I have a scrambler 500 that i bought new and it has always been well maintained and always ran good. untill this past weekend i was riding and it stalled. started right back up and ran good. stalled again later in the day and would not start back up. it has spark and seems to have compression but when i was checking it out i found a lot of gas in the breather box. any body got any tips on what to check or look for. Thanks....Sam

 

Gas in the air box is usually a sign that the needle and seat are worn and gas is backing up into the air box and could be contaminating the fuel also (If the oil in the tank smells like gas,change it and the filter) Also check the cam and valve clearance! This could be another problem if the exhaust cam lobe has worn down! Could be it not taking fuel properly and misting back into the air box! This was the last year on the soft cams that caused problems (1995-2000 425 and 500 engines) OPT

 

thanks for the quick reply O.P.T. Ill check both of those out. (I was probably lucky that cam lasted this long anyway)

 

Well I tore in to it and found that the timing chain is broken. Ill have to do some more reading and decide what to do next.

 

Hopefully NO bent valves? I would just go ahead and pull the head to see if any valve damage or any other damage. I've had em shear lower cam chain sprocket wood ruff keys and have had stretched chains,but can't remember any broken chains? Anyway, hopefully no major damage! Keep us updated! OPT

 

pulled head off and no damage. ended up needing crank sprocket and chain. had trouble with some guy on e-bay getting me my parts. three week delay. ended up getting them from my local dealer put it back together and it runs like a new one again. another quick question does any body know the difference in spark plug numbers example bkr6e bkr6es bkr6ey bkr6e-n-11 thanks again sam

 

NGK's website will show you,but briefly BKR5E and BKR5ES (s standards for standard copper core)
-8 to -20 on the end of the number stands for the gap (-11 shows gap to be .044) Just Use BKR5E or BKR5ES OR if you do a lot of high speed running use BKR6ES(runs at a cooler temp) gap is pretty close out of the box. OPT