Author Topic: Carburettor set up for first start after rebuild (1971 K0 500 Four)  (Read 1652 times)

Offline paulbaker1954

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Anyone any advice on setting carbs up. I am anticipating investing in a balancer but for now have bench set using a small allen key so all 4 are the same. I have also set the mixture screws all at one turn out.

My plan is to get her going first then adjust the mixture screws before balancing but is there a methid of setting the mixture screws up without using a Colortune. There is something in the Honda setup manual that is downloadable from the site but seems there might be a page missing.

Any help/advice most welcome
If you think there's light at the end of the tunnel it's usually another train !!

2016 Yamaha MT09 Tracer
1971 Honda CB500 Four K0

Offline Bryanj

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Re: Carburettor set up for first start after rebuild (1971 K0 500 Four)
« Reply #1 on: February 03, 2016, 07:03:08 AM »
Make sure that the slides are all closing fully if the tickover screw is all the way out as it is easy to have them all adjusted using a drill/allen key a bit up and they its a problem getting it to start. Set the mixture screws as the manual and it should be fine

Offline gtmdriver

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Re: Carburettor set up for first start after rebuild (1971 K0 500 Four)
« Reply #2 on: February 03, 2016, 10:26:13 AM »
On my 350F I set the idle screws 1 1/2 turns out then I used a 3mm drill on the engine side of the slides to set all the slides to the same height.

I used the large idle screw to open up all of the slides then used the adjusting screws on top of the carbs to equalise the heights (then remembered to wind the idle screw back again).

When I put the vac gauges on it and fired it up the carbs were so close that, were I not completely OCD, I could have left them alone. Only one carb needed a tiny adjustment.


Offline paulbaker1954

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Re: Carburettor set up for first start after rebuild (1971 K0 500 Four)
« Reply #3 on: February 03, 2016, 04:44:47 PM »
OK so let me confirm I have the process right

1) Slacken idle speed fully so it is not doing anything
2) Back out the mixture screws all the same at the same setting (Honda manual would suggest 1 turn)
3) Set up each carb with a 3mm drill in the slide to give a) bench sychronisation and b) a small amount of air to allow initial start
4) Fire it up (hopefully)
5) Balance carbs and fine tune idle mixture


If you think there's light at the end of the tunnel it's usually another train !!

2016 Yamaha MT09 Tracer
1971 Honda CB500 Four K0

Offline Bryanj

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Re: Carburettor set up for first start after rebuild (1971 K0 500 Four)
« Reply #4 on: February 03, 2016, 04:56:46 PM »
 A 1/16 drill or 1mm is better, and at that you will need to screw in the idle screw to just lift the slides for a start

Offline gtmdriver

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Re: Carburettor set up for first start after rebuild (1971 K0 500 Four)
« Reply #5 on: February 03, 2016, 07:42:06 PM »
OK so let me confirm I have the process right

1) Slacken idle speed fully so it is not doing anything
2) Back out the mixture screws all the same at the same setting (Honda manual would suggest 1 turn)
3) Set up each carb with a 3mm drill in the slide to give a) bench sychronisation and b) a small amount of air to allow initial start
4) Fire it up (hopefully)
5) Balance carbs and fine tune idle mixture

1) No! Tighten up the idle screw to lift the slides up until the lowest one is a nice sliding fit on whatever drill you are using as a gauge.
2) Using the screws and lock nuts on the top of the carbs adjust the other three slides to give the same sliding fit on your drill.
3) Remember to back off the idles screw or the revs will shoot sky high when you fire it up.
4) Set each mixture screw to 1 or 1 1/2 turns out from lightly bottoming.
5) Fire it up and warm it up. Ensure the Ignition is correct.
6) Set up the carbs using a vac gauge.

 

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