When to Jet up

It seems to be well recognised that the area that causes the most trouble to owners is carburetors.
Well if thats half true it certainly is the case in my case of the KZ1100.

So - I've done everything possible to get perfect proper running with correct colour plugs - balanced, re-kitted, tried every combination setting possible with the fuel/air mixture screws on each carb, set the float tab levels, put a standard air filter back on etc etc.

Best performance (pulling strongly on all stages of acceleration I can get with minimal popping is a fuel/air setting that always shows the plugs a black, but it certainly isn't perfect (in terms of the popping (still pops consistently on cruise - only stops if going full blast

Now here's the thing - the bike is running an after market muffler/silencer and there I am guessing is the issue. (cant get original anywhere I can see)

Its got all original jets - so now I feel I need to up the main jet? Friends have said only the main jet needs changing - to 140 (current standard is 120R (whatever the R stands for??)

Now I discover I have a jet kit but the mains are only 125 - Doesn't sound like much of a change - but I don't know - no experience in difference between jet sizing.

If anyone has been through this process and has any thoughts - before I pull the carbs out "again" , please let me have your thoughts.

On stock engines the two carb issues I have read the most about is leaking carb holders (which is easy to detect) and removing the stock air cleaner. If you have installed pods or some other non-stock air cleaners rejetting can be a very big challenge because it changes the dynamics of how the carbs breathe - not just how they are filtered. If your carb holders are leaking the problem will show up mostly at idle speed and can be tested and corrected if necessary. Ed

Stock carbs likely worked just fine when the bike was new.
Would suspect carb pilot circuits aren't perfectly clean, including the orifices feeding into the bore.

Good Fortune!

Valves adjusted?
Steve

Gregory, take a quick look at the number of posts for the Gents that just gave you suggestions. They all represent good advice. With the engine warmed up and idling, shoot a short blast of starting fluid on the carb holders/carb connection. If the RPMs rise, you have a leak. As Ed said, easy. Careful where you shoot that stuff as it is ridiculously flammable.

Patton has a diagram of the carb circuits I suspect he would share if you are committed to verifying the circuits are clean. Once those two things are one of the best ways to set the idle circuit AFR is a Colortune plug. You can actually see the combustion in the cylinder. It costs $75.
www.amazon.com/Colortune-for-14mm-Spark-...colortune+spark+plug

If you don't know where the valves are set, you should establish where they are and address any out of spec issues. In part for this issue you are working but also for the health of your motorcycle. If the valves aren't closing fully it is going to honk up the vacuum to the carbs which directly affects their performance. Plus you are going to burn a valve. Just to verify, are we talking about BS34 carbs here?

The valves are commonly ignored. Po's say the carbs need cleaning when they were too lazy or cheap to adjust them. Basics first then go to the carbs.
Steve

Thanks for the input Guys. Along the journey there was a split boot and leak but no leaks now. The carbs are completely clean and new jets. When I bought the bike (before restoring) there were pods but now just good old original airbox.
The one thing not checked from your combined list is the valves. If anyone knows of a good article, info or video that you can recommend I start to learn through please let me know thanks. Rgds Greg

The factory service manual explains the procedure for checking and adjusting the valve clearance pretty thoroughly. There are even pictures and a chart.

I had almost the same symptoms as your having. I had freshly cleaned /rebuilt carbs brand new holders and boots and still had the issue. I took my bike to a local vintage bike shop and the valves were the culprit. I have the spec sheet somewhere that he documented the clearance( or lack of) and what shims he used to get the proper clearance. They were off quite a bit. Sounds like this might be your next thing to check.