Author Topic: the '750FK'n Mutt'  (Read 24908 times)

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Offline flybox1

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the '750FK'n Mutt'
« on: April 08, 2012, 02:46:15 PM »
Picked up this titled no-runner in Seattle on 4/5/12 for $700.
Its a K8 frame with a K1 motor and rotted #4 (HM405's)
PO indicated it hadnt been started or run since sometime fall 2010.
New : fork ears, tires (still have nubbies down the center tread),chain, cables.
everything else i'll dig into to see....
« Last Edit: April 21, 2014, 09:29:26 AM by flybox1 »
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #1 on: April 08, 2012, 02:48:56 PM »
leaving in a week for vacation with the family...i wanted to wait and start on this when we got back.
THAT wasn't going to happen! ::)

Started with tearing carbs off to get a Simple Green bath.
« Last Edit: April 11, 2012, 02:58:33 PM by flybox1 »
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #2 on: April 08, 2012, 02:52:53 PM »
as you can see, bowl #4 is still on.
couldnt for the life of me get it off, until I poured boiling water over it.

looks like old trident gum gasket sealer  >:(  some was on each bowl but this one was caked.
more hot water and fingernails got it off....
« Last Edit: April 09, 2012, 09:00:26 AM by flybox1 »
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #3 on: April 08, 2012, 02:55:14 PM »
bowls all clean
thanks to following a nice build thread by brandEn, PD accel pump/diaphragm all clean and functional.
« Last Edit: April 09, 2012, 09:00:46 AM by flybox1 »
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #4 on: April 08, 2012, 03:04:21 PM »
bath time. 
sprayed down with SG, and rinsed dry.
frame will need PC this winter...
did i mention this was sitting in a chicken coup for the last 2 years :o
rims will need attention too.  ill hit these after the kids go to bed...
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #5 on: April 08, 2012, 03:08:49 PM »
A screwdriver and leverage is NOT the way to get a head off.  >:(

anyone have an idea what the red stuff is?
probably will leave it alone if she doesnt leak, and wait to tackle this when its time for powder coat.

Fuse holder was melted.  rigged up a temp to allow me to check the electrics...


'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 lucky

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Re: The Mutt - '78 K8/K2
« Reply #6 on: April 08, 2012, 03:11:13 PM »
Make sure that check ball in the bottom plate of the accelerator pump will work.
To test put all the float bowls back on and don't forget the little o ring on the #2 float bowl top edge.
On the bench... Fill all of the float bowls with gas and actuate the throttle a few times and make sure all 4 of the brass nozzles in the venturis squirt gas.

Make sure the check ball in the top edge of float bowl #2 will not allow gas to go downwards. Only upwards. Make sure it has the little O ring in that top edge of the float bowl for that check valve.
« Last Edit: April 08, 2012, 03:12:57 PM by lucky »

Offline lucky

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Re: The Mutt - '78 K8/K2
« Reply #7 on: April 08, 2012, 03:14:25 PM »
A screwdriver and leverage is NOT the way to get a head off.  >:(

anyone have an idea what the red stuff is?
probably will leave it alone if she doesnt leak, and wait to tackle this when its time for powder coat.

Fuse holder was melted.  rigged up a temp to allow me to check the electrics...

That red stuff is the sign that an amateur worked on this bike. That is red RTV sealant applied before or after the head was on.

Offline flybox1

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Re: The Mutt - '78 K8/K2
« Reply #8 on: April 08, 2012, 03:25:56 PM »
RVT eh...well, we shall see how she runs, when she runs, and go from there.  :-\
I am the 4th owner  ::)  might need to put that on the Bad PO thread.....

thanks Lucky, i verified the carb passages are functioning as they should.
I only wanted to wrestle them back on once.

Neutral light not working.  cleaned the neutral switch, and all is good.
no high beam light, but headlight wired as it should be. 
bulb was missing in the tree, and i had one from the 350F.
Theres chrome under all that crap!!!
sheared off intake #3 tappet cover. >:(  They dont need to be on THAT tight.  FK!
PB plaster by finger and a few choice words, and it budged.  replacements are on order
« Last Edit: April 09, 2012, 09:02:43 AM by flybox1 »
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #9 on: April 08, 2012, 03:34:18 PM »
one of my helpers...
'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 KB02

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Re: The Mutt - '78 K8/K2
« Reply #10 on: April 08, 2012, 04:08:43 PM »
New : fork ears, tires (still have nubbies down the center tread),chain, cables.
everything else i'll dig into to see....

Be careful and check those tires out. Still having nubs only means that they have low miles. Old tires are still OLD tires. As tires age they get hard and loose traction. You'll probably be okay, but all tires have date codes on them, it would be worth checking it out to find out just how old they are.
1978 CB750K Project
2000 Ducati ST2
...and a pedal bike

Join the AMA today!!

My project thread Part I: K8 Project "Parts Bike"
My project thread Part II: Finishing (yeah, right) touches on Project "Parts Bike"

Offline flybox1

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Re: The Mutt - '78 K8/K2
« Reply #11 on: April 10, 2012, 07:20:04 AM »
Those tires were made 22(week) '10, so i think i'm good for 1 season, maybe more, but i'll keep and eye for cracking.
While waiting for parts, gauges came off to be polished, cleaned, and painted. 
Old faces were warped.  new faces on the way. Internal reflector rings got a few coats of gloss white. 
« Last Edit: May 14, 2012, 12:50:27 PM by flybox1 »
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #12 on: April 13, 2012, 02:48:00 PM »
replacement tappet covers arrived, installed. timing checked, again.  wouldn't fire.
checked for spark on all plugs, nothing on #1.  cut back wire and reinstalled cap. 
nice blue spark
took a few tries, but got her started and all warmed up.  sounds pissed off compared to my quiet 350F  ;D
needs cam chain adjustment. 
Throttle still really sticky, and i know its my routing with these drag bars and my controls too close to center.
Norman-Hyde M bars on order.  hopefully this will help.
Hagon shocks on order.
Hondaman Transistorized Ignition Module on order.
a much needed vacation for a week, then home to new toys in the mail!  ;D


« Last Edit: May 14, 2012, 12:51:21 PM by flybox1 »
'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 brandEn

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Re: The Mutt - '78 K8/K2
« Reply #13 on: April 13, 2012, 07:05:01 PM »
Did you get pipes yet?

Offline flybox1

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Re: The Mutt - '78 K8/K2
« Reply #14 on: April 13, 2012, 08:51:19 PM »
Not yet. Might see if I can get this spot brazed?
Metalwork and welding is an art I know very little of.
Played with my new eBay gauge faces...
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #15 on: April 13, 2012, 08:52:21 PM »
Blue LED backlighting
« Last Edit: April 13, 2012, 09:20:18 PM by flybox1 »
'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 KB02

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Re: The Mutt - '78 K8/K2
« Reply #16 on: April 14, 2012, 05:03:02 AM »
That gauge looks nice.  8)
1978 CB750K Project
2000 Ducati ST2
...and a pedal bike

Join the AMA today!!

My project thread Part I: K8 Project "Parts Bike"
My project thread Part II: Finishing (yeah, right) touches on Project "Parts Bike"

Offline flybox1

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Re: The Mutt - '78 K8/K2
« Reply #17 on: April 14, 2012, 05:42:11 AM »
Thanks.   The  gauges are from eBay, white w a clear backing, and the LEDs are the 120deg BA9s-x-x-xv from superbrightleds.com
About $2 each, and are a direct fit for gauge and cluster lights.  5 color choices.
« Last Edit: April 14, 2012, 05:47:43 AM by flybox1 »
'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 MasterChief750

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Re: The Mutt - '78 K8/K2
« Reply #18 on: April 14, 2012, 04:25:21 PM »
have the same bulbs in my gauges. only had one die. so far all the rest are good, a lot brighter than the incandescent bulbs
1978 CB750 K - Project Red Headed Step Child
1976 CB750 K - Drag Bike
Some things i know, others i dont.
I AM THE STIG
Sam is THE STIG
he said i can be STIG3 tho

Offline flybox1

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Re: The Mutt - '78 K8/K2
« Reply #19 on: April 23, 2012, 08:08:56 AM »
Back from a week in cabo, time to detox and wrench.  Had a bunch of stuff arrive in the mail while i was gone.  yesterday, first on the menue was to remount the refreshed gauges.  My 9 year old son now knows the true meaning of knucklebuster as he helped me remove the old grab bar, and shocks, and re-install the new Hagons from Davequinnmotorcycles.com  Great folks and service there.
Took a quick 15 minute ride around the hood and back for an oil change.  This was the first this bike has run (more than just at idle in the driveway) in about 2 years.  Not too bad.  Still need to sort some ergonomics. This seat is waaaaay slick/slippery.
Clutch engagement not as smooth as my 350F, but that is the only other bike i can compare it to.   My gut says it could be better.  I'll play with the position of the foot lever and see if that makes any difference.
At idle, i noticed something more than water vapor out of #1 exhaust over the past few weeks.  Even after it  warmed up well.  After this ride, it was noticeably less.  Something to keep an eye on.
We also removed the controls and the old drag bar and installed the new N-H M Bars.
This afternoon we'll get to the Hondaman Ignition module....

A Great 70deg day in the PNW to be out riding ;D

'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 lucky

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Re: The Mutt - '78 K8/K2
« Reply #20 on: April 23, 2012, 04:28:40 PM »
A screwdriver and leverage is NOT the way to get a head off.  >:(

anyone have an idea what the red stuff is?
probably will leave it alone if she doesnt leak, and wait to tackle this when its time for powder coat.

Fuse holder was melted.  rigged up a temp to allow me to check the electrics...

The red "stuff"is RTV silicone. A sign that a real amatur has been working on it.
The broken fin is another  sign...........Sorry.

Offline tweakin

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Re: The Mutt - '78 K8/K2 - Polishing the Turd
« Reply #21 on: April 23, 2012, 06:30:11 PM »
looking good flybox.  After meeting you, you will love the 750 vs the smaller bike.  If you need any local help, let me know.

Offline flybox1

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Re: The Mutt - '78 K8/K2 - Polishing the Turd
« Reply #22 on: April 24, 2012, 09:16:02 AM »
Hondaman ignition module was super easy to install.  30 min or so. 
Most of which was finding a good mounting position.
Noticeably better start, idle, and accelleration.
rode to work this am. started fast, and i was able to adjust the idle down quicker than normal, even on this chilly am.....wife said I wasnt too loud, and I didnt wake the kidlings....worth every penny!  ;D

looking good flybox.  After meeting you, you will love the 750 vs the smaller bike.  If you need any local help, let me know.
Thanks T!
Youve done some beautiful work on your F's. I might bend your ear on engine rebuild process when this one gets too tired  ;D 
I'm enjoying the heck out of it now tho  ;D
'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 flybox1

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Re: The Mutt - '78 K8/K2 - Polishing the Turd
« Reply #23 on: April 27, 2012, 08:55:03 AM »
Wheel bearings, SS brake line, brake pads, and air box boots are consuming all my cash for the month.
Here's my low-budget ($8) reinforcement of a cracked side cover.
adhesive fiberglass drywall tape.
I later coated with JBWeld, but am unable to post that pic. 
i fat-fingered my not so smartphone and dumped that picture while i was resizing. >:(


I later ditched these for some Frankencovers.
« Last Edit: March 05, 2013, 10:20:13 PM by flybox1 »
'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 flybox1

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Re: The Mutt - '78 K8/K2
« Reply #24 on: April 30, 2012, 09:49:15 PM »
New toys came in the mail today.  ;D
New throttle sleeve to replace cracked one.
New airbox to carb boots.
New GT grips.
I put the kids to bed early, and sent the wife to play with her friends..
From the time I took my sidecovers off, all got installed in 2 hrs.
Just needing a re-sync of my carbs.

Time to enjoy a little Booker's.......
'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…"