Backfire under deceleration - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

 
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post #1 of 8 Old 03-19-2008, 03:38 AM Thread Starter
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Backfire under deceleration

I don't drive my KLR650 that often. It sits in the garage over the winter. When I finally get it started it backfires when I let off the throttle or decelerate. After riding it for a few days it seem to starts easier, but still back fires under deceleration. I bought it new in 2002 and it has about 1500 miles. Its been about two years since the last maintenance at the dealer, but I have only put about 600 miles on it since then. Any suggestions?
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post #2 of 8 Old 03-19-2008, 09:27 AM
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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

2008 DL650 VStrom Yellow and Black
Previous ride was a 2007 KLR Black/Silver, I miss it..
Looking to get back into KLR's sometime soon.

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post #3 of 8 Old 03-19-2008, 09:31 AM
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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."

2008 DL650 VStrom Yellow and Black
Previous ride was a 2007 KLR Black/Silver, I miss it..
Looking to get back into KLR's sometime soon.

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post #4 of 8 Old 03-19-2008, 10:47 AM
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You might also try running some Sea Foam through it.
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post #5 of 8 Old 03-19-2008, 01:21 PM Thread Starter
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Thanks you guys.... I'll try the Sea Foam first.

Could I be damaging the bike by riding it with this condition?
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post #6 of 8 Old 03-19-2008, 01:59 PM
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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.
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post #7 of 8 Old 03-19-2008, 03:43 PM
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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.

2008 DL650 VStrom Yellow and Black
Previous ride was a 2007 KLR Black/Silver, I miss it..
Looking to get back into KLR's sometime soon.

Best Auto/Moto Insurance | Motorcycle Protection Today | FREE Trade-In Quote
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post #8 of 8 Old 03-19-2008, 06:46 PM
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Quote:
Originally Posted by feelthelove View Post
I don't drive my KLR650 that often. It sits in the garage over the winter. When I finally get it started it backfires when I let off the throttle or decelerate. After riding it for a few days it seem to starts easier, but still back fires under deceleration. I bought it new in 2002 and it has about 1500 miles. Its been about two years since the last maintenance at the dealer, but I have only put about 600 miles on it since then. Any suggestions?
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.
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