TDC Evo!

Ex3t3r

Ex3t3r

Club Member
Can someone please confirm that the TDC on a a late Evo is 35 degrees as stated in the manual as this
degree seems excessive. It can't be a typing error as someone would of flagged it up by know?!

The reason why I ask is surely the ignition spark is to early as the piston approaches the compression stroke before the piston has indeed reached BTDC the plug seems to be sparking prematurely due to the 35 degrees! Or I am I missing something here?

See attached from H-D manual

MY TIMING DEGREE.png


TIMING MARK.png
 
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It is correct it allows the flame path to burn and grow/travel for complete combustion at tdc to push the piston down the bore as the charge expands and 35 degreees is not very long at 2000rpm ,if the compression is increased then you can adjust the timing accordingly but other factors come into play ie cam timing duration/overlap ect and head flow inlet and exhaust dynamics and your into Alex and dyno territory with the sum of parts to make a whole….. with_glasses
 
watchman said:
It is correct it allows the flame path to burn and grow/travel for complete combustion at tdc to push the piston down the bore as the charge expands and 35 degreees is not very long at 2000rpm ,if the compression is increased then you can adjust the timing accordingly but other factors come into play ie cam timing duration/overlap ect and head flow inlet and exhaust dynamics and your into Alex and dyno territory with the sum of parts to make a whole….. with_glasses
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Cheers watchman 'I have seen the light' (y)
 
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