Backfiring while trying to start (and she never starts)

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kyle · #1 Unread post by **kyle** » Sun Mar 20, 2005 5:14 am

Bought a 2001 Kakwasaki ZX-6 about a week ago, and on the day I got it home it started a couple times while I tried to drive a couple circles in the backyard before I put it in the garage. Eventually killed the battery, and as it was already past the red towards Empty, I had to let it sit for a week before I had another weekend to look at it. Bought a charger, gave it half a tank, and went to try again today, and now it frequently backfires while I try to start it, and it never will start. There have been a few times where it sounds like its about to, but never quite makes it.

I'm guessing there's a problem with the fuel line somewhere, but I have zero mechanical experience with motorcycles and next to zero experience with automobiles in general (I have only replaced the starter on my truck once).

HELP!

kyle · #2 Unread post by **kyle** » Sun Mar 20, 2005 9:08 am

As far as the knocking, pinging, detonation, et cetera I see mentioned in regards to low octane fuels being used in machines that require higher grade gas, can backfires be caused by this, also?

My owner's manual says to use unleaded gasoline with a minimum Antiknock Index of 87, and that this index is an average of the Research Octane Number (RON) and the Motor Octane Number (MON).. it then says the RON should be 91.... ?

I put 2 gallons of 87 into the tank, fresh from the gas station down the street, and into a brand new container I bought a couple days ago. Should I have put 91 in there?

TechTMW · #3 Unread post by **TechTMW** » Sun Mar 20, 2005 9:41 am

91 is probably the better bet, but I fear that there may be something wrong with your bike other than the octane rating in the tank. Perhaps you have the idle screw too far in a certain direction .. ?

A zx-6 is a high perf. bike, and if (as i'm assuming) you bought it used, it may hve been ragged out and not taken care of. Whether this is the case or not, it may be wiser to haul the bike to a repair shop to have it thoroughly gone over.

If you bought the bike from a private party, this goes double. If you bought the bike from a reputable dealership, you may be able to take it back to the dealership and have it looked at under warranty.

madmax · #4 Unread post by **madmax** » Sun Mar 20, 2005 11:04 am

If the bike has set and not been ridden for a while the gas might have gone bad and gummed up the carbs. Not familiar with this bike, check fuel filter if it has one. You should be able to blow thru it real easy. Make sure fuel is getting thru the system, charge up the battery good and try it again. Some ign. systems wont do well if the battery is not at full charge. Good luck, hope you're riding soon.

BuzZz · #5 Unread post by **BuzZz** » Sun Mar 20, 2005 11:05 am

I think Tech is right, fuel is not the problem here. Sounds like ignition problems or (hopefully not) something worse like a bent valve or other internal boo-boo....

poppygene · #6 Unread post by **poppygene** » Sun Mar 20, 2005 1:16 pm

Hey, Kyle, you didn't say, so I'll ask if you had the chance to hear the bike run before you brought it home. If so, did it display any kind of difficulty in starting or idling smoothly?. Also, can you tell if it's backfiring through the carbs or is it just popping through the exhaust?

Ladymx · #7 Unread post by **Ladymx** » Sun Mar 20, 2005 1:55 pm

May want to check the plugs as well if they are carboned up it will be hard to start. Carbs may need to be cleaned and sync'd( adjustments to air/fuel mixture). Otherwise the same as the others.

kyle · #8 Unread post by **kyle** » Wed Mar 23, 2005 11:40 am

Got my bike back from the shop today. The air boxes weren't connected - just pushed up against the seal. Also, the spark plugs were shot. It was just popping through the exhaust, but that has been fixed, also.

Ran it around a couple times, and she's working fine, now.

The guy did say that it felt like it had some kind of mild carburetor problem when the engine was cold, but after a mile or two it went away. Said he had the same issue on his own Suzuki Katana, and to just be careful with the throttle until it had warmed up. Sound familiar to anyone?

BuzZz · #9 Unread post by **BuzZz** » Wed Mar 23, 2005 8:12 pm

kyle wrote:Got my bike back from the shop today. The air boxes weren't connected - just pushed up against the seal. Also, the spark plugs were shot. It was just popping through the exhaust, but that has been fixed, also.

Ran it around a couple times, and she's working fine, now.

Cool

kyle wrote:The guy did say that it felt like it had some kind of mild carburetor problem when the engine was cold, but after a mile or two it went away. Said he had the same issue on his own Suzuki Katana, and to just be careful with the throttle until it had warmed up. Sound familiar to anyone?

It should sound familiar to almost anyone with a carbed bike, I hope. I may have just has a 'lightbulb moment'.... I wonder how many new riders buy a bike and expect it to run like a modern car? I never thought about it from this angle before, I have always been used to warm-up and cleaning-out rituals with bikes. But bikes are much more visceral machines and require a more personal touch. Especially carbed ones. But every bike is unique, the older they get, the more unique they get. You and the bike end up adapting to each other and soon you are one entity on the road. A car is a car is a car...... well, not quite, but nothing as personal as a bike.

Glad you and yours are getting along.

ronboskz650sr · Thu Mar 24, 2005 9:14 am

Well said...Another item that can go without warning is the resistor in the plug cap. This will cause your coil secondary winding to check bad, when it really isn't. This happened to me this december when the temperature went into the sixties for a couple of days, which I spent waiting for parts (not coils, luckily).

There was no symptom until it just wouldn't start, but it did backfire, because the plugs did fire a couple of more times after the gas built up in the cylinders. These dual coil bikes fire two plugs at once with a waste spark on the exhaust stroke of the other cyclinder, hence the backfire. If your bike is a dual coil bike (probably , but not sure), remember this as a possible cause next time. My bike has had a few ignition-related problems that other people thought were carbs. FWIW.