Kz750E2 running lean PLEASE HELP

So I have a kz750E2 swapped quad it breaks up at 6-7 grand I thought it was because I had resistor plugs with non resistor plugs so I replaced the wires and plugs and ran it. Some other info the bike has open headers and pods so I jetted it up to 145 my float level has been set perfect to spec and my ignition has been gone over as well mechanical advance works great everything else checks out perfect battery voltage to coils even shunted the wire to the coils. So after all this I rode it and pulled a plug after the same issue and the plug was white and ashy (leannnnn) so i jetted it up to a 165 still no change I think my tank might be the issue it’s gravity fed and if the fuel is low at all the fuel filter won’t fill till I sit on the back and the gas moves to my petcock. Has anyone had issues with gravity fed tanks i have the stock petcock/fuel pump should I run that for some better fuel flow I’m confused on how it runs lean with a 165 please help

You must use some kind of air filter with those keihin cv34 carbs. Jetting with pods is 35-65-140.

undiablo wrote: You must use some kind of air filter with those keihin cv34 carbs. Jetting with pods is 35-65-140.

I do run pod filters at all times I just ran it like that to see if they where restricting the air flow if you read what i said it’s still running lean with pods and 165 main jet

Gravity fed fuel should not be a issue as thats the way the 750 fours operate.

What sort of petcock do you have? Is the flow restricted in any way?
Is the gas tank vented?

Is the fuel filter restrictive? Some paper automobile type fuel filters dont flow fast enough without a pump. A motorcycle one is best but even a cheap lawnmower one would be better than one designed for autos.

Have you checked you carb float bowl fuel levels? Search clear tube method here. Low fuel level in the bowls will cause lean running. Your carb bowl fuel level should be 4mm below bowl/ carb body seam and thats measured not eyeballed. Assuming carbs are keihin CV34 which came on the 750 E2. Getting my fuel levels correct was the single biggest improvement I made .

In an earlier post you mentioned cheapo snowmobile pods. If you look into the pods is there a lip which might obstruct and air intake on the carb? Although this would be more likely to cause a rich condition it might be worth checking.

There is also the possibility that the open header is the main cause of your problem but I have no suggestions for that one other than try a slip on silencer or keep trying bigger and bigger jets. 165 for the secondary main is already huge. You could up the primary 70, 80 90 ???

Two things you need

1] DynoJet jet kit for the KZ750H/E
2] Uni or K&N filters.


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Nebr_Rex wrote: [strike]Two[/strike] THREE things you need

1] DynoJet jet kit for the KZ750H/E
2] Uni or K&N filters.
.

3] Mufflers (or at least in pipe baffles)

Nessism wrote:

Nebr_Rex wrote: [strike]Two[/strike] THREE things you need

1] DynoJet jet kit for the KZ750H/E
2] Uni or K&N filters.
.

3] Mufflers (or at least in pipe baffles)

The bike is jetted up already I have uni filters and my exhausts have baffles I think I might have skipped cam timing a tooth I’m pulling the motor out today to check the valves and the cam timing

JR wrote: Gravity fed fuel should not be a issue as thats the way the 750 fours operate.

What sort of petcock do you have? Is the flow restricted in any way?
Is the gas tank vented?

Is the fuel filter restrictive? Some paper automobile type fuel filters dont flow fast enough without a pump. A motorcycle one is best but even a cheap lawnmower one would be better than one designed for autos.

Have you checked you carb float bowl fuel levels? Search clear tube method here. Low fuel level in the bowls will cause lean running. Your carb bowl fuel level should be 4mm below bowl/ carb body seam and thats measured not eyeballed. Assuming carbs are keihin CV34 which came on the 750 E2. Getting my fuel levels correct was the single biggest improvement I made .

In an earlier post you mentioned cheapo snowmobile pods. If you look into the pods is there a lip which might obstruct and air intake on the carb? Although this would be more likely to cause a rich condition it might be worth checking.

There is also the possibility that the open header is the main cause of your problem but I have no suggestions for that one other than try a slip on silencer or keep trying bigger and bigger jets. 165 for the secondary main is already huge. You could up the primary 70, 80 90 ???

I cut the lip off the filters already that was the first thing I did and they don’t make the primary jets so I drilled an extra set I had and still no change the thing is jetted fatttttt and it’s still lean could it maybe have gpz cams or something it does idle with a lot of lope it barely wants to idle

You posted conflicting information about your filters.
The UNI filters for that engine do not have a lip.
Quit being so obstinate. If you have the correct filters all you need is jet kit.
A constant velocity carb takes more than just jets to be jetted .
With a jet kit all this has been figured out.


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I'll be the bad guy here, you will never get it to run correctly with the exhaust setup you have.

they don’t make the primary jets so I drilled an extra set

They do
www.z1enterprises.com/catalogsearch/result/index/?p=2&q=Keihin

Stock jetting is pilot 35, primary 62 and secondary 125 which i assume is the one you drilled to 165.
With K&N pods and a 4 into 1 exhaust 35, 62, 140 should work. I have used 35, 70, 140

As i said earlier the open header is probably your main problem.

I think, not totally sure , that the gpz exhaust cam does not have a tach drive for a mechsnical tach

JR wrote:

they don’t make the primary jets so I drilled an extra set

They do
www.z1enterprises.com/catalogsearch/result/index/?p=2&q=Keihin

Stock jetting is pilot 35, primary 62 and secondary 125 which i assume is the one you drilled to 165.
With K&N pods and a 4 into 1 exhaust 35, 62, 140 should work. I have used 35, 70, 140

As i said earlier the open header is probably your main problem.

I think, not totally sure , that the gpz exhaust cam does not have a tach drive for a mechsnical tach

Then it’s not the cams cause my worm drive for my tach is still their and I did not drill the mains I had 165 main jets the ones that where 125 stock I drilled my intermediate jet that was a 62 but still no change I cut the tiny lip off the filter ( their was one but not enough to cause problems but I cut it to be safe) I’m pulling the motor to check Valves and cam timing as well as doing a leak down test