Author Topic: K1 - Carb Question  (Read 1150 times)

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Offline Johnie

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K1 - Carb Question
« on: July 04, 2009, 02:34:29 PM »
K1 - This is the bike I started restoring in March 2009.  Rebuilt the carbs, air screws 1 turn out, points, timing, valves, sync, etc.  New OEM filter and HM300's.  The bike runs, idles and takes off without a miss.  The problem I was having was it did not want to hold a cruise over 55 - 60 MPH and would try to die out.  Not completely die out, just hesitate trying to hold a cruise.  I could give it gas and it took right off at the higher speeds.  But to hold a high cruise was the problem.  An old Honda mechanic who owned the local Honda dealership lives in the area.  He asked where my needle was set and it was at #3 position.  He said that is only a "starting point" and told me to raise the needle 1 notch to a higher position allowing a little more gas flow.  Did that today and appears to have solved the problem.  Held a good cruise at 70 MPH.  I do have some popping now on deceleration and at idle out of #1 pipe.  Would this raised needle position need for me to adjust those air screws now?  I was a bit concerned moving from the #3 position since the service manual says #3, but figured I could always put it back.  What are your thoughts on this move?  I certainly did not want to do something that would blue my HM300's.
Thanks
« Last Edit: July 04, 2009, 02:48:35 PM by Johnie »
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline Gordon

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Re: K1 - Carb Question
« Reply #1 on: July 04, 2009, 03:15:55 PM »
Definitely sounds like an idle mix screw adjustment is in order.  As far as an opinion on what I think about the needle setting:  whatever works for your bike in your situation is what is best. 

Offline 736cc

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Re: K1 - Carb Question
« Reply #2 on: July 04, 2009, 04:40:39 PM »
Richen the idle screws until you get highest rpm at idle then turn them back a bit. Then adjust the idlw bank screw to 1000 rpm + - Vac gauges simplify it.

Offline Johnie

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Re: K1 - Carb Question
« Reply #3 on: July 05, 2009, 06:24:04 AM »
Richen the idle screws until you get highest rpm at idle then turn them back a bit. Then adjust the idlw bank screw to 1000 rpm + - Vac gauges simplify it.
And to be sure I have this correct, richen means turning the air screws in which direction?  Should this be done in 1/8th or 1/4th turns to start out.
Thanks...
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline Gordon

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Re: K1 - Carb Question
« Reply #4 on: July 05, 2009, 06:46:16 AM »
Richen the idle screws until you get highest rpm at idle then turn them back a bit. Then adjust the idlw bank screw to 1000 rpm + - Vac gauges simplify it.
And to be sure I have this correct, richen means turning the air screws in which direction?  Should this be done in 1/8th or 1/4th turns to start out.
Thanks...

Turn the screws in to richen, out to lean.  1/8th turns are a good place to start. 

Offline Johnie

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Re: K1 - Carb Question
« Reply #5 on: July 05, 2009, 08:35:23 AM »
Richen the idle screws until you get highest rpm at idle then turn them back a bit. Then adjust the idlw bank screw to 1000 rpm + - Vac gauges simplify it.
And to be sure I have this correct, richen means turning the air screws in which direction?  Should this be done in 1/8th or 1/4th turns to start out.
Thanks...

Turn the screws in to richen, out to lean.  1/8th turns are a good place to start. 
Excellent and thanks.  I will fine tune it today.
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline phactory

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Re: K1 - Carb Question
« Reply #6 on: July 06, 2009, 03:32:14 PM »
Johnie,

 Did you tune your bike, and if so what are the results?

Thanks, Phil

Offline Johnie

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Re: K1 - Carb Question
« Reply #7 on: July 06, 2009, 04:09:26 PM »
Johnie,

 Did you tune your bike, and if so what are the results?

Thanks, Phil
It ran good on the high end, but crappy on the low end no matter what I did with the air screws.  So I decided to put the clip back to the middle position right away so I could compare the 2 clip positions the same day.  Low and behold, runs great at high end and low end now.  Go figure...I still get an occasional low blurp from exhaust #1 at idle and on deceleration.  I tried to richen the #1 air screw but it makes no difference.  All air screws are back to 1 turn out which gave me the best performance.  Spark plugs look good too.  Think I will just live with it.  I can sure get the carbs off and on fast now.  ;D
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA