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Old 07-03-2013, 12:49 PM   #78271
refokus
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Really?

Another scientific carb discussion?

Here goes the fireworks and just in time.
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Old 07-03-2013, 12:50 PM   #78272
motolab
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Quote:
Originally Posted by Rusty Rocket View Post
Actually, the fuel isn't picked up. It is pushed up by the higher pressure in the float bowl.
Is it the higher pressure under a wing or the lower pressure above a wing that causes lift?

Regards,

Derek

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Old 07-03-2013, 01:05 PM   #78273
Mambo Dave
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I want to go riding with you.





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Unless of course you actually plan to adventure ride past Starbucks.....



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Old 07-03-2013, 01:24 PM   #78274
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Old 07-03-2013, 01:25 PM   #78275
Mongle
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Quote:
Originally Posted by motolab View Post
Is it the higher pressure under a wing or the lower pressure above a wing that causes lift?

Regards,

Derek

Yes....

Since we are getting all zen like...remember there is no such thing as cold...only lack of heat....
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Old 07-03-2013, 01:30 PM   #78276
Albie
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Quote:
Originally Posted by Foot dragger View Post
Interstate at altitude 2-up on a DR.........Why would you do such a thing?
Apparently there are a lot of people out there that really don't understand what riding a motorcycle is all about. interstates are great.............. for getting products shipped across the country inexpensively.
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Old 07-03-2013, 01:35 PM   #78277
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Quote:
Originally Posted by motolab View Post
If the altitude changes, the slide will try to keep the velocity of the air constant for a given intersection of throttle position and rpm. For a given throttle angle and rpm, less O2 will enter the engine at higher altitude than at lower. It's velocity over the lift holes that causes the slide to rise against gravity and spring pressure until an equilibrium is reached. Less density means that the slide will have risen less at equilibrium. The slide having risen less means that the jet needle will have been pulled out of the emulsion tube less, restricting the fuel flow to match the reduced density and therefore availability of O2.
Yes when all this happens exactly like you say your bike will slow down because it is not getting enough O2. Then you have to twist open the throttle further to maintain speed. Opening the throttle raises the slide to the new equalibrium which has no particular advantage mixture-wise for riding at high altitude.

You would have to change the relationship between the slide height and the needle cross section to alter the mixture to compensate for altitude.

Quote:
Originally Posted by motolab View Post
The slide having risen less means that the jet needle will have been pulled out of the emulsion tube less, restricting the fuel flow to match the reduced density and therefore availability of O2.
This is no different from what happens in a non CV carburetor.

Again, it makes a lot more sense to forget about throttle position and instead focus on horsepower required to maintain a given speed. The rider is going to open the throttle however far he has to to ride at the speed he chooses.
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Old 07-03-2013, 01:51 PM   #78278
motolab
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Quote:
Originally Posted by procycle View Post
Yes when all this happens exactly like you say your bike will slow down because it is not getting enough O2. Then you have to twist open the throttle further to maintain speed. Opening the throttle raises the slide to the new equalibrium which has no particular advantage mixture-wise for riding at high altitude.
At the equilibrium, the slide will be lower at higher altitude. This applies at all openings, except when the slide is against a stop.

Regards,

Derek

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Old 07-03-2013, 01:53 PM   #78279
refokus
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Quote:
Originally Posted by procycle View Post
Yes when all this happens exactly like you say your bike will slow down because it is not getting enough O2. Then you have to twist open the throttle further to maintain speed. Opening the throttle raises the slide to the new equalibrium which has no particular advantage mixture-wise for riding at high altitude.

You would have to change the relationship between the slide height and the needle cross section to alter the mixture to compensate for altitude.

This is no different from what happens in a non CV carburetor.

Again, it makes a lot more sense to forget about throttle position and instead focus on horsepower required to maintain a given speed. The rider is going to open the throttle however far he has to to ride at the speed he chooses.
+1, very well said.
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Old 07-03-2013, 01:56 PM   #78280
eakins
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Quote:
Originally Posted by Albie View Post
Apparently there are a lot of people out there that really don't understand what riding a motorcycle is all about. interstates are great.............. for getting products shipped across the country inexpensively.
can't tell you how many times i've seen someone's multi-state ride planning report posted for all to see and give feedback...the map shows them traveling a lot of interstates out west. i've seen some that are days on end on the interstate while missing all these great roads. wtf?

the only time i'm really happy riding my DR is on a twisty paved road or a dirt road/track. anything else is out of the DRs element.
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Old 07-03-2013, 02:20 PM   #78281
refokus
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Grifter, those are some nice photos. I like the SW as well. Does it get any better.
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Old 07-03-2013, 03:05 PM   #78282
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Quote:
Originally Posted by refokus View Post
Grifter, those are some nice photos. I like the SW as well. Does it get any better.
Sure it does
Let's see 2 up on the interstate or 60mpg which matters to me?






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Old 07-03-2013, 04:09 PM   #78283
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FlowBee on the soapbox here. Please indulge me for a minute. I've just got to give say how much I appreciate how easy it is to adjust the valves on the DR. I'm fortunate enough to have multiple bikes (3), and I do all the wrenching myself. All of the bikes got their annual full PM this week, and all use screw/ locknuts for valve adjustment.

The last done was the BMW RT. The difference: the half hour it takes to remove all of the tupperware and the half hour it takes to replace it all on the BMW! "But the heads are exposed" you say. Yes, but you need to do a throttle body sync afterwards and THAT entails all the tupperware be removed. WTF BMW?? All those little Torx screws all over the place. Be sure to keep track of which ones go where ...! Be sure you have the special tool to pull the spark plug igniters. Be sure you have lots of room to lay out all that tupperware.

The DR took 30 minutes total, and that included pulling the side covers, seat, and tank. All of the clearances were still within specs after 5000 miles since the last check. Hint: be sure to empty a Safari tank before pulling it. It weighs 65 lbs full ! OOF!! Thanks Suzuki! I love how easy this bike is to service.

The only bike easier was the Guzzi, and that goes without saying. No bodywork to remove and you can adjust the valves while seated. With a cup of coffee by your side.

I can't imagine having to pull multiple cams and buckets to then drive down to the dealer to buy a bunch of shims (if they stock them) while the bike sits in pieces. GAAH!!!

Thanks for indulging me. Now back to our regular DR talk ....

FB
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Old 07-03-2013, 04:12 PM   #78284
MrBob
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My contribution to photos of having fun on the DR.

Across the burning plain.


The Big Empty.


Finding artifacts near a prehistoric rock shelter.
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Old 07-03-2013, 04:17 PM   #78285
Kommando
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Quote:
Originally Posted by Foot dragger View Post
Interstate at altitude 2-up on a DR.........Why would you do such a thing?
I don't like to trailer it, and time can be scarce.

Quote:
Im already sitting in the passenger area on mine going down the hiway and Im just 6' tall.
Cant be real comfortable with 2.
We're not big people, but it's definitely no Wee. If I didn't want slab ability or passenger ability though, I'd have gotten a lighter bike with out-of-the-box adjustable suspension. The DR truly does it all for us, because we aren't racers. It slabs us and luggage. It runs sandy, muddy, hilly, rocky, rooty trails. It commutes on surface streets.

Quote:
But Yeah Id always enjoy more power,Im just not willing to spend the money and time to fool with the thing,and it pulls my 180lbs around pretty dang well hiway or dirt.
The DR seems so easy to work on that even the carb seems simple to me. I'm also 200lb + gear.
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