irratic idle

[b1pig]

hey, guys. got an issue that has been nagging on the wife's GZ for a while now. The idle is all over the place. I'd think it was a vaccum leak, but there really isnt one. I finally got a replacement choke cable in, so I replaced it. The bike was completely unridable before this. With no tach, I could only guess it wanted to idle around 2500-3000 rpm. Mainly due to the choke, I know. I went ahead and pulled the carb and broke it down. i cleaned the whole thing out. There was some ugly residue that came out, but only a very small amount. The only place where there was any real evidence of gumming up was... guess... the "choke". (more of a manual enrichment....) I also did a valve adjustment. the top end was horribly noisy. well. i got the exhaust right, but I dont have the smaller gage for the intake... so I guessed at it. It ain't perfect, but its a LOT better than before.

Now.
The idle is whacky. if youre cruising and slow down, you can tell that it doesnt return all the way down. after you come to a stop, the idle hangs a tad high. drag the clutch and it comes down and stays there. if you rev it a little, sometimes it eases back down, sometimes it hangs up there a bit. its more annoying than a hazzard to riding or damage. All the vent lines are routed like they should be, includeing the "fuel pump" vaccum line to the fuel valve.

Any thoughts?

thanks!
Billy

[alanmcorcoran]

First, I must give you my "I'm not a mechanic" disclaimer (I'm sort of the opposite.) Second, I had the same problem as you. I was unable to fix it myself (not that I tried very hard - but I did pull the plug, mess with the idle setting, put Seafoam through, etc.) I took it to my dealer three times before they fixed it. They claimed they cleaned the carb each time, but if I had to hazard a guess, I'd say there are degrees of cleaning a carb, and my problem required that you REALLY, REALLY, REALLY clean the carb. It is also possible that something was hosed in the emissions canister, The valves needed adjustment, or something else was tweaked, but I really think the problem was something clogged in one or more of the jets in the carb.

The good news is, they did fix it on the third try - this was over a year ago - and it's been running great ever since. Idles consistently and not high. Bike is very quiet and very steady once warmed up (five minutes or so.) Before it was fixed, it would rev super high and also stall - annoying and dangerous to ride. I burned a nice hole in some expensive touring pants pushing the thing out of an intersection. If I hadn't had the pants on the hole woulda been in my leg. Plus, all the effing around with it while you are riding uses up the parts of your focus that help you avoid getting killed.

Good luck. There are carb experts on here - I am certain they will all weigh in. Take all of the advice, and add it up and divide by the number of posts.

[Easy Rider]

Originally Posted by b1pig

I'd think it was a vaccum leak, but there really isnt one.

Does that include the air box too......and the air box drain plug ??

How about sticky throttle cables ?

I'd run some carb cleaner through with the gas. Sometimes that gets "places" that you can't see with a manual cleaning.

[blaine]

Originally Posted by b1pig

i got the exhaust right, but I dont have the smaller gage for the intake... so I guessed at it. It ain't perfect, but its a LOT better than before.

Now.
The idle is whacky. if youre cruising and slow down, you can tell that it doesnt return all the way down. after you come to a stop, the idle hangs a tad high. drag the clutch and it comes down and stays there. if you rev it a little, sometimes it eases back down, sometimes it hangs up there a bit. its more annoying than a hazzard to riding or damage.

thanks!
Billy

Have you tried adjusting the idle mixture?If the idle mixture is lean it will cause the idle to be erratic and slow to return.Also valves need to be adjusted as close as possible to each other.
:2tup:

[b1pig]

Originally Posted by alanmcorcoran

Good luck. There are carb experts on here - I am certain they will all weigh in. Take all of the advice, and add it up and divide by the number of posts.

:lol:
thats funny...


the throttle cables are fine. when the idle hangs, i can twist the throttle a little harder closed. it goes no farther than it was and has no effect. the airbox is nice and clean. drain is clean as well with the cap in place. air filter is spotless.

as for the valve adjustment, i've got to order a gage with the right thickness. mine doesnt go that far down. the one i have was actually a couple hundredths of a milimeter thicker than called for, but i adjusted it tighter than i normally would have, but in any case the same amount of tension was achived in inserting/removing the gage. once i get the right gage, i'll be taking her apart and readjusting the valves. i'll put it into perspective. when I took it apart, a .003"
feeler gage slid right in there. :shocked:
80% of the topend noise is gone now. should be resolved 100% once i get the new gage in.

i haven't tried the fuel mixture. i looked it up once, but I didnt drill the plug out. might be my next adjustment along with shimming the needle.

[blaine]

Originally Posted by b1pig

i haven't tried the fuel mixture. i looked it up once, but I didn't drill the plug out. might be my next adjustment along with shimming the needle.

Try turning your idle mixture screw out 1/2 turn(rich)I think your problem will be fixed.The G.Z is notoriously lean from the factory.My bike had the same problem till I made the mixture a little richer.I also done the needle shim & main jet at a later date.Good luck.
:roll: :cool:

[Water Warrior 2]

Lynda must have been very fortunate with her GZ. The bike would sit for months at a time in the winter and fire up perfectly in the spring. Never had any fuel stabilizer or fuel additives at all. Carb was untouched from factory settings and only the idle was turned up a bit for the first few spring rides. Must be a Canadian thing eh.

[alantf]

Originally Posted by Water Warrior

Lynda must have been very fortunate with her GZ. The bike would sit for months at a time in the winter and fire up perfectly in the spring. Never had any fuel stabilizer or fuel additives at all. Carb was untouched from factory settings and only the idle was turned up a bit for the first few spring rides. Must be a Canadian thing eh.

That's the difference between the Canadian / European GZ, & the American. :plus1: Plus, I never need the choke to start up. :2tup:

[Water Warrior 2]

I thought the U.S. and Canadian models were the same.

[dentheman]

Does Canadian gas contain ethanol? I think that is a big contributer to the gumming, but others will disagree.