Reasons for poor gas mileage?

[Easy Rider]

Originally Posted by alanmcorcoran

I am going to try letting it warm up with the choke on for a few minutes and then take off with the choke completely off and take my chances.

OK, so you are not going to take my advice and that's OK because you don't REALLY know me but...........

HEED THIS: Don't screw around with it long enough that the warranty expires. You could have a physical defect in the carb. that will require a new one to fix it. No reason for you (or the next owner) having to pay for something like that. Right ??

[alanmcorcoran]

Ok Easy, my plan (with riding with the choke off) didn't work too well. I'm back on leaving it at least halfway on until I'm about half way in to the office (7-10 minutes). As it happens, it was raining when it was time to go home today. Had a couple of problems: Power was pathetic for the first few miles. Also, stalled out on me about a mile in (I wasn't going to sit on it in the rain while it warmed up.) Gave me trouble when I tried to re-start it, coughing and then a loud backfire in the muffler. I got it started soon after and got the rest of the way home without incident. Power got better after it warmed up, but it quit on me once again and I sort of rode the throttle.

I'm going to take it back to the dealer when my Strat is ready to pick up. I'm going to ask the service manager to ride it cold after it sits all night. I'm going to read the manual to see if I can check on the air filter being clogged.

Oh, and Rick? Sorry for hijacking your thread, man. My bad.

[alantf]

A backfire? Now - I'm not a mechanic, but I was always taught that (in a car) a backfire was the sign of the timing being out. Could this happen with a single cylinder engine? Anybody out there able to say "nay" or "yea"?

[jonathan180iq]

We get lots of "backfire" stories on here simply becuase people are running with a rich mixture.

That being said, I still think this is a valve adjustment problem, which could be considered a timing problem, I guess.
If your valves are opening and closing at the wrong time, then your mixture, which is possibly good coming out of the carb, will be exploding and escaping at the wrong time, thowing it off.

Also, Al, checking your air filter takes all of 5 minutes and you only need a phillips head screw driver. You can't mess anything up. It's a simple slide in/slide out contraption.
1: Remove the seat
2: Remove the FAT phillipshead screw that holds the left (passenger side) side cover
3: Remove the 4 screws that hold the filter inside the housing
Installation is the reverse of removal.

viewtopic.php?f=9&t=1111&p=8098&hilit=uni#p8098

[Easy Rider]

Originally Posted by alanmcorcoran

Ok Easy, my plan (with riding with the choke off) didn't work too well.

I'm going to read the manual to see if I can check on the air filter being clogged.

Really? What a surprise !!! :poke2: Not! :roll:

While you are checking the air cleaner, LOOK for loose, cracked or missing stuff around the air box (thing the air cleaner fits INTO) or a loose air filter itself. Also look for the plug on the bottom of the drain hose.

Your symptoms all tend to indicate that some extra air is leaking in somewhere. Believe it or not, that little drain hose can make a significant difference if it is missing, cracked or un-plugged.

It is not very unusual for a bike to be a little erratic and rough when it is raining out; especially if it has been sitting in the rain for a while. Combined with your other problem, I'm surprised you made it all the way home.

The good news is that you are gaining valuable experience in nursing a sick bike and keeping it running. Maybe you could teach a class.......... :biggrin:

[Easy Rider]

Originally Posted by jonathan180iq

We get lots of "backfire" stories on here simply becuase people are running with a rich mixture.

That being said, I still think this is a valve adjustment problem, which could be considered a timing problem, I guess.
If your valves are opening and closing at the wrong time, then your mixture, which is possibly good coming out of the carb, will be exploding and escaping at the wrong time, thowing it off.

Hmmmm......uuuuuu.... I don't think so. :whistle:

GZ's (and modern bikes in general) tend to run LEAN, not rich.
A lean condition gives a POP, usually on deceleration. A real after-fire is a loud BANG, along with fire from the pipe; that is caused by a really rich mixture.

Valve clearance is measured in THOUSANDTHS of an inch and is seldom out of adjustment more than .001-.005 inch. You can sometimes HEAR a difference but the affect on performance is TINY, if any at all. Impossible, no, but highly unlikely.

[alantf]

When I mentioned the timing being out, I was refering to the timing of the spark in relation to the piston position. Cars have an automatic advance/retard, but I remember on my Dad's old Norton 500cc single cylinder bike (in the late 1940s / early 1950s) he had an advance/retard lever on the handlebars which he had to adjust depending on what the engine was doing. I'm assuming that there's an automatic one on modern bikes. Could this be playing up, or am I on the wrong track altogether?
(there was also an exhaust valve lifter lever, to stop you breaking your leg whilst kick starting it. Thank the lord for electric starters!)

[Easy Rider]

Originally Posted by alantf

I'm assuming that there's an automatic one on modern bikes. Could this be playing up, or am I on the wrong track altogether?

Yes, it could be, especially when wet from rain exposure but again, highly unlikely. If something like that is off, it would likely continue to be "off" regardless of the engine temperature.

[alanmcorcoran]

If this were "House" it would probably be lupus.

Before you write I'm not a fan - my daughter and her boyfriend used to watch it until I ruined it for them by checking my watch everytime they speculated what the disease of the week was and saying, "Nope, can't be that, too much time left!"

[dan_]

Or Wilsons. haha.