Author Topic: brandEn's K4  (Read 180094 times)

0 Members and 2 Guests are viewing this topic.

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #700 on: October 29, 2013, 08:22:16 PM »
Vent lines from the carbs have no hoses on them.
Wondering if it could be bad gas. I am using 86 octane from my mower can. I filled it up a 1-2 months ago. Gonna get a can of 91 octane tomorrow and try that.

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #701 on: October 29, 2013, 08:23:52 PM »
float level should be 3 or 4 mm below the gasket...that looks too low

Really? Hmmm, I though I  had the 26mm set good. Maybe I measured from the wrong spot. I measured from the bottom of the little notch of the carb body casting.
setting the float to 26mm is supposed to result in the fuel level being 3 or 4 mm below the gasket.  I have found that it often does not.  So much so, that I don't even measure the float position anymore.  I just adjust the float until it results in the actual fuel level being 3 or 4 mm below the gasket.  No idea how much of this really has to do with your idle problems, but it has worked for me.

I'm gonna keep that in mind. Pretty sure I can do that without pulling the carbs. It would make a mess with fuel though.

Offline seanbarney41

  • not really that much younger than an
  • Really Old Timer ...
  • *******
  • Posts: 10,849
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #702 on: October 29, 2013, 08:27:17 PM »
yep, that snap wire float bowl retainer thingy is my favorite thing about these carbs
If it works good, it looks good...

Offline Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,920
  • Bought her new 4/75
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #703 on: October 29, 2013, 09:28:29 PM »
float level should be 3 or 4 mm below the gasket...that looks too low

Really? Hmmm, I though I  had the 26mm set good. Maybe I measured from the wrong spot. I measured from the bottom of the little notch of the carb body casting.

I've done my measuring from the cut out notch right below the hole for the bowl retainer clip. None of the pictures in any of my 4 manuals are good but the one I'm looking at now in my CycleServ manual shows a float tool being used that has a fat base that fits right into that notch and is the same width as the notch.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #704 on: October 29, 2013, 09:58:10 PM »
Thanks man. I read on another site that was the right spot, good to have some more confirmation. I'm gonna try and raise the fuel level a bit like suggested.

Now about those vent lines Chef mentioned. Those need hoses for proper operation?

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #705 on: October 29, 2013, 09:59:19 PM »
Comment: Lucky-

"I adjusted my floats to 26mm before installing them. One thing I  noticed is that the float valve springs would not compress under the weight of the float when it was resting on the tang. Not sure if that would cause problems or not."

That is right. The float tang should just touch the needle it should not depress the spring. The spring does NOT shut anything on or off.
It is just sort of a shock dampener. Look at it closely and you will see that.

If you take a float needle and look at it closely you will see that the little pin that pushes up and down does not open or close ANYTHING and does not OPEN
If you installed new float needles and seats and adjusted them the way the book tells you there is NOTHING else you have to do.
They do not control the way the engine runs.
All they do is supply gas for the carb to run thats it.

Hopefully you did not use that clear tube method to set your floats.

Are all of the mixture screws set to the same EXACT number of turns open??
Very important.

And remember DO NOT touch the mixture screws to sync the carbs !






Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #706 on: October 29, 2013, 10:16:21 PM »
Vent lines from the carbs have no hoses on them.
Wondering if it could be bad gas. I am using 86 octane from my mower can. I filled it up a 1-2 months ago. Gonna get a can of 91 octane tomorrow and try that.

You have to have those vent lines on the carbs!
If not, they can spill over and start a fire when the engine gets hot.

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #707 on: October 29, 2013, 10:34:41 PM »
Thanks, I will get some installed ASAP.

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #708 on: October 29, 2013, 10:38:44 PM »

Comment: Lucky-

"I adjusted my floats to 26mm before installing them. One thing I  noticed is that the float valve springs would not compress under the weight of the float when it was resting on the tang. Not sure if that would cause problems or not."

That is right. The float tang should just touch the needle it should not depress the spring. The spring does NOT shut anything on or off.
It is just sort of a shock dampener. Look at it closely and you will see that.

If you take a float needle and look at it closely you will see that the little pin that pushes up and down does not open or close ANYTHING and does not OPEN
If you installed new float needles and seats and adjusted them the way the book tells you there is NOTHING else you have to do.
They do not control the way the engine runs.
All they do is supply gas for the carb to run thats it.

Hopefully you did not use that clear tube method to set your floats.

Are all of the mixture screws set to the same EXACT number of turns open??
Very important.

And remember DO NOT touch the mixture screws to sync the carbs !

Thanks lucky!
My screws are at one turn open each. When I synced my carbs I did not touch the screws. I got a great sync on the carbs now and adjusted the slide adjustments only. 

I used the clear tube method to see where the fuel was and to double check my work on the bench. All levels are even but seem to be 2-3 mm low.

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #709 on: October 30, 2013, 09:14:42 AM »

I used the clear tube method to see where the fuel was and to double check my work on the bench. Which is the right way to do it. All levels are even but seem to be 2-3 mm low.

...and this can be caused by those new float valves with new/heavier internal springs.  make that float height 25mm as I mentioned yesterday.  1mm float height makes +/-2mm fuel level change.  should be good to go. 
get that exhaust leak figured out?
'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

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #710 on: October 30, 2013, 09:33:16 AM »
Exhaust leak is fixed. The #1 copper gasket was leaking for some reason. Replaced all four. Good to go. Gonna try adjusting the floats later today.

Offline Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,920
  • Bought her new 4/75
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #711 on: October 30, 2013, 12:26:30 PM »
Vent lines from the carbs have no hoses on them.
Wondering if it could be bad gas. I am using 86 octane from my mower can. I filled it up a 1-2 months ago. Gonna get a can of 91 octane tomorrow and try that.

You have to have those vent lines on the carbs!
If not, they can spill over and start a fire when the engine gets hot.

Did we not notice the bike's name?  :o
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #712 on: October 30, 2013, 07:02:31 PM »
Got the idle issue ironed out I think.
I raised the float levels a couple mm's and it definitely idled better. But once I richened up the air screw from 1 turn out to only 1/2 turn it ran even better.
Went and got some fresh 92 and better yet. Pretty happy with the way it idles now.


I can pull the airbox, carbs, and adjust the floats then put it all back together including adjusting the cable in under 30 minutes....
Not to bad.
 8)




Now.... I need to try and remove some of that dampening fluid out of the tach. I overdid it and it moves SLOW. I also need to fiddle with the neutral switch as it is always on even if I put it in gear.




IDLE FIXED and Rosco is confused at the end
CB750 idle fixed

Offline cheftuskey121

  • Super Newbie
  • Expert
  • ****
  • Posts: 1,305
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #713 on: October 30, 2013, 07:04:06 PM »
very glad to hear it Branden! super jealous of that tone. I am hoping my next bike will have a motogp pipe on it ;)

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #714 on: October 30, 2013, 07:23:06 PM »
very glad to hear it Branden! super jealous of that tone. I am hoping my next bike will have a motogp pipe on it ;)

Thanks!
This pipe sounds completely different than my Yamiya. Way throatier. I know that's not a word but it fits the description well I think.

Offline cheftuskey121

  • Super Newbie
  • Expert
  • ****
  • Posts: 1,305
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #715 on: October 30, 2013, 07:34:01 PM »
do you have video of the yamiya pipe? how much is that one?

Offline andy750

  • Really Old Timer ...
  • *******
  • Posts: 7,939
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #716 on: October 30, 2013, 07:37:33 PM »
Well done! It's great to get all these updates and then you solve the issue. Can you post another video when you get the chance as curious to hear the difference. Thank you! Glad to hear you have become a carb expert - it's much easier when everything is new!

Enjoy the ride and all your hard work!
Cheers
Andy
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 brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #717 on: October 30, 2013, 08:02:14 PM »
Thanks Andy. I have some riding videos of TAO with the Yamiya pipe in the build thread and my You Tube page. I can get a garage idle vid if you guys would like.
 ;)
http://www.youtube.com/channel/UCjNgibJ82CxNiAj_V_KA4rw

Offline cheftuskey121

  • Super Newbie
  • Expert
  • ****
  • Posts: 1,305
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #718 on: October 30, 2013, 08:10:14 PM »
Thanks Andy. I have some riding videos of TAO with the Yamiya pipe in the build thread and my You Tube page. I can get a garage idle vid if you guys would like.
 ;)
http://www.youtube.com/channel/UCjNgibJ82CxNiAj_V_KA4rw

oh yes of course! lovely sound. I would like to hear both of them idling and rev'ing. I am narrowing my search for a pipe down....too many choices. even considering a Benjie 4-4 for a retro racer look...

Offline Stev-o

  • Ain't no
  • Really Old Timer ...
  • *******
  • Posts: 34,356
  • Central Texas
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #719 on: October 30, 2013, 08:29:54 PM »
Great news, glad you found it relatively quick. Rosco did look totally confused!
'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #720 on: October 30, 2013, 08:51:05 PM »
Anybody have some advancer springs they can rob/sell off an old advancer for me ?

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #721 on: October 31, 2013, 08:22:34 AM »
Anybody have some advancer springs they can rob/sell off an old advancer for me ?
yep...
'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

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #722 on: October 31, 2013, 08:24:46 AM »
Dang it. Just bought one from eBay! Oh well looks to be in great shape and was only $20 shipped.

Offline MCRider

  • Such is the life of a
  • Really Old Timer ...
  • *******
  • Posts: 14,376
  • Today's Lesson: One good turn deserves another.
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #723 on: October 31, 2013, 10:57:09 AM »
Dang it. Just bought one from eBay! Oh well looks to be in great shape and was only $20 shipped.
That's a good price. I've seen them go for $50, being as they are NLA. If you need one there's no alternative.
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline brandEn

  • Old Timer
  • ******
  • Posts: 3,205
Re: La Flama Blanca aka The K4 - painting the tank... AGAIN.
« Reply #724 on: October 31, 2013, 12:32:10 PM »

Dang it. Just bought one from eBay! Oh well looks to be in great shape and was only $20 shipped.
That's a good price. I've seen them go for $50, being as they are NLA. If you need one there's no alternative.

Yes it is a good price. Lucky for me it was one of the cheapest and best condition advancers.