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Old 06-03-2012, 07:59 AM   #16
DoktorT
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A very good indication of quality of function for the hundreds of carbs I have rebuilt and adjusted is the sensitivity of the adjustments. Very sensitive, very good function. Poor sensitivity, something is not flowing properly or consistently.

My Airhead has a spec for idle mix of 1%-3% CO. I tune it by ear and feel. I then hook up my CO meter and verify. Both sides quite close to 2%, in spec. With todays fuels and and a high comp R100, I want a final setting right at high spec. I want to reduce issues with preignition while not giving away too much MPG. To achieve the optimized CO out put of 2.7-2.8% takes very small adjustments.
To the subject. If I am tuned for optimum at my home, then find myself at 5000ft for more than a few days, very easy to make an adjustment, in most cases not necessary with the earlier Airheads. Many with good background all agree that with changes to smaller carbs and EPA crap in the 80's, the factory jets and settings were just too lean to begin with. Lots of reports suggesting MPG on these machine is pizz poor when compared to the earlier Airheads with stock jets and settings.

If you pull the plugs at 50 miles or so of high elevation, you can see if there is enough of an issue to be concerned about. If too rich, just drop the float levels by 2 or 3 mm and readjust the mix/idle. That is every bit as legitimate an adjustment as changing jets or needle positions.

I rode 6000 miles out west from sea level to Rocky mountain passes. No running issues at all. Plugs looked good the several times I checked them. My machine can still ping if using heavy throttle from modest RPMS. So I don't do that. Shift down or easy accel into the stronger RPMS that always work better for spirited acceleration.
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Old 06-03-2012, 12:04 PM   #17
supershaft
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I use to use gas analyzers all the time. It's part of servicing older K bikes, F650's and Triumphs. Both makes instructed a very small time window to adjust idle CO after starting a cold engine. Triumph even instructed to disconnect the headlight. Yes, even the load of the alt. effects the CO reading at idle. Engine temp is super critical. I swear you can watch the coolant thermostat open and close via the CO meter as the engine warms up. Using an analyzer to set aircooled engine's idle mixture is a joke IMO. Engine temp is ALL over the map compared to liquid cooled engines. A gas analyzer and a dyno? You bet! Get a load on the motor and now we have some useful info. Without the load, they are about worthless. Even the state of California figured that out and has stopped sniffing idling engines and now sniffs them under a load on a dyno. I can't think of one decent tuner that cares about no load CO. It's a joke.

Richer jetting/better mileage? No. Sorry but that ain't the reason(s).

supershaft screwed with this post 06-03-2012 at 12:28 PM
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Old 06-03-2012, 08:42 PM   #18
DoktorT
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What a baffon. Factory idle mix setting procediure IS via CO measure. See the sticker under the seat or any factory manual of the era.

But no, factory procedure is wrong according to the Stupid Shaft.
IMHO is a catch phrase for you. Humble??? not a dimes worth. Just arrogance cum laude.
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Old 06-04-2012, 09:19 AM   #19
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It's OK to disagree on thoughts. Name calling is not OK.

Cut it out.

Thanks,

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Old 06-04-2012, 01:44 PM   #20
supershaft
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Originally Posted by DoktorT View Post
What a baffon. Factory idle mix setting procediure IS via CO measure. See the sticker under the seat or any factory manual of the era.

But no, factory procedure is wrong according to the Stupid Shaft.
IMHO is a catch phrase for you. Humble??? not a dimes worth. Just arrogance cum laude.
I just looked at two stickers under the seat of a '83 and a '92 airhead. No CO info whatsoever. I just looked at one period factory manual. No CO info whatsoever. I just looked at my BMW factory school books on airheads. No mention of CO whatsoever. I have never seen any airhead CO info that I recall. I never heard anyone speak of it at BMW factory service school the numerous times I have been there. I have never seen anyone at BMW factory service school or at any dealership adjusting idle mixture with a gas analyzer on a airhead. Not only would it take some figures but some very specific procedures on getting the numbers since the numbers are VERY sensitive. That is certainly the case with K bikes and F650's. Where are you getting your info?
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Old 06-04-2012, 02:47 PM   #21
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Originally Posted by supershaft View Post
No CO info whatsoever.
I didn't want to say anything as I don't have any formal training from the bavarians, but an exhaust sniffer sounded a little higher tech than something they'd suggest in an airhead service manual.
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Old 06-04-2012, 07:17 PM   #22
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lulz

This thread has been very informative, and I thank you guys for that. Though Im not sure what direction it took towards the end there...
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Old 06-05-2012, 06:36 AM   #23
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Quote:
Originally Posted by supershaft View Post
I just looked at two stickers under the seat of a '83 and a '92 airhead. No CO info whatsoever. I just looked at one period factory manual. No CO info whatsoever. I just looked at my BMW factory school books on airheads. No mention of CO whatsoever. I have never seen any airhead CO info that I recall. I never heard anyone speak of it at BMW factory service school the numerous times I have been there. I have never seen anyone at BMW factory service school or at any dealership adjusting idle mixture with a gas analyzer on a airhead. Not only would it take some figures but some very specific procedures on getting the numbers since the numbers are VERY sensitive. That is certainly the case with K bikes and F650's. Where are you getting your info?

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Old 06-05-2012, 09:15 AM   #24
supershaft
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Thanks Alibaba. I didn't look at THAT manual. It's NOT in a lot a them. There's still no CO figures on the fender stickers I looked at. And so on like I said before. They never taught us that method in BMW service school. But there is a CO figure. I wonder if any other models have a CO figure? Doc says his spec is 1-3%. What model is that? I don't have all the later manuals. The last sentence is pretty telling. I suspect that would go on a lot without a much more specific procedure for getting those numbers. K bike manuals and F650 manuals do.

Then there is my main point about using a gas analyzer on a aircooled motorcycle engine with no load. It's a joke. They are bad enough on water cooled engines. I still can't think of anyone besides DT that uses one on airheads to adjust the mixture screw. Different story on a dyno with a load on the engine.
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Old 06-05-2012, 09:51 AM   #25
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You'll be OK up here with stock jets. it is when people rejet for up here they have lean issues at sea level. The only thing it would do is run a tad rich up here and that aint bad at all! I run what would be stock sea level jets in my 1977 R100RS and it runs spectacular up here all beit a tad rich, blacks the pluggies after a month or so. No sweat. Still honks along great.
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Old 06-05-2012, 11:22 AM   #26
craydds
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You'll be OK up here with stock jets. it is when people rejet for up here they have lean issues at sea level.
Correct; and if I were to visit my brother in Long Beach, CA, I would pop my stock jets back in.
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Old 06-06-2012, 12:26 PM   #27
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Originally Posted by LandLeftBehind View Post
This thread has been very informative, and I thank you guys for that. Though Im not sure what direction it took towards the end there...
Sometimes a tad bit of JoMama creeps in unwanted.
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