Will not start

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Will not start

trikeboiler
Hi all, my 1979 Honda cb750kz refuses to start, I have fitted new cdi units, have a good spark at the plugs and fuel is getting to the plugs, I had the carbs off last year to clean them out and they seemed all ok, now my question is that under the float bowls there are the 4 rubber pipes from the drain off screws but there is another one in the centre of the carbs that I cant see what it is for. I have read that the carb slides operate by vacuum, could this be a vacuum pipe that I have not connected and if so where does it connect to. thanks for any info, oh I changed the cdi units as they had melted the resin and I had no spark.
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Re: Will not start

TOOLS1
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The rubber tubes under the carbs are the overflow drains. They are there in case the float bowels overflow, so the gas will have somewhere to go other then in the engine. The melted resin on the igniters is common and does not hurt anything. If you have spark at the plugs, and fuel is getting into the cylinders it should at least try to fire, or backfire. I would check the timing, and maybe the compression.
TOOLS
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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
Maz
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Re: Will not start

Maz
In reply to this post by trikeboiler
If my memory serves me correctly, the rubber pipe in the middle is just a breather. It should sit in a slot/hole in the metal bracket that holds all 4 carbs together as a set and then feeds up next to the air box. It has a small "channel" to hold it in place but more often than not, they just lay on the air box. It connects to a T piece at the carb end and nothing at the other end.

Maz
'76 CB500T
'75 GL1000 'Wing
'79 CB750L
'90 FJ1200
'93 GS500E

In a little place called Bexley, Kent, UK (Just south of London!)