Author Topic: 750 K1 project  (Read 5020 times)

Offline JamesH

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Re: 750 K1 project
« Reply #120 on: August 11, 2019, 12:44:48 PM »
Great progress - looking awesome. Keep the pics coming...

Offline paul G

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Re: 750 K1 project
« Reply #121 on: August 12, 2019, 08:09:24 AM »
Coming along nicely Mick  :D
Honda CB400 4
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Honda CB750 UK K1
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Offline Crispy

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Re: 750 K1 project
« Reply #122 on: August 12, 2019, 10:44:34 AM »
Thanks all, I'm not expecting to get it on the road soon though, still missing quite a few parts  :o. I've  set myself a target of getting it ready for the next Crich show, if i manage it before then that will be a bonus.
I'm sorting the wiring out at the moment, trying to get it all in place and working while the frame is relatively bare, I'm not sure about the rectifier it looks a bit battered and the rubber surround to it has perished but hey ho! overcoming these little problems is one of the joys of restoring these old bikes. :)
Next problem to sort is an oil tank leaking from the base of one of the hose connections where it enters the tank, I'm going to try and get it brazed I think, anyone else had similar leak to sort?
« Last Edit: August 12, 2019, 10:58:50 AM by Crispy »

Offline Trigger

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Re: 750 K1 project
« Reply #123 on: August 12, 2019, 09:16:16 PM »
These were brazed from the factory. You will have to get all the paint off and make sure the tank is free from rust on the inside.

Offline Crispy

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Re: 750 K1 project
« Reply #124 on: August 25, 2019, 02:12:40 PM »
Made a bit more progress today, got the Carburettors reassembled, everything seemed to go back together ok, good job I took loads of pics and notes!  :). here's before and after pics.
« Last Edit: August 25, 2019, 02:24:15 PM by Crispy »

Offline Nurse Julie

  • 1973 CB750 UK K2.1977 CB550/4 Mongrel Brat. 1978 CB400/4.
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Re: 750 K1 project
« Reply #125 on: August 25, 2019, 06:01:14 PM »
They have come up fantastic Mick, great job 👍👍👍
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Andrew-S

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Re: 750 K1 project
« Reply #126 on: August 25, 2019, 06:08:34 PM »
Carbs look great, it may be one of the jobs I'll have to tackle on my K1.
Bikes: 1970 US CB750 K1 and a UK 1976 Z900 A4
Cars:  1958 Triumph TR3A and a 1972 TR6

Offline Crispy

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Re: 750 K1 project
« Reply #127 on: September 09, 2019, 07:52:49 AM »
Pleased to report that I've had the oil tank repaired, I've painted it and it's now fitted to the bike along with whatever else I have that is ready to bolt on. I need to sort a brake out next as the bike is getting difficult to stop when I roll it back into the garage from my hill of a drive! :o Can anyone enlighten me as to how the oil tank works? In particular what does the pipe connected to the crank case do? Is it just a breather?   Thanks!  :)

Offline SumpMagnet

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Re: 750 K1 project
« Reply #128 on: September 09, 2019, 06:07:32 PM »
Looking much shinier than my efforts :)

Not sure about the K1...but my F2 had a complex arrangement of pipes coming off the crankcase, through a catch tank bolted to the bottom of the battery box.
It wasn't connected to teh oil tank...the oil tank had a breather/overflow pipe running from the top back side of teh filler cap...straight down to the deck.

Now....that may not be correct...but it's how mine was when I got it

CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline K2-K6

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Re: 750 K1 project
« Reply #129 on: September 09, 2019, 07:26:17 PM »
The F2 came in the era of emmisions and trying to avoid output to atmosphere.  They effectively collect any oil suspended in air (smoke to most of us)  and seperate it at the air filter contraption to burn any contaminant by drawing in through intakes.

The early tanks vent to air from the top generally,  they have a built in air oil separator inside the tank that splits oil vapour to drip back into oil supply,  with air going out to ground.  This is from description in KO manual,  you'd have to look at later manuals to see your K model.

They have to vent both tank and crankcase,  ultimately to atmosphere, to prevent overpressure in engine.

Sealed completely, it'll try to push oil out of oil seals etc.  Also interferes with dry sump system on 750 as you don't need either vacuum or pressure exerting against oil pump operation.

Offline Crispy

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Re: 750 K1 project
« Reply #130 on: September 09, 2019, 10:28:51 PM »

The early tanks vent to air from the top generally,  they have a built in air oil separator inside the tank that splits oil vapour to drip back into oil supply,  with air going out to ground.  This is from description in KO manual,  you'd have to look at later manuals to see your K model.

They have to vent both tank and crankcase,  ultimately to atmosphere, to prevent overpressure in engine.

Sealed completely, it'll try to push oil out of oil seals etc.  Also interferes with dry sump system on 750 as you don't need either vacuum or pressure exerting against oil pump operation.

Thanks, I understand what it's doing now, mine has the built in separator inside the tank, which as you say vents to ground from the top, the crankcase connects to the bottom.


Offline Green1

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Re: 750 K1 project
« Reply #131 on: September 12, 2019, 09:44:19 PM »
looking great Mick fancy having a crack at mine when your done?   :D
Current bikes
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Honda CB750k1 Candy Gold
Honda CB550k Candy Jade Green
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Offline Crispy

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Re: 750 K1 project
« Reply #132 on: September 13, 2019, 07:13:32 AM »
looking great Mick fancy having a crack at mine when your done?   :D
Cheers Mick, I'm pleased with how it looks but the acid test will be when I come to eventually try and start it it!  :o I might have to work on other peoples bikes at some point! I don't think I could afford another one!  ;D

Offline Crispy

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Re: 750 K1 project
« Reply #133 on: September 13, 2019, 03:59:41 PM »
Well having connected the oil tank up I started to put some oil in It Only to find it pouring out onto the bike and floor! Damn! On removing it and having a look,  I found that the rear oil hose had broken at the tank connection. I suppose better now than later when it's finished!  I know These are not cheap!  :-\ don't suppose I should trust the one that's left!

Offline Green1

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Re: 750 K1 project
« Reply #134 on: September 13, 2019, 04:28:31 PM »
I would risk keeping the other hose and then regret it as having one new one old would bug me.
Current bikes
Honda CB750k1 Valley Green Metallic
Honda CB750k1 Candy Gold
Honda CB550k Candy Jade Green
Honda CG125
Aprilia Pegaso 650
Moto guzzi 1200 sport
Kawasaki EX650R (Mine until dave pays for it)
Kawasaki ZXR400 J

 

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