24-27mm Bing needle seat installation

[pklinck]

I have a Sachs powered 1973 penton 125.
1.) i removed the needle seat using a 7mmx1.00tap without problem.
2.) i noticed the new seat from Bing Int'l didn't have side holes on the seat which i learned you drill out using a dumerel bit to do so after installing this seat so the holes are correctly there.
3.) how important is it that these slanted side holes (3), needed to be installed/drilled out?  isn't the volume of fuel enough for a 125 cc displacement engine???
4.) I also noticed the old needle seat had a larger diameter hole in the bottom to allow more fuel though(?).. Bing only sells the one size "51-540-2.5" for hard tip needles

Any advise comments on (1) seat hole size, (2) whether we need all those 3 side holes drilled out for improved fuel flow......

let me know here on this site.  thanks,  peter klinck


peter klinck

[Pat Oshaughnessy]

It  will run better with a Mikuni[]

[Larry Perkins]

It will run faster with a properly setup Bing!  mm for mm the Bing flows more than a Mikuni.  Most everyone that goes Mikuni is because they had some worn out parts that should have been replaced in the Bing.  The needle jet and slide wear more in a Bing and the needlejet in particular should always be replaced.  I realize this does not answer your question but had to put my 2 cents worth in on the Bing vs. Mikuni debate.  I have never had to replace the piece you are talking about and always just put in a new seat needle and never had trouble.

Larry P

[KJDonovan]

Peter,

The only hole needed in a Bing float needle seat is the single hole the float needle seats in.  I have seen the seats you are referring to with the diagonally/angle drilled holes in the side, but those just blind out to the body of the carb and are not for fuel flow.

Thanks,

Kevin

[Pat Oshaughnessy]

Larry is right! The needle jet & slide are the a trouble with bing carbs. As far as I know not so with a Mikuni;)

[pklinck]

Larry, KJ Donavan,  
Thanks for the info on the bings.

1.) The float needle seat: as Donavan mentioned, when replacing the flost needle seat, i don't need to dril out the side holes with a ball-bit dremel bit, apt 1/16".  I'll just install the seat with no drilling of the 3 side holes.  i wonder why the volume of fuel needed to come down in the carb to justify the side holes??  Is that just the way bing sells their carbs, 3 side holes drilled out?  Maybe the bigger displacement engines need more rapidly the fuel.

2.) The other source of seepage fuel leak from the bowl is that brass tube factored into the float bowl which can get a hair line crack, as Bing int'l Mr. Charlie told me yesterday.  Sure enough, my bowl seep leaked later when i tested it with 1/2 bowl of fuel (on the bench), it seeped into think paper over 1-2 hours...changed my bowl.

3.)the float needle seats do ware out. They get very champhored over time as i inspect 3 27mm bing carbs and saw the difference.

4.) About changing out a bing for a Mikuni:  more knowledge is needed in understanding the bing's functions and as Larry said, are "very performant" when maintained.  they have certain parts that "wear" and need to be replaced"......

I'll put in the new Bing seat and bowl change.

Thanks Guys,

peter klinck



peter klinck