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TOPIC: Lean Idle

Lean Idle 3 months 2 weeks ago #24906

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I gotta say Scotch, you remind me of a couple of Control Techs who worked for me for years in Nuclear Waste. When we had a problem with the remote operated welding machine, the mechanics would point their fingers at the Control Techs and say the problem was electrical. The Control Techs would point their fingers at the mechanics and say the problem was mechanical. I being the Boss over both groups and coming from the mechanical side of life would agree with the mechanics and in the end the Control Techs would put their money where their mouth was and bet me. I lost more $50 bills to the Control Techs than I would prefer not to disclose. The Control Techs stuck to their guns and relied on past experience and inevitably would prove all of us mechanical types wrong.

Daro is probably the first member to report a soaking wet air filter saturated in fuel. That's definitely reverse flow in the intake tract which on a 4 stroke is late intake valve closing.

I've been so focused on camshafts over the past 2 years that i believe a lot of the reported drivability issues are related to chain stretch and the inability to correct (adjust or compensate for) without replacing chains. So when someone reports that they have drivability issues and they've confirmed the carb circuits are functioning properly, my brain goes to the camshafts and valve timing. We're all shooting guns in the dark here trying to make sense of a problem to help a guy out. Our varied backgrounds tend to lead our thoughts based on prior experience and in the end, all of the ideas we put forth are well worth looking in to.

You make a great point about the Nitrophyl floats and I keep losing that thought for some reason. Maybe because I never worked on older equipment when I was an auto mechanic at the dealership. Had I been a mechanic at Canadian Tire working on all the Canadian Tire customers cars which were "outside of warranty" I may have gone directly to "you need to replace the Nitrophyl floats". I've seen sunk floats, but not as often as the Canadian Tire mechanics. Hence the swayed opinion in a different direction. IE, if not a carb problem, then ......

I also have to say Scotch, your microscopic inspections and determinations of issues related to float needles and pilot jets is fascinating to me. It's Fluid Dynamics on a micro level and you have taken us all here at KZ1300.com to a whole new level of understanding of why the carbs on these bikes are soooooo finicky and for that I'm eternally grateful.

That's it from me for now. I just thought raising these points in this topic would be relevant and useful to Tackelhappy but in a way it's a bit of highjacking the thread.

Looking forward to seeing where this all leads Tackelhappy. Hopefully it helps you resolve your issue.

KB

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Last edit: by Kawboy.

Lean Idle 3 months 2 weeks ago #24907

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I couldn't have worded it better Kawboy ! And sorry about the "Drum Noise" ! :woohoo: Yes, we tend to be led by our own experiences and bias. Keeping an open mind is always important.
"If you think it can't happen - it probably can and will !" ......so I tend to listen to the "little voices". :evil: Surprisingly, they're often worth heeding.
There is a solution - we just haven't discovered it......yet !
1980 KZ 1300 sr# KZT30A-009997
Always High - Know Fear !

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Lean Idle 3 months 2 weeks ago #24911

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Hi, i will allow me to join the conversation. My opinion here is based on the experience i have made during the repair process of the engine i have gone through.

The problems:
1- hesitation and stumbling off idle
2- lean cruise mixture
3- rich wide open throttle
4- starting difficulties and rough idle (missing out)
5- excessive heating of the engine

Steps taken to tackle the problems and how it contribute to resolve the problems listed: scale 1-5 (where1 is weakest)
1- cleaning the carbs beyond imaginable (boiling, flushing, blowing, ultrasonic etc.) 3
2- replacing butterfly valve shaft seals 2
3- setting fuel level in carburetors to various heights, also far beyond the recommended spec 2
4- re-jetting the idle and main circuit and changing the needle height 3
5- adding weights to vacuum slide to change rise height to vacuum ratio 1
6- install of the lambda measurement device to see it while riding 5
7- constructing entire new ignition system to provide "better" spark 4
8- installment of the camera inside the air-box to visually inspect the problem "inside" of the carbs 4
9- using different filter configurations to restrict or improve the air flow 3
10- changing the timing on the intake and exhaust camshafts 5
Also i have made various changes on three different carburetor sets to verify the problems on different part configuration.

Should you at any point feel the need of expanding the points i have listed ill be more than happy to do so. I didn't do it now because it will instead of help only pollute the thread.
Also i like to add that with out the help of the forum members here, all i have been able to achieve otherwise would never be possible.
Regards
Daro

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Lean Idle 3 months 2 weeks ago #24912

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hi Daro. Thanks for the list - it does help clarify to some degree. I'll start by simply answering the individual items as though that item is the only concern. because you've made many changes in an attempt to correct the problems a final solution still can't be determined.....yet!

The problems:
1- hesitation and stumbling off idle
Typically: pilot(idle jets) that have deteriorated or been physically damaged from surface crystallization, deformation from improperly fitting driver, cleaned with "tip" cleaners or drill. Must be replaced
2- lean cruise mixture
Raising main needles generally will cure this.
3- rich wide open throttle
Normally, lowering the needle but this contradicts #2 ?????
4- starting difficulties and rough idle (missing out)
Choke Air Mod deals with hard start. Rough idle ? Replace Pilot-jets and Pilot-needles. re-sync (average should be 7.5 "hg to 8" hg) stock engine
5- excessive heating of the engine
Water pump and/or rad. issues ? Install "cooler" thermostat.

Steps taken to tackle the problems and how it contribute to resolve the problems listed: scale 1-5 (where1 is weakest)
1- cleaning the carbs beyond imaginable (boiling, flushing, blowing, ultrasonic etc.) 3
Agree, they should be clean by now.
2- replacing butterfly valve shaft seals 2
This raises a big red flag ! I'm not an advocate of removing the butterfly's. The slightest disparity/misalignment in replacing them could be part of your problem.
3- setting fuel level in carburetors to various heights, also far beyond the recommended spec 2
6.5mm to 8.5mm should be maintained if for no other reason then to have a known constant factor. Some of your problems could be fuel level too high and conversely, some could be related to too low a fuel level.
4- re-jetting the idle and main circuit and changing the needle height 3
You should be able to get enough idle fuel by increasing the pilot-needles more turns out. Nothing you can do with the three transition ports but they should accommodate the bore increase. Raising the main-needle one notch should have accounted for the bore kit requiring more top end fuel.
5- adding weights to vacuum slide to change rise height to vacuum ratio 1
No idea ! Remove the weights to return to a "Norm".
6- install of the lambda measurement device to see it while riding 5
remove it ! Too much concern about this and frankly I think it's confusing - especially with so many radical changes to the systems.
7- constructing entire new ignition system to provide "better" spark 4
no issues here, as a rule.
8- installment of the camera inside the air-box to visually inspect the problem "inside" of the carbs 4
Cool video !
9- using different filter configurations to restrict or improve the air flow 3
Remove the air filter(s) until you start seeing progress and improve. An open free breathing intake will provide a constant.
10- changing the timing on the intake and exhaust camshafts 5
Kawboy addressed this but my two cents is retime them to the manual, otherwise you're compounding and/or masking other issues.
Also i have made various changes on three different carburetor sets to verify the problems on different part configuration.

Again; 3 carb sets (?) all set-up differently? I applaud your resolve but with each set you have probably made changes elsewhere (with no success) and unless you return your changes to exactly what they were - you're lost in a maze.
Clearly you're motivated to resolve the problems and seem capable but perhaps your enthusiasm has taken advantage of you.
Some of us here share the philosophy that when tackling a problem it's best to make 1 change at a time - compare the results - note EXACTLY what was done if there's some improvement and then move on. NO results - refer to your notes and go back to the start (exactly) and try something different......and .....repeat.
Personally, at this point I'd feel compelled to undo everything and go back to the manual's specs, and start over. Sounds counterproductive but at this point I would feel like I had no choice - especially if I got caught in the trap of "too many adjustments - all at once" and truly not knowing where I was in the grand scheme.!

And to all those out there with running big bore kits who have not bothered to add anything.......Thanks for all your help, input and ideas !!!!!
Sarcasm completely intended and aimed !!!
1980 KZ 1300 sr# KZT30A-009997
Always High - Know Fear !
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Last edit: by scotch.

Lean Idle 3 months 2 weeks ago #24913

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Hard to believe but there's only a handful of contributors feeding input on this site. Right now as I write this, we have 2 members logged in and over 400 guests "having a look around". It certainly would be nice if some of our other members and in this case, those who have installed big bore kits took the time to add their 2 cents in.
So there's the invite.......

In the meantime, after reviewing all of the post over the past 3 years as a member and now a moderator, I feel confident in saying- Many have tried aftermarket jetting kits on stock and big bore engines and in the end, finished up with stock jets and the needles in the middle groove. This supports the fundamental principal of a "constant velocity carb" The carb doesn't give a shit if it's a stock or big bore engine. All the carb knows is what to add in fuel for a given flow of air through the carb.
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Lean Idle 3 months 2 weeks ago #24914

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Hi, I thing I'm being misunderstood. I have a perfectly running bike, but to get there it was quiet long road I have traveled. I was reading threads here and applyed the ideas to my bike, also I've donne some things on my own and now I just wanted to share the information back. That was primerly my intension so someone else don't have to go through steps like for example putting weighs on the slides or double and tripple check evrything. The main principle of tech forum is to share knowledge and if no one wrights about there experience thann where will it comme from ? Ok I hope I clarified my self, and thanks for understanding. As my time allows I will describe the particular things here one by one.
Daro
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