What'd I screw up?

I have been running my '80 KZ1000 LTD with the stock airbox (K&N element), Kerker 4-1, VM28SS (w/accel pump) carbs, 112.5 main, 15 pilot, for awhile now and it ran good except for a slight bog on take off.

Today I installed some K&N pods so I upped the mains to 117.5 and pilot to 20's. I sync'd the carbs and ran the Gunson color tune to set the idle mixture. Took it out for a test ride and it launches better but, at about 4K, it starts stuttering...almost like a misfire.

Did I make too big of a jump in the jets?

Gotta make this work as it was SO much easier to re-install the carbs this time!

Sonny

WHOA! Guess I didn't make a big jump in jet size. I rode out this morning and did a plug chop and it's running LEAN....electrodes were WHITE!

I wouldn't have thought those pods would flow that much more than the airbox. Guess I'll try some bigger jets to reel that dude in.

Is there anything else I should check that would cause the lean condition other than the jet size?

My needles don't have slots for different height adjustments although, I could maybe stack some washers under to raise 'em.

Sonny

sbulla wrote:

I have been running my '80 KZ1000 LTD with the stock airbox (K&N element), Kerker 4-1, VM28SS (w/accel pump) carbs, 112.5 main, 15 pilot, for awhile now and it ran good except for a slight bog on take off.

Today I installed some K&N pods so I upped the mains to 117.5 and pilot to 20's. I sync'd the carbs and ran the Gunson color tune to set the idle mixture. Took it out for a test ride and it launches better but, at about 4K, it starts stuttering...almost like a misfire.

Did I make too big of a jump in the jets?

Gotta make this work as it was SO much easier to re-install the carbs this time!

WHOA! Guess I didn't make a big jump in jet size. I rode out this morning and did a plug chop and it's running LEAN....electrodes were WHITE!

I wouldn't have thought those pods would flow that much more than the airbox. Guess I'll try some bigger jets to reel that dude in.

Is there anything else I should check that would cause the lean condition other than the jet size?

My needles don't have slots for different height adjustments although, I could maybe stack some washers under to raise 'em.

Welcome to Planet Pod. :pinch:

SO much easier to re-install the carbs -- that's beneficial :dry: , what with being a constant regular procedure on Planet Pod. :laugh:

High speed plug chop test was important, and mostly helps with determining main jet size absent other carb or fuel delivery issues. Isn't much help as to jet needle clip position (mid-throttle range) and no help regarding pilot jet size (low-throttle range).

Stacking washers to raise jet needle is imo a bad idea. A replacement needle with a different taper might conceiveably help mid-throttle range performance, but would defer that for now, and concentrate instead on the fuel mixture at maximum throttle (main jet size) where jet needle isn't a factor.

Is there anything else I should check that would cause the lean condition other than the jet size? YES -- would first assure there's no fuel starvation issue, such as vent obstruction in fuel tank cap, or a clogged filter anywhere (petcock pick-up tubes; petcock sediment cup screen where so equipped; inline fuel filter).

Are pod filters properly oiled?

Good Luck!

Forgot to mention --- would also confirm ignition timing being set to specs, using a strobe-type timing light to visually observe advancer position being correct at 3000+ rpm.

Good Luck!

Thanks Patton, for all the suggestions.

I don't think I have any timing problems or fuel flow problems as it was running good the day before the pod transplant and as I was doing the tune up I could see the fuel flowing in the clear lines I use from the tank to carb.

I will double check my float heights before (and after) I change jets to make sure I didn't foul them up with the first jet change.

As far as the pods being oiled, when I took them out of the box, they were pink already and I could pick up oil off them with my fingers so, I assumed K&N pre-oiled them.

Think I ought to go up to a 120 or 122.5 main?

Sonny

sbulla wrote:

Thanks Patton, for all the suggestions.

I don't think I have any timing problems or fuel flow problems as it was running good the day before the pod transplant and as I was doing the tune up I could see the fuel flowing in the clear lines I use from the tank to carb.

I will double check my float heights before (and after) I change jets to make sure I didn't foul them up with the first jet change.

As far as the pods being oiled, when I took them out of the box, they were pink already and I could pick up oil off them with my fingers so, I assumed K&N pre-oiled them.

Think I ought to go up to a 120 or 122.5 main?

Sonny

Short answer -- probably yes.

Long answer (groan :lol: ) --

Carb parts diagram on kawasaki.com shows '80 KZ1000 LTD having 102.5 main jet and 15 pilot jet as oem sizes.

Imo, K&N filter in airbox flows about as well as K&N pods (shoot me now :laugh:). So that changing to pods with the same 112.5 mains and 15 pilots would have in itself made very little difference (no significant change in air flow, unless the airbox K&N was clogged or airbox was obstructed by some item stored under the seat such as shop rag or gloves).

Would confirm plugs are correct heat range NGKB8ES, not B7.

Hope an inline fuel filter is fitted, and would suggest assuring there's no crud or grit obstructing the main jet orifices.

As pre-pod plug appearance may be unknown, and since other possibilities have mostly been ruled out, would next test with 122.5 or even larger mains to get darker plug reading, then downsize mains from there if indicated.

Good Luck!

Patton wrote:Imo, K&N filter in airbox flows about as well as K&N pods (shoot me now :laugh:).[/quote]

That's what I assumed by info gleaned from this forum.

b]Patton wrote:[/b]Would confirm plugs are correct heat range NGKB8ES, not B7.[/quote]

Yep, B8ES...brand new.

Patton wrote:As pre-pod plug appearance may be unknown, and since other possibilities have mostly been ruled out, would next test with 122.5 or even larger mains to get darker plug reading, then downsize mains from there if indicated.[/quote]

I just stuck the 122.5's in there (largest I have on hand), checked float levels and now, headed out to re-install the carbs and give it another try.

Thanks,
Sonny

dyno jet makes a jet kit for your bike give it a try the kit comes with adjustable needles which what you need to try to get past the flat spot.

sbulla wrote:

it was running good the day before the pod transplant

I am thinking that should be the title of a thread sticky....:laugh:

timebomb33 wrote:

dyno jet makes a jet kit for your bike give it a try the kit comes with adjustable needles which what you need to try to get past the flat spot.

I guess I'll have to drop the cash on that.

I just went out and tried to make another plug chop run but, everyone is getting off work now and traffic was all over. Couldn't find enough space.

But anyway, the low end and top end seem to be fine. It's the mid range that's screwy and that would be the jet needle, I guess.

Heck, I guess I really don't need to eat this week.

Thanks,
Sonny