TOPIC:

It wasn’t too cold in sunny Scotland today, so I took the 1300 out far a bit of a blast. It went like a bag of nails, I just can’t seem to get this beast to run properly. There’s a flat spot at low revs which is always there, sometimes it’s really bad, sometimes it’s a bit less noticeable. Today it was just awful. I’m convinced it’s the carbs that are the problem; they seem to be an endless source of trouble. I have been looking for a replacement set but in the UK they are like rocking horse doodoo.
I have shoved it back in the shed, trying to resist listing it on e-bay.

Hi.
Have you looked in on forum under FAQ re carb problems.Some good info.
When I purchased mine, ran like a bag of shite. Hunting at tick over and plenty of flat spots. Took them of and dismantled one at a time.
Removed all jets and placed in thinners. Used Halfords carb cleaner to blow through all air ways. The amount of muck that came out was gross. Cleaned all needles up with duraclit. Fitted carbs back and fired up and all fine.
Mind you do have another problem at the moment. No friggen spark? The joys of owning a classic

mczed wrote: There’s a flat spot at low revs which is always there, sometimes it’s really bad, sometimes it’s a bit less noticeable.

Sounds like what I refer to as the "transistion" ports are partially plugged by loose debris floating around in the circuit. It takes very little by amount and/or size. The ports are approx. .025".

The remedy is explained in the "79 carb rebuild".

www.kz1300.com/index.php/forum/carburato...lat-spot-issues#5531

I do not reccomend blowing the passages until they've been soaked in a strong solvent such as lacquer thinner. Any solid debris in the circuit will get "rammed" into these tiny outlets and could create a more challenging cleaning task. There has been some justifiable controversy regarding the throttle-shaft seals and the length of time to soak the carb-bodies to avoid potentially damaging them, so keep the time short - 10-15 minutes should disolve anything disolvable with minimal impact to the seals. The first application of compressed-air should be from inside the bore into these 3 drilled ports - backwards toward the (removed) jets. Or to put it another way; Reverse to the normal direction of flow. The throttle plates will need opening, "just enough" to access them.

There are two ways of confirming these ports are open, free of any debris and capable of flowing a nice strong stream of fluid. 1) Visually, using the syringe method, or 2) Do less then a thorough job of flushing and cleaning, put the carbs back on the bike and take your chances ! I highly reccomend the 1st.

Until all 3 ports (per bore) flow fluid equally with a single strong stream, they are not clean and will continue to create stumbling, off idle.

For clarity I'll add this: When the engine is running, the amount of fuel actually required and distributed progressively from these three drilled ports will NEVER be that of the volume of the fluid that will be forced by the syringe. The only point of using the syringe is to force fluid through these holes to: 1) flush debris, and 2) THE BIG ONE - to visually confirm each of the 3 ports has a strong and singular stream with all three appearing equal in flow and pattern.

This should help you.

Thanks for the advice Scotch, I'll have an investigate at the weekend. I'v had these carbs off so often I could dismantle them in my sleep