Encarwi « Myrons Mopeds

Encarwi Carburetors

October 25, 2014

Contents: 1. Encarwi “Tomos” 2. Encarwi “Batavus” 3. Encarwi “Trac”

4. Encarwi Jets 5. Encarwi Info 6. Encarwi “Early” 7. Bing Jets

1. ENCARWI A83, 88A85/102, 88A85/103

– Used on 1976-83 Tomos A3 mopeds.
– Located above engine, difficult to remove.

– Serviceable from sides.

– No choke cable. Choke is part of throttle.

Pic Number Description Price Remarks
a 209070 carburetor A8300/000 N/A Ø12 1976-83
b 000000 carburetor 88A85/102 N/A Ø12 1980-83
c 000000 carburetor 88A85/103 N/A Ø12 1984-85
1 209116 short 3.5 jet #46 $18.0 =0.445
1e encl46 long 3.5 jet #46 $15.0 =0.445
2 206765b l-holder for short jet $25 see below
2e 206765e l-holder for long jet $20 see below
3 209118 slide Ø14 426 w/hole $18 auto-choke
4 209003 spring Ø9.5 x 42    $5
5 206763 carb top screw-on   $15 M18x1 thread
11  206770 float with needle $25 can repair this
12  206772 float top with seat    $25 can polish this
13  206771 gasket for float top   $10
14  206773 banjo black plastic   $15 breaks easy
14 mbanjo banjo metal upgrade $12.0 w/2 washers
16  206775 banjo bolt $7.00
17  206774 fuel filter all metal $15.0 clean & reuse
18  027053 screw M4 x 10 slot  $1.30
20  027079 clamp bolt   $5
24 200384 air filter metal mesh $30.0
25  209215 air box (silencer)   $20
26 209216 junction sleeve rubber $30 gets hard
27  209217 inlet tube connector $3
28  209579 inlet tube (not shown)  $3
30  200382 intake gasket thick $8
32  217315 intake manifold oil inj  N/A w/M6x1 hole
33  209085 intake manifold   $22 OD 16, ID 12
34  031932 lock washer M6 $0.25
35  044284 hex bolt M6 x 22 $1.00

Left, 1974-83 Tomos carb, Encarwi A83, bare.
The jet and jet holder unscrew from the side hole.
The jet can be cleaned out easy, on the roadside.
Right, 84-86 Tomos, Encarwi 88A85/103, complete.
The side hole is blocked. Jet access is from bottom.
The engine must be lowered to access the jet.
Jetting/servicing is ten times more difficult.

Encarwi 88A85/103

At right is a 88A85/103 with the non-removeable jet-holder-spray-tube removed. The jet is a 4mm thread, not 3.5 like all the other Encarwi jets. This one was not a tight fit and needed epoxy to hold it. When the jet was unscrewed the whole brass tube turned.

2. ENCARWI S8A, S23, S22, S25, 88S25/101

– Original on Laura M48 engine

– Used on 1976-79 Batavus, 1977-78 Badger.
– Located behind and below engine

– Needs longer throttle and choke cables.

Pic# Number Description Price Version
a   487180 carburetor S22 (Ø12) N/A 30mph
56 jet, Ø14 slide 405, Ø16 air inlet
b   541780 carburetor S25 (Ø12) N/A 30mph
56 jet, Ø14 slide 167, Ø16 air inlet
c 481790 carburetor S8A (Ø8 ) N/A 25mph
52 jet, Ø14 slide 190, Ø14 air inlet
d   486795 carburetor S23A (Ø8)   N/A 20mph
50 jet, Ø14 slide 190, Ø14 air inlet
e   5417xx carb 88S25/101 (Ø12) N/A 30mph
56 jet, Ø14 slide 188, Ø16 air inlet
1a 541729 orig short jet #56=0.523 $7.00 30mph
1a 335200 generic short #52=0.520 $4.00 subst.
1b 335000 generic short #50=0.500 $4.00
1c 334900 generic short #49=0.490   none subst.
1c 481727 orig short jet #52=0.493 $5.00 25mph
1d 334800 generic short #48=0.480 $4.00 subst.
1d 481726 orig short jet #50=0.478   none 20mph
2 206765b long holder for short jet $25 see below
2e 206765e long holder for long jet $20 see below
3    481758 throttle slide #405 N/A S22 30mph
3a 561742 throttle slide #167   $35 S25 30mph
3b  5617xx throttle slide #188 N/A 88S25/101
3c  486723 throttle slide #190   $25 25 & 20mph
4   209003 spring Ø9.5 x 42   $5
5   206763 carb top screw-on   $15 M18x1 thread
9   481746 idle screw M4-0.7   $12 can use M4
10  481747 spring Ø4.6,Ø6.6 x 9  $3
11  206770 float with needle   $25
12  206772 float top with seat $25
13  206771 gasket for float top   $10
14  206773 banjo black plastic $15
14 mbanjo banjo metal upgrade $12.0 w/2 washers
16  206775 banjo bolt $7.00
17  206774 fuel filter $15.0
18  027053 screw M4 x 10 slot  $1.30

Left 1970’s original float, right 90’s replacement

20  481724 clamp bolt $5
21  481743 choke plate   $7
22  481745 bolt choke pivot $3
23  481744 spring choke    $3
24 200384 air filter metal mesh $30.0
25a481713 air box (inlet 16mm)  N/A 30mph
25b481734 air box (inlet 14mm) $35 25 & 20mph
26 481733 rubber band              N/A
27 481735 wire clip $8

3. ENCARWI H12, H8 CARBURETORS

– Made special for Laura M56 engine.

– Serviceable without removal.

– Used on 1978-80 Batavus Regency (M56)

– 1981-85 Trac Clipper, Eagle, Hawk (M56)

a  561782 carburetor H12 (30 and 25mph) $220
a  56xxxx Ø12 with #56 jet
b  561787  carburetor H8 (20mph version) N/A
b  56xxxx Ø8 with #46 jet
1a 565756   orig. short jet #56 =0.523 mm $7.00
1a 335200 generic short jet 52 =0.518 mm $4.00
1ae encm56 orig. med. jet #56 =0.523 mm $12
1b 209116 orig. short jet #46 =0.445 mm $18.0
1be encm46 orig medium jet 46 =0.445 mm N/A
2a 491722b short holder for s. jet see below $40
2e 491722e short holder for m. jet see below $30
3   561748 slide throttle Ø14 (H12) #3 $25
3a 561742 slide throttle Ø12? (H8)       N/A
4   481759 spring throttle Ø9.5 x 44       $10
5   561721 carb top white plastic    $25
6   046430 rubber cover over carb top       $7
7   481739 screw M5 x 15 slot   $0.50
9   206770 float with needle   $25
10  206772 float top with seat   $25
11  206771 gasket for float top $10
12 mbanjo banjo metal with 2 washers $12.0
13 swash8 banjo seal washer 8mm $1.00
14  206775 banjo bolt   $7.00
15  206774 fuel filter   $15.0
16  027053 screw M4 x 10 slot $1.30
18 561740 idle screw M5-0.80 x 16    $5
19 481747 spring idle screw Ø5,Ø7 x 10   $2
20 561743 choke slide N/A
21 561745 o-ring for choke 1 x 4.5, qty 2    $3
22 561747 choke cable wire   $5.00
23 491724 spring choke return   $8
25 561795  air box with filter   $65
26  823514 screw M5 x 30 phillips   $0.60
27a  561714  air filter screen (two) N/A
27b  561713 air filter foam strip $5

Encarwi H12, with no top, on Trac M56 engine

4. ENCARWI JETS

Encarwi Jets: Most Encarwi carburetors use standard Bing 3.5mm jets. Those jets have a “short” head that is only 3mm long. To use a short jet, the jet holder must be for a short jet. But some Encarwi carburetors have longer 3.5mm jets with 8mm “medium” or 12mm “long” heads.

Encarwi “medium” jets for Laura M56
3 encm56 size 56 $12 thread=3.5 head=8

Encarwi “long” jets Laura M48, Tomos A3
2  encl45 size 45 $12 thread=3.5 head=12
2  encl46 size 46 $15 thread=3.5 head=12
2  encl52 size 52 $12 thread=3.5 head=12
2  encl56 size 56 $12 thread=3.5 head=12
2  encl58 size 58 $$7 thread=3.5 head=12

Encarwi jet holders
1  206765b long jet holder for short (Bing) jet $25
2 206765e long jet holder for long Encarwi jet   $20 can be a substitute for 3
3  491722e short jet holder for medium Encarwi jet $30
4 491722b short jet holder for short (Bing) jet   $40

5. Encarwi Info

1971-1977 Tomos Automatic N had a Laura M48 engine with an Encarwi carb

Before 1973, Tomos had Puch and Laura engines. The 1971 Tomos Automatic N had a Laura M48 engine with Encarwi carburetor. Tomos continued to use Encarwi on their A3 engine, until 1983.

1977 Flandria Bermuda
Encarwi A-type carb

Welcome. Encarwi (made in Holland, now the Netherlands) was a division of Bing (Germany). On US models, Bing-Encarwi carburetors were used on mopeds by Batavus and Badger, with Laura (Holland) engines, Flandria (Belguim), and pre-1986 Tomos (Yugoslavia).

Encarwi carbs on US models of Batavus and Tomos.
Top, S-series. Bottom, A-series (no idle screw).

Encarwi “A” series carbs had an “automatic” choke, controlled by a special twist throttle with thumb button. The choke button lets the throttle twist opposite, below “zero”. This exposes a hole in the slide valve, in front of the fuel nozzle. After starting, twist throttle and choke clicks off automatically.

A11 (8mm, Ø14 slide 408, jet 52-54), for 20kmh Laura M48 engine (Euro model)

A22 (8mm, Ø14 slide 108, jet 50-52), for 25kmh Laura M48 engine (Euro model)

A21 (12mm, Ø14 slide 202, jet 56-58), for 40kmh Laura M48 engine (Euro model)

A83 (12mm, Ø14 slide 426, jet 46), for 20, 25, 30mph Tomos A3 engine 1974-80+

88A85/102 (Ø12, Ø14 slide 426, jet 46) for 20, 25, 30mph Tomos A3 engine 1980-83+

88A85/103 (Ø12, Ø14 slide 426, jet 4mm #50, no jet access from side) for Tomos A3 1983-85

All of these jets have 3.5mm threads except for the 88A85/103 which has 4mm threads.

Encarwi “S” series carburetors had a “standard” choke, controlled by a small lever on the handlebar via a cable.

88S23A (8mm, Ø14 slide 190, jet 54), for 20kmh Laura M48 engine (Euro model)

S23B (8mm, Ø14 slide 190, jet 52-54), for 25kmh Laura M48 engine (Euro model)

S23A (8mm, Ø14 slide 190, jet 50-52), for 20mph Laura M48 Batavus 1976-77

S8A (8mm, Ø14 slide 190, jet 52-54), for 25mph Laura M48 Batavus 1976-77

S22 (12mm, Ø14 slide 405, jet 54-58), for 30mph Laura M48 Batavus 1976-77

S25 (12mm, Ø14 slide 167, jet 56-58), for 30mph Laura M48 Batavus 1977-78

88S25/101 (Ø12, Ø14 slide 188, jet 56-58), for 30mph Laura M48 Batavus 1978-80

Encarwi “H” series carburetors were designed specifically for the Laura M56 engine, later made by Trac (Daelim).

H8 (8mm, Ø12 slide ???, jet 46), for 20mph Laura M56 eng Batavus 1978-80

H12/102 (12mm, Ø14 slide 3, jet 56), for 25 & 30mph Laura M56 Batavus 1978-80

unmarked (12mm, Ø14 slide 3?, jet 56), 25 & 30mph M56 remake Trac 1982-85

Top, Encarwi carburetors, engine view, with slides slightly open, showing the idle air channels or slots or holes.
Bottom, the corresponding throttle slides, all 14mm diameter, bottom view. The pair of large holes is for the cable.
Substitutions or conversions: Any S-type slide can be drilled and machined to be made for an A83 or H12 carb.
The S-type slides (190, 405, 188, 167, 2) all interchange, but have different idle mixture idling behaviors.
The Tomos A3 slide 426 fits a Trac M56 with H12 carb, with only minor widening (drilling) of the sprayer hole.

The amazing Encarwi 426 auto-choke throttle slide (Tomos A3) is explained in four steps:
1. Full power – throttle cable is pulled all the way. The slide does not have to be there. Main jet controls the mixture.
2. Partial power -throttle cable is pulled part way. The slide limits the amount of air. The main jet controls the mixture.
3. No power (idle) -throttle cable is pulled slightly. The slide blocks most of the air. Idle slot size controls the mixture.
4. Cold start – throttle cable is not pulled at all. The choke jet hole and choke air hole in slide 426 control the mixture.
Substitutions or conversions: The S25 and A83 Ø12 carbs are the same, except for the throttle slide and idle screw.
The Ø14 throttle slides 167 and 426 are nearly the same, except the Auto type 426 has extra choke holes and cut outs.

Encarwi Carburator, from 1960’s or 70’s

6. ENCARWI “EARLY”

Carwi Carburator, from the 1950’s

Encarwi A30 carburetor

Encarwi A30 on
1960’s Flandria

You can see that these early Encarwi carbs have many things in common with the later ones. The most obvious thing is the angle of the throttle slide with the venturi. Most carburetors have the slide valve 90 degrees to the air flow, but Encarwi carbs are more like 60 degrees. The other thing unique to Encarwi is the “automatic” choke, indicated by the absence of an idle speed adjustment screw, the choke holes and cut-away in the slide, and an extra thumb button on the throttle control that lets the throttle cable go completely slack, below normal idle or “zero”.

Bing Jets

October 26, 2011

Bing jets are in Bing and some Encarwi carburetors.

3.5 mm thread (M3.5-0.60) Bing jets are on Puch-Bing, Solo-Bing, Kreidler-Bing, and Encarwi.

4.0 mm thread (M4.0-0.70) Bing jets are on Sachs-Bing, late 80’s AD-Bing and 90’s Korado-Bing.

Myrons Mopeds Bing Jet Sizes Chart

These jets are on other 1970’s – 80’s small engines with Bing carburetors.

The Bing 3.5 main jets are also idle jets on some bigger Keihin carbs.

The Bing 4.0 main jets are also idle jets on some bigger Dellorto carbs

Original Bing jets are numbered wrong, in a sense. The jet number is not the millimeter size. An original Bing 54 is actually 0.51 mm, not 0.54. This was discovered this in the early 2000’s when aftermarket Bing jets came out. 200 jets were carefully measured with precise wire guages, and then plotted on the graph at right. The original jets (and the first A&R generics) form one line. All other generic jets form a different line.

Generic Bing jets are numbered correctly. The size they say is the millimeters they are. So a generic Bing 54 is actually 0.54 mm.

Bing Jets (3.5 mm)

part # maker jet# close to measured size price applications

78drill   custom #00 =Bing48 0.016″ = #78 drill —————————————————————
3.5×44 custom #00 =Bing46 0.0173″=0.440mm  $15.0 soldered, 78-drilled, then filed with .017 guitar string
Bing46 original #46 =Bing46 0.0175″=0.445mm $18.0 76-83 Tomos early A3 models (30, 25, and 20mph)
3.5×45 custom #00 =Bing47 0.0177″=0.450mm  -N/A–
77drill   custom #00 =Bing48 0.018″ = #77 drill —————————————————————
3.5×46 custom #00 =Bing48 0.0181″=0.460mm  -N/A–
Bing48 original #48 =Bing48 0.0182″=0.462mm $15.0 78-80 Puch (2-spd hi torque Ø12 carb 20mph)
3.5×47 custom #00 =Bing49 0.0185″=0.470mm  -N/A–
Bing50 original #50 =Bing50 0.0188″=0.478mm none 76-78 Batavus (Laura M48 Ø8 carb 20mph)
3.5×48 generic #48 =Bing51 0.0190″=0.480mm $4.00
3.5×49 custom #00 =Bing52 0.0190″=0.490mm  -N/A–
Bing52 original #52 =Bing52 0.0194″=0.493mm $5.00 76-78 Batavus (Laura M48 Ø8 carb 25 mph)
3.5×50 generic #50 =Bing53 0.0195″=0.500mm $4.00
76drill   custom #00 =Bing48 0.020″ = #76 drill —————————————————————
Bing54 original #54 =Bing54 0.0200″=0.508mm $5.00 74-83 Puch (1-spd alum. cylinder, Ø12 carb 2.22, 20mph)
3.5×51 generic #51 =Bing54 0.0201″=0.510mm
3.5×52 generic #52 =Bing55 0.0204″=0.520mm $4.00
Bing56 original #56 =Bing56 0.0206″=0.523mm $7.00 77-80 Batavus M48 and M56 (30), 80-83 Trac M56 models
3.5×53 generic #53 =Bing56 0.0209″=0.531mm
75drill   custom #00 =Bing48 0.021″ = #75 drill —————————————————————
3.5×54 generic #54 =Bing57 0.0212″=0.540mm $4.00
Bing58 original #58 =Bing58 0.0213″=0.541mm $7.00 78-83 Puch (2-spd hi torque cyl. Ø12 carb 2.22 30mph)
3.5×55 generic #55 =Bing59 0.0217″=0.551mm $4.00
3.5×56 generic #56 =Bing60 0.0220″=0.561mm $4.00
Bing60 original #60 =Bing60 0.0222″=0.564mm $7.00 78-83 Puch (1-spd hi torque cyl. Ø12 carb 2.22 30mph)
3.5×57 generic #57 =Bing61 0.0224″=0.571mm $4.00
75drill   custom #00 =Bing48 0.0225″=#74 drill —————————————————————
3.5×58 generic #58 =Bing62 0.0228″=0.580mm $4.00
Bing62 original #62 =Bing62 0.0229″=0.582mm $7.00
3.5×59 generic #59 =Bing63 0.0232″=0.591mm $4.00
Bing64 original #64 =Bing64 0.0234″=0.594mm $6.00 74-83 Puch (1-spd al cyl Ø14 carb 2.22 needle jet 30mph)
3.5×60 generic #60 =Bing64 0.0235″=0.600mm $4.00
Bing66 original #66 =Bing66 0.0239″=0.607mm none
75drill   custom #00 =Bing48 0.024″ = #73 drill —————————————————————
3.5×61 generic #61 =Bing65 0.0240″=0.610mm $4.00
3.5×62 generic #62 =Bing66 0.0244″=0.620mm $4.00
Bing68 original #68 =Bing68 0.0248″=0.630mm $7.00  78 Sears (1s al cyl Ø14 carb 30mph), Kreidler (30mph)
3.5×63 generic #63 =Bing68 0.0248″=0.630mm  $4.00
75drill   custom #00 =Bing48 0.025″ = #72 drill —————————————————————
3.5×64 generic #64 =Bing69 0.0252″=0.640mm  $4.00
Bing70 original #70 =Bing70 0.0254″=0.645mm N/A 84-86 Puch Cobra (Ø14 carb, 2.17 needle jet 25mph)
3.5×65 generic #65 =Bing71 0.0256″=0.650mm $4.00
75drill   custom #00 =Bing48 0.026″ = #71 drill —————————————————————
3.5×66 generic #66 =Bing72 0.0260″=0.660mm $4.00
Bing72 original #72 =Bing72 0.0260″=0.660mm N/A 84-86 Puchs had bigger main jets, but smaller needle jets.
3.5×67 generic #67 =Bing73 0.0264″=0.670mm $4.00
Bing74 original #74 =Bing74 0.0267″=0.678mm N/A 1990’s Puch remakes also had 70’s jets, 2.17 needle jets.
3.5×68 generic #68 =Bing74 0.0268″=0.681mm $4.00
3.5×69 generic #69 =Bing75 0.0272″=0.690mm $4.00
Bing76 original #76 =Bing76 0.0273″=0.693mm $6.00
3.5×70 generic #70 =Bing77 0.0278″=0.705mm $4.00
75drill   custom #00 =Bing48 0.028″ = #70 drill —————————————————————
3.5×71 generic #71 =Bing78 0.0280″=0.715mm -N/A--
Bing78 original #78 =Bing78 0.0280″=0.711mm N/A
3.5×72 generic #72 =Bing79 0.0283″=0.725mm $4.00
Bing80 original #80 =Bing80 0.0287″=0.729mm N/A
3.5×73 generic #73 =Bing81 0.0287″=0.735mm none
3.5×74 generic #74 =Bing82 0.0291″=0.745mm $4.00
75drill   custom #00 =Bing48 0.0292″ = #69 drill —————————————————————
Bing82 original #82 =Bing82 0.0292″=0.742mm $7.00 2000’s Bing Ø15 carb with smaller 2.17 needle jet
3.5×75 generic #75 =Bing83 0.0296″=0.755mm none
Bing84 original #84 =Bing84 0.0300″=0.762mm none 1978-79 Puch Magnum X

cleaning a #25 jet

Bing Jets (4.0 mm)

At right, the smallest of the small. The #25 pilot jet is bigger than wire wheel wires, but smaller than wire brush wires in the background. It’s three hairs wide!

part number maker jet# close to measured size price applications

Tomos243222 Dell.  #25 =Bing27 0.0107″=0.272mm     $8 Tomos A55 pilot (idle) jet
Tomos243110 Dell. #29 =Bing31 0.0124″=0.314mm     $8   same as Tomos #25 idle jet “cleaned” with #80 drill
D1486-030 Dellorto #30 =Bing33 0.0128″=0.325mm $8  good for A55 pilot jet, mix screw 1 turn more out
77drill   custom #00 =Bing48 0.0135″ = #80 drill —————————————————————
D1486-032 Dellorto #32 =Bing35 0.014″ = 0.355mm     $8 same as drilled with #80 drill, sub for A55 pilot jet
77drill   custom #00 =Bing48 0.0145″ = #79 drill —————————————————————
D1486-035 Dellorto #35 =Bing39 0.0149″=0.378mm N/A
77drill   custom #00 =Bing48 0.016″ = #78 drill —————————————————————
D1486-040 Dellorto #40 =Bing45 0.0170″=0.431mm     $8
4mBing45 Bing orig #45 =Bing45 0.0171″=0.434mm N/A Sachs 504/1A DK (19mph)
77drill   custom #00 =Bing48 0.018″ = #77 drill —————————————————————
4mBing48 Bing orig #48 =Bing48 0.018″ = 0.46mm      $8
D1486-043 Dellorto #43 =Bing49 0.0182″=0.462mm N/A
4mBing50 Bing orig #50 =Bing50 0.0183″=0.465mm     $8 Sachs 504/1B and 505/1B (Ø10 carb 20mph)
D1486-044 Dellorto #44 =Bing51 0.0187″=0.475mm N/A
4.0×48 000 generic #48 =Bing51 0.0189″=0.480mm
D1486-045 Dellorto #45 =Bing51 0.0190″=0.483mm   $8
4mBing52 Bing orig #52 =Bing52 0.0194″=0.493mm N/A Sachs 504/1A and 505/1A (Ø12 carb 30mph)
D1486-046 Dellorto #46 =Bing52 0.0194″=0.493mm N/A
4.0×50 000 generic #50 =Bing53 0.0197″=0.500mm
76drill   custom #00 =Bing48 0.020″ = #76 drill —————————————————————
4mBing54 Bing orig #54 =Bing54 0.0200″=0.508mm N/A ’84-86 Puch Austro Daimler (30mph)
D1486-047 Dellorto #47 =Bing54 0.0198″=0.503mm N/A
D1486-048 Dellorto #48 =Bing55 0.0202″=0.513mm   $8 Sachs 504/1A and 505/1A (without air filter box)
4.0×52 000 generic #52 =Bing56 0.0205″=0.520mm
4mBing56 Bing orig #56 =Bing56 0.0206″=0.523mm N/A ‘
D1486-049 Dellorto #49 =Bing56 0.0207″=0.526mm N/A
75drill   custom #00 =Bing48 0.021″ = #75 drill —————————————————————
D1486-050 Dellorto #50 =Bing57 0.0210″=0.533mm N/A
4.0×54 000 generic #54 =Bing58 0.0212″=0.540mm
4mBing58 Bing orig #58 =Bing58 0.0213″=0.541mm     $8 Sachs 504/1D and 505/1D (Ø12 D-carb 30mph)
D1486-051 Dellorto #51 =Bing59 0.0215″=0.546mm N/A
4.0×56 000 generic #56 =Bing51 0.0220″=0.560mm
75drill   custom #00 =Bing48 0.0225″=#74 drill —————————————————————
D1486-055 Dellorto #55 =Bing63 0.0230″=0.580mm   $8
4.0×58 000 generic #58 =Bing63 0.0230″=0.580mm
4.0×60 000 generic #60 =Bing65 0.0236″=0.600mm
75drill   custom #00 =Bing48 0.024″ = #73 drill —————————————————————
4.0×62 000 generic #62 =Bing68 0.0244″=0.620mm
D1486-060 Dellorto #60 =Bing69 0.0250″=0.635mm   $8

Encarwi Carburetor Service

May 4, 2008

Encarwi A83 carburetor on Tomos A3 engine

Encarwi Carb Service for Tomos A3 1974-83

This very simple, early Tomos carb is designed to be serviced without removal. After 1985, Tomos A3 & A35 models came with Dellorto SHA14/12 carburetors. The Tomos A3 carburetor is in a confined area above the engine and below the sheet metal gas tank/frame. It is difficult to remove.

Two super usfeul and easy checks:

1) Check the jet. With a large flat head screwdriver or a 9mm wrench, remove the jet holder #2. Remove the jet #2 with a medium-thin flat head screwdriver. Hold the jet up to a light source, such as a sunny white wall. Look through the tiny hole to see if light gets through. If it’s pitch black it’s completely blocked. If it’s not circular then it’s partially blocked, like by a fiber.

2) Check everything else. When the jet holder is removed, and the gas valve is turned on, gasoline should flow out of the gas tank, through the banjo bolt #16 at the float top #12, and then dribble out the hole where the jet holder was. This is a way to quickly test the fuel system, tank, valve, line, filter, and float, all at once.

If gas does not spill out with the jet holder removed, then gas is not getting to the jet. Check if gas comes out of the tank. If gas is getting to the carburetor, but not getting to the jet, then either the inlet banjo #14 or banjo bolt #16 is clogged, or the float top #12 is clogged, or the float #11 is in upside down, or the float is stuck in the up position. Several things can cause this kind of float to stay up and not drop down and let gas come into the float bowl reservoir: being installed upside down (pointy end goes up), rust powder filling up the guide hole at the bottom of the float chamber, the float bulb being pushed too far down the rod, the wrong float, or a dented float chamber wall.

Encarwi S25 carburetor on Batavus M48 engine

Servicing

The jet holder #2 unscrews from the left side. It holds the jet #1, Bing 3.5mm size 46.

To remove an old, hard, shrunken and very stuck on, fuel hose, be careful not to break off the “neck of the banjo”. That means you only pull straight out and rotate, never pull or twist sideways. If that fails, a diagonal pliers aka dikes aka wire cutters, can be used to cut the old fuel line, parallel to the hose, without cutting the banjo underneath. The cut does not need to go all the way through the old fuel hose, but far enough to weaken it.

To service the float, loosen the clamp screw #20 and rotate the carb so it is tipped to the right. Remove the 11mm hex head banjo bolt. Remove the two slot head screws #18. Lift off the float top. Lift out the float with your fingers. It should lift out freely and not feel stuck.

Float versions, left 70’s bulb, right 90’s solid

Encarwi S12 carburetor on Trac M56 engine

Things that cause not enough gas:

Rust powder filling up the guide hole at the bottom of the float chamber. Remedy is twisting a correct size drill bit with your fingers, to pull the powder up and out of the hole. With the jet holder removed and the gas valve turned on, gasoline should flow out of the tank, through the float valve, and spill out the jet holder hole. The amount should be enough to fill the float reservoir in a few seconds, which is roughly a spoonful every 4 seconds.

The bulb being pushed too far down the rod. Remedy is to push it back up. See the above photo with measurements.

Dented float chamber wall. Remedy is to grind or sand down the high spot.

Blocked float reservoir air vent. Gasoline cannot come in unless air can get out. Remedy is to find where it is blocked at, and remove the blockage. The vent follows a channel in the back mounting surface. An empty float reservoir should fill up in a few seconds after the gas valve is turned on. To test for a blocked air vent, first empty the reservoir, then turn the gas valve on for 8 seconds and then off. Then remove the jet holder, allowing gas to dribble out, to see how much gasoline there was in the reservoir.

Blocked gas tank air vent. Gasoline cannot leave the gas tank unless air comes in. So there is a pin hole in the gas cap. When the tank is full, and the vent hole is blocked, the bike will seem to run out of gas. To test for a blocked gas cap vent hole, first fill the gas tank, then close the gas valve, then remove the fuel hose. Place a clean container under it (to check for purity and to put the gas back in the tank). Turn on the gas and observe the flow. It will flow normal at first. But in a few seconds, as negative pressure builds up, the flow will slow down and stop, if the vent is blocked. If the flow continues for 20-30 seconds (or indefinitely) then the gas tank is vented.

Things that cause too much gas:

Worn float needle tip. Remedy is to sharpen it. Examine the tip with a magnifier. Spin the float with a drill while pressing the tip gently against a sheet of emery cloth or very fine sandpaper, at the same angle, and move it slowly around to fresh parts of the sandpaper. The needle rod must be straight first. Examine the tip with a magnifier. There should be, everywhere on the cone tip, circular sanding marks, and no more circular “potholes”.

The needle is bent. Remedy is to straighten it. Normally the bend is just above the top of the bulb. It is done with just fingers and eyes. Rotate to see which way it needs to go. Bend a little. Repeat.

The bulb being pushed too far up the rod. Remedy is to push it back down. See the above photo with measurements.

Worn float seat hole. The float valve seat is part of the float top. It is the tiny hole at the bottom of the small hole. Examine the hole with a magnifier. It should be perfectly circular and free of nicks and scratches. Polish it with a spinning tooth pick, or the stalk of a Q-tip.

Float bulb has gasoline inside it. If the float too heavy, it won’t have enough buoyancy to stop the gasoline from getting in. Remedy is to evacuate the fuel with compressed air, locate the leak hole, and apply a minimal amount of fuel tank sealant.

Servicing the M56 engine’s H12 or H8 Carburetor:

One problem unique to this carb is warping of the engine side surface. This is caused by over tightening the two mount bolts, and maybe also because the heat block behind it is semi-soft. The back side must seal not just air, for good idling, but also there is a fuel passage that can leak because of a warped carburetor body. The remedy is to grind the back side flat again, without taking too much off. In the body, there is a narrow fuel hole at the bottom of another hole, that is impossible to see directly. That hole must be checked and cleaned with carb spray and compressed air.

The float is the same as the other carbs. The float top is the same except it has no air vent pin hole. The idea was to not let gas spill out the vent hole. Instead the vent goes to the mounting gasket, where there is a small opening to the atmosphere, higher up.

Jet Drills

January 27, 2007

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