Needles and jets and sizes...oh my

[BoxerTwin]

I'm trying to work through my low gas mileage issues on my R100/7.

Remembering the PO had rebuilt this bike from the ground up...poorly.

I got the kit from Bing to rework it.
One thing I notice is the new needles are shorter than the ones installed.
The ones from Bing are 2.165" long
The ones currently on the bike are 2.4" long
Maybe the one installed is wrong, maybe I received the wrong one from Bing (probably not).

The needles were on the second notch down from the top, I put the new ones in on the second notch too, but they are quite a bit shorter.

Both the shipped And the installed needle jets are marked 268

Any idea which needle would be the correct one?

[Deleted User 287]

I would give Bing a call and ask their technical guy.

[SteveD]

Mr. BING's book shows 3 R100/7's.

2 have flat top carbs.
64/32/219-220 uses the 2.68 jet and 241 needle. 3rd clip position.
64/32/223-224 uses the 2.66 jet and 241 needle. 2nd clip position.

1 has the hard tip float needle.
64/32/19-20 uses the 2.68 jet and 241 needle. 3rd clip position.


The R100 with 123-124 40 mm carbs uses 2.66/371needle/2nd pos.
The R100 with 125-126 40 mm carbs uses 2.66/341needle/3rd pos.

Hope that helps.

[BoxerTwin]

Are 241 needles a size or specific length?

[Major Softie]

Are 241 needles a size or specific length?

They are a number.

Needles vary by length, diameter, and taper.

[Kurt in S.A.]

The Bing book lists the length of the taper as well as the pointy end diameter. For the life of me, I can't relate those part numbers back to the jet needle sizes such as 241, etc.

Kurt in S.A.

[Major Softie]

The Bing book lists the length of the taper as well as the pointy end diameter. For the life of me, I can't relate those part numbers back to the jet needle sizes such as 241, etc.

Kurt in S.A.

Yeah, and, as far as I know, overall length only varies between carbs, not tuning. So, if you had two needles, and one was a 1/4" longer than the other, I would usually assume that only one could be a correct needle for a particular carb.

There may be cases where that isn't true, but it has been in my limited carb tuning experience.

[BoxerTwin]

Now to figure out how to tell what a 241 needle is.

[Major Softie]

Now to figure out how to tell what a 241 needle is.

I've seen needles with numbers printed on them.

Course, I've seen ones that didn't have them too...

[BoxerTwin]

mine have no numbers on them of course.

I was getting about 24mpg on my bike. I put in the needles I received from Bing, set them to the 3rd notch as per my manual, set the carbs to the default starting setup, tuned and balanced them.

I topped off the tank and took a 52 mile ride, mixed bag of freeway, hills, street, etc. managed about 32.7 mpg.

It's getting better.