hannon Posted October 1, 2007 Report Share Posted October 1, 2007 recently my uncles 2005 4rt started to backfire after he revs it up he checked the plug and changed it to a new one and generaly can not find anything wrong it otherwise runs good Quote Link to comment Share on other sites More sharing options...
munch Posted October 1, 2007 Report Share Posted October 1, 2007 is the exhaust leaking at the joint? check it ,if it is it will do it when shutting off. have you recently taken out the restrictors? Quote Link to comment Share on other sites More sharing options...
sr34 Posted October 1, 2007 Report Share Posted October 1, 2007 i found like others if you dont let them warm up until the fan kicks in you will have problems with plug fouling & back fireing youve just gotta leave that throttle alone i also have found changing to the jitsie air filter & removing the flame guard has made my 4rt run much better Quote Link to comment Share on other sites More sharing options...
bucki3 Posted October 2, 2007 Report Share Posted October 2, 2007 I agree, when starting from cold leave the throttle and let the bike warm up itself untill the fan comes on then you can ride off hassle free! Quote Link to comment Share on other sites More sharing options...
svleigh Posted October 2, 2007 Report Share Posted October 2, 2007 I've got to agree with the above statements about warming up, I had similar problems until I let it warm up, and it does take a while for that fan to cut in. I've not tried the jitse filter yet, sr34 can you say what is noticeably different over using the stock filter and flame guard? more power? quicker to rev up? regards Leigh Quote Link to comment Share on other sites More sharing options...
sr34 Posted October 2, 2007 Report Share Posted October 2, 2007 I've got to agree with the above statements about warming up, I had similar problems until I let it warm up, and it does take a while for that fan to cut in. I've not tried the jitse filter yet, sr34 can you say what is noticeably different over using the stock filter and flame guard? more power? quicker to rev up? regards Leigh the bike just breaths better & less plug fouling more responsive compard to the standard filter & guard Quote Link to comment Share on other sites More sharing options...
malibudon Posted October 2, 2007 Report Share Posted October 2, 2007 I installed a Jitsie air filter and removed the flame guard on my '07 4RT. I didn't notice even the slightest difference. hannon, when was the last time your uncle cleaned the air filter? Quote Link to comment Share on other sites More sharing options...
hannon Posted October 2, 2007 Author Report Share Posted October 2, 2007 many questions/statements he cleaned his air cleaner the day before our last ride the baffels in the muffler were removed the first week he got the bike about two years ago the exhust doesnt leak he does let the bike warm up which doesnt take long being that we go riding in the desert during the summer were temps start at 80 F and get up to 100 F by 10 am even at the end of the day he can rev up the motor and then it will back fire, typically what most of our group does it let the bike idle to warm up and check tire air pressure put helmet on etc this hole thing just started maybe a month ago it just seems weired to just start backfireing after owning the bike two years and the performance hasnt changed Quote Link to comment Share on other sites More sharing options...
sirhc Posted October 2, 2007 Report Share Posted October 2, 2007 The only other thing I would recommend would be to check the valves. Quote Link to comment Share on other sites More sharing options...
tombleds Posted October 4, 2007 Report Share Posted October 4, 2007 One thing to check is oil buildup in the bottom of airbox. That has caused my bike to not rev and to run erratically especially at high rpms. I just wipe it out with a paper towel. Hope this helps. Tom Quote Link to comment Share on other sites More sharing options...
windlestone Posted October 4, 2007 Report Share Posted October 4, 2007 recently my uncles 2005 4rt started to backfire after he revs it uphe checked the plug and changed it to a new one and generaly can not find anything wrong it otherwise runs good Does it backfire while still trying to rev the engine or after you have closed the throttle ? Riding in the temperatures your describing the engine may be overheating in which case the engine management will put the bike in 'limp home mode' In other words the bike can't rev past 2000 rpm it'll run perfectly up to that point and let you ride it back to the van. Have to let the engine cool down then it will run normally again Quote Link to comment Share on other sites More sharing options...
hannon Posted October 4, 2007 Author Report Share Posted October 4, 2007 the bike runs fine no loss of power and revs fully but after you shut of the throttle as the motor is slowing it backfires Quote Link to comment Share on other sites More sharing options...
malibudon Posted October 5, 2007 Report Share Posted October 5, 2007 I'm with sirhc...I'd check the valve clearance. If that's correct and the problem persists, a leakdown test is in order, as a valve may not be sealing when it is seated. Quote Link to comment Share on other sites More sharing options...
hannon Posted October 29, 2007 Author Report Share Posted October 29, 2007 Well here is the latest we have checked every single electrical connection and cleaned them all adjusted the valves cleaned everything we could see and reach with a cloth someone suggested that we hold the throttle wide open and kick it 3 times (which i guess re starts the computer) the bike still back fires and the plug is still black running rich you can even see it running rich with black smoke coming out of the pipe any more ideas Quote Link to comment Share on other sites More sharing options...
malibudon Posted October 29, 2007 Report Share Posted October 29, 2007 One of the EFI's sensors has got to be bad. The EFI computer is being fed bad information, causing it to run rich. Quote Link to comment Share on other sites More sharing options...
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