 750K tune up..
« Reply #7 on: March 13, 2013, 04:08:39 PM »
Impact driver! The only tool for it
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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #8 on: March 13, 2013, 04:31:03 PM »
Margaritas!

Yeah, long day in the shop so I made a pitcher. Went out and broke free all the stator screws.  8)

Had to grind down the tip of a screw bit but there easlily replaceable. One left to easy out.

When I first did this bike I ordered all new OEM gaskets and screws. Did some polishing today.

tt
« Last Edit: March 13, 2013, 04:40:09 PM by toytuff »
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Online RAFster122s

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Re: 1977 CB 750K tune up..
« Reply #9 on: March 13, 2013, 04:58:30 PM »
As they say, pictures or it didn't happen...

Glad the success in removing a bunch of the screws for the cover and the polishing.  Hope your "easy out" experience is a good one.  Just don't break the sucker off in there if you are using an easy out screw extractor.  Most are cheap and brittle.

David

BTW, How's the other bikes?  Riding some in the afternoon to enjoy the warmer weather?
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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #10 on: March 13, 2013, 05:16:01 PM »
Quote from: RAFster122S on March 13, 2013, 04:58:30 PM
As they say, pictures or it didn't happen...

Glad the success in removing a bunch of the screws for the cover and the polishing.  Hope your "easy out" experience is a good one.  Just don't break the sucker off in there if you are using an easy out screw extractor.  Most are cheap and brittle.

David

BTW, How's the other bikes?  Riding some in the afternoon to enjoy the warmer weather?

I'll get it out. If I have to I can drill the head of the screw off. It's in a position to do so.

Been to busy in the shop so haven't done any riding. Giving the 750 my time and working on buying the Kawasaki KZ 650. Spent about nine hours out there today. Like having a job! Did manage to get the bike dialed in and polished the clutch cover, new gasket, cable and adjusted.

I am getting ready to head up to the cabin for a three day break. Need to fire up the quads, barbecue and relax. ;)

tt
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Offline Stev-o

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Re: 1977 CB 750K tune up..
« Reply #11 on: March 13, 2013, 05:57:45 PM »
Where's the cabin, up in the Mts, right?  You keep the quads up there??
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'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #12 on: March 13, 2013, 06:05:04 PM »
Quote from: Stev-o on March 13, 2013, 05:57:45 PM
Where's the cabin, up in the Mts, right?  You keep the quads up there??

Yes, I posted pic's a while back. In the CBX thread I believe.

tt
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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #13 on: March 13, 2013, 06:07:03 PM »
Ya know, maybe cut the head with a slot might work better.
 
Bien, llegando a cargó para ahora utilizar herramientas aéreas. ;D

tt
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Offline Stev-o

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Re: 1977 CB 750K tune up..
« Reply #14 on: March 13, 2013, 06:40:56 PM »
Nunca es demasiado cargado para utilizar herramientas de RI, tal vez hould tener otra margarita?!
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'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #15 on: March 13, 2013, 06:44:22 PM »
Yo mejor se abstiene de utilizar cualquier herramienta en esta etapa.

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Offline Stev-o

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Re: 1977 CB 750K tune up..
« Reply #16 on: March 13, 2013, 06:55:36 PM »
Not sure if you realize this, but when you get drunk on tequila, you type in spainish!
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'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #17 on: March 13, 2013, 07:37:41 PM »
Quote from: Stev-o on March 13, 2013, 06:55:36 PM
Not sure if you realize this, but when you get drunk on tequila, you type in spainish!

¡Para que sea lo que pasa! Me pregunté causaba qué demonios esto. Maldiga tequila

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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #18 on: March 14, 2013, 07:24:16 AM »
OK! New day!

After two (2) hours of fiddle/faddle the screw finally broke free! Hooray!

Man, that thing fought me all the way. I did not want to cut the head of the screw off. It was becoming "why in the he!! did I start this" project.  ::)

You can see the screw head in the lower left. When that thing made a "snap" noise I was dancing around the shop. Literally.

Onward!

tt
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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #19 on: March 14, 2013, 07:38:28 AM »
I also learned the hard way that you can not run a cheap set of flea bay points. When I first started this build I bought a set. After trying to set these I just removed them and put in a OEM set. I was rather surprised at the difference. Lesson learned.  ;)

Checked the timing and it was spot on. The carburetors were a different story. I kept going with the factory suggestion of out 1 1/2 turns on the pilots. The bike ran awful. Had to keep the RPM high just to keep it running. Kept dying and when I opened the throttle it was horrible.

The heck with this! I backed out the one (1) and four (4) pilots until the engine smoothed out. Then went for number two (2) and three (3). About 2 to 2 1/2 turns. (richer) Problem solved. Idles lower, snappy responce. No popping and the exhaust sounds sweet. These 77 models were just leaned out to much for emissions.

Since changing out the points and adjusting the pilots guess I better sync the carburetors again. On a good note between this site and the shop I continue to learn.

tt
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Offline flybox1

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Re: 1977 CB 750K tune up..
« Reply #20 on: March 14, 2013, 08:17:34 AM »
Hey tt...nice work above.  im still battling a few nasty cylinder studs on my F3 rebuild.  good times when one breaks free  ;D
I'm interested in knowing the details of your K7 intake/exhaust setup, the model carbs you have, and their internals...

my K1 idles well with my PD carbs, but only around 1400-1500.  it should go lower.
no popping.  good plug color, but always trying to make it better....
thanks..
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #21 on: March 14, 2013, 08:46:42 AM »
Heading out for a CBX ride.  8)

I set the valves to spec. .005/.008

Carbs.. PD 41 A.

Pilots out 2 turns (plus or minus, whatever sounds good)

Points @ .015 with feeler.

Accelerator pump rod checked and OK. (.000-.002)

tt
« Last Edit: March 14, 2013, 08:52:30 AM by toytuff »
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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #22 on: March 14, 2013, 04:31:32 PM »
Well, celebrating with Margaritas again.

You know what that means!

 :o :o

tt
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Offline toytuff

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Re: 1977 CB 750K tune up..
« Reply #23 on: March 15, 2013, 06:32:43 AM »
The side case covers were pretty bad. Since I was up at 0300 hrs. it was once again, shop time.

Polished up the alternator cover and repaint. Wish I do the valve cover.  :(

tt
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Re: 1977 CB 750K tune up..
« Reply #24 on: March 15, 2013, 07:02:05 AM »
Looking NICE!
Hope it is a productive day...
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David- back in the desert SW!
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