Way back when dyno testing the old Rotax twin at Zipkarts for Hines Superkart,I found that the closing timing of the RV is very
responsive to tiny changes.
The stock timing was 134/86 , and moving the closing out to 88 gave a big result in peak and overev power.
That engine only reved to 13400 max tho, and any more timing simply killed the upper midrange way more than it increased the topend.
Opening ended up at 138 as going any more made it all but impossible to jet correctly with a huge amount of standoff badly affecting the acceleration
both under dyno load and on the track.
So my advice is to cut the blade in only 2* increments at most.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
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