72' Six Day Carb

[Steve Minor]

(1) Will I have any problems running a 32 Bing on a 72 Six Day? I believe the stock carb was a 26.

(2) Any suggestions on a starting place for jetting the 32 for the Six Day?





Steve Minor
Wilmington, NC

[Ron]

Hi Steve,
I have a 30mm Mikuni on my Six Day 125, works great. I never rode it with the stock Bing so I can't compare it.
A 32mm Bing will probably take away some low-end throttle response, but add a few 100 rpm on top.
I can help you with jetting a Mikuni, but don't have any info for the Bing.
RonW

[Steve Minor]

Thanks Ron....that's a start.

Steve Minor
Wilmington, NC

[socalmx]

I also run a 30mm Mikuni.....better choice for your 125

[Steve Minor]

Thanks for the input....the thing is, I have several Bings that I'm sorting through.

Steve Minor
Wilmington, NC

[Ernie Phillips]

Steve, I am running a 30mm Bing on modified 6B with good results.  Cylinder spigot has been opend to match with mild porting, Circle F pipe and digital PVL.

1.0 slide, #3 Needle - full rich, 276 needle jet, 40 pilot, 148 main. sea level to 3000 ft elev.

Watch out for worn slides and worn needle jets on the Bings.  Mikuni's are good carbs but I find the 30-32 body too big to fit without major mods.  We are running 28mm Mikuni's (smaller body) on Six-Day & Berkshire. One advandge the Mikuni offers is in the event of a fall.  The Mikuni is less likely to load up in my experience.  For max performance, I prefer the Bing.

Ernie P.
Chattanooga, TN

[Steve Minor]

Thanks Ernie....I'll take all opinions.
I still have the original 26 if all fails.



Steve Minor
Wilmington, NC

[VICTOR MONZ]

Steve:

I have ran a 32 Bing on a Six Day with the "Carl Cranke" porting, stuffed case Sachs bottom end and a modified pipe. Once dialed in it was very fast and I miss that machine.  Sold it after my heart attack.

I now use a 28 Bing on my current "D" motor and it is a very nice set up.  I also have a 30mm Mikuni on another bike and, sorry to say, not totally sold on it, yet !  Still dialing it in.

Just my experience.

Good Luck.

Victor

[Steve Minor]

Thank's Victor...I'll make note of your set up.

My Six Day is a pure stock, one-over bore, fresh Doug W. rebuild. I'm thinking a 32 might be too much carb...Guess I'll have to experiment.

Steve Minor
Wilmington, NC

[john durrill]

Steve,
 If your just going to trail ride the 125 the 26 mm will do a very good job. Stock was a 27 mm look on the id stamped on the carb body.
If you give me the model# we can get you very close on jets and needle.
Make sure all the parts are in good shape and the stock carb will work for years for you. A or B engine?
John D.

[socalmx]

Use a small body 30mm and you will not have any problems. Mine started life on a late 70's YZ100 and with some rejetting works just fine.

quote:Originally posted by Ernie Phillips

Steve, I am running a 30mm Bing on modified 6B with good results.  Cylinder spigot has been opend to match with mild porting, Circle F pipe and digital PVL.

1.0 slide, #3 Needle - full rich, 276 needle jet, 40 pilot, 148 main. sea level to 3000 ft elev.

Watch out for worn slides and worn needle jets on the Bings.  Mikuni's are good carbs but I find the 30-32 body too big to fit without major mods.  We are running 28mm Mikuni's (smaller body) on Six-Day & Berkshire. One advandge the Mikuni offers is in the event of a fall.  The Mikuni is less likely to load up in my experience.  For max performance, I prefer the Bing.

Ernie P.
Chattanooga, TN

[Steve Minor]

Hi ya John.....It's a 6B motor. I rechecked and it's a 27 carb...the carb stamping Bing 53 1/27/19. Can you get me close with the jetting @ sea level?

My intent is trail ride it and then take it to Zink Ranch in October for the ISDTRR ride.....(If I can lose about 30 lbs by then..haha)



Steve Minor
Wilmington, NC

[john durrill]

Steve,
 With a 40 to 1 premix we used,
A 35 to 40 pilot jet, 276 needle jet if you spin the engine up some. 273 if you trail ride and don't spin it up much , 276 is normal jet. A # 4 needle ( 4 small lines just below the clip grooves ). Start the needle out rich and work lean with the clip setting. Start rich with the jetting and go leaner till your happy with the way it responds. 3 rd notch worked well for me at sea level.  Main jet 140 , can go to a 135 if your riding style is easy not much high rpm.  145 if you hold the hammer down all the time.  Make sure the slide is tight ( no smiley face) , the needle jet is not worn out ( not egg shaped when you look at it from the top down toward the main jet ). If the enricher piston's plastic seal ( on the bottom ) is soft or looks damaged replace it with a new one
 Keep checking the float at first to make sure its shutting off the fuel when it should. If it leaks some times I would replace the needle  , seat and or the float ( Bing has all these parts in stock, make one order to keep the cost down on shipping ).
 Your restoring a 35+year carb that has been used and abused , ridden hard and put up wet. chuckle chuckle!
 Once its reconditioned it will be as good as a new one was. We never , never had a need to change out the stock 27 mm Bing for any reason on our enduro / trail bikes.
  Use a good inline fuel filter. Turn the petcocks off when you stop for any length of time.
 If you use the leaner jetting do what Jack P taught us in Tallahassee in 73. On a long straight, like a road section , pull the enricher in slowly with the throttle open. Back off a little if the bike slows from too much fuel. We were able ,if the road was long enough, to pull the lever all the way in at wide open throttle. This let us run a little leaner in the tight stuff (less fouled plugs) and not hurt the engine at sustained high RPM's. That gave us better corner to corner or turn to turn throttle response.
 It sounds like a lot to do but the jetting is factory and will work for sure on a stock engine.
 If you decide to use another type or size carb you will have to buy jets ( Multiple - main , pilot , needle , air ), slides and needles to jet the engine properly.
  Your 400's main and pilot jets are the same part #'s as the jets in the 27 mm carb that may be some help. Only the needle jets , slide and needle are different in the 36 or 38 mm Bing from the type 53 27 mm.
 Unless someone has the same carb  you are using , the same porting, compression ratio , same pipe , using the same premix ratio , you are starting from scratch.
It takes time to get that right . Odd things happen . Like running great for a year on the trail or track only to find for some unknown reason this day the engine seizes .  Because ? you had to run at some specific throttle setting , due to conditions, for a long period of time , the piston and cylinder try to become one. The jetting we thought was spot on was not quite right at some throttle setting for an extended period of time. chuckle chuckle!
 The engine slows just slightly ( about 1/4 of a sec. ) before it makes that teeth grating sound. You can tell an old dirt bike rider because his clutch hand twitches when he hears that sound LOL. Get the clutch in quick enough , let the bike roll a bit , dump the clutch and you can usually break the engine free and ride it back to the trailer slowly.
 Was this enough info?
Good luck my friend
John D.

[Steve Minor]

John......that's just the info I was looking for. You're a great Pal for taking the time to put it together. I'll start right on that carb as soon as I can.


Thanks again

Steve Minor
Wilmington, NC