Hesitant from stop, Stuttering acceleration

Hi - first time poster. I've searched throughout these forums and others and have not found another problem quite like mine. If a thread dealing with this exists, please point me to it.

I've got a '82 KZ650 that I've pod filtered and exhausted. After those mods, I went up one jet size on both the mains and the pilot. Running well (with some backfiring) last season when I winterized the bike. I pulled the carbs and brought them in my house so they'd be subjected to less extreme temperature swings. Warm weather has arrived and I threw everything back together - and now my problems have arrived.

The bike struggles off the line (not appropriate response to throttle position), and once going I get spurts of power around 5000rpm. These symptoms are present when the intermediate choke is both on or off. Full choke prevents starting.Took it on the freeway today to make sure it was getting fully warmed up(because I'm an idiot) and although I could get up to 70, the bike would then fall down to 55-60 even with throttle maxed. I could kick down a gear to some effect, but not much, until it the RPMs or speed fell enough and then it would come "on cam" or "on boost" again and speed me up.

Lastly, when coming to a rapid stop the bike wants to die. This was happening last year as well. Slow, controlled stops are fine, but if I rapidly back off the throttle in first it just kills the engine. Not sure if all these symptoms are related or not, but would obviously love for a magic bullet solution.

Thanks for your input.

Search for "Pod's"
There are thousands of posts on this.
It sounds like you are to lean still. You would probably need to shim up your needles, and go up still on the main etc. Have you set the fuel level in all 4 carbs? What do your plugs look like, lean?
You could buy a kit from Dyno-Jet, that would give you adjustable needles.
I vote for the stock airbox, and jetting especially with the CV carbs.
Good luck.

All that motorhead said and more. Check whole fuel system including old fuel and moisture in carbs. Dont give up

Thanks. I've searched for "pods" - before and just now - and still not seeing anyone with my exact problems. I can't believe that it's a jetting problem as it was working fine last year. I've cleaned out the carbs, pulled the jets - pilot and main - and cleaned, and installed an in-line fuel filter. Fuel is new. I checked the float level last night before posting - if that is what you (Motor Head) mean by fuel level? My plugs are OK but not great looking. One is somewhat fouled, one looks great, two in-between.

Could you explain what you mean by "shim up your needles?" Also, I keep reading about an "air screw" that needs to be a certain amount of turns. What is this and how do I know how many turns it should be? Thanks for your help.

the way your first post reads, it sounds like a lean condision, like dirty carbs. but since u have cleaned them , this may not be the problem. r u sure u were able to pass fluid through all of the passages in the carbs?
the "air screw" is common on manual slide carbs to add fuel or air to the pilot circuit. not sure if yours have these or air jets. check your manual. adding a shim under the needle, raises the needle to make the circuit run richer.
here is some carb info that will give u a better understanding of there operasion.
go here
kzrider.com/filebase/cat_view/231-not-model-specific?start=20

and read this artical
Principles Of Modern Motorcycle Carburetor Function
hope this helps.

or u could also have an electrical problem.

Since it is an 82 I would assume the carbs are mikuni BS32s (CV style) and not mechanical slide (VM style). I agree with Mark it does sort of sound like a lean issue. Since it was running fine last year and you removed the carbs over the winter, I would first look for air/vacuum leaks on the carb holders and on the vacuum ports on the carbs.

I would also check for proper voltage to the coils (should be close to full battery voltage)without it there can be insufficient spark.

Would also check to make sure the advance unit is working correctly (free moving and lubed)

The Idle mixture screws are turned out for a richer fuel/ air mix. This will effect Idle to about 1/8th throttle the most, but will map over to around 1/4 throttle. Shimming the needles up will richen the mid throttle, from off 1/8th throttle up to 3/4 or so, when the mains take over.
If you set the float level with the carb dry, upside down on the bench, I would go and check the Fuel Level. This is with a piece of clear tubing hooked to the float bowl drain and held up against the side of the carb body. Drain open and on prime. Fuel level is just below the mating surface of bowl to carb body.

Thank you all - you've given me a bunch of stuff to learn and try. I'll be back in couple days if nothing is solved.

Thanks again.

Even though you say running well, popping and backfiring is not running well. If you did not shim your needles or replace them with adjustable ones you have been running lean. From what you describe you have been running lean for an entire season and the loss of power with open throttle is a lean indication. Lets hope you did not damage the engine.

If you pulled the carbs and put them back on have you performed a carb sync? If not, you should. the most overlooked part of carb work that I have noticed.

Another thing overlooked is simply replacing the spark plugs. Have you done that? Running lean can damage those as well. They are cheap. Just replace them regarless of what the eye tells you.

Alright! I just shimmed the jet needle and my acceleration from a stop is great if not perfect. I've only gone on a 30 second test drive so we'll see, and I'm still getting backfires when off throttle (despite going up on both jets AGAIN) and I don't think it's accelerating perfectly yet but obviously I've got to get more saddle time before I can diagnose. If it is still rough from 1/8 throttle to 3/4, I'll be back with more questions.

Thank you all for your help and time. It means a lot and I'm looking forward to my riding season again.

Pull the plugs at 1000 2500 5000 7500 rpms to see what they tell. Make a change to get light tan colored plugs and you will be set. That being said, fuel levels must be right. Vent tubes must be clear, and fuel must flow freely to the carbs. Plugs will never lie to you. One more thing, the ignition must be right as well. If you need details on how to do this stuff, the mikuni bible from sudco will tell you all you need to know. Good luck and happy bug eating. (Mike)

I went through something similar that just drove me nuts...it wound up being crap in the tank...I had put some methyl hydrate in to fix a minor amount of water, had the methyl eat some crud away that then went right through the filter and into the float bowl...a couple of days of draining the float bowls every 20 mins or so when running eventually fixed it. A reset and re synch and it runs fine.