Another Carburetor Project.

Interesting, Bill. Looking forward to hearing about the outcome.

I am compelled make the following corrections:

"......and supposedly blocks off a passage that adds fuel....."
The Enrichment system does not ADD fuel.  It cuts off the supplemental mixing-air which in turn makes the fuel/air ratio, richer.

".........the fit between the plunger and the hole in the carb body is that it's way too loose....."
The diaphragm-piston to bore fit is not a high-tolerance fit.  It is intentionally loose to ensure freedom of movement.

".........was to plug up the holes in the carb throat that admit the fuel for this enrichment system. I know that others have chosen to defeat this system by interrupting the vacuum signal to the enrichment diaphragm but doing so does not address the loose fit I found between the plunger and the carb body.  I'm thinking that even when closed off that loose fit allows excess fuel into the carb throat......."
The enricher system does not deliver fuel.  From the vacuum port in the carb throat (1 per carb and on the left side of each - total of 3)  to the diaphragm, there is only vacuum.  On the piston side of the diaphragm there is only ambient /static air.   The piston starts to move (cut-off air) @ approx.. 10"Hg  and is closed at approx. 20"Hg.  When "closed" the piston does not fully cut-off this air.  The small screw in the end of the diaphragm cover is a piston travel limit adjustment dealt with at the factory to allow a predetermined amount of air to still pass into the fuel/air delivery galleries.
And yes, I know the "Manual" says this screw is to adjust the spring tension.  IT DOES NOT have anything to do with spring tension.  Consider the  # of coils,  wire gauge diameter and total unwound length and additionally  the .5? pitch and overall length of this screw and common sense should prevail, with this detail.

Hope this helps clarify






 


 

wrote:

I am compelled make the following corrections:

"......and supposedly blocks off a passage that adds fuel....."
The Enrichment system does not ADD fuel.  It cuts off the supplemental mixing-air which in turn makes the fuel/air ratio, richer.

".........the fit between the plunger and the hole in the carb body is that it's way too loose....."
The diaphragm-piston to bore fit is not a high-tolerance fit.  It is intentionally loose to ensure freedom of movement.

".........was to plug up the holes in the carb throat that admit the fuel for this enrichment system. I know that others have chosen to defeat this system by interrupting the vacuum signal to the enrichment diaphragm but doing so does not address the loose fit I found between the plunger and the carb body.  I'm thinking that even when closed off that loose fit allows excess fuel into the carb throat......."
The enricher system does not deliver fuel.  From the vacuum port in the carb throat (1 per carb and on the left side of each - total of 3)  to the diaphragm, there is only vacuum.  On the piston side of the diaphragm there is only ambient /static air.   The piston starts to move (cut-off air) @ approx.. 10"Hg  and is closed at approx. 20"Hg.  When "closed" the piston does not fully cut-off this air.  The small screw in the end of the diaphragm cover is a piston travel limit adjustment dealt with at the factory to allow a predetermined amount of air to still pass into the fuel/air delivery galleries.
And yes, I know the "Manual" says this screw is to adjust the spring tension.  IT DOES NOT have anything to do with spring tension.  Consider the  # of coils,  wire gauge diameter and total unwound length and additionally  the .5? pitch and overall length of this screw and common sense should prevail, with this detail.

Hope this helps clarify






 


 
 

Hi Scotch,
Thanks for those corrections. So if the deceleration enricher diaphragm does not move the air continues to flow. I guess I understand why the plunger fit is less important, when it's function is not to stop all flow.
In an earlier thread you described how you had defeated the enricher system. Would you please describe it once more?
Thanks
Bill

Simply remove the piston/diaphragm and spring - make a solid gasket (replaces the diaphragm) and seals the vacuum side of the cover.

scotch wrote:

Simply remove the piston/diaphragm and spring - make a solid gasket (replaces the diaphragm) and seals the vacuum side of the cover.

I’ve done this mod on my bike and it’s made no difference to the running BUT it has increased the MPG figure to 45mpg from 30mpg average 
well worth doing in my opinion 
 

thanks  Paul 

Although I won't dispute your claim about your increase in mileage I would suggest to others that  a 50% increase should not be anticipated or expected as typical.

It would be great  to hear from others who have done this simple mod. and after some diligent and consistent riding (At least 3 fills) could objectively report their results so a base-line could be established.  Doing this mod PLUS re-syncing, "Color Tuning, adjusting the ignition timing, bringing your tires up to the correct pressure, new plugs, etc., ALL at the same time would not be subjective and will merely mask the true result.