i've got a quick question that's bugging me to death. my 99 srx 700 ran lean on 1-1-13 and ate up the mag side piston top and scared the cylinder wall bad and beat the head up bad to in about 10 min. of riding. luckily no lower damage, dodged a major bullet. sled ran great up until that day, carbs cleaned, powervalves set and clutch weights close but just a little fine tuning to do. the only thing i did this day before riding was top it off with 93 premium and top off yamalube oil in res. i had cleaned the carbs just a month before but didn't know about the top-hat filters' at that time and missed that part of cleaning. anyways i'm wondering if it was either bad gas or the top-hat filter on that mag side cylinder being dirty or a combo of both. after tear-down of the motor i sucked the gas tank dry with transfer pump and could see little particles in the bottom of the tank so took off the fuel line from tank to fuel pump and put in-line filter there. took fuel pump apart and found nothing there.so then did some research here and found-out about the top-hat filters' and went straight to mag. side carb and shazam there was a chunk of black rubber about the size of a no. 2 pencil lead maybe 1/16" long sitting on top of the filter. would this be enough to restrict the flow of gas to that carb for 10 min. of riding, granted it was some wot runs, to due the damage it did or maybe the gas and rubber chunck together. other 2 carbs were clean in the top-hat area. all bearings', seals', carb boots, powervalves and reeds' are perfect and good to go so now i'm just trying to figure out this problem of it running lean on the exhaust side of piston and melting down. any help thanks. 
Where are your needles set at?
tons of factors for a burndown!!id say lengh of run a wot,then instant letoff of the throttle starved it for gas causeing the burndown,dirty carbs.just my opinion~smoke
a few wot runs in 10 minuets ,she wasnt even warm yet!!!
coulda been a cold seize..lucky she held togheter that long!!!
and i believe with the yamalube you should be useing some ring free if im not mistaken.
a few wot runs in 10 minuets ,she wasnt even warm yet!!!
coulda been a cold seize..lucky she held togheter that long!!!
and i believe with the yamalube you should be useing some ring free if im not mistaken.
Last edited:
FJViper
New member
Where did the chunk of rubber come from?