I've been messing with a 1979 kz1300 A1with 20,000+ miles that i had in the garage for years. I sent the carbs to oldschoolcarbs.com and had them rebuild it. The bike came to life but was having issues with two cylinders. One of the pickup coils was bad, so I ended up switching out the pickup coil from a kz1000 assembly. It now runs ok at higher RPM's, however it will not idle. I moved the carburetors to a running kz1300 that I have and the problem moved with the carbs.
So what's next? Any suggestions would be appreciated!
I'm wondering if I have something wrong with the throttle cables or idle adjustment? I can hold the bike at around 1k and it does seem to idle, but anything less that that it dies. The idle adjustment is as far up as it will go.
Or possibly the idle jets aren't right? The Idle jets are currently screwed out to 3 1/2 turns which I believe is the starting point for adjustment?
You may have blocked idle circuits in your carbs. If the adjustments don't work then you will have to clean the idle circuit ports from engine side through to intake side (so debris is flushed in the right direction). If the carbs were cleaned and set up for you I would imagine they would all have been set the same - so this is the likely problem. The ports are very difficult to clean as the fuel turns into a lacquer in them when it dries. Scotch created a special tool to clean them but I don't think he has stock at the moment. Find Scotch's notes on using the carb cleaning tool and you'll see the three very small holes in the engine side of the venturis that have to be back flushed.
Also check that the throttle slides return slowly by themselves after being raised. I had one pair that was sticking slightly and took me ages to find.
To adjust you need a colour-tune plug (14mm) and a set of vacuum gauges. I use 6 but you can get away with 3 as you can only balance each carb body and not each side of each carb.
You need to adjust the idle screw for the cylinder with the colour-tune plug. From tightened (don't over tighten) as the screw is turned anti clockwise the burn colour should be yellow through to blue then through to yellow again (this is the rich end of the burn. From the rich yellow adjust the screw back in (clockwise) until the blue burn is steadily seen again. Do this slowly as I don't think this is always instantaneous. Do this for each cylinder.
A good starting point is 3.5 full turns out. You don't need to adjust in to see the lean yellow colour but I mentioned it for info. If it's already blue turn the screw out until yellow and then back in the get the blue flame back again (from the colour-tune instructions)
Hook up the vacuum gauges to all 6 or 1 on each carb body inlet (i.e. 2, 4 & 6). Many vacuum gauges have dampers in the tube line to dampen the needle movement. Adjust these so the needles are moving but not too much. Adjust the balancing links to get each of the carbs as close to each other as possible. you need an 8mm spanner for the lock nut and a 3mm (i think) spanner for the adjuster.
Each of the processes can throw the other out a little so repeat colour-tune and balance until things are settled. Tightening the balance link adjuster also screws up the balance so need to be patient with them!
1980 KZ1300 B2 Touring/A2
1990 ZZ-R1100 C1
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