Author Topic: 1972 CB750K2 - engine freshen up  (Read 9295 times)

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Offline hotdog

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1972 CB750K2 - engine freshen up
« on: March 23, 2014, 01:55:49 AM »
Yet to pick it up -



HD
« Last Edit: May 04, 2015, 02:56:20 AM by hotdog »
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Offline petercb750

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #1 on: March 23, 2014, 03:01:38 AM »
Cool  8)
You don't see many that colour....good to see.
Congratulations.
1972 750/4 K2 (his), 1976 400/4 (hers)
1982 CB1100RC (ours)

ken65

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #2 on: March 24, 2014, 10:04:22 PM »
been watching that 1, looks to be a gooden, i got mine from brad aswell, nice bike it is and rides well, my mate got one from him to.   , heres mine,     i found him easy to negotiate with,  are you going to pick it up or get it delivered?  he has a nice man cave, ken


Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #3 on: March 27, 2014, 03:11:28 PM »
Hi Ken, unfortunately it will be delivered to a friends bike-shop & I'll pick it up from there. I agree Brad has been easy to deal with.

Regards.
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Offline Wollongongwolf

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #4 on: March 29, 2014, 05:03:43 AM »
Is that an import or Aussie delivered? Great condition, restored or original?
Suzuki DRZ400
1976 Suzuki TS400
1984 XL350R
1976 CB550F Super Sport

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #5 on: March 29, 2014, 05:36:45 AM »
Import Semi-restored - repainted, wheels rebuilt, engine side cases polished.

The frame has not been painted...
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Offline Retro Rocket

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #6 on: March 29, 2014, 04:10:58 PM »
Nice Bike Hotdog.... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline Green1

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #7 on: March 29, 2014, 04:36:43 PM »
Looks great I love all the oddball colours.
Who ever thought a bike would look so good in brown.
Current bikes
Honda CB750K1 Valley Green Metallic
Honda CB750K1 Candy Gold
Aprilia Pegaso 650ie
Moto Guzzi 1200 Sport

Offline Wollongongwolf

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #8 on: March 30, 2014, 02:15:54 AM »
Looks like I am going to have to polish even harder now!
Suzuki DRZ400
1976 Suzuki TS400
1984 XL350R
1976 CB550F Super Sport

ken65

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #9 on: May 14, 2014, 03:28:00 PM »
gday hotdog, did the  bike end up being as good as you hoped it would be?

Offline Stev-o

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #10 on: May 14, 2014, 04:30:01 PM »
You get it yet??
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #11 on: May 14, 2014, 10:14:36 PM »
Hi gents, I have got the bike home.
For the most part is seems to be good, had to remedy a few small things after receiving it...these would have been nice to know about prior to purchase.
But in saying that... I am happy with the bike. I have already installed a pamco e.i. and am planning a ride in the coming days. I'll post a photo or 2 in that other thread where people put up pix of their "bikes on the road".
Actually have had several admirers already. One at the petrol station the other day - we talked for 20 minutes.

Sent from my Agora HD+ using Tapatalk
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Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #12 on: October 23, 2014, 04:31:05 PM »
Photos...



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Offline Retro Rocket

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #13 on: October 23, 2014, 07:23:19 PM »
I hate those stock style bars, way to high for me but thats still a gorgeous bike Hotdog.... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #14 on: October 23, 2014, 07:31:15 PM »
Good for cruising, pretty comfortable...too stock to start doing the cafe racer thing with it.
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Offline Retro Rocket

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #15 on: October 23, 2014, 08:10:25 PM »
Good for cruising, pretty comfortable...too stock to start doing the cafe racer thing with it.

Haha, I'm no cafe racer fan either Hotdog, I just like the superbike bars better, like the  bars that were stock on the European 750's, i think they balance the bike better and are more suited to spirited riding...... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline petercb750

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #16 on: October 24, 2014, 12:16:34 AM »
Good for cruising, pretty comfortable...too stock to start doing the cafe racer thing with it.

Haha, I'm no cafe racer fan either Hotdog, I just like the superbike bars better, like the  bars that were stock on the European 750's, i think they balance the bike better and are more suited to spirited riding...... ;)
That's what I've got on mine....just right.  8)
1972 750/4 K2 (his), 1976 400/4 (hers)
1982 CB1100RC (ours)

Offline SBR-CB400F

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #17 on: October 26, 2014, 04:05:06 AM »
Looks mint Hotdog, keep it the way it is  ;)
I'm with Retro though  ;D

Adam
1975 cb400f, 14.435 @ 89.01MPH at Willowbank Street Series 28 March 2015
1976 cb400f Nostalgia Drag Bike.
1.871 @ the 60'
8.632 @ 78.44 mph over the 1/8.
13.822 @ 91.91 mph over the 1/4
1977 cb750f2 Resto Project
1973 cb750k4 Chopper project
1971 cb750k1 Restoration Project
1975 cb750f1 Drag bike
1.549 @ 60'
4.425 @ 330'
6.895 @ 98.05MPH  1/8 mile
10.993 @ 116.76MPH  1/4 mile

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #18 on: March 03, 2015, 08:29:40 PM »
Thought I might throw a few pics up here of what I'll be doing with the k2 soon. After having this bike for a year or so it has unfortunately developed the dreaded top end leak from the blind head bolt seal/s. That's what you get for playing with old bikes right...?
While its apart I'll be installing the cheap eBay 836 kit, a Norris d+ cam I won on eBay the other week, mls gasket, HD ape cylinder studs, new cam chain, adjustable sprocket, clutch fibres, new air box intake rubbers, new manifold rubbers, cam chain roller/tensioner/guide, Ampco guides, new valves, new valve springs.
Giving it a bit of a birthday really, headwork will remain modest, using my own knowledge and additional information from Hondamans book. I'll cut the Valve seats as I have a Neway kit, but just realized I don't have a 6.5mm pilot - better get one of those.
The bike will be a nice stocker with a bit of extra grunt.
I recently bought a couple of old bashed up cb750 bikes for future projects, but with them came an additional 1 3/4 engines - let me say its nice to have some spares. I have been able to prep one set of barrels for machining without having to pull down the k2 just yet. The barrels are already 812cc an looked worse for wear. After straightening some fins, deburring others and giving it a bead blast, they have come up real nice.
One of the spare heads is a bit worse off however with a few broken fins, and while removing one of the intake spigots yesterday one snapped in half, I was using a MAP torch to heat them, one came out, 2 moved but did not come out - Ill give them another try and the last one snapped. I have walked away from it for now to have a think about if I proceed with attempting to resurrect it or not.....

Before


After


Parts


Rocker cover


Had a play with this spare Cylinder head from one of my spare motors - unfortunately it is to beaten up to use/repair


Hopefully get the barrels off to a machinist soon - ciao
« Last Edit: March 16, 2015, 03:54:17 PM by hotdog »
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Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #19 on: March 04, 2015, 09:37:03 PM »
With the parts I've ordered I have a tsubaki endless cam chain, firstly I didn't realise it was endless, secondly do people join them or does everyone drop their cranks to swap it out.?

« Last Edit: March 04, 2015, 10:00:30 PM by hotdog »
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Offline Retro Rocket

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #20 on: March 05, 2015, 02:00:26 AM »
With the parts I've ordered I have a tsubaki endless cam chain, firstly I didn't realise it was endless, secondly do people join them or does everyone drop their cranks to swap it out.?

Drop the crank mate, not worth trying to join it.   
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #21 on: March 05, 2015, 02:24:23 AM »
OK cool, back in the day in the shop we just used to join them. Won't hurt to split the bottom end while its apart, I'd like to check the primary anyhow.
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Offline Retro Rocket

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #22 on: March 05, 2015, 02:58:29 PM »
Really, unless you have some way of testing the strength of the newly joined link its a potential accident waiting to happen, I'm sure i don't have to explain what happens if it lets go.... :o  ;D  I've bought classic cycle cities diamond primary chains for my engines mate, they are far superior to the stock, they take something like 100,000K's to stretch the same amount as the stock chains at 15,000 k's, more expensive but worth it i think... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #23 on: March 05, 2015, 05:39:50 PM »
Yep, that's just what we used to do, never had one fail. Was a HD/Honda/BMW/Kaw dealership & did a few like that on KZ/CB's.....was 20 years ago too, maybe a bit has been learned since then. The one in my XS650 I have done the same, just have to have to right tool to pein/crimp the master link.
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Offline hotdog

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Re: 1972 CB750K2 - engine freshen up + porting tips
« Reply #24 on: March 14, 2015, 03:35:38 AM »
While the barrels are away being rebored for a cruizinimage 836 kit, some other parts have started arriving. So this afternoon I decided to pull the motor and get ready for strip down tomorrow.

Getting started


Carbs out, pipes off and motor loose.


She's out


On the bench ready for strip down tomorrow.


Ports will be getting some attention while its apart.


All up the engine looks good on the outside, can't wait to see inside the cases tomorrow and do a through inspection.
« Last Edit: March 14, 2015, 04:49:59 AM by hotdog »
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