Sounds like your running lean. The sitting may have gummed up the carb some, you may need to clean it out. Also you may want to do the air mixture screw mod if you haven't done it yet:
http://www.klr650.marknet.us/Carb_AirMix.pdf
Back the screw out about 2 - 2 1/2 turns. There is also what they call the .22 cent smile mod. You remove the stock needle and place one or two #4 stainless steel washers under the head of the needle effectively raising it some to become richer and gives a much better throttle response to the bike.

You might also check out this link for the 22 cent mod. I couldn't find one here, but it is early and I have not had coffee yet. Short attention span.. LOL
http://klrworld.com/forums/index.php?topic=1380.0

 

Found this also:
"In general, backfiring on deceleration (as opposed to acceleration) is generally caused by a lean condition in the pilot circuit. What happens is that the mixture leans out enough to where is fails to ignite consistently. This, in turn allows some un-burnt fuel to get into the exhaust pipes. Then when the engine does fire, these un-burnt gasses are ignited in the exhaust pipe, causing the backfire. I would say check the pilot circuits, and set them a bit richer. Aftermarket pipes often increase backfiring, probably because they may the bike run leaner."

 

You might also try running some Sea Foam through it.

 

Thanks you guys.... I'll try the Sea Foam first.

Could I be damaging the bike by riding it with this condition?

 

A lean mixture will create more heat, but from your description it doesn't sound like it is extremely lean. Are you using fresh gas? Modern gas doesn't keep very long and can contribute to the problem.

 

It will create more heat, but you won't see it show up engine temp wise, it will be thru the exhaust. Sea Foam is good stuff. Give that a shot first.

 

Try a good carb cleaner, watch the mixture, read the can, run a couple of them thru it and see if it clears up better, if you let your bike set use STABIL in the gas, and ALWAYS, keep a full tank of gas to cut down on moisture. Just don't get cheap on the cleaner, if it has a mositure barrier in it all the better.:16a:

 

I had the Same problem, first I kind of like it but then it started more often and annoying. Find out that it was Missing Nut on the Exhaust pipe
next to engine. After putting new nut, tighten both of them my bike runs Like New again. Im so happy... hopefully it will help somebody to fix his KLR or any bike really. Before I found missing nut I change the air gilter, changed Spark plug, No changes but just one Missing nut made all difference

 

You can rule out carb synch...Sea Foam works. I suggest putting the correct amount into fresh fuel. Drain the float bowl of the old crap. Start the bike, ...run it until it reaches operating temp. Revving it above 1/4 throttle a few times during the warm up. Shut it off. Let it set for a bit. Take it for a ride...see if that helps.

 

dittos on sea foam. many years ago I too participated on the DSN_KLR list and it was like this with lots of fine experts. I wish I could name more than I can now (see Dual Sport News) anyhoo, I felllow who went by " Dooden" whom I met once on a ride, he spoke highly of sea foam and I have had great luck with it ever since. I use it in sleds and the KLR as well as all other lawnmower gas etc.

Dooden told a story of some small engine - say a roto tiller or something. and it was running crappy and not smooth. some Sea Foam in the gas and let it idle for a half hour. it is then running well.

"no money was exchanged and nor was this an official endorsement compensated by Sea Foam or any other player in said supply chain"

except for Big Lue who said he would install a sproket on my vertebrae should I not have protection payment to him in 12 hours.. line6distortion

 

This thread is 12 years old...... anyhow, I always run non-ethanol fuel when possible, drain the float bowl before winter and add Stabil to the tank (and run it until it's distributed), but this year I ended up with corn-contaminated fuel and carb issues (including pilot circuit problems and backfiring) on both KLR's.......I hate ethanol. Time to pull the carbs and clean them....sigh.

Dave

 

This thread is 12 years old...... anyhow, I always run non-ethanol fuel when possible,................, but this year I ended up with corn-contaminated fuel and carb issues (including pilot circuit problems and backfiring) on both KLR's.......I hate ethanol. Time to pull the carbs and clean them....sigh.

Dave

This is exactly how the rest of the world feels, Dave. ;(

Seems like you are getting a late start? Is life getting 'in your road'? I've got about 135 miles this year.

I might could have missed another 300 mile tank of fuel on last years gas by .45 miles, if I hadn't had the oem fuel tap.
280 miles on 5.514 gallons = 50.532394 mpg x 5.928 gallons (most ever previously burned) = 299.55 miles.
I had turned to reserve at 247 miles.

 

Yeah, between work, this virus crap and moving into a new house, things have been a bit hectic. I started a 685 on two KLR's just after Christmas (tore them down and sent the cylinders to EM) and by the time I got back from Holidays and had time to do them, Covid hit and my buddy whose 2015 we are doing, couldn't come out. Finally, I had him send me the cylinders and I put my 2001 together......only to find that it wouldn't run worth a crap; hard to get to idle, running lean and backfiring like crazy.......since I did my usual Stabil and drain the carb before winter and I hadn't touched the carb, I figured it was timing or intake leaks........after ripping everything apart and re-doing/re-checking my work, I slowly realized that the last fill before winter was corn-contaminated and that my issues are almost certainly carb related.

All the while, my wife is having difficulty understanding why working on my motorcycles is taking priority over landscaping the new home.......

Duane is coming over this weekend and hopefully we'll get his 685 done, my carb working and I can move on to other projects. I've been riding my 2000 to work the past few days but it's also showing signs of carb contamination - I've added some Seafoam and if it doesn't clear up, I'll have to rip it out for a cleaning when I'm done with the other bikes.

Dave

 

Good luck with the carbs DPelletier! I hope its a simple fix for you. You are always there to give helpful advice to folks! It can be a challenge to balance yours versus spouses priorities sometimes...

 

I had bad popping on decel, pulled the carb and cleaned it, did the 22c mod and set mixture 1.75 turns out and it is 99% gone


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