Post your jetting info here!

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Post your jetting info here!

Postby Tab » Sun Jun 03, 2007 4:33 pm

I thought this might be a good way to help others when they are kitting or restoring mopeds. Post your moped type, jetting info, cylinder type, exhaust and air box info. Make notations of anything else that may be pertinent.

PLEASE not post pictures or ask questions here. Either start a new thread or use the PM function.

(Added by jd on March 7, 2008:)
Here are some basic guidelines to follow if you're trying to figure out how to choose the proper jet for your moped:

First, take a look at page 17 in the Tomos A35 Repair Manual in the Moped Repair library. There are several pictures of spark plugs that can help you diagnose problems. It doesn't matter if you have a Tomos or not.

Second, learn how to do a "plug chop." With a plug chop, you can use the spark plug to evaluate your jet's performance and eliminate all doubt. Start with a new spark plug. Then warm up the engine, run it flat out (riding, not on a stand) for at least 30 seconds (a minute is better), and shut it off immediately with the kill switch. DO NOT allow it to return to idle first. Remove the spark plug (it will be HOT) and "read" it. Compare it to the pictures in the Tomos manual.

Generally, you want to look at the color of the insulator. In a perfect mix, it should be a tan, or maybe "coffee with milk" color. If it's white, you're too lean. If it's black or sooty, you're too rich.

A lean condition may result in your engine's best performance, but it will run extremely hot, cause detonation and ultimately result in cylinder and/or piston damage. The piston will expand faster than the cylinder and it will eventually get caught in there, referred to as a "seize." A "soft seize" will be temporary until the piston cools, but it could leave some serious scoring in the cylinder wall. A full seize will lock the piston up good, and may require major repairs.

A rich condition , on the other hand, will not damage your engine, although you may foul some spark plugs. The engine will appear to run OK until you open the throttle wide, in which case it will start to stumble, bog or "four-stroke." It's like trying to run a warm engine with the choke on.

Therefore, it's always better to start at the rich end with the largest reasonable jet, do a plug chop, and then decrease the jet size gradually, each followed by a plug chop, until you get a good reading on the plug.

Lastly, be conscious of the ambient outside temperature. Colder air is denser and will tend to cause any two-stroke engine to run leaner. Hot air does the opposite. If you do your plug chops on the hottest day of the year, you may end up underjetting and still being too lean when the weather cools. Doing this on a very cold day could results in an overjet.

The most important thing to remember is that you never want to use a jet that is too small. It will be a lot of fun for a very short time. It's always better to err on the size of too rich with an oversized jet.
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re: Post your jetting info here!

Postby Tab » Sun Jun 03, 2007 4:38 pm

2002 Tomos Revival
A-35 engine with Airsal 70cc kit
16mm Dellorto carb.
Intake bored to 16mm
Airbox restriction removed from inside
Technigas Next Pipe
Jetting - 64
alt - 930 feet
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re: Post your jetting info here!

Postby Tab » Sun Jun 03, 2007 4:41 pm

2006 Streetmate Type R
A-55 engine with Airsal A-55 kit - stock head
Stock carb and intake
Opened air box inlet as wide as I could
Fabricated a new snorkel that was similar to the original - just wider (tip from Tomos03)
Technigas Next exhaust
Jetting - 58
25 idle jet
alt - 930 feet
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re: Post your jetting info here!

Postby John » Mon Jun 04, 2007 4:23 am

1999 Tomos LX
A 35, Airsal 70cc kit
Dellorto 14/14 carb clone
K&N direct coupled cone filter
Sized boost bottle
20 tooth rear sprocket
Technigas Next exhaust or Techno Circuit Racing or Bi-Turbo, depending on what and where ped is being used.
Rear tire 2.50 x 16 Sava slick on Streetmate swing arm, wheelbase 3" longer.
60 jet at present
Oil injection removed, 40:1 full synthetic Ipone
Tomos fairings and all plastic removed except left side of motor
Puch Magnum headlite and fairing added with side lites
Bobbed front & rear fender(inner fender removed)
mini signal lights
European rear light and tag holder
Honda dirt bike seat modified to fit
hydraulic rear adjustable shocks
Altitude 422 ft

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re: Post your jetting info here!

Postby ped58 » Mon Jun 04, 2007 3:19 pm

2005 Revival
A-55 engine with Airsal A-35 kit
A-35 stock carb, intake & airbox
Technigas Next exhaust
Jetting 58

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re: Post your jetting info here!

Postby samsporter » Tue Jun 05, 2007 7:12 pm

1977 Puch Maxi
E-50 engine with Athena 70cc. Double reed valve kit.
Amal 17mm. carburator
Biturbo exhaust
jet size #45 (@8,000 ft. stock was #65)
Air filter Amal screw on screen came with carb, no airbox

1977 JC Penney Pinto
E-50 engine stock
Bing 12mm. carb
stock exhaust
Puch Magnum airbox
jet size #50
needle set 2nd from top position
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re: Post your jetting info here!

Postby Ike » Tue Jun 12, 2007 10:57 am

2006 Racing Streetmate ("Dago Red" }

A35 Airsal kit, stock A55 head
Stock SHA 14/12 carb.
Stock A35 Intake
stock A55 airbox
Tenigas Next "R" pipe
# 58 jet
Oil injection removed.
960 FT. ASL

Radared at 46mph out of the box.

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and only Tomos can make a Moped!
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re: Post your jetting info here!

Postby CityMoped » Sat Jun 23, 2007 10:07 pm

2006 Revival.
A55 Stock Engine.
Tomos Performance Pipe.
Reworked Stock Airfilter.
Stock Dellorto Carb.
56 Jet, 28 Sprocket.
Sea Level.
Standard Tomos Performance Kit.
Excellent Performance.
300lb. Load 60-65KPH.
Performance improved after 3200 Kilometers on engine.
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re: Post your jetting info here!

Postby KaineOfElderon » Thu Jul 19, 2007 5:23 pm

I have 2 bikes

1)2002 Tomos Revival
a-35 Euro 70cc kit
Anamal 17mm carb
2 piece bi turbo
27th front sprocket
20th rear sprocket
size 62 jet
stock idle jet
No Reed valve(removed and custom fabbed replacement valve)
14,029 mileage on bike
Top Speed 61mph by police radar(and ticket)

2)2005 Streetmate
stock a-55 engine(debating on either using spare a-35 kit or getting a-55 kit)
24th rear sprocket
26th front sprocket
stock exhaust(soon to be replaced) drilled out
stock airbox modded(used the arrow air box mod)
stock jet(soon to be 60 or 62 jet)
stock idle jet
Replaced stock handle bars for revival handle bars(taller and more comfort)
replaced front head light with modded 77 harley head light
modded stock transfer from engine to carb
1,649 Mileage on bike
Top Speed 42 mph
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re: Post your jetting info here!

Postby flim » Thu Aug 02, 2007 3:08 pm

Batavus City with a Anker-Laura M48.
11 mm Encarwi with a #52 jet.
Stock exhaustpipe and muffler.
Slightly widened the exhaust port.
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re: Post your jetting info here!

Postby tomosLX » Tue Aug 07, 2007 12:31 pm

2005 tomos LX A35
-airsal kit
-technegas next "R"
-K&N filter
-64 jet
-stock carb
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re: Post your jetting info here!

Postby xrongor » Sat Aug 25, 2007 7:59 pm

QT60 (yt60 cylinder):
stock QT50 head
stock exhaust
drilled out stock airbox
bp7hs plug
41:8 rear end gearing (not qt, not pw, chinese pw copy)
4000 ft elevation
70 jet

stock QT50 with holes drilled in the stock airbox:
65 jet

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re: Post your jetting info here!

Postby m6onz5a » Wed Oct 10, 2007 6:54 am

1995 Tomos TTLX
Stock motor
15mm carb with #68 jet stock filter no airbox
28T front & 22T rear sprockets
Biturbo exhaust
Does 40+mph
Elevation approx. 170ft.
199? Puch Korado
1978 JCPenny Swinger
1978 Motobecane 50v (yellow)
1978 Motobecane 50v (orange)
1978 Puch Maxi ZA50
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Kinetic TFR

Postby macelius » Wed Oct 24, 2007 8:29 pm

1997 Kinetic TFR
Polini long pipe exhaust
Polini 65cc kit with Vespa Si style head
Dellorto 13.13
Malossi style airbox with oiled black foam filter.

I started the break in with a 70 which was quite rich. I am now back down to the 66 that came stock with the 13.13. and my plug is nice and lighter brown now. You may need a bigger jet if running a fatter expansion chamber exhaust like proma circuit or bigger kit like the malossi 70cc. One guy here in Seattle runs just fine with that setup and the 66, says his plug chops are coming out tan, but the guy on ran lean and soft-seized.

The stock jet was a 45 which works fine in India or for hot weather or high altitude, but it's usually too lean for the US. Cosmopolitan motors usually up-jets to a 48 before they ship on their stock new bikes for the USA.
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re: Post your jetting info here!

Postby typ2 » Fri Nov 02, 2007 7:17 pm

1986 Puch
One speed engine
15mm bing with stock air filter
Jet #58 in warm temp and #60 in cold dry
Tecno circuit
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