95 VFouR burning gas like a V8

hey guys,
My 95 viffer has 14k miles on it and I have done a lot of general maintenance on it and it still burns A LOT of gas. I changed the air filter, oil, oil filter, new chains, fuel filter n sprockets, new tires. nothing seems to be helping.

any idea what the issue might be or where I can start looking? what am I missing as far as other maintenance goes? I bought the bike last Aug and only put 1k miles. Thanks.
thanks.

 

By A LOT of gas, what do you mean? A MPG figure would be helpful. These V4's aint the best mileage motors out there to begin with tho.

 

so here's the crappy thing. My speedometer and my mileage counter doesn't work because the speed sensor is broken (I think). so I have no way of knowing how many miles im getting. but what I do know is the tank shouldn't be emptying out as fast it does. i ride about 80-90 miles at the most and the tank is done. It def wasnt like that when I bought it.

 

Don't you have a GPS....? This can help you determine how many miles you ride and just add them up.
80 to 90 miles per tank is unheard off.

 

What do the plugs look like?

 

Yeah, Rangemaster is absolutely right, the plugs will tell you a lot. Sure sounds like carbs, any black smoke? Running that rich is hard on the oil. I get about 150-170 a tank on my 4th gen, but I ride it pretty hard. I know others that do better. At 80-90 miles per tank tho, something is definately wrong.

 

The sensor is an easily replaced item. It fits over the front sprocket bolt and it's not unusual for the flats that engage the bolt head to get rounded/stripped.

A possible mcgyfer fix would be to use some gasket sealer to help the surfaces mate.

As pointed out, w/o any figures it's hard to assess the problem.
How much gas are you pumping to fill the tank after your estimated 80-90 miles of running?

Any signs of gas leaking from the carbs?

The V4 is so smooth that you could be without spark in one cylinder and may not notice any roughness. (With you only having 1000 miles on it, you might not be aware of it being a bit down in power.) So in addition to looking at the spark plugs, check to see that you have spark to all of them. With that many years on it, a coil or associated wire could be bad.

 

Would think it would run very badly if sucking fuel at that rate.

 

We haven't been able to establish what the rate is.
I lost spark to one of my plugs on a trip and it didn't run badly at all, down in power yes and gas mileage took a big hit. That's why I'm raising the possibility.

 

I got my plugs replaced two weeks ago hoping that would fix the problem. I got NGK iridium plugs and my local mechanic replaced them. I'm pretty sure all the cylinders are firing. the bike still has the same amount of power is it did before. there is no black smoke at all. i asked whether i should clean the carbs and my mechanic said the engine is running so smoothly that it cant be the carbs. I put 93 octane gas and put about 3.5-4 gallons when I fill up. But today I topped it off to the brim at 4.5 gallons. how much do you guys put?

The gps idea is great, I will try that and see if I can guesstimate how many miles im getting. I dont smell a gas leak either. Its really baffling me now. thanks for all the help guys.

 

pic of the sensor

I removed the sensor from the front sprocket and this is what it looks like. is it stripped? Do I need a new one?

 

what if I try a gas treatment or something like SeaFoam? have any of you guys tried anything like this? thanks.

 

After a ride, cost to a stop and check each brake disc for heat; dragging brakes, caused by sticky brake pistons, will reduce mileage, but not to the extent of your problem.

Most likely causes would be low compression in one or more cylinders or improperly adjusted float heights or leaky float needles or dripping float bowl O-rings.

Also, a defective thermostat that won't bring the engine to proper operating temperature can be a contributing factor.

 

check the T stat sounds like mine when it was stuck open, also air temp sensor if it it fuel injected.

 

My money is on Squirrelman and the T-stat.

 

Your confidence is duly noted, but there are unknow unknown possible causes of that problem.

 

When they took out the old plugs, what color were they? Your mechanic should have given them to you. Were they all a nice tan color? This will identify/rule-out a lot of possible culprits.

 

Sorry for the delayed response, I didn't get any notification of new replies until today.

Hard to tell if your sensor is stripped to the point of failure or not. It is showing some wear, but doesn't look that bad in the pic. I checked the maintenance manual and can't find any testing methods described to check it to see if there's a fault in the circuit. With the ignition switch on, you could try spinning the sensor socket with a low speed drill and see if the speedometer indicates anything. If it shows speed, than the sensor is stripped. If not, check the wiring/connections and if nothing is obvious there, the break may be within the sensor, so I'd replace it and try again. Someone else may have a better method.

Regarding the stuck thermostat possibility - that won't cause the trouble you're reporting (the 4th gen is not FI).

Until you get some specific diagnostic info on the engine, it's all just guesswork and a hit or miss approach usually misses.
Based on your mechanics comments and since you haven't mentioned any engine stumbles/power issues, Seafoam or other gas treatments aren't indicated. They wouldn't hurt anything directly, but there's a possibility that some may contribute to o-ring/rubber deterioration, so I wouldn't use them in a bike that old unless there was an indicated problem that they might help with.

1 - Get hard mpg numbers.
2 - Check plug condition as has been suggested.
3 - Confirm spark because that's an easy and necessary check (though I don't know if a weak spark could occur and/or cause your issue).
4 - In the absence of any carb/fueling issues being indicated, do a compression check and or leak down test to see if you have engine issues. (Which may be the most likely issue at this point, but the above checks can be done on the way to setting up for either or both of these).

If that all checks out, then it's back to a carb/fueling issue of some sort in spite of your mechanics opinion.

Good luck