37
votes
Symptoms of Lean or Rich carb settings on a motorcycle
Lean and Rich Symptoms in Motorcycle Carburetors
In your post you indicate that some of the symptoms you have read are contradictory. I will try and clarify between the two conditions and attempt to ...
- 33k
16
votes
Accepted
Does a carburettor engine apply fuel at high speeds when the pedal is no longer depressed?
At a base level, carburetors meter the amount of fuel they let into the engine by the amount of air that is moving through them.
Vacuum is created by the piston moving in the engine and creating an ...
- 176
15
votes
Does a carburettor engine apply fuel at high speeds when the pedal is no longer depressed?
Carburettors are very crude in comparison to EFI systems, and so the amount of fuel entering the engine is simply a factor of the amount of air going in, which is controlled by the position of the ...
- 28.7k
14
votes
Accepted
Motorcycle Four Body Carburetor Synchronization Balancing
Background
Multi-cylinder vehicles with multiple carbs
To port this question over to applicability with cars. This is the same issue that has plagued older Ferrari and Jaguar mechanics over the ...
- 33k
10
votes
Does a carburettor engine apply fuel at high speeds when the pedal is no longer depressed?
Carburetor Circuits Will Still Pull Fuel from the System
If the engine is running on a carbureted vehicle, off throttle or not, it will consume fuel.
Throttle Settings
There are three basic ...
- 33k
8
votes
Accepted
Is it possible to fit mashroomhead air filter in Honda Stunner CBF 125?
I wouldn't
You have a carburetor on that bike. You may need to do some adjustments, if not, you will make the air fuel ratio leaner and that will be really hard on your exhaust valves.
The more ...
- 33k
8
votes
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Basic operation of a choke valve
You should avoid over-use of the choke if possible, as over-fuelling the engine will cause more carbon build up, shortening the life of the plugs and reducing the time before the engine needs a "...
- 28.7k
7
votes
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Bad pitting on carburetor causing small fuel leak
JB Weld is gasoline resistant.
I would disassemble the carburetor and inspect suspicious cracked components prior to applying any epoxy to the surfaces.
Ensure components are absolutely clean
...
- 33k
7
votes
Accepted
Carb. Rebuild or Adjustment?
I'm not a watercraft Mikuni guy, but I've dealt with a few two-stroke carbs that work in this manner.
There's a few possibilities:
The internal filter screen is clogged, but I'm discounting this as ...
- 12.4k
6
votes
Carburetted motorcycle stalls when accelerator is applied
A free flow exhaust requires more fuel to the engine
The baffles created back pressure in your exhaust system that restricted the flow of the exhaust gasses. When you removed the baffles it allowed ...
- 33k
6
votes
Accepted
Testing automatic choke on a scooter
How the choke works
The choke of a scooter consists of a dedicated choke nozzle in the fuel reservoir and two narrow drillings leading to the venturi (the pipe where the air goes through):
When the ...
- 7,047
6
votes
carburetor failure in yamaha dt lanza
The DT 230 Carburetor will fit on some DT200's
The 1999 model of your bike uses the Mikuni TM30x1 Flat Slide Carburetor
Older models use a different carburetor model. The slide is round.
Here is ...
- 33k
6
votes
Accepted
Yamaha Seca - Motorcycle Idle problems
More than likely, you have an air leak
If you haven't cleaned out and rebuilt a bunch of 4 carburetor banks in your life there is a good chance you have accidentally created an air leak in the system....
- 33k
6
votes
Can't start a Kawasaki GPX 750
Your carbs are clogged with varnish and bad gas
The remnants of gas that has evaporated are a gummy hard varnish inside of your carburetors. You have a bit of work to do.
You need to completely ...
- 33k
6
votes
Accepted
How to troubleshoot carburetor?
These symptoms are typically caused by one or more blocked jets in the carburettor.
Small particles of grit can block any one of the jets in carburettors. The fuel still gets to the engine through ...
- 1,432
5
votes
Vespa PX 150 Fuel and Carbon issue
Your experiencing fouled plugs. Fouled plugs have carbon buildup that grounds the electrode of the spark plugs over the ceramic with carbon. The carbon buildup occurs because the AFR (Air Fuel ...
- 33k
5
votes
Accepted
What is the yellow precipitate in my outboard's carburetor?
Those are the remnants of gasoline
When you let gasoline evaporate it leaves behind various elements within the gas that can't dissipate through evaporation.
These remnants can clog various galley'...
- 33k
5
votes
Can't start a Kawasaki GPX 750
It sounds like your carb(s) are plugged and need cleaned. If the fuel in the carbs has ethanol in it, the carbs are going to be caked with crap. The floats could be ruined. There are a lot of things ...
- 153k
5
votes
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Motorcycle bogs down under load
You are describing a lean condition
The more you open your throttle the more vacuum you are creating in your carburetor venturi and your intake manifold. When you are operating at higher RPM any ...
- 33k
5
votes
Accepted
Adjust carburettor without hi-speed adjustment
Yes, you can bend the tab
The metering diaphragm enriches the entire range on every circuit. If the fuel level is higher it will require less vacuum under Venturi's Law to pull the fuel from the '...
- 33k
5
votes
Accepted
Properly draining a motorcycle carburetor
A few minutes of fuel leaking is more than you should expect. Usually, when you drain a carburettor, if the fuel lines are full as well as the carburettor, I expect about 10-15 seconds maximum. If ...
- 5,245
5
votes
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07 Suzuki Boulevard S40 leaking gas
Sounds like the carburetor, float, and/or float valve may be dirty.
NOTE: A service manual will be extremely helpful as you go thru this process.
There is no reason to take this carburetor apart ...
- 9,035
5
votes
Accepted
What is this tube coming off from 1 of 2 motorcycle carburettors?
Well... Mr google said:
The OEM petcock is vacuum actuated. With a properly operating petcock,
unless the engine is producing vacuum the petcock will not flow
gasoline while in the ON or RES ...
- 12.4k
5
votes
Accepted
Purge carburetors on Yamaha XJ 600
I finally got the motorbike to start!
As suggested by @Pᴀᴜʟsᴛᴇʀ2 in question comments, I purged both the carbs and the tank.
The picture is not that great, but the fuel in the right jar on the last ...
- 201
4
votes
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Rough idle while warming up, goes away after a tiny rev
You have two separate idle settings on your carburetor.
One is for the choke idle and the other is for your off-choke idle.
When you start your vehicle in the morning the idle setting will be fixed ...
- 33k
4
votes
Lost torque on my Yamaha XVS650
If you synchronize and clean the carburetors the bike will not have the same power that it did before you removed the baffles from the exhaust system.
The baffles created back pressure in your ...
- 33k
4
votes
Accepted
Why does the bike idle lower after balancing carburetors?
Background
Multi-cylinder vehicles with multiple carbs
To port this question over to applicability with cars. This is the same issue that has plagued older Ferrari and Jaguar mechanics over the years....
- 33k
4
votes
Basic operation of a choke valve
What is the optimal use of a choke?
Knowing how to use it as explained by Nic C
What are the cons of using it incorrecly?
Fouling spark plugs which will cause a misfire even after it warms up.
...
- 8,010
4
votes
Accepted
What fuel lines are recommended for a propane carburetor?
In Australia, our Automotive LPG hose standard is:
• AS/NZS 1869 class D
According to the following document, it appears that in the US propane hoses for automotive use needs to meet:
• NFPA 58, ...
- 1,586
4
votes
Dirt bike carburetor problems
Replace the float as well. Sometimes depending upon what material it's made the float can be somewhat soaked with fuel changing the weight of it.
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