Leaning Out Fuel Without Rejetting Carb

GoldenMotor.com
T

TheE

New Member
Jun 26, 2009
185
0
0
Canada
My bike is running too rich. I have the "E" clip on the highest setting, and it's still causing a black plug. I get the feeling it's because Zoom uses the same carb on their 49cc and 66cc engines.

Rejetting the carb seems to involve calipers and really tiny drillbits- two things I don't have. This is where I ask the experts here: Is there a simple way to lean out the fuel:air mixture? I've tried taking off the air filter and closing the fuel petcock, but it didn't make much of a difference at all (the fuel flows better with the petcock closer to the "off" position). I was thinking of drilling a really small hole somewhere to create an intentional air leak, but I'm sure that's a stupid idea.
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,271
1,810
113
Los Angeles, CA.
DO NOT run your bike without the air cleaner! road dirt & tiny rocks can go straight into your engine!
& definately DO NOT drill holes to make a air leak!!!

If you can't solder & re-drill the jet; You can just take out the jet, take it to a motorcycle shop & order a smaller jet or two...

What ratio are you mixing your fuel at??? & how many miles are on the engine??
 
Last edited:
C

city of angels

New Member
May 24, 2009
470
0
0
tucson az
you suposed have your e clip second from the top down also what kind of mix ratio are you running the way it sound you are using way to much oil cut it down right now i am using amsoil oil at 100:1 it works great i had the same problem you did i change the spark plug and switch to amsoil oil and i dont have this problem anymore
 
T

TheE

New Member
Jun 26, 2009
185
0
0
Canada
I'm running two-stroke Quicksilver Marine synthetic oil at somewhere between 24:1-32:1 (I ballpark it). It's an outboard oil, but they say it's good for air-cooled engines too. The engine has over 100km on it now. I was thinking of mabye filling up the jet with JB Weld and then using a sewing needle or similar to bore out a smaller hole, would that work?
 
Last edited:
Bikeguy Joe

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,837
252
63
up north now
I would not try JB for that purpose.

You can do a few things to "lean" your engine.
Drill some holes in the air cleaner cover.
24:1 is "leaner" gas to air than 32:1.
Buy a new jet.
 
spad4me

spad4me

New Member
Jan 20, 2008
472
0
0
Arizona Bullhead
This works 4 me remove the stock jet.

Remove the two screws that hold the bottom of the carb on.
The bottom of brass tube is where the jet is located unscrew it .
If the whole tube comes out just unscrew the end.
screw the tube back where it came from.

Select the smallest bread tie. you can find remove the wire inside .
You want a really thin steel wire.
This is what you will use.

Get some solder, Dollar store solder is fine.


4 me a needle was too big.

Run the steel wire from the bread tie through the hole in the jet, it should be loose.
Gently bent it into a big circle .
Holding the jet bread wire set up with a pair of pliers.
thrust his into any flame source stovetop, charcoal, small wood fire, propane torch, etc.
when it is really hot touch the end wire and all with the solder and allow to cool.
When safely cool after about 5 minutes.
Gently pull the bread wire from the soldered opening with a pair of pliers.
You should have a much smaller jet to try.
I use the bread ties from dollar store trash bags myself .

Trial and error.
Lots of error.
Good luck.
 
T

TheE

New Member
Jun 26, 2009
185
0
0
Canada
Thanks spad4me, I'll give that a try next chance I get (might be a while, gotta burn through all the fuel currently in the line)!
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,271
1,810
113
Los Angeles, CA.
Doood.... the tiny drill bits are 50 cents a piece at the hardware store!!! & WAY more accurate the a bread tie or a needle!!!!!!
Take the jet with you to the HWS, find which drill bit is the same size as the jet, & then buy that one (incase you need to drill it back to stock) & buy the next smaller two.

Also... don't use marine oil... it's made for water cooled engines, NOT air cooled!!!
 
Last edited:
thatsdax

thatsdax

Member
Feb 22, 2008
868
4
16
www.thatsdax.com
Mix 32:1. Use A 2 stroke oil that burns completely in the combustion chamber such as Valvoline 2 stroke oil. Also.. Joe is right that 20:1 is leaner than 32:1 fuel to air. But.. Joe.. That will confuse many.. Typically, mix ratios for 2 stroke motors is fuel to oil and 32:1 is leaner than 20:1 fuel to oil. Leaner meaning less oil per unit benzene. Also.. I would caution those that have the desire to lean their motors searching for the.... Perfect burn. As these are not high performance motors and any attempt to make these little motors burn "lean and mean" will shorten the life of these motors considerably. Fat is the burn you want if you want your little motor to last. Running them fat means they will sputter on the top and in the middle and will not give you the top speed you think or feel you should have.. But.. The motor will last. Also critical to a longer life is fresh air leaks. Check often for this and fix a fresh air leak as soon as it is found. If you have a really super good running motor that out runs your buddies on their bikes.. Then.. You probably have a fresh air leak. A fresh air leak is certain death for any 2 stroke motor. So.. Check it !! And.. Fix it when found.. And then.. Enjoy the ride....
 
T

TheE

New Member
Jun 26, 2009
185
0
0
Canada
VENICE BOY said:
Doood.... the tiny drill bits are 50 cents a piece at the hardware store!!! & WAY more accurate the a bread tie or a needle!!!!!!
Take the jet with you to the HWS, find which drill bit is the same size as the jet, & then buy that one (incase you need to drill it back to stock) & buy the next smaller two.

Also... don't use marine oil... it's made for water cooled engines, NOT air cooled!!!
Click to expand...
I looked on Canadian Tire's website and couldn't find any tiny drillbits. Mabye I was not looking at the right section, but anyways, no point in taking a trip for nothing. The oil I use specifically says it can be used in air cooled applications such as motorcycle and chainsaws as well as outboard motors. Unless they're liars, I should be good =p

Anywho, I tried the "solder and breadwire" method. I made it too small and then it ran too lean, lol. So I drained the fuel, and used the lead from a germanium diode instead to set the hole. The lead was wider than the twist-tie, but narrower than the original jet, and guess what?

It works perfectly!

Yes, the power is spread more evenly across the throttle and it runs much smoother. I have it on the second notch from the top now, so I've still got some play for fine-tuning. I'll ride it for a bit and then pull the plug to see where I'm at on the mixture.

@Dax: I hear what you're saying. I'm no expert, but I didn't think it was good to have the plug a black charcoal colour either. I'll try keep it on the rich side though.

Anyways, the reason I bought a cheap motor was so I can tinker around and learn. All part of the experience, right?

Thanks for the help, guys. I'll keep an eye out for a proper drillbit on my next trip to the HW store.
 
spad4me

spad4me

New Member
Jan 20, 2008
472
0
0
Arizona Bullhead
VENICE BOY said:
Doood.... the tiny drill bits are 50 cents a piece at the hardware store!!! & WAY more accurate the a bread tie or a needle!!!!!!
Take the jet with you to the HWS, find which drill bit is the same size as the jet, & then buy that one (incase you need to drill it back to stock) & buy the next smaller two.

Also... don't use marine oil... it's made for water cooled engines, NOT air cooled!!!
Click to expand...
I do not want to buy a kit for fifty dollars. Plumbers propane jet kit Ouch!!!
I have ace and lowes .
They do not sell small drill bits for 50 cents locally.
I wish they did.
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,271
1,810
113
Los Angeles, CA.
I think they are called "jewelers" drill bits... If I remember correctly, #70 is stock, & I usually drill the jets to #71 or 72 to get the right jetting... (bigger # being a smaller bit)

Also... after you solder the jet closed, there is usually a drip of solder inside the jet, I try to get as much of that out too. because the needle tip goes down in there.
 
Last edited:
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Also called "Orifice Drills". Used by air conditioning and heating techs to redrill gas orifices in natural gas and propane appliances.
Tom
 
Venice Motor Bikes

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,271
1,810
113
Los Angeles, CA.
The store I bought my bits from also sells drill bit guages... The guy at the store let me use one to check & lable each bit before I bought them.
To this day, each bit has a little masking tape flag on it with it's size, so I don't get them confused. ;)
 
B

buzzkill

New Member
Aug 22, 2009
24
0
0
atlanta, ga
I trick I try is I take out the jet, then I cut a small circle peice out of a soda can that fits into the hole the jet goes in, once I have that done I take it out put on a peice of wood and using a needle with a small hammer I poke a tiny hole in the center of the piece of can, very tiny hole. I then put it back into the jet hole and screw the jet back over it to hold it in, if it's to lean I take it out and poke the hole a little bigger, if still to rich I try again trying to make even a smaller hole and just keep trying till you get it right. It's not the best way to do it but it works.
 
You must log in or register to reply here.
Top Bottom