76 250 MC5 carb settings

[Doofus]

Hi, can someone let me know the standard Bing 54 carb settings for a 1976 MC5 250? The carb mounted is a 54/36/101. I assume that is correct?? If yes I need to know stock jet sizes and any other useful tips. I've really struggled with the set up and now I'm questioning the basics, probably far later than I should have! Bike starts ok but runs like a pig, burbling at the low rev range and very hard to sustain good power. When it does pick up and clear it's lungs it's like an exocet missile. Just doesn't sustain it. I'm going to get all new parts and work through it, just need to know what to buy.  Any help gratefully received.

[Mike OReilly]

I have the carb from my 1976 MC5 apart on the bench now. I rode the bike last August and it ran well.
I'm working the next couple of days but will have a look first thing Monday and get back to you with the numbers.
Mike

[Larry Perkins]

Did you put a NEW needle jet in it and is the slide NOT worn?  Almost Always when a Bing is performing poorly it is one or both of those.  The needle jet on a old bike with a Bing MUST be replaced.  I have heard this story a jillion times.  If the slide is bad it will look like it has a smiley face.

Larry P

[Carl Hill]

According to owners manual they came with 165-170 main, 322 needle jet, 50 pilot .Needle position 2 from the top. Air screw opening 1-1/2 turns out. I would guess this is Ohio jetting... I know Bing carbs get a bad rap but in my experience work pretty well when fresh, but the slides and such do seem to wear a lot worse than Japanese carbs. When they wear they do suffer.

[Doofus]

Thanks guys. The slide is worn and will be replaced. I have a new needle and now just have to get the correct jets. Carl, thanks for those numbers. I'll give them a go.

[Larry Perkins]

322 Needle jet sounds way big to me.  Memory says more like 285.  But I am old.  I would bet lunch though that 322 is too big.

Larry P

[Andreas Piepke]

You may want to contact the Bing Agency (http://www.bingcarburetor.com/index.html). They sell Bing components and from the carburetor numbers they can often find out which components were mounted originally. You may also want to replace the needle.

Andreas

'73 Penton Hare Scrambler
'73 Norton Commando
'77 Maico 440 GS

[Andreas Piepke]

David, I've just seen that you are in the UK! A US vendor might not be ideal for you. You might want to try to get your components from Germany (still an inner EU purchase).

Bernhard Greiner
Oldtimer Motorradhandel
Am Bangraben 16
72336 Balingen

is the vendor of choice for Bing Germany (see http://www.bingpower.de/service/ersatzteilvertrieb/). Greiner's web site has an electronic look-up function that allows you to identify the components that were originally mounted on your 54/36/101. Here is what my search yielded (http://www.greiner-oldtimerteile.de/search.php?sid=979001523231507&ret=&action=exec&start=0&pattern=!54/36/101!&artnr=on&key=maxprice&name=on&desc=on&category=-1&minprice=&maxprice=):
Main jet: 160 (Bing number 44-051/160)
Jet needle: 4O1 (Bing number 46-360-4O1)
Needle jet: 3,16 (Bing number 45-120/3,16)
Nebulizer: type 4 (Bing number 51-554)
Slide: 22-645-230 (not available)
Pilot jet: 60 (Bing number 44-350/60)

Cheers

Andreas




'73 Penton Hare Scrambler
'73 Norton Commando
'77 Maico 440 GS

[Doofus]

Andreas,

Dankeschoen!! No idea how to type an umlaut!!

I'll check that out.

Vielen Dank!

[Mike OReilly]

I pulled my carb apart today, and this is what I found:
Main: 175
Pilot: 35
Needle jet: 3.22
Needle: no number on it, but has four "bands"
Needle clip: top of 3 positions.
The slide shows some signs of wear, including the beginning of a "smiley face" on the engine side.

1976 MC5 with a Bing 54. The bike ran well in August at approx. 50 metres above sea level. All other things being equal, this is a start point. If you are close to this set-up and still have problems, I believe it is time to start looking for air leaks (ie: crank seals, carb spigot, etc.).
Get back to me with any questions.
Mike

[Mike OReilly]

BTW.
In reviewing this, your reference to an Exocet missile is a very strong clue that there is some kind of intake vacuum issue which will only allow the bike to run well at high revs.

[Doofus]

Thanks Mike. I'll get the carb sorted at least to some accepted settings first.

The bike did run away a couple of times too and it wasn't a sticking slide. I do suspect an air leak but wanted to exclude worn carb issues first and then move on.

Larry,

New needle but need to replace the jet. Slide has slightly smiley features!! All will be changed.

Thanks agin all. Great advice and info.
Dave

[Pat Oshaughnessy]

Larry is right about the needle & needle jet. I ran out of gas before the gas check at an Enduro because of this same problem! Thanks POG members for great info.[]

[skiracer]

Throw the Bing away, and buy a real carb.  If money is tight get a Mikuni, if you have a few pounds, buy a Lectron, you won't regret it..... How do I know?  I have owned my MC 5 since it came out of the box in 1976.  Been there, done that.  Move on, Bing carbs are antiques.

1976 MC 5 Original Owner
1976 Penton 175 XC
1985 20' Hi Point trailer

[Pat Oshaughnessy]

Skiracer is also right. In 1976 or 77 I put Lectron on my 74 250 it ran better & no more problems. Also period correct![]