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View Full Version : harsh sounding 400ex...HELP


journeyman
04-12-2005, 06:20 PM
ok heres the deal....my buddy has an 01 400ex that he bought brand new back in 01...about 2 years ago someone ran into him while riding and crack the side cover which houses the stator...so he replaced the side cover and anything else he saw that needed replacing being as he did it himself and didnt have a manual....so about 5 or 6 months ago we started hearing this awful noise coming from the bike when you give it a good amount of throttle...i can only compare the sound to a 440 or running with a muffler just straight header...but you dont hear it at idle speed, only when gunning on her...he has recently ordered an hmf slipon,uni air and jet kit, but dosent want to put his new pipe on until he can figure out what is wrong...his bike is bone stock at the moment with no engine mods.Some people said it could have some thin to do with his valve timing,cdi,icm module, and even maybe a bolt backed out inside the side cover where the stator is?????any suggestions????
Quadman250R
04-13-2005, 07:04 PM
my brothers EX has a sound sort of what your describing when you take the airbox cover off, when you get on the throttle it gets real "throaty". although it isnt as awful sounding as you make your buddys bike sound. my only suggestion is bring it to a local bike shop and let them listen to it and check it out. i would also consider getting a manual if you already havent, clymers for a 400 EX cost about $30.00. Good luck
journeyman
04-13-2005, 07:57 PM
yea ive got the manual...we started tearin her to pieces tonight and discovered that he only has 3 of the 4 nuts on his head bolts and there is some severe carbon build up near the missing nut..so goin tomorrow to get a washer and nut and gonna try that..ill keep ya posted
400exrider707
04-13-2005, 08:37 PM
Originally posted by Quadman250R
my brothers EX has a sound sort of what your describing when you take the airbox cover off, when you get on the throttle it gets real "throaty". although it isnt as awful sounding as you make your buddys bike sound. my only suggestion is bring it to a local bike shop and let them listen to it and check it out. i would also consider getting a manual if you already havent, clymers for a 400 EX cost about $30.00. Good luck

yeah that throaty sound was probably the air being sucked into the intake via the removal of the airbox lid..........