How far to screw carb jets. 78 kz750

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23 Sep 2015 08:13 #691507 by Lwassner
How far to screw carb jets. 78 kz750 was created by Lwassner
I have a 78 kz750 twin with stock carb and jets. I just put pod filters on and am adjusting for for fuel. I move the clip on the needle from 2nd to 3rd notch and now am trying to figure out how far to screw the two jets that unscrewed out of the inside and outside of the bowl to clean.

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23 Sep 2015 09:59 #691524 by 1977-Z1-A1-LTD
Replied by 1977-Z1-A1-LTD on topic How far to screw carb jets. 78 kz750
The pods air filters allow more air flow through the carbs, and normally require bigger main jets in order to compensate for this added air flow. Need to increase main jet size to get the right air/fuel mixture and increased performance (I'm assuming that's why you installed these filters). Dynojet makes a kit complete with instructions that will help you in your mission to get better performance using these air filters. The main jet is in the bowl of the carb, your manual should have details on how to remove the bowl and the jet. If the bike was running great before you put on the pods, you might consider going back to the stock set up. Best of luck!

1977 KZ1000 LTD
1990 FXR
1998 KTM 300 EXC
1974 CBR 350

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25 Sep 2015 19:28 #691969 by timmythecop
Replied by timmythecop on topic How far to screw carb jets. 78 kz750
If you are referring to the idle mixture screws here is how i have had good luck:

Start and idle for a while. one carb at a time, go backwards (anti clockwise) from a lightly seated adjuster. take note when the idle gets higher. dont worry if it is too high, just go back and forth until you have the most rpm. now re-adjust the idle back to around 1200rpm. do the same on other carb, until you have the fastest idle. re do the idle adjuster, and your screws are set.

for diagnosing problems, it helps to know that idle mixture screws on the airbox side regulate air and if it is on the engine side, it regulates fuel. also remember that this adjustment handles idle, an a fraction of off idle, so dont fiddle with them when there is a problem with any other rev range.

good luck

Can I convince you to paint it flat black?

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26 Sep 2015 03:28 #691979 by 650ed
Replied by 650ed on topic How far to screw carb jets. 78 kz750
The '78 KZ750 came with CV carbs, so I suspect you have your work cut out for you. I hope you didn't toss the airbox. B) Ed

1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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26 Sep 2015 10:27 #692016 by bountyhunter
Replied by bountyhunter on topic How far to screw carb jets. 78 kz750

Lwassner wrote: I have a 78 kz750 twin with stock carb and jets. I just put pod filters on and am adjusting for for fuel. I move the clip on the needle from 2nd to 3rd notch and now am trying to figure out how far to screw the two jets that unscrewed out of the inside and outside of the bowl to clean.

On mine they run best at 2 turns out (CCW) from all the way in. I have stock airbox.

1979 KZ-750 Twin

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26 Sep 2015 12:55 #692033 by Randombeat
Replied by Randombeat on topic How far to screw carb jets. 78 kz750
1980 kz750h, UNI pods, 3turns out... (runs great, but wasnt so great with cheapo pods)

1980 KZ750H LTD-- pods-- vance & hines 4-1 --speedo/tach/blinker/switch deletes -- brat style

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26 Sep 2015 13:21 #692038 by Topper
Replied by Topper on topic How far to screw carb jets. 78 kz750
I think he's asking about the jets in the bowl. You screw those all the way in until they're tight. As stated by others, stock jets aren't going to cut it with pods though.

Permanent and perpetual noob.

1979 KZ750 Twin
2009 Kawasaki Versys

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26 Sep 2015 13:25 - 27 Sep 2015 03:51 #692039 by Randombeat
Replied by Randombeat on topic How far to screw carb jets. 78 kz750
yessir. i went from stock (125/68/35) to 140/70/38 on jetting, seated fully snug... dont be“ieve it wuld be a good idea to run jets loose, atall... i was speaking about pilot air/fuel screws.

1980 KZ750H LTD-- pods-- vance & hines 4-1 --speedo/tach/blinker/switch deletes -- brat style
Last edit: 27 Sep 2015 03:51 by Randombeat. Reason: correct slow jet to 35

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26 Sep 2015 13:41 #692040 by undiablo
Replied by undiablo on topic How far to screw carb jets. 78 kz750
Randombeat:

Are you using slow pilot jets #38 from JetrUs? some time ago, keihins cv34 slow pilot jet where only obtainable form Kawasaki dealer and only #35.

Kawasaki KZ 750/4 LTD 1981
Kawasaki KLR 650 2011
Argentina - Buenos Aires

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26 Sep 2015 23:08 - 26 Sep 2015 23:09 #692097 by bountyhunter
Replied by bountyhunter on topic How far to screw carb jets. 78 kz750

Randombeat wrote: yessir. i went from stock (125/68/38) to 140/70/38 on jetting, seated fully snug... dont be“ieve it wuld be a good idea to run jets loose, atall... i was speaking about pilot air/fuel screws.

I believe the 78 750 is essentially identical to the 79 and has BS-38 carbs. For stock aiirbox, best pilot jet size is 45 - 50 and you run the mix screws about 2 turns out. For pods? Good luck, I don't have those.

Pilot jet type is BS30-96.

1979 KZ-750 Twin
Last edit: 26 Sep 2015 23:09 by bountyhunter.

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27 Sep 2015 03:49 - 27 Sep 2015 03:50 #692106 by Randombeat
Replied by Randombeat on topic How far to screw carb jets. 78 kz750

undiablo wrote: Randombeat:

Are you using slow pilot jets #38 from JetrUs? some time ago, keihins cv34 slow pilot jet where only obtainable form Kawasaki dealer and only #35.


yes, link here: jetsrus.com/a_jets_by_carburetor_type/jets_keihin_3M_slow.html

1980 KZ750H LTD-- pods-- vance & hines 4-1 --speedo/tach/blinker/switch deletes -- brat style
Last edit: 27 Sep 2015 03:50 by Randombeat.

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15 Oct 2024 21:05 #905167 by kanexx
Replied by kanexx on topic How far to screw carb jets. 78 kz750
I have the same set up as you , i finally got it to idle great now I need to get it to run good after I let up from wot. After I let up on throttle it revs high and I will down shift and then up shift the it  settles down , but every time I open up does the same thing, any ideas ? Thank you
kane

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