cleopatrisha

Member
Dec 16, 2006
86
0
my 81 yz250 will not even fire. here what I know for sure. the carb is good because I tried it on another bike, the spark plug has nice blue spark set at .025 , timing mark is at tdc, the spark plug gets wet with gas, feels like it has good compression, I have not inspected the reeds yet, they looked ok when looking in from intake boot. but if the spark plug gets wet it should at least fire, backfire, anything. one thing I just thought of, does this bike have a woodruff key? if it does and it gets sheared will it still have spark? thanks for any advice.
 

cleopatrisha

Member
Dec 16, 2006
86
0
Bike does fire when I pour a little gas directly into spark plug hole. the only thing I notice with the reeds is a couple of the petals have a slight stick when I initially push on them with my finger to open them. other than that they look good not warped or cracked.
 

originaldirt

Member
Apr 25, 2000
103
0
I believe that the correct timing is before top dead center (BTDC) and not at Top dead center (TDC). If you are not technically checking the timing correctly, it may not fire.
OriginalDirt
 

2strokerfun

Member
May 19, 2006
1,500
1
Indeed. No engine will run corrrectly with spark firing at true TDC. Now, you may indeed have timing marks aligned correctly, I don't know. But if you actually have it firing TDC, the spark is too late. By the time anything is ignited and burned, the piston is already far along its downstroke. My '76 elsinore 250 is 20 degrees BTDC. Yours should be timed somewhere along those lines.
 
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