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Discussion Starter · #1 ·
Hello I am new to the forum and appreciate any help.

last fall i purchased a used CB175K6. I am in the process of trying to get it running again, however i have encountered a few issues where i seem to find myself stuck so to say. I have managed to put 220 miles on it since purchase.

I am wondering if anybody on here can tell me the carb float height setting for this particular model? and the Keihin Model number for the carbs?

I have two service manuals but they are both dated a couple years prior to this model(K6) being introduced.
I can get it to idle on both cylinders but when after driving fo a short distance the left cylinder seems to fall off, but i t will start firing again after the throttle is opened a bit all the way to full throttle (1/4 to full approx). When both cylinders are firing the bike seems to run great as long as it is accelerating when i let off the throttle however theleft cylinder will drop off again and kind of backfire and sputter however upon opening the throttle more the cylinder will again fire.

After my ride i check the left spark plug and find that it has a lot of carbon build up and seems very wet. on several test rides the left cylinder has stopped firing all together and i suspect it is due to the plug being fouled. This leeds me to beleive that my float setting is wrong and i am getting too much gas in that cylinder.
 

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Sensei
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Could be the mixture setting on one carb...could be a very minor air leak.... could be point timing /gap/ or cleanliness.... Could be carbs need sync'd......Float height should be 21mm.....carb venturi size is 20mm equivalent (oval port)
 

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Discussion Starter · #3 ·
Thanks for the reply

Ive never noticed a difference with the mixture screw at all yet when testing. Static timing should be good but ive never checked the advance. The Points are new from Honda, gap should be good. I haven't checked exhaust ports but intake seemed clean. I was setting the float to 19mm so i will try 21, i was using an aftermarket float bowl gasket but i have ordered one from Honda and will soon be using that.

If i can get it tuned proper i think this will be a fun little bike.

It came a long way today i found out float height, and was able to get the flywheel/and the oil filter/clutch/oilpump off my spare engine. thanks for the help and i definately appreciate the forum. These are cool little bikes. The 220 miles 'ive managed from this bike have been a blast.
 

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Sensei
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If the mixture screw has no effect, the passage is clogged...perhaps all the way back to the float bowl, or into the intake on the engine side of the slide (very small hole)....I have seen where the screw was tightened too far, and broke the tip off plugging the passage...
 

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Discussion Starter · #5 ·
Well i got my carbs cleaned up again and the float height set to 21mm and man did it really help. The test drive was the most enjoyable ride yet. Not having the bike die at every stopsign was a real help. Thanks alot for the help.

Now to fine tuning. When i cleaned out the carb i blew air through the mixture screw setting and was able to detect air coming from a small hole on the intake side of the main jet. I am assuming this means it is unclogged and in working order. I still dont notice much of a difference in idle though except for when i screw it all the way in. Maybe it is more of a subtle rise in rpm i need to be listening for. My pipes are on the loud side.

To be correct the screw should be turned out 1 full revolution +/- 1/8 turn? It almost seemed like i noticed more of a difference in the half turn range.

The bike ran so well today i am considering using it to get my endorsement on thursday. I will have to test ride it tomorrow some to be sure, and maybe do some plug readings.
 

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Float height

Hi there, new here. Can anyone confirm if this 21mm is with the float valve spring compressed? Service manual says 19 with a tolerance of 1mm.

Thx!


Well i got my carbs cleaned up again and the float height set to 21mm and man did it really help. The test drive was the most enjoyable ride yet. Not having the bike die at every stopsign was a real help. Thanks alot for the help.

Now to fine tuning. When i cleaned out the carb i blew air through the mixture screw setting and was able to detect air coming from a small hole on the intake side of the main jet. I am assuming this means it is unclogged and in working order. I still dont notice much of a difference in idle though except for when i screw it all the way in. Maybe it is more of a subtle rise in rpm i need to be listening for. My pipes are on the loud side.

To be correct the screw should be turned out 1 full revolution +/- 1/8 turn? It almost seemed like i noticed more of a difference in the half turn range.

The bike ran so well today i am considering using it to get my endorsement on thursday. I will have to test ride it tomorrow some to be sure, and maybe do some plug readings.
 

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Sensei
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21mm is correct..... a larger number means less fuel height in the bowl, so leaner mixture....
Height set with float JUST touching the thin spring-pin....NOT compressing it
 

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Question: the surface from which the 21mm is measured - is this the recessed surface on which the gasket rests, or is it the top of the shoulder that surrounds it? Thanks!
 

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Thanks, much appreciated!
 
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