Reply To: Camshafts, 125 vs 250
250 cams are heavier than 125cc and ofcourse they are thicker and have bigger egg lobes , so they may “press” down the cam buckets a bit further in to the cylinder so the valve could hit piston or just about “miss it” . Risky gamble but can try it.
Another problem = extra weight , more load on valve springs and slim cam chain. The 250 uses much fatter cam buckers and thicker chains ofcourse.
The sprockets of cam shaft may be removed , and use 125cc cam shaft sprockets to keep using the 125cc chain. However be warned on accelerated wear on valve parts, so frequent inspection may be advised.
250cc and 125cc vtwins have the same timings and same clearance, so i would not expect big performance gains. The most costly part in the engine is the crankshaft, so have to make sure crankshaft teeth of the 125 don’t get extra stress.
Just my thoughts 🙂
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