Maico MC250 - SHOP BULLETIN #2: Carburettor Jetting Specifications

SHOP BULLETIN #2
400cc
400CC
400cc
400cc
501cc
250cc
250cc
250cc
I
4
1
6DP
1
1
0
6DH
6fJ
Needle
Needle-Kotches from
2
2
2
2
2
2
5
3
lean oosition
159
159
159
1610
275-280
0-5
285- 290
280-285
109
p-o
1)-5
Needle Jet
--
5
1
2.5
1
1
3.0
2.0
1,5
Slide
-----
35
40
35
35
40
20
35
35
Pilot Jet
I
,
-
-
2.0
-
-
-
2.0
2.0
Po
ir Jet
i
1,5
I
1,5
1,5
1,5
1,5
1,5
1,5
2.0
1 1/2
Air Screw (Turns)
'-
165
170-180
210
180-190
17 5-18 5
I
420
270
310
Main Jet
Engine Timing
3.0
2.7
2.7
3.5
3.8
3.8
3.8
__ ,_,l-,~
BTDC (mm)
----"----
----------_.
30
36
34
36
36
I
36
34
36
Carburettor (mm)
Binz
Bin~
,
Mikuni
BinR
Bin:7
!
Amal
Mikuni
Mikuni
Size and Make
Champion spark
L-2G
L-2G
L-2G
N-2G
L-2G
L-2G
L-2G
L-2G
nlup-. GAP at
.022-.024
L-3
L-3G
L-3G
-
-
i
-
-
-
Hot Plug
I
This jetting was developed using a Zollner engine dynomometer at C.R. Axtell's in Glendale,
Calif. The jetting is for maximum horse power Sea level to about 3500 feet. If jetting
changes are required always chanp,e the pilot jet first, then the needle jet, then slide, then
the main jet.
for a rouf.h rule of thumb reduce the jet sizes 10% for every 5000 feet of altitude ie 40 pilot
to 35 then to
30.
NOTE: The Bing Carburettor is usuallv supplied one needle jet too rich.
Carburettor-Jettin~ for sea level
SHOP BULLETIN #2
400cc
400CC
400cc
400cc
501cc
250cc
250cc
250cc
I
4
1
6DP
1
1
0
6DH
6fJ
Needle
Needle-Kotches from
2
2
2
2
2
2
5
3
lean oosition
159
159
159
1610
275-280
0-5
285- 290
280-285
109
p-o
1)-5
Needle Jet
--
5
1
2.5
1
1
3.0
2.0
1,5
Slide
-----
35
40
35
35
40
20
35
35
Pilot Jet
I
,
-
-
2.0
-
-
-
2.0
2.0
Po
ir Jet
i
1,5
I
1,5
1,5
1,5
1,5
1,5
1,5
2.0
1 1/2
Air Screw (Turns)
'-
165
170-180
210
180-190
17 5-18 5
I
420
270
310
Main Jet
Engine Timing
3.0
2.7
2.7
3.5
3.8
3.8
3.8
__ ,_,l-,~
BTDC (mm)
----"----
----------_.
30
36
34
36
36
I
36
34
36
Carburettor (mm)
Binz
Bin~
,
Mikuni
BinR
Bin:7
!
Amal
Mikuni
Mikuni
Size and Make
Champion spark
L-2G
L-2G
L-2G
N-2G
L-2G
L-2G
L-2G
L-2G
nlup-. GAP at
.022-.024
L-3
L-3G
L-3G
-
-
i
-
-
-
Hot Plug
I
This jetting was developed using a Zollner engine dynomometer at C.R. Axtell's in Glendale,
Calif. The jetting is for maximum horse power Sea level to about 3500 feet. If jetting
changes are required always chanp,e the pilot jet first, then the needle jet, then slide, then
the main jet.
for a rouf.h rule of thumb reduce the jet sizes 10% for every 5000 feet of altitude ie 40 pilot
to 35 then to
30.
NOTE: The Bing Carburettor is usuallv supplied one needle jet too rich.
Carburettor-Jettin~ for sea level
Maico 72-74.5 Radial Manaual
www.maicowerk.com
Courtesy of vintagemaico@gmail.com