220SR derestriction
Posted: 01:49 am Jun 02 2018
Big thanks to all on the forum for the useful tips and advice (especially cornishwrecker220 for the repeated posts recommending 35mm carb and starting point for tuning (40, 152, 1173L).
220SR now converted - bit of a mission but result is road legal 220 at pretty much full spec, so well pleased.
For the record, the conversion needed new intake side all the way - new airbox, new carb boots, reed block ported out to match profile of inlet manifold.
Started with 33mm pwk, and (following jetting guide) finished up with 42 pilot, 148 main and CGJ needle, middle clip (sea level, 10-15 degrees C).
Then on to 35mm - got to 40 pilot, 158 main, still using CGJ - good up top , but too rich in low + midrange (sluggish until powervalve opening) - revert to 1173L - WOW!
Found the 1173 to be very flat in 33mm carb, but perfect for 35. Great low range control, snap wheelies, top end with smooth transition. 80mph top (13/46 gearing, which is more or less stock) - would probably do a bit more, but need to get forks done for that!
Thanks again guys - forum tips invaluable help
220SR now converted - bit of a mission but result is road legal 220 at pretty much full spec, so well pleased.
For the record, the conversion needed new intake side all the way - new airbox, new carb boots, reed block ported out to match profile of inlet manifold.
Started with 33mm pwk, and (following jetting guide) finished up with 42 pilot, 148 main and CGJ needle, middle clip (sea level, 10-15 degrees C).
Then on to 35mm - got to 40 pilot, 158 main, still using CGJ - good up top , but too rich in low + midrange (sluggish until powervalve opening) - revert to 1173L - WOW!
Found the 1173 to be very flat in 33mm carb, but perfect for 35. Great low range control, snap wheelies, top end with smooth transition. 80mph top (13/46 gearing, which is more or less stock) - would probably do a bit more, but need to get forks done for that!
Thanks again guys - forum tips invaluable help