Throttle hesitation-Floats? Idol Jets?

I have a 78 KZ650 that is running pods and 4-to-1 Mac exhaust. The bike runs great and we've taken the carbs apart several times to get them dialed in. I am still getting a little weak throttle response (when you hit the throttle in first from a stop light, it seems to bog down before revving up). This makes me think it is something relatively simple such as float bowl height, but I am just curious. We have a stage 3 DynoJet kit in the bike. Everything is great except this one little issue and I know that it is not something that should be happening on this great bike. Any suggestion is appreciated. I can provide the jets and all that I am running too if needed. Thank you for any help you can provide.

When pods are involved, the engine bogging at all is usually associated with improper jetting

nickleo373 wrote: When pods are involved, the engine bogging at all is usually associated with improper jetting

Yup. Not at all unusual. If the engine is stock you will find it challenging to make it run as well using pods as it did with the airbox throughout the rpm range. I never have seen anyone post the perfect jetting combination despite many thousands of postings on the subject on this site. Ed

My 78 KZ650 is jetted perfect and it's running pod filters and a 4 into 1 pipe. In fact is runs better than it did when it was stock and I bought in new in 1978. Even when it was new It had a very slight flat spot right off idle that I could not get rid of. I tried all the tricks of the day, installing a KZ900 advance unit, fancy spark plugs, electronic ignition, ect. I finally cured by getting a jet kit, installing pod filters, RC pipe and spending a few weekends dialing the carbs in. It was a pain the ass but worth it. The thing runs great to this day, very smooth from idle to the redline with no weird hesitations or bogs. It runs great from sea level to 13,000 feet, in the rain, windy days hot or cold temps. I really don't know what the aversion is to Pod filters it just takes some time and an good understanding of the carburetors systems. I have tuned a lot of carbs over the years and have managed to get all of them dialed in with pod filters.
My jetting on the VM24 carbs are
Dynojet main #118
Pilot jet is 17.5
Dynojet needle with clip in the 2nd slot from top.
Pilot air screw I move around depending on the season, 2.5 turns out in the summer and 2.00 turns out in the winter.

baldy110 wrote: My 78 KZ650 is jetted perfect and it's running pod filters and a 4 into 1 pipe. In fact is runs better than it did when it was stock and I bought in new in 1978. Even when it was new It had a very slight flat spot right off idle that I could not get rid of. I tried all the tricks of the day, installing a KZ900 advance unit, fancy spark plugs, electronic ignition, ect. I finally cured by getting a jet kit, installing pod filters, RC pipe and spending a few weekends dialing the carbs in. It was a pain the ass but worth it. The thing runs great to this day, very smooth from idle to the redline with no weird hesitations or bogs.

That's good to know. Hopefully pnedac will be able to replicate your success using your jetting specs. Ed

I just got home from work and I am going to pull these puppies and see what the deal is. Thank you baldy110 and to everyone and I will report back shortly with the results.

Pnedac

Okay so I put the settings to be the same as baldy110:

My jetting on the VM24 carbs are
Dynojet main #118
Pilot jet is 17.5

---

This is the only one I changed as I had everything else the same already. Mine had the 11.5 jet.
Dynojet needle with clip in the 2nd slot from top.
Pilot air screw I move around depending on the season, 2.5 turns out in the summer and 2.00 turns out in the winter.

So it still is bogging down just a bit and it smells a little rich. Can I accomplish the leaning out by manipulating the pilot screws ever so slightly? I believe I can, but I would love to get a little confirmation that I am headed in the right direction before I go tinkering too much more.

Thank you again! I attached a picture of the bike for fun. I will say, it is a great bike!



Pnedac

Keep in mind that the Dynojet 118 main is pretty much the same as a Mikuni 110 main. I am not familiar with the dynojet needle but would think it would be longer and have a different tapper than the stock needle.

In general I think a good starting point for the vm24ss carbs on a KZ650 when running pods and a 4 into 1 exhaust is as follows
110 main
17.5 pilot
On the 5DL3 jet needles, clip to the 3rd position and the others get clipped to the 4th slot.

Again want to stress that this a good starting point and not necessarily where you will end up.

pnedac wrote: Okay so I put the settings to be the same as baldy110:

My jetting on the VM24 carbs are
Dynojet main #118
Pilot jet is 17.5

---

This is the only one I changed as I had everything else the same already. Mine had the 11.5 jet.
Dynojet needle with clip in the 2nd slot from top.
Pilot air screw I move around depending on the season, 2.5 turns out in the summer and 2.00 turns out in the winter.

So it still is bogging down just a bit and it smells a little rich. Can I accomplish the leaning out by manipulating the pilot screws ever so slightly? I believe I can, but I would love to get a little confirmation that I am headed in the right direction before I go tinkering too much more.

Maybe, but the slide is also lifting off the base just as you start opening the throttle and needle position can make a big difference there. You might try going one click leaner on needle position.

So I've got the carbs off again. I think I may be on to something bigger here. I am curious. I see that there are two plugs, one on number 2 and the other on 4. Should they be capped as they are? I suspect not and I suspect now that this could be the root of the problem.


NOTE: The petcock was changed from vacuum to gravity so I am not sure that these should have been plugged, but perhaps the one port SHOULD have been. The one little one is for the vacuum petcock and should be. Can anyone confirm that for me?


Lastly (please don't beat me up here as I got this bike as a motor, frame, and an ice cream bucket of bolts) Is there supposed to be a rubber plug in these holes? I see 4 holes, but I am not sure if they are supposed to have a plug in them. The manual does not appear to make me think that they should be plugged, but I also can't seem to find a good picture.


As always I appreciate all the help!

A few quick questions: Are these two supposed to be plugged or have a hose attached? The petcock was changed to gravity from vacuum if that makes any difference.


Also , should this one be plugged because of the switch to gravity fed?


Lastly, I think these holes should be open, but just checking.


Any help is appreciated. I think I am almost there!