GS1100GK outrageous fuel consumption.

[sv650]

Here's my tale of woe; I hope someone on this forum can help

Last fall, I spent some time cleaning the carburators on this '83 GS1100GK. It was then sent to the local Suzuki shop for a final tune up -- balance the carbs, check and adjust the valves, etc. This spring, when I picked it up, it seemed to run well (it could not be road tested due to late spring weather). However, when I took it out for a run, it got about 9 (yes, 9) MPG.

Upon return from the ride, I oiled the air cleaner as it was dry as a bone, and took it for a short spin, but still could watch the gas guage drop.

When idling in the driveway, there are no liquids accumulating beneath the bike, so I assume that all the fuel is being consumed.

I have not ridden this bike in it's 'natural' state, but it does not seem to have the 5th gear roll-on power that I would expect from such a large displacement bike -- my SV650 seems to generate more acceleration in top gear.

I have not yet checked the spark plugs, but the bike does not seem to have a rough idle, and starts easily, hot or cold.

Compression was tested by the shop, and reported as: 120 115 110 120, which seems low, especially for a low mileage engine -- there is less than 10,000 km on the odometer.

There appears to be no loss of gas into the crankcase, through the exhaust, or other places, but the 22 litres must have gone somewhere! There are also no noticible losses past the petcock while the bike is parked.


Any ideas or suggestions?

David

[earlfor]

Re: GS1100GK outrageous fuel consumption.

I cannot imagine the bike could be burning that much fuel and not flooding out. Remove the spark plugs and check their color. The color on the center ceramic is what you want to look at. Also, how do the electrodes on the plugs look?

Earl

Here's my tale of woe; I hope someone on this forum can help

Last fall, I spent some time cleaning the carburators on this '83 GS1100GK. It was then sent to the local Suzuki shop for a final tune up -- balance the carbs, check and adjust the valves, etc. This spring, when I picked it up, it seemed to run well (it could not be road tested due to late spring weather). However, when I took it out for a run, it got about 9 (yes, 9) MPG.

Upon return from the ride, I oiled the air cleaner as it was dry as a bone, and took it for a short spin, but still could watch the gas guage drop.

When idling in the driveway, there are no liquids accumulating beneath the bike, so I assume that all the fuel is being consumed.

I have not ridden this bike in it's 'natural' state, but it does not seem to have the 5th gear roll-on power that I would expect from such a large displacement bike -- my SV650 seems to generate more acceleration in top gear.

I have not yet checked the spark plugs, but the bike does not seem to have a rough idle, and starts easily, hot or cold.

Compression was tested by the shop, and reported as: 120 115 110 120, which seems low, especially for a low mileage engine -- there is less than 10,000 km on the odometer.

There appears to be no loss of gas into the crankcase, through the exhaust, or other places, but the 22 litres must have gone somewhere! There are also no noticible losses past the petcock while the bike is parked.


Any ideas or suggestions?

David

[KEITH KRAUSE]

Using your numbers, have you actually filled the tank, ridden the bike 18 miles and then put 2 gallons of gas in it to re-fill the tank? Or are your calculations based on the fuel gauge reading? The fuel gauges are famous for dropping too soon, making you think your mileage is poor.
If you do have a richness problem, the carbs could get varnished up from sitting from fall to spring as you said.
For it to actually get 9 mpg and still run fairly well does'nt make sense.

[Anonymous]

Outrageous fuel consumption

Hi,

At 9 MPG you're lucky that you aren't in the UK, we pay about $5.50 for a US gallon.

A 50cc moped looks more attractive each day.

Doug

[Sweaburg]

I just had the same problem on my 850....burned through 3/4 a tank in a 50km ride. Check that you're getting spark. I was getting VERY weak spark from two of the plugs and had to replace a coil.
Good luck

[sv650]

Using your numbers, have you actually filled the tank, ridden the bike 18 miles and then put 2 gallons of gas in it to re-fill the tank? Or are your calculations based on the fuel gauge reading? The fuel gauges are famous for dropping too soon, making you think your mileage is poor.
If you do have a richness problem, the carbs could get varnished up from sitting from fall to spring as you said.
For it to actually get 9 mpg and still run fairly well does'nt make sense.

Actually, I filled the tank, rode about 75 km before having to switch to reserve, so I am not depending on the guage reading.

I agree that to get 9 - 10 MPG and still run fairly well makes little sense, and was hoping that someone with more experience that I could shed some light on the situation.

I will be checking spark plug colours today.

David

[chuckycheese]

Jets

My guess is that it has something to do with your carb jets...one or more may be loose. I believe that could easily cause the problem. Please let us know!! (and good luck figuring it out; I bet it's something fairly simple)

[dpep]

I agree that the compression seems a bit low for 6000 miles. That is close to the point I consider these engines broken in. I would be a little cynical. But that level of compression is not the cause of 9 mpg. Since you aren't leaking any fuel the cause almost has to be mixture. But if I deliberately left my choke on as much as I could and still keep the bike running, I think I would get better than 9mpg.

In addition to the suggestions already given, check your brakes and make sure they are fully releasing. Can you push it around easily? I suspect there may be multiple causes.

My GK gets low to mid 30's (mpg) with a fairly brisk riding style.

[sv650]

GK

Still working on the beast.

I've just lowered the needles, and am giong to block the vacuum line to the petcock. Then take a test ride. The previous owner may have gibbled the jets with a wire -- I'm not sure.

The back brake drags the tiniest bit -- I renovated the caliper last fall, but may have to do a bit more work on that.

There is a dirty gassy drip from the LHS exhaust manifold that leads me to wonder about the inbtegrity of the petcock seals.

With a mid 30's MPG and a 6 US gallon tank, I figure that I should be getting about 250 km before hitting the reserve -- at 80 - 100 km I'm not even close.

Will post later with more info.

David

[redliner1973]

From your descriptions, sounds like your petcock is either messed up real bad, or you have been using it on 'prime' instead of 'run'. this can result in too much gas getting by the float bowls and going through the engine. This would explain your 'gassy drip'. also, if the petcock is full of crud, it could be making you go to reserve when in fact you have more gas than you think, giving teh impression of low MPG. Or maybe a combination of both. But that is where I would look first. Especially if you can suck on the petcock vacuum line and get any gas out of the vacuum line at all. :twisted:

[earlfor]

The float needle/valve controls the fuel level in the carb float bowls in relation to whatever you have the float heights set to. It does not matter if the fuel coming to the needle valve has been allowed to reach that point with the vacuum activated side of the petcock, or the gravity feed/prime portion of the petcock. The float needle shuts off fuel when a specific fuel level is reached in the float bowl regardless of where it came from.

Earl


[quote="propflux01"]
From your descriptions, sounds like your petcock is either messed up real bad, or you have been using it on 'prime' instead of 'run'. this can result in too much gas getting by the float bowls and going through the engine. This would explain your 'gassy drip'.

[redliner1973]

If the float needles are worn or dirty, or the o-ring is worn fuel can seep by these thereby flooding the engine and 'usually' ending up in the crankcase. this helps explain the many posts on here about oil level suddenly rising, and flooding problems. this problem is especially componded when the petcock is set to 'prime'. :twisted:


Quote: The float needle/valve controls the fuel level in the carb float bowls in relation to whatever you have the float heights set to. It does not matter if the fuel coming to the needle valve has been allowed to reach that point with the vacuum activated side of the petcock, or the gravity feed/prime portion of the petcock. The float needle shuts off fuel when a specific fuel level is reached in the float bowl regardless of where it came from.

Earl

[Anonymous]

either a leak in the fuel line between petcock and carbs or stiff chain and brakes .those are my guesses.honestly i picked up like 8 or 9 mpg just from a new chain once. Mark

[earlfor]

Under certain conditions, it can be, yes. I think we both know how a petcock works and how it interelates with a float needle, bowl and float. :-)
If you wish, we can continue with the thrust and parry for amusement sake. :-) :-) Dance sir?

Earl :-)


( this problem is especially componded when the petcock is set to 'prime'. :twisted: )

If the float needles are worn or dirty, or the o-ring is worn fuel can seep by these thereby flooding the engine and 'usually' ending up in the crankcase. this helps explain the many posts on here about oil level suddenly rising, and flooding problems. this problem is especially componded when the petcock is set to 'prime'. :twisted:


Quote: The float needle/valve controls the fuel level in the carb float bowls in relation to whatever you have the float heights set to. It does not matter if the fuel coming to the needle valve has been allowed to reach that point with the vacuum activated side of the petcock, or the gravity feed/prime portion of the petcock. The float needle shuts off fuel when a specific fuel level is reached in the float bowl regardless of where it came from.

Earl

[Dink]

Make certain your emulsion tubes ( the bit with all the holes that the main jet screws into the base of) if it is not fully seated, it will allow a lot of fuel past it. Disassemble your petcock and check the diaphram (if it is split it will allow a lot of fuel to flow into #2 and cause fuel to leak out the left side exhaust) it does however seem that the entire carb rack is running very rich, How is your spark? do you feel you need to use a lot of throttle?
did you replace the o-rings that go around the neddle seats?
Dink