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5

The secondary venturi act as a second carburetor when there is a demand for more fuel. When an engine is designed the carb must be large enough to flow enough fuel and air for the entire RPM range. A single barrel (venturi) carb large enough for the higher RPM range may flow inefficiently at low RPM. A carb small enough to flow efficiently at low RPM may run ...


4

Don't worry, you're not the only one who had to endure this pain... I had an old KZ650 I pulled the carbs from what it looks like a similar design. Like yours, it was older and the plastic air intake tubes were very stiff. Here is what I had to do. Pull gas tank off and disconnect from carbs. Pull the seat off to access the air filter and air box. Pull ...


4

You said that it is leaking from somewhere "under the tank" and then jump directly to the carbs. If it is the carbs, you'll probably have to tear into them. If it is from under the tank, there are a few things you can check: Is the tank intact? You may have rust burrowing through the tank and causing leaks. This is bad. Should be visible in the fuel ...


4

I need to get a carb kit and just haven't gotten around to it. A carb kit for a 1975 Honda may be harder to find than you think. You'd better start searching for that now or maybe even a used carburetor, if you can find one. My guess is the obvious one: Something did not seal when you worked on your carburetor. Pull it apart again. You missed ...


4

I'm not an expert on bike carbs, but if they are the same as car ones there will be two settings - one for mixture and one for idle. Once you have them balanced, you'll need to adjust these to get the right levels, while still keeping the pair balanced (i.e. increase the idle on both by the same amount, then check the balance, then decrease the mixture a ...


4

Gasoline sitting for two years in the float bowl of a carburetor will surely lead to some varnish. The hydrocarbons evaporate from the fuel and oxygen acts as an oxidation catalyst changing the remaining components into other compounds leaving varnish in their wake. Varnish will coat and clog the inside of the carburetor. Float bowl, floats, needle and ...


3

Simply cranking the car for 10 - 15 seconds should prime the carb. Crank the car for about 15 seconds Stop for about 15 seconds Pump the accelerator petal twice Crank the car again, if it doesn't start immediately keep cranking the car for a maximum of 15 seconds. Stop Wait at least 2 minutes, this is to prevent damage to the starter. Then go back to step ...


3

If by "spark plug was dirty" you mean "black and sooty" then you're running rich and need to either lean out your mixture or double-check your air cleaner and make sure it's good. I know my old 73 CL125 would occasionally accumulate an impressive amount of dead leaves and pine needles around the screen of the air filter. Only took a few seconds to pop off ...


3

Found the culprit the jets were fine, however the float bowl was full of residue and water, as well as the jet carrier bolt being snapped in half so the jets were moving along to where they were not able to fuel the cylinder. After a full strip down, rebuild and calibration its now firing on both cylinders correctly.


3

A shop manual (particularly one with colour photos) will offer some spark plug diagrams / photos, to compare against your plugs, but they're not particularly useful. As you said, claims are contradictory. The problem is, that a symptom of too lean/too rich is that it doesn't run as well as it should. That's both ways. So a too-lean symptom for one person is ...


3

An air screw on a Keihin PWL26 effects the idle circuit of the carburetor. The idle circuit pull through the pilot jet exclusively. The pilot jet typically can deliver no more than 15% of the overall fuel when the throttle is wide open. The claim of 15% is based upon the inside diameter of the pilot jet and the inside diameter of the main jet. The air ...


2

On my old bike I had to pull the fuel tank off to get the carbs out. If anything it will make the job much easier in terms of access for your hands.


2

Two main reasons: Already some races require restrictor plates to keep the speed down, so swapping out the carburetor for modern fuel injection would increase the need for restriction. It is easier to inspect and monitor a carburetor, therefore it is more fair for each team since it is harder to cheat (or at least easier to get caught). However, from ...


2

In addition to Troggy's sequence, make sure that the clamps on the airbox boots, and the intake boot are fully loose with some slack, and using some heat from a hair-dryer or heat gun will make the rubber boots much more supple.


2

I'll assume first that you've tried spraying carb cleaner into it since you've had it out, so your question is more about what other adjustments there are, specifically relating to the idle. Beyond the Mixture screw you mentioned, there is usually 'Pilot Jet(s)' that allow some fuel regardless of RPM (as opposed to the 'Main Jet(s)'), and if they get gummed ...


2

The back pressure and flow change of the exhaust will have an effect on the combustion and mixture. Usually with a free flowing exhaust, you have to rejet the carb a little richer and with a free flowing airfilter, doubly so. Running it without an airbox is making it worse, the mixture is already lean and stuffing more air down the bores isn't going to help ...


2

Yes, you can install it, but no, won't do anything for fuel consumption. Carburetors don't automatically adjust themselves to take advantage of new fuel characteristics or other changes in the engine's combustion characteristics. Nano fuel economizer does the same job that your engine oil does. So, if you regular put new oil in your car, you're already ...


2

A carburetor is a carburetor: it doesn't matter what kind it is - it allows air to flow through it and meters the fuel to produce the optimal air/fuel ratio to allow the engine to run. That said, you'll have two things to look at: First, fitment. Will a different carburetor physically fit within the confines of the current carb? Will the carb output size ...


2

I'm not sure if the answer is still relevant, but I own the XR650L big red pig and may say that it's rather safe to mess with the carb of this bike even if you don't have specific skills. It's very forgiving unless you do something really wild. I used to ride about 500 km on my with mixture being extremely lean and was lucky enough to have my engine ...


2

Your best bet is to get a replacement carb. Some have had good luck rebuilding them, but for the trouble of it, it's just a lot easier to buy a new one off the internet. Personally, I can never get them to run right after a rebuild. You can usually get one for less than $50 depending on the model. After you put a new one on, ensure you have a cut off valve ...


2

The 1998 XL650 has a fuel petcock that has a safety feature on it, as do many other bikes of the gravity feed carb era from about 1980 to present. Since you are running an XR650 you should not have the vacuum line. There is a vacuum line that runs from the manifold side of the carb to the petcock on the XL650. When the engine is turned over and creates ...


1

You might expect about 19.6 km/l (all things perfect, maximum efficiency), but 14.5 km/l highway to 11.5 km/l (city) is realistic if fuel/ignition/engine are in excellent condition and the tires are correctly inflated; those numbers are original factory spec. There are physical limits to the efficiency one might expect from any given car due to weight, wind ...


1

Your description is making me question your diagnosis so far, in terms of is it one cylinder affected or all. Because a GSXR should be able to run (badly) on 3 cylinders, and cleaning the fuel cap shouldn't make a difference to just one cylinder. From your description i'd start by replacing the fuel and ensuring it flows freely to the carburettors. (is it ...


1

This is a carburetor issue, most likely caused by ethanol gas. Ethanol laced gas reeks havoc upon small engines. The easiest fix for it is to purchase a new carburetor for it, due to paying the price for a replacement carb outweighs the cost in time and frustration which will be brought upon you trying to rebuild it. I have tried to rebuild small engine ...


1

I had the same problem with my Katana 600. Ran some Seafoam through it and it got better, presumably cleaned up any deposits from gas sitting in the carbs too long.


1

In the images I've seen of the engine/carb setup, the original rubber intake manifold piece, due to design, could not be made out of metal. You still need a way to attach it to the engine, and that is going to be some sort of rubber part to connect the two pieces. Due to this, I have two suggestions: Make a mount out of metal which would go between the ...


1

Your automatic choke has failed and is not closing as it should when cold. If you want very much to keep the car original or just don't want to deal with a manual choke, then you'll need to find a replacement automatic choke actuator that works for the Stromberg. If, on the other hand, you'd just like to get the car functional again, then you can easily ...


1

UPDATE This Answer was valid until recently. BikeBandit.com stopped carrying Ducati. Ducati Omaha does carry schematics online that allow the below answer to work, but they only have schematics 2000 and newer. However, their webpage says "For Prior Years - PLEASE CALL, we have access to the parts catalog back to 1993 for most models. 402-934-6627" ...


1

I figured this would be the problem. Turned out someone before me forced an SAE 1/4" bolt into the M10 hole on the engine block, and that's exactly where the vacuum leak was. I had a mechanic put a helicoil in, and the problem has gone away.


1

This to me sounds like some form of vacuum actuator that's leaking somewhere under load. I would look for any dry or thinned out vacuum lines. I had something similar happen, though it was on a throttle body injected truck. Enough vacuum was pulled that a line either collapsed or flattened out enough for it to get pinched by something. Either way I would ...



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