Author Topic: Andys CB810 K2 -updated 29 Oct: new harness routing questions  (Read 72121 times)

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Offline andy750

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So I opened up the K2 carbs tonight and found a few issues...evidence of brass-aluminum corrosion, and carb #3 had a bent float - probably explain why it was the cold cylinder at start up - surprised it wasn’t overflowing at idle. See pics below...

#2

The broken pilot jet







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Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

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Offline andy750

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Explains the #3 plug...that I checked previously


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Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline jaytee-nz

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I might be seeing things, but the pilot jet on the right hand carb looks bent to me ?

Offline andy750

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I might be seeing things, but the pilot jet on the right hand carb looks bent to me ?

Never noticed that...Ill take a closer look and let you know!
Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline MRieck

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That pilot jet does look bent. Were you playing soccer with those carbs Andy??
Owner of the "Million Dollar CB"

Offline andy750

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That pilot jet does look bent. Were you playing soccer with those carbs Andy??

Never touched them!

I may need your help though in extracting the broken one  :-X :-\

I have a spare set of carbs that I am hoping to install tonight and test ride tomorrow morning so will update here with progress.
« Last Edit: July 24, 2020, 06:35:33 am by andy750 »
Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline PeWe

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If the bent looking jet really is bent, the broken jet might have been bent too. Can be why it broke.
Remove the other jets very slow. No quick twist.

Edit: Buy Keihin jets.
« Last Edit: July 24, 2020, 08:53:04 am by PeWe »
CB750 K6-76 1005cc JMR Billet block.
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

Offline andy750

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Ok so...the pilot jet was not bent...optical illusion I think - see pics

All four carbs

Pilot jet on the right looks straight to me


Close up

Arrow points to jet in question



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Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline andy750

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Switched the carbs and success!!! - no leaks on start up and test ride showed what I have been missing these last few months - snappy throttle, growl of the HM300s, fast acceleration - got it up to speed on the highway and was not disappointed. Smiling again!! Can’t wait for the next ride :)

Thanks for all the comments they really motivated me.

Post-highway ride



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Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline Alan F.

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Good news Andy!

Offline PeWe

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Quickly done too!
CB750 K6-76 1005cc JMR Billet block.
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

Offline knowsnothing

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #286 on: July 28, 2020, 01:26:23 pm »
 Nice work young Andrew
1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline andy750

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #287 on: July 28, 2020, 06:19:49 pm »
Thank you Treeve! I was over in your neck of the woods on Saturday morning at 8am....did the Blue Hills-Wollaston Beach loop from mine and back to test ride the K2. Passed with flying colours! Next time Ill shoot you a text before I head over. I was back home by 8:30 before the heat hit.

How is your bike coming along? Running yet? Need any parts?  8)

Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline knowsnothing

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #288 on: July 29, 2020, 11:45:57 am »
Thank you Treeve! I was over in your neck of the woods on Saturday morning at 8am....did the Blue Hills-Wollaston Beach loop from mine and back to test ride the K2. Passed with flying colours! Next time Ill shoot you a text before I head over. I was back home by 8:30 before the heat hit.

How is your bike coming along? Running yet? Need any parts?  8)

Let me know next time for sure. 

The bike is finally running.  I still need to finish the tank and seat, but I have a stock tank and seat on it for now so I can get a few miles on it while i finish.

 Right now i am working on tuning.  It has a hanging idle issue I think is likely due to a lean condition, so I am working on that.  Still need to open it up on a highway, but its nice and peppy so far. I am just pumped it didn't grenade on first start up since i did do most of the work    ;D  . 

1978 CB750k Green - 811 engine
1978 CB750k Blue - for sale
1974 CB375F Faded Black - had to have that 6th gear
1976 CB400F Red - in many pieces
1973 CB350F TBD - in many pieces

Offline RAFster122s

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #289 on: July 29, 2020, 07:57:55 pm »
Are the felts on the throttle shafts lubed? That can cause a slow return to idle.
David- back in the desert SW!

Offline Stev-o

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #290 on: July 31, 2020, 07:12:57 am »
Looks good Andy!
'74 "Big Bang" Honda 750K [836].....'71 Honda 750K project.....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline andy750

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #291 on: July 31, 2020, 06:41:12 pm »
Looks good Andy!

Thank you! Big relief getting it back on the road. Now thinking about tires - what do you like? I always buy BT45 but feel like a change for this bike
Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline Alan F.

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #292 on: July 31, 2020, 07:11:21 pm »
BT-46 is available, I haven't heard any ride reports though.

Offline RAFster122s

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #293 on: July 31, 2020, 09:46:30 pm »
Someone recently mentioned putting a new BT-46 on the rear of their CB. Do not recall whom. Would a Google search find reference to BT-46?
David- back in the desert SW!

Offline Kevin D

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #294 on: August 01, 2020, 03:10:31 am »
https://grippingstories.com/articles/2019/battlax-bt46-the-new-reference-bias-touring-tyre

BT46: wet road performance improved about 10% by modification/enhancement of sipe design.
At least, that’s the Bridgestone pitch.
UM application, tube or tubeless.
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Offline PeWe

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #295 on: August 01, 2020, 07:05:14 am »
Rear with longer life would be fine. Over 4000 miles with some inspired accelerations.
CB750 K6-76 1005cc JMR Billet block.
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

Offline MRieck

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #296 on: August 01, 2020, 08:09:13 am »
 Happy to say the broken pilot jet has been extracted and Andy should have the carbs back very soon.
Owner of the "Million Dollar CB"

Offline PeWe

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #297 on: August 01, 2020, 09:47:44 am »
Golden boy to live that close to a superb support, huge knowledge and fantastic craftsmanship!
Good friend too!
CB750 K6-76 1005cc JMR Billet block.
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

Offline andy750

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #298 on: August 01, 2020, 01:56:00 pm »
Golden boy to live that close to a superb support, huge knowledge and fantastic craftsmanship!
Good friend too!

Very well said Per and couldn’t agree more. I first met Mike about 15 years ago through the forum and it has been an honour to know him.
Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350

Offline andy750

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Re: Andys CB810 K2 road racer- updated 07.24.20 on the road again!
« Reply #299 on: August 01, 2020, 01:56:46 pm »
Happy to say the broken pilot jet has been extracted and Andy should have the carbs back very soon.

Thank you Mike!!!!   ;D
Current bikes
1. CB750K4: Long distance bike, 17 countries and counting...2001 - Trans-USA-Mexico, 2003 - European Tour, 2004 - SOHC Easy Rider Trip , 2008 - Adirondack Tour 2-up , 2013 - Tail of the Dragon Tour , 2017: 836 kit install and bottom end rebuild. And rebirth: http://forums.sohc4.net/index.php/topic,173213.msg2029836.html#msg2029836
2. CB750/810cc K2  - road racer with JMR worked head 71 hp
3. Yamaha Tenere T700 2022

Where did you go on your bike today? - http://forums.sohc4.net/index.php?topic=45183.2350