kr250a crank rephaseing

[azwood80]

Just wondering if anybody ever set there kr cranks to fire at the same time or 90 degrees apart the pickup coils runn one per crank same as the cdi,s has this been done before if so what was the result in theory both pistons hiting both tdc and btc at the same time would be bad for the harmonics of the engine i would have thort 90 degees would be bietter

[Jeram]

its all been done and tried before.

there is a reason all parallel twins are 'twngles' (0 deg firing)

vibrations

[azwood80]

its all been done and tried before.

there is a reason all parallel twins are 'twngles' (0 deg firing)

vibrations

not sure i understand why the tandum engine cant fire 90degrees apart i get why a 0 deg fire would suck on a single crank twin but the kr,s run like two motors of there owne wouldent 90 deg fire be more like a cross plane crank motion the idear is very intersting is there a good website on this stuff so i can resurch some more. I am allways trying to learn more about this sort of thing.

[azwood80]

Ok after doing some light reading i understand that the crank layout of an engine deterimines the point where the critical point of vibrations occure or at what rpm changeing the phase would change this critical point. Also it may change the power curve of the engine to i think i have more of a grasp on the ider.

[Jeram]

2 cranks spinning oposite directions cancels out secondary vibrations perfectly.

secondary vibrations are the type that you 'feel' the most when riding the bike.

if you go 90 degs, you then have harsh secondary vibes from 2 cylinders