motorcycle fuel question

[hipshot]

not v r specific,but motorcycles in general.

does the oem fuel filter "calibrate" or restrict" the amount of fuel that is delivered to the carbs?

if you replace the oem filter, with a larger bore "inline" filter,would that in turn reduce your gas mileage and power?

 

this is about a kz1000. two like bikes, one has twice the power of the other,and twice the fuel effeciency. just wondering if the fuel filter might be the reason.

just jt

[Yammer Dan]

Does the one with twice the power have the better MPH? Don't sound like fuel problem if that is so. Could be WAY WAY out of sync. Or maybe one plugged.

[hipshot]

yes ,dan, the one with twice the power gets twice the mileage.

low mileage is a 98 model.high mileage one is an 02 model. other than that , they are the same bike.

the low mileage one has an inline fuel filter, the high one has oem filter.

 

still think it is a sync problem?

 

just jt

[Monsta]

More power + more fuel efficiency just doesn't compute. Those two things are not synonomous.

 

I would suspect a mechanical problem but since you have access to both bikes, why don't you just swap the filters and see. Although I highly doubt it is the fuel filter. The floats will prevent any overfilling.

 

Check the air cleaner and then pull the plugs and "read 'em".

[Yammer Dan]

Way way out of sync or something plugged.

[Condor]

Could also be a spark advance vacume sensor that isn't functioning.

[V7Goose]

To answer your original question - no, the fuel filter is not causing any of the things you are experiencing, and no, the stock filter does not (or should not) materially restrict the gas flow.

 

Bottom line on fuel filters is this - they should always pass as much gas as the engine is trying to suck. The amount of fuel that enters the cylinders is limited by the carbs or fuel injectors, and it is also related to the amount of air being sucked into the cylinders.

 

The only negative impact a fuel filter can have is to get clogged and not allow enough fuel to reach the carbs. This will rob power, and it can especially show up when the engine is pushed hard and trying to suck the maximum fuel.

 

Your problem sounds more like restriction in the air flow. How about the air filters? If they are clogged, then you will be running very rich, have poor power AND poor fuel economy. Pull the plugs and see if they are sooty black to confirm this possibility. Good luck,

Goose

 

BTW - have you done a compression test and verified that all cylinders are firing?

[KingSizer]

I don't know if this will help but, I had an 82 kz1000 that had NO fuel filter when I bought it. The fuel line went right from the tank to the carbs. I replaced all the fuel lines and spliced in a $3.00 inline clear fuel filter from Advance Auto. I didn't notice any difference in performance and when I rolled on the throttle and looked at the filter I could see the suction pulling more gas into the filter, as much as it needed. The filter never went completely empty and never filled up all the way, regardless of how much or how little throttle I was giving it.

I think I would try to sync the carbs like several have mentioned already.

Good Luck.

[pegscraper]

Have you checked and compared the carb setup - things like float level, jet sizes, and needle position? Having two of the same bike or car makes diagnosing things like this much easier. Shoot, try swapping the entire carb setup and see what happens.

[hipshot]

i thank you all for your support and knowledge, i will start with the k&n air filter ,and check out everything ,from that point!

just jt

[Condor]

Still think it's the ignition advance not working on the older bike. Lack of power and low MPG is usually indicative of that.

[GeorgeS]

The one with half the power, burning twice the fuel, has got a Major Problem of some sort!!

 

Such As

 

Very Rich Mixture, Pull the plugs, see what they look like.

If you don't know how old the plugs are " Replace them "

 

Replace the Plug Wires !!!

 

Do the spark plug Resistor caps appear to Ever Have Been Replaced???? If not, Replace them.

 

clean the Air Filter, and Replace.

 

Pull out the Carb Diaphrams, check them for Holes in the rubber

if the Carbs do indeed have rubber diaphrams.

 

Put some Fuel Injector cleaner, or SEA-FOAM in the gas and run a tank thru, to Clean the

Carbs.

 

Check Crank case Breather system, does it have a filtered air intake?? if so, clean it.

 

Is it Necessary to set the Timeing on this Engine??? If so, did sombody screw it up???? Check timeing with a good timeing light.

 

Check the Carb " Idle Mixture needle valve screw position" What should it be set AT ????, check service manual, Reset these to correct position, a good start point would be about 2 1/2 turns open, then do a Carb Sync, YOU NEED A CARB SYNC ING TOOL TO DO THIS.

 

Check for Vaccume leaks!!!!!!!!!! Replace any rotten vaccume hoses, and check the Intake manifolds from Carbs to the Intake point at each cylinder !! Do you hear any sucking sounds at the Intake manifolds ??

 

There should be a Vaccum port on each Intake manifold, It should have a cover on it. Is it there???

Is it made of rubber?? Is it Leaking ??? If they look rotten, replace them !!!

 

Has sombody INcreased the Size of the Air Feed to the Air Cleaner ????? If the Intake is to big this might be a problem.

 

VALVE CLEARENCE !!!!! Check the Valve Clearance settings !!!

 

From what you have said, there deffinatly is something wrong with this bike!!

[bisquit]

Just so ya know JT. The air filter is new, the plugs are new, the compression is fine. The valves were checked recently and the carbs synched at the same time. I ran a bunch of Sea Foam through it. I think the problem is the diaphrams. It wouldn't hurt to pull the carbs completely off the bike and and tear them down for a good cleaning, and then re-synch them. Kinda like the idle problem your bike has, it almost has to be in the carbs. Next question is which one do you wanna tackle first??? Yours or mine???? With colder weather coming...someday...this would be the perfect time to do them both. I have the service manual for mine. Lemme know when ya wanna get started........Don

 

I have a K&N filter for my bike so dont go buying one. I doubt you would anyway cause they are higher than a cats back..$170.00 from Yamaha/Kawasaki...