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Setting Float Level #91196
04/27/06 12:55 am
04/27/06 12:55 am
Joined: Jun 2003
Posts: 224
Florida
J
Junior Offline OP
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Junior  Offline OP
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J

Joined: Jun 2003
Posts: 224
Florida
Not whating to beat a dead dog,but lately their
has been plenty on the how critical and necessary
it is to check and properly set float level.

Write ups and everyone is saying to push down on tab of float,no doubt this is true,but I`ve been
taught by a Guru an easier way.Hold the tips of
each thumb on each end on the pin.(to keep it in
place) and turn the bowl upside down and look to
see that the float doesn`t drop below top rim of bowl. very simple and easy,no tools.

Is there a problem with this method?

JR...

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Re: Setting Float Level #91197
04/27/06 1:27 am
04/27/06 1:27 am
Joined: Feb 2006
Posts: 60
Marietta, GA
L
Leo Offline
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Leo  Offline
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L

Joined: Feb 2006
Posts: 60
Marietta, GA
i've been wondering this too, however there seems to be alot of play between the float tabs and the needle so it's hard to get a correct reading.


'78 Triumph Tiger TR7RV
Re: Setting Float Level #91198
04/28/06 2:51 pm
04/28/06 2:51 pm
Joined: Jun 2005
Posts: 626
Western Oregon
enigmaT120 Offline
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enigmaT120  Offline
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Joined: Jun 2005
Posts: 626
Western Oregon
I like to detach the bowl from the upper carb with hoses still attached. I hold the bowl level, with a couple fingers over the ends of the pins, and open the petcock. When the bowl is full you can see the exact level. It will also show you if your float isn't. Floating, that is!

Ed Miller


Ed
1970 Bonneville
Re: Setting Float Level #91199
04/28/06 3:19 pm
04/28/06 3:19 pm
Joined: Sep 2005
Posts: 2,000
Sunny South Carolina, (US)
T140V-Rich Offline
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T140V-Rich  Offline
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Joined: Sep 2005
Posts: 2,000
Sunny South Carolina, (US)
I'm in the same boat as the rest of you guys except for the fact I wasn't aware the floats were adjustable.

Go ahead, chuckle a bit. Twenty years tinkering on Bonnie engines and I never knew.

For clarity's sake, we're talking about the plastic float in the 900 series AMAL? And you bend the plastic tab the shut off needle rides in?

Richard


1977 T-140V
1973 T-140V
2011 Bonneville SE
Author of "Relics and Reminiscing."
Re: Setting Float Level #91200
04/28/06 4:23 pm
04/28/06 4:23 pm
Joined: Jul 2005
Posts: 1,919
new jersey usa
J
John RGS Offline
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John RGS  Offline
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J

Joined: Jul 2005
Posts: 1,919
new jersey usa
The above methods vary in certain aspects but don't address what must be done if they are out of spec.. Mr Healy addresses this in another post in detail if you search. Below is an article touching on float levels.

Several articles have been published about setting the float level on Concentric Carburetors and this is a summary of the important points from people in the know:

The actual specification, from the engineer who designed the Concentric Barry Johnston, gives a gas level of between .170" to .240" below the top edge of the float bow, 170 being rich and .240" being lean. This level has a dramatic effect on the running of a properly tuned motorcycle. It pays testaments to the design of this carburetor that the range of miss-adjustment it can tolerate and still have the motorcycle run, if only poorly. It is suggested that you set the float level first before doing any carb adjustment.

The level can be estimated by placing the round edge of the plastic float between .060" and .090" below the edge of the bowl when the needle is depressed by a slight force on one of the float's needle tangs. You can turn the bowl upside down to establish this. With the float above the top of the bowl, as described in the Norton Tech manual, the float can contact the bottom of the body and not allow the float needle to seat firmly. It also makes the carb rich through the jetting range. With the float, level with the top of the bowl, although not as rich as when it is above the top, it is still out of the specified range.

The brass needle seats are installed and adjusted cold by the factory. Using a proper sized drift, you can adjust the brass seat on a solid surface.


,_o
_ -\_<,
(*)/'(*)

NOPGS #2
Re: Setting Float Level #91201
04/28/06 4:36 pm
04/28/06 4:36 pm
Joined: Oct 2003
Posts: 11,267
North Georgia, USA
RF Whatley Offline
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RF Whatley  Offline
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Joined: Oct 2003
Posts: 11,267
North Georgia, USA
All -
Don't feel bad, after working in a large Triumph dealership for several years, it wasn't until 1973 when the Triumph rep stopped by and showed me the trick that I learned!!

The rep taught me to turn the bowl up-side-down; my boss (who is BSA and Norton factory trained) does the push method. I think there is a difference, and the difference is the wear and fit of the brass pin.

To see why I consider up-side-down a better method you have to consider the forces at work. The fuel is trying to raise the entire float. This will tend to raise the float position on the pin also.

The "push method" lets gravity hold the float down against the pin; the up-side-down method lets the float rise against the pin. Yes, it's a very small amount at the pin. But due to the pin being offset to one side of the bowl, that amount of free-play is amplified by the offset ratio of approx 5:1. Therefore .008" at the pin becomes .040" at the opposite tip of the float. IMHO 1mm (.040") can be significant.

The "push method" has weaknesses in that it really matters where you push and how hard you push. These are very hard to explain. On the other hand, in the "up-side-down method" gravity (a rather universal constant) supplies all the forces.

However, I will admit that the most important thing for you to remember is that whatever method you like, then do it the same way on all your carbs. Especially if you are tuning dual-carb twins or triples. The need for identical setup on multi-carb bikes cannot be overstated.

Hope this helps! bigt


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA
Re: Setting Float Level #91202
04/28/06 4:55 pm
04/28/06 4:55 pm
Joined: Sep 2005
Posts: 2,000
Sunny South Carolina, (US)
T140V-Rich Offline
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T140V-Rich  Offline
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Joined: Sep 2005
Posts: 2,000
Sunny South Carolina, (US)
If I'm following correctly, I am thinking the upside down method may provide more accuracy since the entire float rises as gas is introduced to the bowl.

And, if I'm not mistaken, there is a gap between the float pin and the gasket (and, in turn, the carb body bottom), which would make any adjustments a tad off.

This may be what you guys just said, but after a few tech turns and numbers, I had to let off the throttle a bit. I was following you pretty good for a while, though. smile

I think this weekend I'll check my float levels, see if I can bring them somewhere around the 170-240 mark mentioned if they're not.

Reason I asked is I feel the only dumb question...

Appreciate it lot

Richard


1977 T-140V
1973 T-140V
2011 Bonneville SE
Author of "Relics and Reminiscing."
Re: Setting Float Level #91203
04/28/06 5:19 pm
04/28/06 5:19 pm
Joined: Oct 2003
Posts: 11,267
North Georgia, USA
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member

Joined: Oct 2003
Posts: 11,267
North Georgia, USA
Hey, I'm the "King of Dumb Questions" and don't try to steal my crown! bigt


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA
Re: Setting Float Level #91204
04/28/06 5:33 pm
04/28/06 5:33 pm
Joined: Feb 2006
Posts: 307
Saint John, New Brunswick
BSACafe Offline
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BSACafe  Offline
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Joined: Feb 2006
Posts: 307
Saint John, New Brunswick
John posted above "The actual specification, from the engineer who designed the Concentric Barry Johnston, gives a gas level of between .170" to .240" below the top edge of the float bow, 170 being rich and .240" being lean."

When I look at Bushman's Carb tuning secrets, he indicated .080" below the rim of the bowl.

Any suggestions on which level to use.

I'm running rich now on AMAL 930's using 180 Mains. If I adjust the floats to what John suggested, will that lean it out?


Jer

http://www.caferacer.ca

1968 BSA Lightning Cafe
1968 BSA Thunderbolt
1969 BSA Royal Star
1972 BSA Thunderbolt
Re: Setting Float Level #91205
04/28/06 5:51 pm
04/28/06 5:51 pm
Joined: Apr 2006
Posts: 78
Yardley,PA
I
internetay Offline
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internetay  Offline
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I

Joined: Apr 2006
Posts: 78
Yardley,PA
The .170" to .240" is the level for the gas itself, while the .080" below the rim of the bowl is where the float should be.


1972 Triumph T-120V
Re: Setting Float Level #91206
04/28/06 5:55 pm
04/28/06 5:55 pm
Joined: Feb 2006
Posts: 307
Saint John, New Brunswick
BSACafe Offline
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BSACafe  Offline
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Joined: Feb 2006
Posts: 307
Saint John, New Brunswick
Gotcha....just re-read after your post internetay. Sometimes I read too fast and don't catch the more important details.


Jer

http://www.caferacer.ca

1968 BSA Lightning Cafe
1968 BSA Thunderbolt
1969 BSA Royal Star
1972 BSA Thunderbolt

Moderated by  John Healy 


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