Carb setting with pods and 4x2 exhaust

I have a 78 kz650B with a set of 4 x 2 exhaust with baffles, and Emco pod filters.

I'm rebuilding the carbs with the K & L kits, and am wanting to know a good starting point for the main jets, needle height, and anything else that might need adjusted / changed on the carbs with this setup.

This is the carbs on my bike....



Thanks !!

With a 78 B2?/VM22SS carb and a stock exhaust(?), I don't think you need to re-jet because of the pod filters. I would keep it all to factory settings unless you are having issues maintaining idle or going through the rpm range. Make sure those carbs are cleaned piece by piece based on the visible amount of varnish in the photo.

Unless you are changing compression ratios in the engine by changing heads and valves, etc, the pod filters will not contribute to more horse power. Moreover if you have access to a dyno you may find less horse power. The engineers at Kawasaki Heavy Industries did a fine job back in the day designing these KZ engines and the "air box" was designed to provide each engine with a specific amount of air flow. Once you deviate from the factory spec all bets are off (on your own).

Those are VM24SS carbs. The VM22SS carbs have an extra orifice at the 10:00 position (see image below). I think you will find the engine will run lean with pods (not a good thing). I don't know if anyone here has stumbled upon the magic jetting combination to make the engine run as well throughout the powerband when using pods instead of the stock filter. Just curious - what made you decide to install pods? Ed

The VM24SS was re-introduced (edit) in 1979 (no extra orifice, but with the air injection system (vacuum petcock) and carburetor accelerator pump added to the @2 carb). The VM22SS for 1978 B2A (edit) do not have the extra orifice [strike]as they do on 77 models[/strike] (edit).

UNLESS NON-USA MODELS ARE DIFFERENT

Picture of my 1979 VM24SS carbs.

Your information source is wrong. The VM24SS were the ONLY carbs on the KZ650 models (C1 and B1) in 1977. These VM24SS carbs did not have air injection, vacuum petcock, or accelerator pump components. Prior to 1978 there were no VM22SS carbs on any KZ650. The VM22SS carbs were installed only on the 1978 KZ650-B2A and D1A, and the VM22SS carbs all had that extra orifice at the 10:00 position. The 1978 KZ650- B2, C2, and D1 models all had VM24SS carbs.

Take a look at your Kawasaki Service Manuals for specs. Below is an example from the 1977 KZ650-B1 & C1 manual. Ed

1978
KZ650 -B2A, D1A
Mikuni VM22SS

1979 (supplement)
KZ650 -B3, C3, D2
Mikuni VM24SS

1980 (supplement)
KZ650 -B4, C4, D3, E1, F1
Mikuni VM24SS

My FSM covers 1978-1980 KZ 650, and the VM22SS carb section does not indicate the extra orifice for the 78 B2A, D1A. He probably owns a 78 B2 model with VM24SS carbs which is what you are confirming.

I believe ONLY the 1978 KZ650-B2A and KZ650-D1A models, may have VM22SS carbs without the "extra orifice". And both these models were USA market only in 1978.

I don't have the extra orifice on my carbs, nor do I have an accelerator pump.

650ed, I decided to go with the pod filters because of the hassle it is "for me with a bad back" to be able to remove the carbs from the bike. I purchased a set of 4 x 2 exhaust for the bike, and I figured with that exhaust, and the pods, I might be able to get a bit more out of the engine. I know it's not going to pull my hands off the grips, or slide me back on the seat, but I believe it will be a bit stronger running. I could be wrong, but I have to find out on my own. I'm goofy that way...LOL

Also, I've always been the type of person that couldn't leave anything stock. I always had to tinker / play with my bikes, and that is what this bike is, something for me to play with.

Knowing that the new aftermarket exhaust and pods would open things up, and lean it out, is what brought me here, hoping someone else had a similar setup, and could get me close to the magic combination as far as jetting and needle height.

I always get a kick out of the "the airbox is a hassle when I have to remove the carbs" reason for switching to pods. :laugh: In more than 38 years I have removed my carbs exactly 2 times. Once because I screwed up and left gas in them for a year, and once to replace the carb holders. The airbox added about 10 minutes to the process, so 20 minutes over 38 years doesn't seem like much to me. On the other hand, tuning for pods will most likely mean removing the carbs at least a few times to rejet, and without a doubt will mean spending a lot more than 20 minutes fiddling with them.

As far as adding more power - it isn't going to happen. Usually, if you're looking for more power on a stock KZ650 engine the very best thing you can do is perform a complete tuneup. As you say though, you want to find out for yourself. I suggest you fully tune up the bike first, make a few measured speed passes so you understand the baseline performance, and then after you're done installing pods try a few more passes to see how they compare. Be sure to see how the pods perform at all rpm ranges as there's usually a power loss in performance at one rpm range for a boost is another rpm range. Consider what rpm range you normally ride at, and see if that's where you lose power.

Here's an article by one of the Mikuni engineers about the airbox vs after market filters. There's no doubt in my mind that he knows what he's talking about. Below that is a link to an excellent, extensive test report done by experts who spent a good deal of time, money, and dynometer time comparing pods to the stock airbox. I suggest you read them both before you start. Oh, and hold onto the airbox just in case. Ed



kzrider.com/forum/3-carburetor/585949-po...-a-free-lunch#585949

For a bolt standard bike in regular use carb cleaning isn't routine maintenance I know, but on all of my bikes I've done it several times over the years.

Pods look cool imo and sound great, also greatly eases maintenance. They have a number of disadvantages too. I've been told for the last 25 years that a bike will never run 'right' on them but with some experimentation they can be set up nice. Slide carbs are generally easier to tune than the later CV carbs...

You will probably need to experiment yourself with the jetting and set up, this is the time consuming bit.
The original linked 4-2 pipes work really nicely with the airbox, that grunty tourque of the z650 is what makes it imo.

I like pods myself but you will likely lose more than you gain plus a small decrease in gas mileage. A contradictory reply I know.

I appreciate everyone's advice, and the info posted about the experts experiences !!

My life's experiences are an early 70's Honda 750 that I customized with a 4 x 2 exhaust, and a breadbox filter. Yes it took me a little bit to get it tuned to my liking, but I thoroughly enjoyed the performance after. Then I had a 95 Kawasaki 800 Vulcan. I built my own exhaust, and opened up the air box and put in a K & N filter. Two tries, and the jetting was spot on.The bike ran absolutely fantastic, and I got 70 mpg. Go figure ?? Oh yea, I had a Honda CB500 that I converted into a hill climber. Again a breadbox filter, straight pipes, and of course some jetting, and no complaints. Of course that bike was WOT all the time....LOL

I see it as, to each there own. I'm not one to judge, or say it can't be done. I like to find out for myself. I was just hoping there was another here that had done something similar as I'm doing, and would be willing to share there results. I'm going to continue on with my little project as it's who I am, and it's what I like to do. Yes I will most likely spend more time jetting the carbs, but I will not have to fight the air box, and hopefully will not have to pull the carbs again after this rebuild. Right or wrong, I'll let you know how it goes, and post my likes and dislikes about my experience with this project. I hope to say I like the changes, but there's always the chance that I won't.......

There are no good rules for jet jumping. I see posts like go one up on the main for pods, another up main for less restrictive pipe. The pipe and intake system form a tuned flow system and that reaaly affects getting ideal fuel setting.

On mine, I increased the main jet in steps until I felt it bogging down on WOT crank uo to about 5k then used the next leaner min which was stock on mine (stock air box).

To tune in the pilot jet: I would put it in first gear and try to hold it at every RPM increment from idle up to about 2500. Too rich and the engine would surge, too lean and it would "weak sputter".

Needle height adjustment: I went by feel on cruising at 40 mph in high gear and roll the throttle on. If the engine hesitates or cuts back, too lean raise needle. I have .010" flat washers that are exactly 1/2 slot for fine tuning.

This kind of tweaking takes a LOT of time.....