I mentioned this in a post on another thread, but I've been thinking about it and decided it's a serious enough concern to warrant it's own thread. Last night I rode 260 or so miles from Orem, UT where I live to St. George, UT where my grandparents live, for their 50th wedding anniversary. I think I averaged just over 30mpg the whole trip... I normally get between 45 and 50? I'm going to try pulling the spark plugs in a few minutes to see if maybe they are fouled, but if they are I don't know what to do.
What would cause these problems? What might fix them?
Also I'm headed home this afternoon... if I don't figure it out before I leave, I'll still want to know, but it would definitely be nice to figure it out before then.
I *think* there is a k&n air filter installed on it, but Kerry isn't around to double check that and I don't remember where the air filter is on the bike.
Thanks
Alright, followup. I just pulled the spark plugs, and they are both *very* white. I'm trying to remember what that means... I know I've seen it before on posts here.
I think that means I'm running lean... but I don't know why or how to fix it. any ideas? I'm running out of time, but this is a lousy time to hope for people to be on the list. ;-)
I can't see where "lean" is going to kill fuel mileage under steady state cruising. For sure, check the air filter before you hit the road. With mileage that bad, there must be other symptoms...? Or, at least bad math.
Air Filter is under the gas tank. You can remove the two tank bolts and slide the tank back a few inches. With one hand, hold the tank up and with the other remove the four air filter screws and remove the filter.
I don't think it being lean affected the gas mileage.. I think all the deposits on the spark plugs affected it. however, a cousin of mine (hey, I am at a family gathering) tells me that white actually means too rich... that would probably make more sense.
Anyone know what might be causing that? He says he thinks it's just the way the bike is, and there is nothing I can do about it... but he also admits he only knows cars.
Quote from: richard.... a cousin of mine (hey, I am at a family gathering) tells me that white actually means too rich... he also admits he only knows cars.
He has a problem with internal combustion spark ignition engines in general if he thinks white means rich.
White = Lean Light brown/grey = about right Dark brown/Black= too rich.
The stock GS500 tends to have plugs that are ALMOST white - but if you look down "inside" the plug on the insulator it will tend to be very light brown/grey. Whatever your milage problem is it is not the mixture. Check tire pressure, alignment, chain tension (a too tight chain will eat both the sprocket and a lot of gas) etc. Were you driving at unusually high speed? Mostly uphill? Into the wind? With a lot of luggage strapped on? All seem at least possible for a spring trip in Utah - and all would screw up you milage. Then again, you might just have divided wrong - check the tires & chain, fill it up and check the milage again before you get too whipped up about one tank with bad milage.
Normally, a little lean should get you better gas mileage. I agree that you should probably look elsewhere: look at tires, chain, bearing and... fuel leaks :) .
It sounds like you're guessing that your mileage is worse? Did you have to stop and refuel during the 260 mi.? If not then you're doing great.
260/4.8 (guess) = 54 mpg.
1. With the bike on the centerstand, top off the tank and reset the odometer.
2. Ride 100-200 miles and then fill the tank to the same spot.
3. Divide the miles traveled by the number of gallons added
miles/gallons = mpg.
:)
+1 on what mjm said. I would check your tire pressures. I had a gas mileage problem and just thought it was my heavy throttle hand :lol:
I added air to my tires and gas mileage shot back to what it was almost getting before :)
Small engines are affected more by things like the air filter being clogged. You said it was running lean though so I doubt its the air filter. If it were clogged, the bike would be running rich because of less air getting through
How is your chain adjustment?
Alright, I made it home, and here is some more info... the prob seems to be more serious than I thought.
First, it wasn't "just one tank" with bad gas mileage... I hit reserve at consistantly about 100 miles into each tank, each time. I used to hit that at 140-160, but over the last several months it's been decreasing slightly... but never like this.
I was going uphill in a lot of cases, but I've gone on worse rides (just as much luggage, worse uphill, and I rode it *hard*) and gotten tons better gas mileage... but that was a couple months ago as well.
Also, and most concerning to me, there were several times during the trip when the bike felt like it was out of gas, chugging, etc, and when I switched it to reserve or prime it would work again. I could then usually switch it back w/in a few minutes to normal tank and it would work just fine.
Each time I filled it up, I put 3+ gallons in, so I know it really was on reserve those times. I even checked the trip meter against the mile markers... almost dead on. it's not a miscalculation.
I also didn't feel like I had as much power as I would expect... but that *could* be the hills (what y'all in flat country would call towering mountains, but not really that bad).
I pulled the (new) plugs when I got home and looked at them. the outside is all really white, and the actual contact (source of the spark to the destination of the spark) was coal black. I'll let those with more experience make guesses as to what that means... but upon closer inspection, that's what the old ones looked like too. oh, well, for $2 each it was worth a try.
Does anyone have any ideas? if that's lean, could it be the air filter or fuel filter? I'm not much of a mechanic, I'm just speculating wildly in Kerry's absense. ;-)
Thanks,
Well spark plugs have abousolutely nothing to do with it. I would check vacuum lines and all that was mentioned above, and also your petcock filter inside the tank. Have you had to do any sort of adjustments at all on the bike, anything that deals with the fuel system lately, anything new at all? Just some ideas.
For the halibut, you might want to do a compression check. In the meantime between now and when you beg/borrow/steal the compression tester, check the breather hose that drains the airbox. If it's full of oil and crap, and has a strong gasoline smell, you might have a valve/ring job in your future. Let's hope it's something else! :cheers:
Other stuff to check:
-- All the other recommendations in above posts, esp. chain and tire pressure issues. Faulty ignition components must also be considered.
-- Are your tires (especially the front) worn? As the tire wears, the odometer will indicate higher speed and more miles because the circumference of the tire is decreasing. (The stock speedo reads fast, and the odo probably does too). Or, you may have a new tire wth a smaller circumference than what the speedo is calibrated for. It may not be as bad as you think.
--You might want to ask around (Kerry's in India, or else he'd know) to see if the gasoline you're buying has been reformulated from "winter gas to summer gas" (for lack of a better term). Many parts of the country reformulate gasoline seasonally to reduce pollution.
Alright, slowly narrowing this down, as i find more time and discuss things with people. Managed to talk to Kerry for a few minutes on AIM last night (this morning for him) and he helped me figure out a few things. The spark plugs look "optimal" according to the site he normally compares things against, so that's not a problem.
We cleaned the carbs just before I bought the bike from him, but I haven't replaced the fuel filter or the air filter. Air filter is the OEM, not the k&n replacement.
Also, new development, the engine when clutch is in and bike is warmed up tends to rev up to 4-5000 rpm, as if the choke was on. checked, and it is not... in fact, if I turn it on, the engine starts spluttering and dies.
Fun, eh?
So, maybe this will spark some ideas. In the mean time, My clymer and haynes manuals should get here soon, and then I'll see if I can figure out how to replace the air filter and fuel filter, see if that helps.
I'm still riding the bike... does anyone think that's a problem? I'm noticing more the more I ride it, but I think that's because of the more situations I ride it in, not because it's getting worse.
Thanks,
i know mine was getting lower mileage on my long (140 miles is long for me) trips, something like 35 mpg. i chalked it up to holding higher rpms, like 7-8K, as compared to >5K in town. on my trips i would go on reserve around 110 miles. nowadays, with shorter jaunts on the interstate and more town riding, i go on reserve around 140. i haven't ran a full tank yet after the new plugs, but i always figured my reduced mileage was because of sustained high rpms.
but it sounds like you have fuel economy problems at ALL rpms, so i'm just talking out of ass again. :dunno:
OK richard I'll also check oil for smell of gas and see if the oil was good and up to the level. Else all the others were right on... my virago BTW gave 30 mpg and had no power when the crank trigger for the back cylinder was bad. Dirty air filter also is bad for mileage.
Cool.
Srinath.
One of the carbs might be clogging or clogged, wich causes gas to exit through the overflow tube, plus it would cause your mix to be very lean, wich explains your spark plug withness.
Quote from: JoeSuzukiOne of the carbs might be clogging or clogged, wich causes gas to exit through the overflow tube, plus it would cause your mix to be very lean, wich explains your spark plug withness.
Sorry WHITENESS
:? by the way, what does the exhaust smell like. ive got semi-poor mileage, and go through plugs rather quickly, bike runs fine, but exhaust smell tells me its running hella rich :x :dunno:
Are you filling the gastank all the way up to the filler neck?
I am filling the gas tank up all the way, and rocking it to get the bit of extra that gives me.
I got my haynes manual last night and removed the gas tank, checked the fuel filter (seems to be fine), and removed the air filter. The air filter looks pretty bad, but I don't know how to tell how bad exactly. I'm picking up a new one today and I'll try installing it tonight. any maintenance things I can think of while I'm at it I'll go ahead and check, but if it looks like it might just be the air filter, I'd rather not disassemble the carbs just yet... time, you realize, and I want to get back on the road! I drove my car today for the first time in weeks.
I'll keep you posted.
Glad the manual made it.