Just done a few changes over the last few weeks. Ill start by chronological order:
-about 1.5 months ago I changed the timing on my stage 1 998 to the setting "F" on my 123ignition which is 34* at max advance and 22.5 at 2000rpm.
Performance was improved a bit so I left it there
-about 2 weeks ago I "vizarded" my hs4 by cutting the butterly spindle and and aerofoiling the butterfly+spindle.
once again, performance went up, throttle was really responsive and got my 998 to rev to 6000 without any issues. Something my mini wouldn't manage on my daily test route on some B roads behind my house. The AAA needle was slighty lean as there was more air flowing through so I turned the nut a 16th or 2
-today I swapped my old battered RC40 for a Maniflow center exit (small bore) and the smallbore LCB that was installed for a maniflow cooper freeflow.
and once again, performance has gone up a touch. Definitely feelable. sounds a plus too ;) but!!! something doesn't suit the current setup. Downlow its fine, at around 2000-3000 rpm theres a bit of a hole, then from 3.5 up to 6000 it revs like crazy. By feel, Id say its running slightly lean in the middle there and after adding 2/6ths richer, the hole went, but ofcourse the plugs go black at idle.
Whats on my mind is: where do I start now?
When do I know if the timing is correct?
When do I look for a balance between carb needle, dashpot oil, spring?
What is the norm: get idle to run smooth and mixture correct, then change/find needle to match rpms, then check mixture under acceleration to change dashpot oils/springs, and then set the timing?
I am looking for someone with an exhaust measuring machine thingy to find out whats going on mixture wise....I know its not best practice to do any of the above without measuring the exhaust gases...
edit: added image if anyones interested in seeing the bore diameter difference of the freeflow vs the smallbore lcb
Edited by luismx123, 09 November 2019 - 05:08 PM.