Poor gas mileage/choke works poorly

[cacker]

Hi all,

My '82 850 GL is getting only 90 miles on a tank. Last season I could get about 140. The only changes I have made for this season are as follows:
New K&N air filter
Cleaned and sealed the fuel tank
Checked the valve clearances, new gasket etc. Valves were ok, needed no adjustment.
New spark plugs

Now the choke seems to over choke, doesn't produce the 4K revs all the way on the way it does, just kinda sputters.

Gas mileage is poor.

Plugs look good, light tan in color, #4 a touch darker.

When I put in the new filter, I fitted a cardboard gasket on top of it, (cut out the hole for the air screen) because the filter was loose enough to allow unfiltered air into the carbs.

That's all I did except I lubed the choke slider.

Also, the engine idles at about 1900 rpm now when warm. Last year it was at about 1000.

Any thoughts?

Thanks

 

[Guest]

If you lined the tank did you clean the carbs?

 

[cacker]

Did not clean carbs

Did not clean carbs

No, I did not clean the carbs. I removed the tank, removed the filter, petcock, and fuel level sensor. Did the recommended cleaning, rust treatment, rinsing, then coating. Used the POR product. Waited 4 days to dry, reassembled.

 

[Guest]

If there was junk in the tank than it's also in your carbs.
Clean them up

 

[cacker]

When the bike was put away, running great...still runs great..no mileage

When the bike was put away, running great...still runs great..no mileage

The thing that puzzles me is that the engine was running fine when put away.
I lined the tank because of a light rusting issue, but don't think any got into the carbs, at least it didn't all last year.

The new KN filter is probably letting in more air. So, my question is, with the cv carbs, does more air mean more fuel is used as well?

Just took it a long ride yesterday, sounded great, ran flawlessly, but still only got 34 mpg. Running several ounces of seafoam through it at the time, will continue with the seafoam for another tank or two to see it that makes a difference.

Also, what is the common wisdom about adding an in-line filter, good idea, bad idea?

Thanks.

 

[Steve]

... the engine was running fine when put away. ...

How many times have we heard that when trying to buy a bike? :-k

It may have been running fine, but was it put away correctly? I see you live in a state with limited winter-time riding, so there is a good chance it has not been ridden for a while. If the bike is not properly winterized, you can bet there will be some issues when you trying riding again. You seem to experiencing just that thing.

Also, what is the common wisdom about adding an in-line filter, good idea, bad idea?

The common wisdom is that gas already goes through two filters before it gets to the carb bowl, why do you need a third? :-k

There is the filter on the inlet of the petcock and there should also be a filter on the inlet to the float valves, so a third filter is really not necessary. However, some do feel the 'need', so if you insist on getting one, get one designed for a lawn tractor. Most automotive fuel filters are a bit restrictive, as they are designed for pressurized fuel systems. The only pressure for out bikes is provided by gravity and the fact that the gas is above the carbs. An auto-type filter can greatly reduce the flow.

.

 

[cacker]

Thanks Steve

Thanks Steve

I believe I did store the bike correctly. Added the correct amount of Stabil to the last (two )tanks I ran through it. Changed oil, filter.

As noted earlier only thing different is the tank cleaned and lined with POR system sealer, new KN air filter, and the valve clearances were checked, and NOT changed, new valve cover gasket. New spark plugs.

I am running seafoam through the next two tanks, if that doesn't help, I will look into removing and cleaning carbs. Frustrating because the bike is running well, plenty of power, sounds great. Just don't have the mileage I used to.

Chip

 

[DanTheMan]

I see you're here in the midwest. The powers that be are raising ethanol levels here in MN and it may be the same in WI, which will contribute to poorer gas mileage. It's a possibility that is where the problem lies.

 

[cacker]

Thanks Dan, could be the gasoline to some extent, I agree. What kind of mileage do you get on your bike. You and I have basically the same ride, except I am envious of the fairing on yours, and the nice trunks.

 

[DanTheMan]

Right now, I'm messing with my carbs after rebuilding them this year (new o-rings and the works) and I've been holding in the low to mid-30s. At one time I was getting in the 40+ range with judicious throttle use, but I've yet to do my valve shims. I've had too many other things happening lately to spend the time required for that. Hopefully I can get to it in the next couple of weeks, then my mileage should improve considerably.
I know when I'm cranking it and playing with the red line the gas mileage goes down the tubes.

On edit: I also have the K&N filter, it's been on the bike since I bought it. Just make sure you don't over oil it, or clean it more often than necessary. K&N says every 30k, mine's just about due again. doble check that filter and make sure it's not over oiled, it sounds like that could be your problem, I had the same thing happen when I over oiled mine.

 

[BassCliff]

Greetings and Salutations!!

Greetings and Salutations!!

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Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

 

[DanTheMan]

The thing that puzzles me is that the engine was running fine when put away.

The new KN filter is probably letting in more air. So, my question is, with the cv carbs, does more air mean more fuel is used as well?

Just took it a long ride yesterday, sounded great, ran flawlessly, but still only got 34 mpg. Running several ounces of seafoam through it at the time, will continue with the seafoam for another tank or two to see it that makes a difference.

Also, what is the common wisdom about adding an in-line filter, good idea, bad idea?

Thanks.

Clean all the oil out of your K & N filter, then lightly mist it. Your mileage will get better and the bike won't run as rich (that's what's happening, by the way). I just got done cleaning my K & N which I hadn't done for over 2 years. It was over oiled from blowby collecting in the filter, my bike is running real well now, no dead spots and feels real good again. Just a slight over oiling of the filter will cause those problems, especially if you have a tight air box.

I wouldn't add an in line filter either.
Good luck!

 

[cacker]

Thanks for the tip on overoiling the air filter. If I had to guess, I would say that I did over oil. Will clean it and reinstall with just a light misting of oil.

I will keep you posted on if that works.

Next up, finding out what is loose in the front shocks and clunking around.

 

[Big T]

Put on as little oil as you can and watch the oil spread thru the pleat. You can always add more oil if it doesn't get complete coverage.

Then take a test ride out to Roche A Cri and see how it runs

 

[cacker]

Big T thanks for the tip. And I just may take that ride.