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TOPIC: Lean Idle

Correcting carburetor A/F ratio 2 weeks 1 hour ago #24161

  • Daro
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Thanks Kawboy. Yeah slides are some what "lazy" but under load they go up and as the load on the engine drops than the slides are falling too and lambda settles at around 1. But if you wack the throttle wide open than the engine don't pick up the revolutions at all and simply stays in this stadium as long as the throttle is completely open, it was on the video but the light bulb was already gone so you cant see. One thing is interesting, as Scotch have mentioned fuel stand off, could this be, that every one of this machines exhibits similar phenomenon? i got to ride just before and the bike pulls away ok and goes to top speed range quiet ok (riding on flat road slightly over 180 km/h acceleration was not bad and lambda sat at around 0,8) but if you try burnout (obviously on closed private road) its ok as long as you don't close the throttle even slightly, because than the engine start to stall and lambda falls below 0.68 mark. Makes me curious if the cams are ok or maybe the chain is too stretched?? because the air stack or better to say air box and carbs are to book specs and original, also air filter is like the original one, all tho from ebay. I thing I'm gonna take the valve cover of and see. Stan the shiny area in the left corner comes from the light reflection probably in go-pro cam lens cover. Thanks also to Scotch, yeah that explains why the bike runs rich, when the air is moving back out of the carb already mixed with fuel and when it reenters the venturi area it drows the fuel out of the emulsion tube for the second time, hmm.. than is super rich of course.

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Correcting carburetor A/F ratio 2 weeks 1 hour ago #24162

  • Daro
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This is the damage to the camera case after 25 min of riding, probably from the air resonance in the airbox. I thought that the light bulb will burst first but it was the opposite :woohoo:

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Correcting carburetor A/F ratio 1 week 6 days ago #24167

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Constant velocity carbs were designed to overcome over rich conditions under low rpm and wide open throttle conditions. That's why you should see a steady opening of the throttle chokes when you crack the throttle at low rpm and ramp up in speed. The throttle chokes should follow the rpms up to about 4000 rpms then hold wide open. That meters the fuel from the mains keeping the ratio closer to 1 lambda.

.68 lambda is really rich. The visible spit back in the carbs suggests late closing of the intake cam. I would rather see the cams advanced than retarded.
1980 KZ1300 B2 converting to an A2.

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Last edit: by Kawboy.

Correcting carburetor A/F ratio 1 week 6 days ago #24171

  • Daro
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Hi, i took the valve cover off and rechecked the position of the cams. So as Kawboy suggested: " I would rather see the cams advanced than retarded" that's not the case in may engine, which can lead to "You've got a serious problem with Fuel Stand-Off" mentioned by Scotch, because the air pulse flow is disturbed. When i installed the cams i thought it will be better when the intake cam marking dot is closer to the head surface when setting up the cams and those 17 links between the dots, because i was unable to set both points on cams spot on on the surfaces, so i had to choose between theme. Hmm something tells me that both cams should be advanced one tooth. What ya think guys ?



Exhaust cam from the left. This is where the dot is on the other side, to me looks to retarded.



The intake cam also from the left. And it seems to be also retarded ?
Once again with screwdriver pointing at where the dots are on the other side.





And finaly TDC and 17 links between the dots



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Lean Idle 1 week 6 days ago #24173

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very interesting topic, only posted to be advised when a new reply is posted .

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Lean Idle 1 week 6 days ago #24174

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Maybe the chain stretched?
1982 Kawasaki KZ1300 A4
Building an engine from random parts. This will eventually morph into building a bike from random parts - if it ever happens. Need a frame to begin with.

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