Kz 1300 bakfiring and hard start

Hi,

I am new to this forum and i need some help with diagnostics on my 1300 bike.

i just bought this bike two weeks ago and when i first started the bike i noticed it was is was smoking black smoke and some bluish.
i changed the plugs and the bike runs better but there is some serius backfiring on cyl #6 . I messed around with the adjusting screw
and the backfiring stopped but i noticed the exhaust pipe on cyl #6 was significantly lower temp compared to the others so it must not getting enough fuel.

I compression tested the bike and all of the cylinders were in good shape @ 160 psi but cylinder #3 was @ 145 psi

also cyl, # 3 & 4 are popping out of the intake manifold. so i know there is some serous fueling problems.

I used Gunson colortune to check the bike was running rich but i could not see the flame only the spark when i check cyl 4,5,6

vacuum test gave strange reading only reaching 12 cmHg maximum when they should reach 21 cmHg

the hard start is probably related to fuel leaking out of few of the carburetors and after cranking the bike for a while it starts and
revs ok..

i dont know the year of the bike and neater did the previous owner but the VIN is KTZ30A010739
If anybody can tell me what year it is based on the VIN it would be great.

One thing more,, when i looked into the carburetors (while bike was idling) i noticed few of them were just gobbling fuel or more like it seemed as they were leaking more then mixing and not all of them were like this maybe that is a sign.

So am i looking at a complete overhoul of the carburetors + full clean........

or do you have any better idea what is going on here ?

A leaking intake valve for whatever reason when supposedly closed can backfire through the carb.

If not already done, would first assure valve clearances are within specs.

As known, a good compression test result does not assure that valve clearances are within specs. Because the valve may leak only after the engine attains normal operating temperature.

Good Fortune!

KTZ30A010739 is perhaps an '80 KZ1300-A2 (see Zedder, below).

Click here : www.zedder.com/Info/80%20KZ1300-A2.htm

Good Fortune!