KZ650 with Asthma

Maybe not asthma, but tonight was the first time out on its own power and instead of cracking the throttle, it was a fine tune adjustment to keep it where I wanted it. After warming up it would stay at a higher rpm. Anyways, trying to figure out how to get the popping to go away at the low end and to actually respond to the throttle.

Anyways, any ideas on what to look for? It has been rejetted one up on the mains and the needles are up a notch from stock.

Thanks,
KC

Be easier to give advice if we knew more about the set up. Are you running stock exhaust and airbox or aftermarket exhaust and intake?

Also, what condition are the carb holders in? If you have a leak there you'll never get the carbs tuned right or the bike running well.

If you put your bike info in your signature line it generally helps others give advice as well...

Dito

For whatever reason, I have never been able to find the signature portion. Anyways, the bike has stock CSR Pipes, pods, and is stock other than the jetting. My initial thought is that the air jet needs to come out a little more and to raise the needle another notch. However, I wasn't sure if that would cause the sputtering that I get when I open the throttle. The other symptom is that I can use the choke to help overcome some of the problems on the low end only.

The boots are good, I made sure there are no cracks and I installed new vacuum boots. Also, I have tried the "WD-40 around the boots" trick with no effect on the engine.

The good news is I still have a little more to do to the bike right now before it is ready for commuting, I just finally had it wired and bolted up and figured after almost a year of working on it that it would be good to actually take it out rather than to just sit on it while making motor noises.

Sounds like carbs have already been rejetted.

I would suspect a problem in the carb pilot circuits.

Good Luck!

What year KZ650? Different year models likely have different carbs. For instance (just guessing) earlier models might have fixed slide Miks or whatever and later year models have CV carbs.

Good Luck!

KawiConvert wrote:

... have never been able to find the signature portion....

Here's one way of getting to the signature box.

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Good Luck!

The choke circuit causes the mixture to become more rich. So, if the bike will maintain idle on choke but then dies without it I would suspect a lean condition on the idle circuit. With pods and stock exhaust my 81 CSR was jetted at 17.5 pilots, 115 mains, and needles on the #4 clip and she ran like a champ from idle all the way to full scream redline. That was for Mikuni vm24 carbs.

Ok, found the old thread, here is the jetting currently in the bike. I have 107.5 mains and 17.5 pilots with the stock needle clipped in the 3rd grooved and the air screw is out 1.5 turns. The carbs are the VM24's (no diaphram, all slides raised via the gallows attached to a common throttle rod).

I am going to pull them off though and go through them again and look at jetting them a little richer. While apart I plan to put a little pain on as well.

anarki650,
What elevation were you at with that jetting? Also, what kind of weather.

Thanks agian for the help. With any luck I'll have a runner that is ready to go in a few weeks with everything painted. hopefully our cold season will have passed by then.
KC

Have you checked them to make sure they are all properly sync'd?

I have the same model as you with stock exhaust and pods as well. I'm running 110 mains and 17.5 pilots. Mine was running fine with these until I messed up something in the enrichener circuit. Once started and warmed up though, it runs good. Although I do have a flat spot from 5000 to 7000. Thinking I may need to reclip the needle to the 3rd grove like you have done. Syncing my carbs made a noticeable difference. May as well check the timing too.

HerrDeacon wrote:

Have you checked them to make sure they are all properly sync'd?

I have the same model as you with stock exhaust and pods as well. I'm running 110 mains and 17.5 pilots. Mine was running fine with these until I messed up something in the enrichener circuit. Once started and warmed up though, it runs good. Although I do have a flat spot from 5000 to 7000. Thinking I may need to reclip the needle to the 3rd grove like you have done. Syncing my carbs made a noticeable difference. May as well check the timing too.

I have set the points and tightened the cam chain, however I haven't physically checked the cam timing. I am going to check my float height first and make sure they are where I think they are. I started to think the lean may be due to a low fuel level in the bowl that the choke overcomes because it drinks out of the bottom. Looking at others jetting has made me think that the jets aren't the likely culprit. Once I get the carbs closer I was planning to sync them properly. Thank you for the suggestions, anything to help me find the problem is appreciated.

OK, pulled the 2 right carb bowls and raised the floats ever so slightly, put it back together and turned on the fuel and leaked gas everywhere. 30 min later when the floor had dried and the fumes had cleared, pulled the bowls and lowered them a little, put it back together, and now there are no leaks, and it cold (somewhere in the 50's) started and idled with no choke. Now I need to adjust the other 2 carbs to match, but that was part of the problem.

Now it will rev and stay there for about 3-5 seconds before returning to idle. One more thing to work on after I get the other two floats adjusted. Slowly but surely it is getting there. Here is a picture of where it is at right now. Don't mind the garage, haven't had a chance to clean it up while trying to finish everything.