Bing Carb Type 54-2 Jetting Issues

[garrettccovington]

Ok, some of you have replied to my "need a piston" post and you guys sent me to the carb.
This is what I have found.
 Racing Elevation 2000-3900 ft Temp 95 degrees

1. No smiley face on the slide. A little scuffing and wear.
2. Idle Jet. 44-353-45.  I swear there is a little bit of dirt in it.
3. Main jet 44-051-185, Manual calls for a -170. ?
4. Needle jet 45-120-282, Manual calls for a -272.?Kinda goobered up.
5. Jet needle 46-360-4k2, don't know what stock is. I hit this with burnishing cloth earlier in the year. set on 2nd clip. So I will get a new one.
6. Float Black Hinged 35-310.

Now the float level might have been set to low, which might have turned off the fuel too soon.  I readjusted the float level and will put it back together and check it out.

I'm beggining to think it doesn't need a piston, since I smoked all the other bikes on the start the last race.

I'm wondering why such a big difference in jet sizes than what is listed in the manual.  I would think at higher elevations I would need smaller jets.

G


72 six-day
79 KTM MC80 250

[garrettccovington]

Oh yea plug reading 3/4  dry black 1/4 tan.  Humidity 0.

g

72 six-day
79 KTM MC80 250

[garrettccovington]

Haven't done a compression test yet.  I'll pick it up this weekend from my Chino Hills house this weekend and I run a NGK B8HS.  I've only changed it once this year.

72 six-day
79 KTM MC80 250

[john durrill]

G,
 It would be a very good idea to pull the top end and check the ring end gap and how worn the top ring is.
You can check the piston clearance and bore condition at the same time.
 See how the wrist pin and bearing are doing at the same time.
It something  that should be done on any bike that's raced. How often would be determined by porting , ring type and how hard the bike is ridden between checks.
 The top ring wears thin and will catch and break causing a lot of grief.
 We did this to our Enduro bikes once a year. MX'ing  would be more often than that for sure , until we had a feel for how long the parts lasted.
 Until I knew I had a top end that was within service limits and NO air leaks I would be reluctant to change the jets for a smaller size.
hope this is some help,
john d.

[garrettccovington]

I got to make 3 more moto's 2nd or better to win the overall.   My next test is next Tues.  I adjusted the float.  I think that was too low. I'll have my compresion tester then too.  After my test ride, I'll get on the phone to Bing and order a slew of parts.  I'll just nurse it for 3 more races then tear it down.

G

72 six-day
79 KTM MC80 250

[brian kirby]

G, save yourself some time and trouble and just order a new needle jet and needle tomorrow. Any Bing needs a new needle jet and needle unless you yourself put a new one in there. They wear quickly and can cause all sorts of symptoms you will swear is caused by something else.

And someone else already mentioned it, never EVER polish or sand a needle, you will change the taper. 45 pilot and 185 main may not be what the manual calls for, but that is pretty close to what you should be running in a 250, the 282 needle sounds right too.

Brian

[Larry Perkins]

Good advice Brian!  I heard that somewhere before.  It will most likely cure the prob as it has in soooo many Bing carbs before it.  But what do I know?[8D]

Larry P

[brian kirby]

I learned my lesson on Bing needle jets the hard way Larry. Having grown up dealing mostly with Japanese carbs I was not familiar with the Bing needle jet wear issue and when I was first told it was a potential problem for a bike I was working on I ignored some good advice. Now when I get a Bing or a bike with a Bing, the first thing I do is put in a new needle jet and needle even if they look new. Saves a lot of time and frustration.

Brian

[Larry Perkins]

Amen!

[garrettccovington]

I am gonna get those parts,  what shocked me, was how far the float was out of wack.  I've been trying to get the parts locally, but,
FORGETABOUTIT. I'll order them monday.
I know I got a rocketship, if I can only get it to run right!

G

72 six-day
79 KTM MC80 250

[garrettccovington]

Float level didn't change anything.  I'm gonna call bing in the am

72 six-day
79 KTM MC80 250

[garrettccovington]

Got up early this morning and talked to charlie at bing.  Turns out,  I have the Jetting for a 400 in my bike.  DOH!!!  I ordered a slew of parts, If it had the word "JET" NEEDLE" "IDLE" In any combination I ordered it.  Plus various sizes.  Hope it works.



72 six-day
79 KTM MC80 250

[garrettccovington]

Short story.  Thanks for all the input from everybody.  Yep it seems it was the Jet needle and needle jet. I am not worhty:).  Fine tuned with the main jet and the bike works pretty darn good.  Idles perfect. and snaps when you gas it.  good plug color,starts right up, everything. Alot easier to ride.  Had a Blast and it felt like a new bike.

Thanks Again!
G

Long Story
Went to Outlet Center Rd. today to play with all my jets and needles.  Very interesting.  I set the bike up to the stock settings per the manual and I could tell right off it was too lean. Sounded completly different. Like a 125 and the plug was white.[xx(]

40:1 maxum oil with Sunoco leaded race gas, 88 degrees, 22 % humidity, elevation 2000ft. winds 22 mph. Beautiful day.  Wind was kinda bothersome, but allowed for quick cool offs for plug and jetting changes.  5 min's. & Motor is cool enough to touch.

This is what I ended up with
Plug NGK B9HS
Needle Jet 2.78, stock calls for 2.72 it had a 2.82
Main 180, stock calls for a 170, it had a 185
Jet needle -4k2 don't know what a stock one is, just replaced it.
Slide 220, manual calls for a 120, just left it alone.  The manual states the 220 is for a 125MC.  I don't know what the diference is or what it does.[?]
Idle jet, -45, Just replaced it and that is what the manual calls for.

I noticed that if I got to far away from the combination I ended up with, my idle circut wouldn't work very well, if at all, and the plug reading would be too rich or too lean.[:0]

I also noticed it didn't like the stock call out for the needle jet and using the -4k2 jet needle.  As a mater of fact it almost felt like the 2 were binding.[?]

All in all, I am very happy with how it runs.  Now, this weekend at Glen Helen might be a diferent story.  Racing always seems to bring out the gremlins.

Thanks again,  I would have never guessed the needle jet and jet needle.


72 six-day
79 KTM MC80 250

[garrettccovington]

After practice this weekend did a plug reading and everybody agreed it looked good.  Changed to a new plug for the 1st moto and afterwards looked perfect.  2nd moto, I went for it, got squirly comming out of the gate, let off the throttle, a yz 400 went by and after he cleared me I gased it and went by all the guys, that I normally race with.  (not the Pros)  Bike ran great untill the 3rd lap when I was following the pro's and decided to take a diferent line, hit the mud hole and went over the bars. I slammed my shoulder into the berm OUCH!  With my right arm dead, I was able to pick up the bike and it started 1st kick, idled great.  I hobbled on it, lifted my right hand on the throttle with my left hand and away I went.  Mind you, very slowly.  I finished the race a lap down, but at least I finished.
Bottom line the jet needle and idle jet was the main cure, followed up by some fine tunning with the main jet.
Thanks
G

72 six-day
79 KTM MC80 250