Backfire when throttle closed

[Sarris]

My idle varies w/ weather conditions, but I keep it at about 1200 rpm on my tach. My GeeZee idles lumpy at 1000, and seems to be happiest at 1200 rpm. Also, as a side note, my mc guru says that a low idle in hot weather may result in bearing failure (or excessive wear) with less than recommended oil pressure at a lower than spec idle. No prob if moving, but get stuck, and you could overheat. Mr. Suzuki says 1200 ~ 1300, and Father knows best. (PS; I use the $50 tach recommended on site)

Oh yeah, those pop-pop-pops after a drop is usually a minor leak from disturbing the header to cylinder head seal. It may or may not heal it self after a few miles with normal running carbon build up. If not, replace whatever gasket/donut is used at the joint, and don't drop the MF anymore.

:2tup:

[alanmcorcoran]

I cranked up my idle a bit before heading off to work today, also let the bike warm up in neutral for a few minutes before I climbed on. I think I ended up cranking it too high - it was way up when it warmed up and I took the choke off. So I ratcheted it back down a bit when I got to the office. I may look into that $50 tach. Is it hard to install?

I have Yet Another Theory on my stalling problems. I think maybe my throttle cable assembly is a little sticky. Does anyone know if the cable is "relaxed" more, (stretches, say) then the idle will drop down? I think they adjusted the idle when the cable was not fully relaxed, and then, when the bike heats up, things loosen up and stretch, and the idle drops below sustainability. I do find it's all over the map for the first ten, fifteen minutes or so. Once the bike is thoroughly warmed up, it settles into a stable rhythm.

[Water Warrior 2]

The idle should be set on a fully warmed up engine. Maybe try a different brand of gas for a while, might make a bit of difference.

[Easy Rider]

Originally Posted by alanmcorcoran

I cranked up my idle a bit before heading off to work today, also let the bike warm up in neutral for a few minutes before I climbed on. I think I ended up cranking it too high - it was way up when it warmed up and I took the choke off. So I ratcheted it back down a bit when I got to the office.

Sigh!

When you told us you weren't too mechanically inclined, I thought you were probably exagerating your inept-ness; appears that is not the case. :biggrin:

One should NOT set the idle while the engine is cold and ESPECIALLY not while the choke is active. Geeezzzz !! :roll:

I thought about getting a tach a few times.......but it really doesn't accomplish much. I plan to visit my dealer and ask them to connect their induction tach just long enough to set the idle. Once you KNOW what the right speed sounds like, you don't need a tach anymore.

Thanks for setting us straight, Sarris !!

An idle at 1K sounds a LOT different with a thumper than it does with a V-8.......or even a V-twin !!

Yes, it is possible that too much slack and/or sticky cables COULD contribute to an erratic idle.......but it is not too likely. In addition to the spring at the carb, one of the cables actually PULLS the throttle closed when you roll it in that direction. The cables would have to be VERY loose or VERY sticky, unless you slow down by just releasing the handle grip......or you have a limp wrist !! :shocked: :whistle:

[alanmcorcoran]

Yeah, I'm not gonna put my mechanical skills up against anyone on here. Personally, just like a good doctor, I think to be a good mechanic you have to have a deep, holistic understanding of the entire machine. In some cases, symptoms and fixes are isolated to one adjustment or part, but, in most cases, they are a combination of things that need attention, and, more often than not, are also behavior related. (Like using bad gas, or under/overshifting, or riding the brakes, etc.)

But, does anyone else have an erratic idle? Like, you are sitting at a light and it suddenly drops from a steady whine to... nada. Or it starts to climb up, but you let the clutch out a little and it slaps it back down until it behaves itself. Mine is all over the map until the engine is hot. Since I have no problems with the idle when it is hot, it doesn't really accomplish much to adjust the idle when it is hot. It doesn't stall when it is hot. It only stalls when it is cold, warm, warmer and, almost hot. That's why I effed with it before it got hot.

I'll keep screwing with it. Eventually I might learn something.

[Easy Rider]

Originally Posted by alanmcorcoran

It doesn't stall when it is hot. It only stalls when it is cold, warm, warmer and, almost hot. That's why I effed with it before it got hot.

Well CRAP! My memory might not be as good as it used to be but.........I distinctly remember you NOT mentioning that little detail before. :skull: (Possible I missed it, I guess).

Anyhow, now we have a new ball game. Have you done the Seafoam thing yet?

Are you releasing the choke a little TINY bit at a time or are you going all the way from full to nothing?

You should not need full choke if the temp. is above 50 or so; 1/2 or 3/4 shoud be plenty and then 30 seconds or so after it starts, you should adjust the choke a TINY bit to maintain an idle speed that is just slightly higher than normal. You should leave the choke set there (or adjust it only in tiny increments) to maintain that slightly faster than normal idle until it gets thoroughly warm. This might be anywhere from a couple of minutes (miles) to 10 or so. And yes, it is perfectly OK to leave the choke partially operated..........forever really, as it has almost no effect except at idle.

Yes, mine is a little erratic when COLD but responds like you describe ONLY when I release the choke too soon. Did you mention this when it went in for service?

Are we getting close to something that sounds like it might be a factor here ??
This really isn't rocket science, after all !! :poke2: :biggrin:

[mrlmd1]

My bike is a '99 and runs like a fine watch from the day I got it over a year ago, before that it sat idle for a few years. It starts instantly with some choke when cold, warms up quickly, runs smooth, never stalls unless I unintentionally made it do that on starting out from a stop (like being it too gentle on the throttle and too quick on the clutch release as any bike will stall if you don't do it right). I think most of the bikes on here run perfectly without adjusting things on the carb, idle, etc, every day, to try and get it right.
AC, you should bring the bike back to the dealer and have them fix it so it doesn't stall, set the idle to specs, stop theorizing and adjusting things you don't understand or you will continuously get it so out of kilter that it won't run or be reliable at all. As they say, a little bit of knowledge is a dangerous thing - let someone with the expertise and the tools get it running right, or go take a small engine maintenance mechanics course or read the shop manuals to gain the knowledge to do it yourself. This was a new bike 6 months ago and was probably running fine right out of the crate before someone screwed it up or abused it, or filled the tank or carb with dirt, or whatever happened to it. Once it's running right, it should be like "set it and forget it", it should keep on going. It seems like 5% of the members on here have 90% of the problems, and most of these shouldn't happen to a new bike with relatively few miles on it. :??: :poke2: O_o

[BusyWeb]

Originally Posted by Easy Rider

It seems to me that the proper "real" tach to get for the GZ is a "double fire" model, the same as is used for V-twins that fire the plug TWICE on each revolution.

Hi, there.
This is good information that I had suspected about it.
When I measuer on the spark plug it gives read exactly double values compare to the ignitor cable.
On the ignitor cable, it reads what I WANTED values... ha ha ha.
Some strange read I can get is when the engine speed is over 3000 (exactly 3000), it reads DOUBLE value, very strange.... :??: :??: :??:
So, I tride to fix with my calculation as possible as I could, but still double read after 3000 on ignitor cable.
Therefore, I put away my diy rpm meter from my GZ :blush:
I think that there is something going on this little GZ inside ingnition system.
But less than 3000, it seems correct if I ear-measuring with engine speed.
Anyway, it's always fun with GZ....
I also want to borrow the Tachometer from a body shop to see what the exact value GZ runs.

[alanmcorcoran]

Originally Posted by Easy Rider

Anyhow, now we have a new ball game. Have you done the Seafoam thing yet?

Yes, but, since I am only using the GZ for my work commute I'm only about 25 miles into the first tank.

Originally Posted by Easy Rider

Are you releasing the choke a little TINY bit at a time or are you going all the way from full to nothing?

Well, yes and no. I find that moving the choke a tiny bit at a time has no effect. However, you get to a certain magical point, and BAM, it drops to almost stall or actually does stall. So, I don't go from full to nothing, but I don't move it in tiny increments either.

Originally Posted by Easy Rider

You should not need full choke if the temp. is above 50 or so; 1/2 or 3/4 shoud be plenty and then 30 seconds or so after it starts, you should adjust the choke a TINY bit to maintain an idle speed that is just slightly higher than normal. You should leave the choke set there (or adjust it only in tiny increments) to maintain that slightly faster than normal idle until it gets thoroughly warm. This might be anywhere from a couple of minutes (miles) to 10 or so. And yes, it is perfectly OK to leave the choke partially operated..........forever really, as it has almost no effect except at idle.

This is pretty much exactly how mine worked when it was new. Now, that was in June. And it's consistently warm here in June. So... maybe I just have my expectations too high. But it definitely is more stall-y now than it was before.

Originally Posted by Easy Rider

Yes, mine is a little erratic when COLD but responds like you describe ONLY when I release the choke too soon. Did you mention this when it went in for service?

I did. And it stalled right the eff out when I stopped before I left the parking lot. I thought about taking it back, but, to be honest, I just wasn't up for the usual service department bullshit. For starters, they would need to carefully test it when it is COLD. My experience is, this requirement alone is enough to disqualify you from making any progress. Plus, they already had it for FOUR EFFING DAYS! To change the oil, allegedly clean the carb, and perhaps put air in the tires. Sorry, but my conclusion is they are not able to fix anything complicated.

Here's some other stuff:

1) If the idle suddenly drops real low (for some mysterious reason) and I twist the throttle, it will re-settle higher. Thus my sticky cable theory.
2) Conversely, if it suddenly gets crazy fast, and is racing like a MF at a light, if I let the clutch out a tad, to the friction zone, and then pull it back in, it will resettle lower.

These two phenomena make me very suspicious of the stability of the idle. This behavior occurs even when the engine is hot.

On the ride home tonight, I had fewer problems, but I warmed the engine up for five minutes before I left the office. I did not stall at all, but the idle was still too high once the engine got hot.

[Easy Rider]

Originally Posted by alanmcorcoran

Well, yes and no. I find that moving the choke a tiny bit at a time has no effect. However, you get to a certain magical point, and BAM, it drops to almost stall or actually does stall. So, I don't go from full to nothing, but I don't move it in tiny increments either.

OK, this is rapidly becoming pointless. Really wish I was there to SEE the bike. Not much can be done by remote control. Any chance you can get an "old hat" to stop over sometime for a test ride when cold?? I'm beginning to think that's the only way your going to get a good analysis of the situation.

One last thought: Your description of adjusting the choke reminds me of my wife adjusting the thermostat for the furnace. She thinks that they higher you set it, the faster it will get warm. She KNOWS how a thermostat works but it just doesn't sink in somehow.

Apparently something has changed since new but until you get that figured out, I think you need to leave the choke set above that threshold spot for a little longer.

If there IS a problem with something sticking, it's beginning to sound more like the choke cable instead of throttle. Just don't lube the choke lever on the bar; it is supposed to "stick".

Oh, and one more thing: You aren't using "premium" gas, are you ??

P.S. I hope you adjusted the hot idle back down where it should be.