Rejet or Not??
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Rejet or Not??
I have a 2000 Lowrider with V&H Bigshot Staggered on it. K&N high Flow filter,Ngk Irridium plugs. Seem to have a popping on decel. I've checked the jetting and the carb had a 48 & a 190 in it from the previous owner. I have turned the mixture screw out 3 full turns and still the pop. Checked for an exhaust leak and there doesn't seem to be one. Should I take the 48 out and go to a 45 or 46?? PLease help.
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From: Lake Seminole
If you are getting a backfire, you are to lean and that will burn your engine up. I had H-D do my stage 1 upgrade. They put it on a Dyno after install and found that the rear jug had a bad intake gasket.
Take your bike and put it on a Dyno its cheaper than a new engine!
Take your bike and put it on a Dyno its cheaper than a new engine!
Cruiser
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It's my understand that the popping on decel on a properly tuned bike is caused by the engine pulling more air through the carb than the idle circuit can provide fuel at the proper A/F ratio. This creates a lean mixture that is unable to support combustion. As enough of this lean mixture moves into the exhaust it can be ignited by the hot gases from the next time the cylinder fires. As this condition only occurs under decel and is momentary it should be nothing to worry about. If it runs good and the plugs don't indicate a lean condition you should be good to go. You may never be able to get rid of the pop completely. Decel pop and backfire are two different things
Last edited by greggreen; May 9, 2011 at 08:55 AM.
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It doesn't pop just riding around town only when I get on it and it decels, and not every time. didn't start until after I changed out the pipes. I'm pretty sure it's not an exhaust leak. Should I look into putting a 46 in instead of the 48 that is in there? I forgot to mention I did replace the intake gasket front the back of the carb to the manifold
Last edited by lennyb3us; May 9, 2011 at 11:00 AM.
Cruiser
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I'm running V&H slipons, SE air cleaner, 46 pilot jet, 190 main. I've got two .025 washers under the needle. I get occasional pop on hard decel. I don't worry about it. Wife thinks it sounds cool.
Going to a 46 will lean it out and may make it worse. If you think your gasket install is good I would just keep an eye on the plugs and go with what you got.
Going to a 46 will lean it out and may make it worse. If you think your gasket install is good I would just keep an eye on the plugs and go with what you got.
Last edited by greggreen; May 9, 2011 at 11:41 AM.
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From: New Jersey
I put a big sucker stage one kit and after making an appointment with Harley iv decided to give it a go myself trying the below method.
http://www.hdtalking.com/fuel_and_ca...ggestions.html
http://www.hdtalking.com/fuel_and_ca...ggestions.html
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I've got the stock jets in my carb (45 & 190) needle raised with the two #4 washers and a/f mix out about 21/2 turns runs really good. It will also have decel pops on hard accels and getting off the gas real fast. Check your plugs, they will let you know what's happening in the cylinders. By the way this is on a bike with the 95" kit.
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Cruiser
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If you do the washer install it wouldn't hurt to mic the washers. I had to go to 3 different stores to find some that measured .025. First two lots
measured more than .030 each. Don't know how critical the thickness is but I figure better safe than sorry.
measured more than .030 each. Don't know how critical the thickness is but I figure better safe than sorry.
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I ran the bike at 2 1/2 turns out with fresh plugs at 1/4 throttle to check the low side jet. plug had no color on it. turned out 3 turns and changed plugs and ran it again very light tan / off white color. sprayed the intake with wd 40 to check for leaks and found none. doesn't seem to have an exhaust leak. Could a lack of back pressure cause a pop on decel?? Any help would be greatly appreciated
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