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Running lean 22 Jun 2017 08:23 #765035

  • Patton
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The clean air system was implemented to satisfy EPA exhaust emission requirements.
It does not otherwise improve or enhance or increase engine performance in any manner.

If needed ---




Good Fortune! :)
1973 Z1
KZ900 LTD
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Running lean 22 Jun 2017 13:21 #765072

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So, I know, apples and oranges, but my KZ650SR was doing the SAME thing - hanging at 3k RPMs after warmed up.

My mechanic lowered the idle using the idle screw, to the proper idle (about 1k RPMs, IIRC). He also found that the carbs were all super rich, so he leaned them out to a proper place. Now the bike runs better and idles just fine after warm-up.

Hope this helps!

-John
2019 Harley Street Glide Special (FLHXS)
2016 Vaquero - traded
2005 VN800B
1979 KZ650SR
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Running lean 22 Jun 2017 19:51 #765108

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The clean air system was implemented to satisfy EPA exhaust emission requirements.
It does not otherwise improve or enhance or increase engine performance in any manner.






That's funny you posted this because I did that today before I got a chance to come back to the forum. I've kept the bike all stock because I liked it complete and original shape, but the system is just giving this bike so much trouble that I went ahead and plugged everything up. I did some more adjustments to the mixture screws trying to get the idle to go as high as I could by adjusting them. It's definitely a LOT smoother power delivery than it was. Still very slow to return to idle when revved any amount above idle so it's not right yet. I feel like it's going in the right direction. Idle is smooth, about 1k right now. It used to come back down to idle and lope and die. Now it comes back and stays at strong smooth idle, even if it takes 4 second to get there. That's progress, if you'd seen it before you'd know that. The other thing it isn't doing is cutting out and bogging when rev'd up...... which it was doing badly before. I'd take off and it would bog and slowly climb rpms until 4k then take off like a bat out of hell. I don't know yet how much of that was eliminated because its raining here and i could only ride slowly so we will see by sunday how well it's running overall.
Vulcan 750, KZ750, KLX 125, and many more......

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Running lean 22 Jun 2017 20:28 #765110

  • SWest
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Have you synced the carbs? All these bikes pull hard after 5000 RPM. In my clips you'll hear it as it hits that "sweet spot" and goes NUTS. :woohoo: I love the looks on peoples faces when it happens.B)
Steve

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Running lean 22 Jun 2017 21:40 #765117

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One1 wrote: . . . Still very slow to return to idle when revved any amount above idle so it's not right yet. I feel like it's going in the right direction. Idle is smooth, about 1k right now. It used to come back down to idle and lope and die. Now it comes back and stays at strong smooth idle, even if it takes 4 second to get there. That's progress . . . .


Is it for certain that all the carb slides seat fully down immediately upon closing the throttle? (No frayed cable. Cable is lubed. No crud inside the twist grip. Adequate slack in throttle cable. No binding at the carb end. No issue with the carb return spring.)

With such mechanical issues ruled out, some minute cracking may have developed in the carb holders, especially if they are old. Attempted sealing of such cracks is usually just temporary. Brand new carb holders are the lasting fix.





With engine idling, may attempt to locate an air leak by spraying WD40 or carb cleaner onto the holders, which sometimes allows the spray to be ingested and affect the rpm, and perhaps also emit smoke from the exhaust.

Good Fortune! :)
1973 Z1
KZ900 LTD
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Running lean 23 Jun 2017 14:49 #765172

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Paton you and i are on the same wavelength. I did those yesterday before my post. Lol. They look very good.


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Running lean 23 Jun 2017 14:56 #765174

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The idle has been good today. Right now my only complaint is bogging under acceleration. Idle is smooth, power delivery is smooth, engine sounds smoother than ever. Just can't get it to quit bogging....... yet.
Vulcan 750, KZ750, KLX 125, and many more......

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Running lean 23 Jun 2017 18:12 #765210

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One1 wrote: The idle has been good today. Right now my only complaint is bogging under acceleration. Idle is smooth, power delivery is smooth, engine sounds smoother than ever. Just can't get it to quit bogging....... yet.


Bogging on pull-away from idle can result from poor sync and/or imperfect pilot circuits and/or imperfect pilot mixture setting. And even where all those are perfect, an out of spec fuel level may still cause bogging on pull-away from idle, because the incorrect fuel level influences the supposedly correct pilot circuit fuel mixture.

It may be getting time to thoroughly clean the carb pilot circuits. Critical areas include the tiny passageway whereby fuel is fed to the pilot jet and the orifices into carb bore at or near the mixture screw tip. Pictures and diagrams are available as might be helpful.

Good Fortune! :)
1973 Z1
KZ900 LTD
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Running lean 23 Jun 2017 20:40 #765230

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Whatever it is, it isn't inside the carb.
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Running lean 24 Jun 2017 05:32 #765244

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One1 wrote: The idle has been good today. Right now my only complaint is bogging under acceleration. Idle is smooth, power delivery is smooth, engine sounds smoother than ever. Just can't get it to quit bogging....... yet.

One1 wrote: Whatever it is, it isn't inside the carb.



Non-carb-related bogging under acceleration might possibly result from an imperfectly functioning advancer. If not already done, would inspect, clean and lube the advancer. Am thinking that ignition timing on the model at hand isn't owner adjustable. However, a timing light may be used to confirm the timing and view operation of the advancer.

Whatever it is, it isn't inside the carb.--- Wish I had a nickel . . . .:woohoo:

Good Fortune! :)
1973 Z1
KZ900 LTD
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