kz1000J, Popping at Idle and While Riding

Vintage3 wrote: Thanks. Put in new gas. Bike is definitely running better after a few kilometers with less back firing - but it is still popping out of the exhaust. There is also a little hesitation off the start. I was told by my shop to run a tank or two on the new gas and it should resolve itself. Is this the case primarily because there could still be gunk in the jets - assuming there was with the old gas? If there was no gunk, I gather the new gas would deliver good performance right away.

Also is it bad for the bike to ride it in this popping condition?

IMHO, those kind of suggestions from a shop are mostly to shine you on and blow you off.
Assuming you don't have a flakey electrical ignition thing going on....
I've never heard of any modern mixed fuels that go so bad in 30 days or more, that you have these kind of problems. You could try dumping a can of carb cleaner into the fuel tank and see if it helps.... Why? Because it's much more likely that there was some previous crap in your tank and or fuel line(s) that is now in your carbs.
If said junk is insoluble with carb cleaners, you get to pull them apart and physically inspect and remove junk.
And why do so many guys instantly start talking about checking your valve clearances? Unless you ran the bike out of oil the last time it was operated, they just DO NOT change that radically in such short times.... that's simply crazy.

First off, there's no mention of the valves being serviced. Being they are so difficult to adjust, a lot of guys just ride them until it stops running right. Checking the valves is a prudent thing to do. I don't believe in putting any additives in the fuel. It has been said the Stabl is still in the tank, It was suggested to dump it and add fresh gas. Then it was suggested adding carb cleaner. That SHT is not good on plastic parts. Whenever I go to AZ or OR, I'm always asked if I would like to buy this gas additive? These people know me, they are just told to Hawk this stuff no matter what the outcome. The last time the same guy asked me if I wanted this crap, I looked him in the eye, told him I had just replaced all the injectors in a clients Nissan and would he be willing to pay for it should it cause more damage? He said no. I haven't been asked again. There is no substitute for replacing fuel filters and keeping things clean. It is a mistake to add stuff to avoid costly repairs. It just costs more in the long run.
IMO
Steve

Please reread his original post..... he says he has been running it off and on every few weeks.... up to then it sounds like there has been no complaints.
I am not saying 100% it is the carbs. It could be a advance mechanism problem... etc.
IMHO, gas does not go bad enough in that short amount of time to create these issues.
Dirt, rust, debris falling out of the tank, shut off valve and fuel lines can do all kinds of weird things to these carbs.

What plastic parts in the carbs are you talking about?
I don't know what the floats are made of but I've soaked them in raw carb cleaner for years with no issues.
Most plastic parts are some kind of nylon anyhow, aren't they?
I've rebuilt dozens and dozens of carbs in my lifetime and have NEVER had any carb cleaner ruin any parts.
The only down side is that carb cleaner is not good enough alone... you need to replace some brass parts, polish or replace needle and seats, use compressed air and very very thin piano wire of various diameters to push crap through orifices... etc.
Also I have never had Stabil fuel additives do anything but exactly what it is sold to do.
Just dump it all out for the next riding season.

Valves were done a couple thousand k's ago. Tank is new nos with only about four years of service and is silver inside. I drained the bowls before I changed the gas and the gas was crystal clear. The shop is very reputable. They suggested a motul additive, ride for 5-10 minutes, let sit overnight a see the next day. If that does not resolve it they said to bring it in.

Vintage3 wrote: ...popping out of the exhaust. There is also a little hesitation off the start....

Would first suspect carb pilot circuits are not as-new clean.

Good Fortune!

Thanks. Changed oil last night and took it out today and the bike runs beautifully! The new gas worked it's charms over night I guess. No need for additive. Guy's thanks again for your comments. Always appreciated on this forum.

How old was this gas and were you running it with the Stabil in it all this time?

Good job. :woohoo:
Steve

Some of the gas may have been as old as from the beginning of the last riding season with Stabil in it. It would have been topped up also over the summer occassionally and more stabil added and again in the fall. I have a couple of bikes and don't use this bike as much - need to ride more I think and need to deplete the tank entirely before adding more gas and Stabil to start with a clean slate..

You OD'd it on Stabl. :woohoo:
Steve

Yikes.... Stabil.... you only use one ounce per 2 to 3 gallons of gas... that means in my KZ1000... about one and a half ounces for a full tank. And a full tank is what you'd do when the bike is laid off for the season.
Keep the tank full to the top!

Yes. For some reason I was under the impression that this gas was only a couple three weeks old, not a year or so and full of Stabil.
Better dump it all out and start over...