Author Topic: My K8 re-conditioning  (Read 18927 times)

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Offline grcamna2

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Re: My K8 re-conditioning
« Reply #300 on: April 19, 2023, 01:59:20 PM »
How many miles on the new engine now Dennis ?
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
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Do your BEST...nobody can take that away from you.

Online denward17

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Re: My K8 re-conditioning
« Reply #301 on: April 19, 2023, 02:36:09 PM »
How many miles on the new engine now Dennis ?

About 150, I've been busy lately so no riding time.

Online denward17

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Re: My K8 re-conditioning
« Reply #302 on: April 20, 2023, 01:25:23 PM »
Rode a little today, about 165 miles so far.....

Plug read look good?

From left to right 4-3-2-1

Offline grcamna2

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Re: My K8 re-conditioning
« Reply #303 on: April 20, 2023, 02:05:28 PM »
The #1? looks a bit oil fouled,imo..possibly the rings haven't yet seated in that cyl.?
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline RAFster122s

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Re: My K8 re-conditioning
« Reply #304 on: April 20, 2023, 02:33:32 PM »
Well, might tell you if engine is generally OK. Since it is stock you aren’t really going to need to go through doing plug chops unless you are having issues.
#1 insulator does look a bit fouled by rich running or possibly oil, probably will clean up as rings finish seating.

Pop a new set of plugs in and check your clearances on valves.

I wouldn’t worry with less than 500 on the rebuild.
David- back in the desert SW!

Online denward17

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Re: My K8 re-conditioning
« Reply #305 on: April 20, 2023, 02:41:37 PM »
Having no issues, runs good, it is a bit cold natured, I need to leave the choke on for about the first half mile, once going it runs fine off of choke.

I had the idle screws set to 1.5 turns out, then went to 2 turns out, and now on 1 turn out, just to see how it would run, I cannot discern any differences.

Offline Stev-o

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Re: My K8 re-conditioning
« Reply #306 on: April 20, 2023, 03:09:52 PM »
The #1? looks a bit oil fouled...

I wouldnt call that fouled, maybe a little rich compared to the others.
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline BenelliSEI

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Re: My K8 re-conditioning
« Reply #307 on: April 20, 2023, 04:00:59 PM »
Dennis……Did you pull the plugs after a wide open run, instant shut down? If you idled up the street and did a normal ride and shut down, they look good. Even a bit lean on 2,3,4. My K7 and K8 need the same warm up you describe. Once warm, they run great. I usually have to reset the idle a few times as it heats up.

Online denward17

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Re: My K8 re-conditioning
« Reply #308 on: April 20, 2023, 06:30:55 PM »
Dennis……Did you pull the plugs after a wide open run, instant shut down? If you idled up the street and did a normal ride and shut down, they look good. Even a bit lean on 2,3,4. My K7 and K8 need the same warm up you describe. Once warm, they run great. I usually have to reset the idle a few times as it heats up.

It was an idle stop in the garage, cut petcock off, then shut off the engine.  Engine was at operating temperature. No WOT yet.

Offline RAFster122s

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Re: My K8 re-conditioning
« Reply #309 on: April 20, 2023, 07:30:46 PM »
Just so we are clear to make sure you understand plug chops...
Plug chops are done with fresh plugs, warm bike up first on whatever used plugs you were using. Pull old plugs replace with new out of the box properly gapped plugs. Operate bike for several minutes in rpm you are checking to give a deposit on the plugs. Hit kill switch coast off road braking to stop. Pull plugs and then you read the plugs to see if your carbs are tuned correctly for that throttle setting, typically WOT is checked if all is running well at low and mid throttle settings.
You can pop original plugs you previously pulled back in to  ride home if you aren't adjusting and retesting a fully warmed up bike. Depending upon how much road side tuning you are comfortable with performing...
Having a few sets of new plugs with you if adjusting and retesting...
David- back in the desert SW!

Offline BenelliSEI

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Re: My K8 re-conditioning
« Reply #310 on: April 20, 2023, 08:25:18 PM »
+1 to above. On a race car at Mosport, we typically run WOT up the 4,000 ft back straight, hit the kill switch and “roll” through he last three corners, into the pits….

Caution on a roadside plug swap. Great chance to cross thread a cold plug into a HOT motor……

Online denward17

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Re: My K8 re-conditioning
« Reply #311 on: April 25, 2023, 07:58:20 AM »
Going to try to get some riding time in today....yesterday installed 18 tooth sprocket on the front.

Today using a makeshift paint booth to prime my side covers....again.  I did a much better job of getting all the visible scratches out this time.

Still waiting on aerosol can of paint I ordered.


Offline MRieck

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Re: My K8 re-conditioning
« Reply #312 on: April 26, 2023, 04:34:35 PM »
Going to try to get some riding time in today....yesterday installed 18 tooth sprocket on the front.

Today using a makeshift paint booth to prime my side covers....again.  I did a much better job of getting all the visible scratches out this time.

Still waiting on aerosol can of paint I ordered.
Taking a nap in there would be awesome after painting. ;) ;D ;D ;D
Owner of the "Million Dollar CB"

Online denward17

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Re: My K8 re-conditioning
« Reply #313 on: April 26, 2023, 06:42:04 PM »
^Agree with that Mike...

Online denward17

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Re: My K8 re-conditioning
« Reply #314 on: April 28, 2023, 11:10:59 AM »
Changed fork oil today just to see what would come out.  Right side looked red, as in ATF, the left side had some type of brown oil.

The left side has given me indications that it may leak a little, so ordered fork seals, but will wait and see how bad it gets.

I replenished using Bel-Ray 15w. (5 oz).

The left spring free measured 498mm, the right 503mm.  I think they are ok not to replace for now.  The Honda manual for a K7 states 504mm standard, with a 480mm service limit.


Installed new GT style grips last week, the left one would move, so I tried to glue it on, eventually messed it up and had to cut it off.  So ordered a new set, this time will go on with golf grip tape.
« Last Edit: April 28, 2023, 11:12:40 AM by denward17 »

Offline newday777

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Re: My K8 re-conditioning
« Reply #315 on: April 28, 2023, 01:48:02 PM »
Hint, make the springs the same length with a spacer to get even travel of the forks.

Grip installs, spray in liberal amount of brake cleaner to help slide in place than let it dry a couple hours.  No slippy.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline Stev-o

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Re: My K8 re-conditioning
« Reply #316 on: April 28, 2023, 03:06:19 PM »
Grip installs, spray in liberal amount of...

I use hair spray! 

'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline newday777

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Re: My K8 re-conditioning
« Reply #317 on: April 28, 2023, 03:08:02 PM »
Grip installs, spray in liberal amount of...

I use hair spray! 


Yes it works. I have used it too when I had it available.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Online denward17

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Re: My K8 re-conditioning
« Reply #318 on: April 29, 2023, 01:42:00 PM »
Installed new left side hand grip today with a piece of golf tape and some solvent, went on easy and it is stuck on good.

Put about 30 miles on it this afternoon.

Noticed I have an oil leak at the bottom of the left fork, I assume the washer at the bottom.

Will probably take both forks off in a month or so and put in new seals, and new washers at the bottom of the forks.

The wife and I stopped by my son's house for a few minutes.
« Last Edit: April 29, 2023, 01:45:41 PM by denward17 »

Offline grcamna2

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Re: My K8 re-conditioning
« Reply #319 on: April 29, 2023, 02:15:54 PM »
Good to see you out and about with your Wife aboard enjoying the bike  ;) :)
I imagine you'll have more break-in miles soon  8)
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Online denward17

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Re: My K8 re-conditioning
« Reply #320 on: April 29, 2023, 03:32:00 PM »
Good to see you out and about with your Wife aboard enjoying the bike  ;) :)
I imagine you'll have more break-in miles soon  8)

When can I assume it is broken in?  About how many miles?

I think I have about 230 on it.

Offline grcamna2

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Re: My K8 re-conditioning
« Reply #321 on: April 29, 2023, 04:00:37 PM »
Good to see you out and about with your Wife aboard enjoying the bike  ;) :)
I imagine you'll have more break-in miles soon  8)

When can I assume it is broken in?  About how many miles?

I think I have about 230 on it.

Dennis,I do break-in in stages for a street bike.
I go real easy for the first 50miles,then raise the rpm's a bit for around the next 250miles.. always varying the rpms & never letting the tach sit at one preset rpm.
I like to give the engine a few quick 1-2nd gears 'blasts occasionally,which will help 'seat' the rings while the cylinder walls are still 'fresh';I don't back-down too fast using engine breaking while the rpms are up high,but let them come back down slowly which helps smooth the piston skirts.
When I get to about 400-500 miles I'm starting to open it up and use the full rpm powerband through the gears.
I like to think that(depending on how tight the machinist left the clearances..)the break-in is complete around 700?
I am always varying the rpms under different loads during break-in;then after break-in,I can allow the tach to sit at one preset rpm.. and don't Need to vary the rpms(although I prefer varying the rpms:it's my style)while cruising;I do open it up a bunch after 700,while going through the gears to break it in for top-end. I like the idea 'drive it like you stole it' for the last stage of top-end power break-in(speed/rpms)while 'Working' the engine through it's paces. imo  :)
« Last Edit: April 29, 2023, 04:26:36 PM by grcamna2 »
75' CB400F/'bunch o' parts' & 81' CB125S modded to a 'CB200S'
  I love the small ones too !
Do your BEST...nobody can take that away from you.

Offline PeWe

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Re: My K8 re-conditioning
« Reply #322 on: April 30, 2023, 01:40:36 AM »
Easy for the first 20 minutes. Then give the throttle up to 4000 rpm a few times followed by throttle offs on 3-5 gears.
Cruising in 4000-5000rpm.
Then 6000 rpm bursts ;)

The last break ins with 836, 970, 1005 cc got a taste of 8000 rpm on first ride when warm. ;)

Cruising around in legal speeds.
Rings need to be worn in while bores still have the rough grinding surface.
The first 100km is important. Miss that window might delay the rings to adapt to bores or never as good.

I have seen the difference on old 836 pistons and later 836 pistons that got a harder brake-in.

The sissy driven (first 1000km at max 4000-5000rpm on 5th gear) pistons have brown residues under rings. The other alu colored only despite wider worn bores.

The last 970cc take very little oil despite rather high compression.  (Forged pistons with bigger clearance.)

The little oil taken so far mostly due to 3 dyno visits with at least 4 torturing WAT up to 9500rpm at high load each time.
(Rear tire got a shorter life)
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Online denward17

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Re: My K8 re-conditioning
« Reply #323 on: May 15, 2023, 08:04:55 AM »
Not much time to ride lately, only 250 miles so far.

Finally got paint from automotivetouchup, took almost 4 weeks.


Setting up to paint side covers today, again.............this time I have them hanging inside the make shift paint booth, using fishing line.

Offline Mark1976

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Re: My K8 re-conditioning
« Reply #324 on: May 15, 2023, 09:00:22 AM »
   So what type of paint are you going to shoot, do you plan on a clear coat?
Start with the end in mind...