Kawasaki Concours Forum
The C10, aka Kawasaki Concours - The Original => The Bike - C10 => Topic started by: DC Concours on May 13, 2021, 10:09:35 AM
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Hi guys,
My bike is getting lower mpg and seems to be running rich. What are the symptoms of a rich mixture in this bike and how can this happen suddenly? Is it time for a carb service?
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could... be.. check the air filter and air box 1st. mouse may have made a home in there.
'2 mouse jetting mod'. :rotflmao:
also check the vacuum line tot he petcock isn't leaking fuel. if the diaphragm is torn it can suck fuel into #2
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Thanks. Checked and cleaned the air filter a couple of weeks ago when this all started suddenly. The filter was not that dirty.
It happens when I am rolling along at say 60mph, 6th gear.... and then want to accelerate. I give it gas or shift down to 5th and give it gas. The bike makes a breathy sound and shakes a little and slowly picks up. The acceleration is not crisp.
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DC, do you have overflow tubes?
If you do, remove the rubber overflow lines from the drain nipples on the carbs and put the petcock on prime without the bike running and see if any gas is coming out of any of the carbs. You could have a float needle that's not sealing all the way letting too much gas into the fuel bowl.
How does the bike run just sitting at idle for a couple minutes?
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I was going to suggest checking plugs, plug wires, coils. But the symptom doesn't sound like that. Vacuum might be the culprit. Hoping a carb guy responds soon to diagnose. My approach would be to check the simple stuff first then send the carbs to some one to set up properly.
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Thank you for your help Joe. The bike starts and idles perfectly. Runs well while on low speed jets.
Problem is during acceleration in higher speeds.
DC, do you have overflow tubes?
If you do, remove the rubber overflow lines from the drain nipples on the carbs and put the petcock on prime without the bike running and see if any gas is coming out of any of the carbs. You could have a float needle that's not sealing all the way letting too much gas into the fuel bowl.
How does the bike run just sitting at idle for a couple minutes?
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Thanks Bruce.
I really don't think the carbs are off but they should be vacuum checked. This all happened while my gas was winterized. I am on my first tank of non-winterized gas. Could water in the gas cause this?
I was going to suggest checking plugs, plug wires, coils. But the symptom doesn't sound like that. Vacuum might be the culprit. Hoping a carb guy responds soon to diagnose. My approach would be to check the simple stuff first then send the carbs to some one to set up properly.
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Try a 1/2 bottle of Techron in the gas? After that you'll need to change the oil too I think. If idle and part throttle are good I'd suspect something in the carbs. Other than synching them on my '99 I never had to mess with mine. Could be high speed circuit gummed up. But I'd make sure you had good clean gas in it before doing anything else.
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Drain the fuel and refill with fresh fuel . Could also be starvation if happenning only at higher speed acceleration . Check fuel line routing .
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The symptoms sound like a torn diaphragm to me which means one of the needles isn't lifting the same as the others.
What makes you think it's running rich? Can you smell gas in the exhaust?
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are you sure its rich? sounds more like fuel starvation with the added info of the 'at speed' symptoms as z-1000 says. check tank vent/petock flow etc.
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Hi guys,
I went for an investigative ride for this post...
This is what happens:
- when I grab a fistful (suddenly accelerate) in any gear over 30mph the bike seems to bog down
- especially noticeable around 3k+ rpm
- bike shakes
- sounds breathy
- gentle acceleration does not have any issues
- last fill up was yielding 32mpg. I normally get 38mpg mixed hwy/city
- I first noticed this about a month ago JUST after the bike was sputtering running out of gas and after I flipped to reserve
- This bogging and shaking happened a year ago for one day, but after I rode it hard for 15 mins it came back to normal the next day
- start/idle/low speed runs fine
- bike will roll in first gear w/o cutting even at 500rpm
- I have steve's 2 min mod and overflow tubes
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If you have fresh gas in it from this year, I would check the foam, or whatever you used to block part of your air box intake to make sure it's still in place.
Then whether that's good, or not, add a bottle of dry gas to a full tank (Heet or Iso-Heat) and run all of it through till close to reserve, then fill up with fresh gas.
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Hi guys,
I went for an investigative ride for this post...
This is what happens:
- when I grab a fistful (suddenly accelerate) in any gear over 30mph the bike seems to bog down
- especially noticeable around 3k+ rpm
- bike shakes
- sounds breathy
- gentle acceleration does not have any issues
- last fill up was yielding 32mpg. I normally get 38mpg mixed hwy/city
- I first noticed this about a month ago JUST after the bike was sputtering running out of gas and after I flipped to reserve
- This bogging and shaking happened a year ago for one day, but after I rode it hard for 15 mins it came back to normal the next day
- start/idle/low speed runs fine
- bike will roll in first gear w/o cutting even at 500rpm
- I have steve's 2 min mod and overflow tubes
What kind of fuel line is on it ? If it's that clear stuff it gets real flimsy when it heats up and can kink real easy . If there are tight bends in the line (any type of fuel line )you may have starvation when the tank is low on fuel since it is gravity fed . It may flow good enough at low speed but once the fuel demand comes up with the throttle it won't flow enough to keep up .
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Turbojoe, I put my first tank of fresh gas last week. I will check the foam. It was ok last time I checked. I don't know if heet is carb safe. SISF is not a fan of putting these things in the tank.
craz1000, I have the OEM tubing and a inline filter. No tight bend and it has always been fine.
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DC, I know Steve's thoughts on fuel additives, that was why I suggested running it through. You could also run your tank down to half, add a 1/2 bottle of Iso-Heat and ride the bike till you need to add fresh gas. This is something MOB used to suggest for getting water out of you're tank. Did you notice the problem after you put it on reserve? Do you ride till you hit reserve a lot? With my C10 I used to ride to reserve every tank so my petcock stayed exercised and I got the gas down to the lower corners of the tank.
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Hi Turbo,
I think I will let a couple of tanks run through. I think there might might be water somewhere. I used to read MOB always talk about water in the tank. I will use Heet. You all like it.
This problem started after I moved to reserve on my ride back home. I exercise the reserve from time to time so it is used. Maybe not as much as you.
But the thing is wouldn't bad gas cause issues through all gears, speeds and rpms?
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Yeah it really should . I'm afraid it's time for carb cleaning . It's not that hard especially if you go by MOB's method in the Fall 06 Concourier . I've been doing mine for several years now with great success .
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crack the drains on the carbs and catch the mixture in a glass bottle. let sit, look for water. will be obvious. better than guessing.
remember: the main jet is the 'lowest' jet in the carb with the pilot being quite a bit higher. water settles to the bottom of the bowl/tank.
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Hi Turbo,
I think I will let a couple of tanks run through. I think there might might be water somewhere. I used to read MOB always talk about water in the tank. I will use Heet. You all like it.
This problem started after I moved to reserve on my ride back home. I exercise the reserve from time to time so it is used. Maybe not as much as you.
But the thing is wouldn't bad gas cause issues through all gears, speeds and rpms?
If you do try Heet , be sure to get out and ride most of the tank out . Don't want to let that stuff sit long as it's harsh on float tips and the fuel will seperate again after some time .
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" I would check the foam, or whatever you used to block part of your air box intake to make sure it's still in place." That got me once. Also if there is water in the tank it will stay there for a long time way down deep. Ethanol added to gas has changed how water in gasoline can be treated. Might try running the tank low, then removing the tank and pouring what is left out. Take an old t shirt and try to dry the tank's inner recesses where water likes to hide. Refill with a known quality of gas purchased from a busy gas station... and make sure the foam is still partially blocking the air box inlets as it was previously.
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Thank you man. I wish I knew more about these carbs. Too many parts even with good instructions. I have seen people on youtube fill up whole egg cartons with little parts. And I don't have a garage like most of you. I'll have to do this on my dining table! Wished one of you guys lived closer. Beer, dinner and a fat cigar could be doable!
And about Heet, I need to use a little at a time. My riding is not as much as you guys would think. Mostly weekend rides or jammed in traffic!
Yeah it really should . I'm afraid it's time for carb cleaning . It's not that hard especially if you go by MOB's method in the Fall 06 Concourier . I've been doing mine for several years now with great success .
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Thanks man. I plan on doing this. I have heard tapping the carbs may help. I don't know if it is solids stuck there because I have a fine mesh type 3006 inline filter (which is kinda dirty). I must admit haven't changed it in a few years. But it seems like a water issue though.
How much water can these tanks hold? I have almost run down a half tank of new gas by now!
crack the drains on the carbs and catch the mixture in a glass bottle. let sit, look for water. will be obvious. better than guessing.
remember: the main jet is the 'lowest' jet in the carb with the pilot being quite a bit higher. water settles to the bottom of the bowl/tank.
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Thank you greenie.
The first thing I did was "wash" my air filter and reseat the foam. That was my first line of attack. Then new gas-- I am still on my first tank since coming out of winter.
During the winters I have always used 4oz of steve's recommended marine oil plus 2-3oz of stabil per tankful. Worked well for me these past years. Don't know what happened last month. :banghead:
" I would check the foam, or whatever you used to block part of your air box intake to make sure it's still in place." That got me once. Also if there is water in the tank it will stay there for a long time way down deep. Ethanol added to gas has changed how water in gasoline can be treated. Might try running the tank low, then removing the tank and pouring what is left out. Take an old t shirt and try to dry the tank's inner recesses where water likes to hide. Refill with a known quality of gas purchased from a busy gas station... and make sure the foam is still partially blocking the air box inlets as it was previously.
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i have no idea how much water they can hold. but the carbs have drains easiest thing to do to verify.
put on prime, open drain one by one and see whats in there.
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Some years ago a COG member took the time to analyze the Connie tank and found that the lower "cheeks" by where your knees go hold about 1/3 gallon of water, rust, mud, dirt, dead insects, sub-microscopic alien spaceships, and miscellaneous other crud, that cannot be drained out except by dismounting the tank and running it all out the filler hole and the petcock mounting hole, and flushing with new fuel. This area is below the level of the fuel petcock, so there's no other way to get it out. You really really need to do this about once a year.
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I know the old adage about oil & water not mixing but you'd think the water would eventually get sucked into the combustion chambers with the fuel and eventually expelled. But I've also heard the only true way to make sure the water is out of the tank is to remove tank and petcock and drain tank that way. If you run the tank into reserve it isn't a tough task at all to remove it.
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however the pockets at the back dip down and can hold water. even running it on prime or reserve will keep it in there.
when i line my tank with caswell, i made sure the leftover stuff sat in those back ears to reduce the amount that can collect there.
I agree, it should suck it out but ONLY will get pulled out (of the carb bowls) when its pulling fuel out of the main jet circuit.
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Did you re-oil the air filter after cleaning it?
Lack of oil would cause lean running symptoms.
Since this seems to only happens at higher speeds, I have a question:
Are the 2 carb vent tubes in place, and where are they routed to?
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Thank you guys for helping. I appreciate it. I don't want to mess with the carbs because I really don't know how. Just know how to clean lawnmower ones! I will have to send these off if that is the case.
I will drain the bowls as recommended. I can drain the side bowls but I will need a longer allen wrench for 2 and 3. Any recommendation on ball end wrenches that are thin and angled or what you guys use?
Stach, the issue started a few weeks before I did anything to the filter. I then cleaned the filter and oiled it and put it back. No change. The vent tubes are in place and I have not touched them since reinstalling the carbs a few years back. Do they come off by themselves? The routing was what you guys told me years back. Frankly, I don't remember and haven't taken the tank off since.
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Any long ball end allen wrench should work .
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the issue started a few weeks before I did anything to the filter. I then cleaned the filter and oiled it and put it back. No change. The vent tubes are in place and I have not touched them since reinstalling the carbs a few years back. Do they come off by themselves? The routing was what you guys told me years back. Frankly, I don't remember and haven't taken the tank off since.
Then its probably not that. There can be issues similar to yours if they are routed down under the bike by the battery and gas tank vent tubes, which creates vacuum at speeds causing fuel starvation.
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I just had an issue yesterday . After switching to reserve she ran like crap . I barely made it to the gas station and put a little over a gallon in . Got back home and immediately drained the tank then swabbed out the rest with a rag on a coathanger . The fuel at the bottom was pretty crappy . It had been too long since I had run a tank completely out and I haven't drained the tank in months . Fresh fuel and it's all good now .
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Well, I finally ran down to reserve. I then drained some gas through the bowls but found no dirt or water.
Now I am on my second full tank and have ridden 30 miles on it. I am showing 10 mpg loss on my last tankful. Still having the same issue. Low gears have good pickup but when I am on 4-6th gears any sudden throttle starts off with a slight bog and shaking as if you are climbing a hill on a higher gear unable to get a crisp acceleration.
I guess I need to start taking stuff off. How the hell does this happen suddenly one day when I switch to reserve?!
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How the hell does this happen suddenly one day when I switch to reserve?!
You dislodged a bit of crud when you switched to Reserve and it got stuck in one of the float needles, so your fuel level is too high in one carb leading to over fuelling. It needs to be sorted before you get a hydrolock situation.
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Yes. I am getting worried about that too. And I have an inline fuel filter too. So annoying.
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Belated update.
After running 2 tankfulls of fuel the bike got better and finally after the third tankful the richness went away. From this I can only assume the water finally ran through. It's back to normal.
I am surprised the water lingered so long or I was repeatedly getting bad gas. I am on my 6th or 7th tank now.
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I wish my bike would run rich....I need the money.