carb is clean now so where the hell am I getting this bogggggggggggg.

getting some extreme hesitation from my kz200 and I need some advice in my jetting saga. what does bogging like: power-boggggggg-pow-boggggg-powerrrrrrrrrrr-bog-rrrrrrrrrrrrr mean? thought about the float but it did eventually get a good supply and even out so I dont think it was running out of gas.

here's what has happened to far.
-removed stock airbox
-bumped main jet from 105-108 and needle in position 3
-had a local shop fully tank clean the carb today
-new float needle, float, pilot jet
-idles beautifully - pickup on throttle isnt super quick but its as good as I've ever seen it.
- new fine wire plug
- no battery
- clip position 4, idles fine still, better throttle pickup but still the boggggggg.
- clip position 5, had to tighten the idle screw wayyyy in (fully seated) and richen up the mix screw quite a bit. a little chunky on roll on but bog all but went away for a couple passes, felt super strong once into the higher end, but then unceremoniously returned just when I thought I had it licked.... (felt rad when it did work though)



whatcha think?
thanks

Sounds lean. You may have an air leak. Spray WD40 on the intake manifold at idle, if idle changes then you have a leak. Do you have any vacuum hoses, to the petcock? Maybe it's cracked.
I wouldn't think it needs a larger pilot jet, but maybe smaller engines are more sensitive to lean mixtures. Try a larger one and see.
Good luck. Can you still go back to the airbox? Best bet for sure.

Not sure what kind of carbs you have, but when my 400 idled fine but bogged on accel, took me a while to find, but one of my diaphrams on my CV carbs was torn and wouldn't lift the slide.

Here's a 1978 KZ200 carb diagram for reference if needed (see following post).

Thinking an "as new" condition of the internal carb air passages and/or fuel passages has not yet been achieved (nice way of saying that regardless of the efforts to date, tank cleaning, etc., the carb is not yet properly cleaned).

An inline fuel filter is essential. Many a freshly cleaned pristine carb has been immediately clogged by an onslaught of dirty incoming fuel.

Tank soaking is not enough, and many soaking agents often fail to dissolve, loosen, soften, or have any effect whatever on encrusted material. Compressed air is essential (100 psi), together with a cannister pressure spray carb cleaner (always wear protective goggles because it always backfires). And a small wire (such as a guitar e-string) can help. #19 needle jet holder should also be pristine. Professionals like wiredgeorge use a sonic cleaner bath. Some members report success by boiling/soaking in vinegar or lemon juice (do a forum search).

Would return jet needle clip to stock position (guessing middle or third notch position). Assure #31 o-ring is in good condition. Return #30 pilot air screw to beginning default position per FSM (guessing 1.5 turns out from lightly seated).

While carb is on the bench, check and adjust float bowl fuel level, using the clear plastic tube method (static upside down measuring technique is insufficient, and usually a waste of time and effort, sometimes doing more harm than good).

Assure the pod filter is not over-oiled. Return to airbox if possible, with a clean new stock filter, being sure of no obstruction with a shop rag, tool bag, etc.

Should study and understand the text and carb circuit diagrams shown in the factory service manual.

The following is addressed to larger carbs, but may also apply to the KZ200 carb.

Pilot Circuit Overview

Freshly filtered air goes into a small entrance hole on the airbox side of the carb. Sometimes there's an air jet, but oftentimes not. Thinking no air jet on carbs with side located pilot air screw -- just the simple entrance hole. Anyhow, air enters the small entrance hole and continues along a passageway until reaching the pointed tip of the pilot air adjusting screw which regulates amount of air allowed to continue thereafter on to the pilot jet.

Meanwhile the pilot jet has picked up raw fuel from the float bowl. The air reaches the end of the air passage at the pilot jet where the air joins the fuel creating an air/fuel mixture which mixture then travels from the top of the pilot jet on through the pilot passage and out the pilot outlet (a tiny orifice in bottom of carb bore), from where the mixture is sucked through the intake valve into the combustion chamber.

All this is accomplished while the throttle slides are positioned completely down with no additional mixture contributed from the needle jet. And the pilot circuit continues this function of providing fuel mixture until about 1/8th to 1/4th throttle opening position. As the throttle is opened, the slides are raised, which allows increasingly more mixture from the needle jet and lessening effect of mixture from the pilot circuit.

Now, toward achieving a perfect (as new) carb pilot circuit --- And there are undoubtedly other and perhaps better methods, maybe even far superior methods, but here's how I do it, until learning a better way.


Pilot Air Passage

The pilot air passage throughout its entire length from entrance hole at airbox side of carb throat to the pilot jet should be clear and ultra-clean.



Pilot Passage

The pilot passage from top of pilot jet to and through the pilot outlet should be clear and ultra-clean.



Pilot Jet

The pilot jet central hole and lateral holes should be clear and ultra-clean. The pilot jet itself should be in pristine condition and the proper size. Remember, possible damage from previous cleaning efforts (with wire or otherwise) may be visually imperceptible. Holes appearing perfectly round and clean may be faulty enough to disallow the absolute precision needed to properly meter fuel intake from float bowl and infusion of air from the air passage. As new pilot jets are relatively inexpensive, I prefer to replace them. Opinions may differ, but new pilot jets worked for me. And I have yet to see any visual defect in the old original pilot jets (even with some slight magnification).


Cleaning The Passages

With carb on the bench, remove float bowl, float and pilot jet. Wear protective goggles. Plug threaded area where pilot jet was removed so as to block access into float bowl (using finger is okay). If pilot air screw has been removed, block its hole with finger. Direct carb cleaner spray into air passage entrance and blast away until spray freely exits from pilot outlet.


Pilot Air Screw

Remove pilot air screw and examine pointed tip to assure it isn't damaged. Carb cleaner spray directed into the (1) pilot air screw hole has three places where it may exit, (2) Air passage entrance, (3) into float bowl through pilot jet location, (4) pilot outlet. Any two of these may be purposefully blocked so the spray flows between the other two. Spray every combination until assured all the passages are clear and clean as new.

Here's a diagram for reference (with side located pilot air screw).
(Note -- In carb with bottom located pilot mixture screw, the pilot circuit is different -- metered air from a jet at the entrance hole with part of the mixture from the pilot jet going to a bypass outlet orifice in bottom of carb throat and remaining part of the mixture going out a second separate pilot outlet orifice governed by the bottom located pilot mixture screw.)

In any event, all the pilot circuit passages (air passage, fuel passage, and mixture passage) should be returned to as-new condition.

[click on image to enlarge]



Good Luck!

[click on image for larger view]

I've since looked in the shop manual I have for a 200 and your carb does not have a diaphragm (good suggestion Link14) and it also has a manual petcock, thus no vacuum tube. That would make me think the pilot is too small.

Does it run better if you apply a little choke?

How are you running this bike without a battery?

Is the fine wire plug comparable to the stock NGK B8ES?

Would also check and assure valve clearance being to proper specs.

Also assure ample steady fuel supply from petcock. Would consider removing petcock from tank and carefully cleaning the screen intakes, filter screen, and petcock internals.

Fuel tank may need flushing. Crud or grit inside fuel tank often collects and hovers around the petcock intake and clogs flow into the petcock. Would consider removing fuel tank, emptying old gas (dump it out the cap filler hole); add fresh clean gas (say 1/2 gallon); swish it around inside the tank by physically shaking the tank; dump it again; repeat if necessary.

Good Luck!

Possible that fuel tank cap vent is obstructed an thereby disallowing free flow of fuel to carbs, which might cause the surging.

May road test by running with fuel cap ajar (not snapped down).

I'd put the airbox back on and get her back to stock. It will be easier to get her running right that way. You'll get better gas mileage and performance without the headaches which is a 200's forte. Is your exhaust stock? The original building/engineering fathers knew their stuff. JMHO

thanks for all the reading guys! phew!

its not going back to stock. this is a "for fun" bike so practicality isnt too big of a deal here , I'll get it licked. The gas that is in the bike has been sitting for a while so I'm going to chuck a fuel filter in there and top her up with some 94. I can just imagine some crud floating around in the float bowl. thing is , it doesnt display any bogging symptoms when I just have it on the stand and I'm rolling the throttle. maybe the occasional hiccup but nothing like what happens when I just take it for a spin. it does run well when I can blast through the low speed hiccups and burps.

I guess I just thought an easy too rich or too lean might have been the answer though. it did clear up for a bit on one of my later runs on position 5 so maybe I am just sandblasting my carb with all the crap in the bottom of the tank.

thanks for the input

Check your timing! Not saying that is the problem for sure, but I never checked the timing on my bike until a year after I bought it. It didn't run worth a crap after 5k rpms and I kept giving it more gas (bigger jets, changing needle position), and nothing helped. Found out my timing was way too retarded and now the bike is mean as can be! My cousin had the same problem on his 76 Sportster, and we checked the timing on his bike and it was all the way retarded as well. Adjusting it to where it should be made a hell of a difference for both of our bikes. You may want to check yours as well!