Exhaust and port timing coordination

[hendy]

Folks, forgive me if I'm asking the obvious or possibly unanswerable, but I've only recently started to delve into the world of 2 strokes in any meaningful way......

It seem to me that exhaust, carb, cylinder choice etc are chosen (by most people, including me) in a semi random manner. It seems to be along the lines of either "I want balls out power", so I go for a big carb, expansion that has the word 'race' in its name and the longest exhaust port duration one can find.....

Or "I want a nice to ride torquey motor"; in which case everything is small and etc.

However, a few recent threads seem to be saying that the important thing in choosing an exhaust/cylinder is that they are appropriate for each other. For example, I have an ancillotti clubman at the moment, so I believe that it would be detrimental to have transfers open for 130 and exhaust for 190. Conversely, I assume that 122 transfer and 164 exhaust would run badly with a franspeed race (for example). I believe this does not mean that either the expansion or the barrel is 'bad', but rather that they are mismatched.

What I'm asking in a rather long-winded way is would it be possible to generate a list of port timings that are broadly suited to different exhausts or vice versa?

[hendy]

I obviously asked too vague a question and hence no replies!

To get to the point, which exhaust(s) suit my port timings best? I want more power than I'm getting at the moment from my Sito Ancillotti but don't want peaky performance.

I have a gt186 but my exhaust has been raised to 178 and transfers are 124.

[tavspeed]

have a look on mb's tech site under advanced tuning,some good info on port timings and what rev range they will pull,then you need to find out where your exhaust produces it's best spread of power,then alter timing.s to suit

[hendy]

have a look on mb's tech site under advanced tuning,some good info on port timings and what rev range they will pull,then you need to find out where your exhaust produces it's best spread of power,then alter timing.s to suit

Thanks, that's really useful. My cylinder is tuned to make peak power around 7000rpm.

I'm now looking for a pipe that will match it.

I am considering:

NK road
Franspeed Supertourer
Avanti clubman (when they are for sale)
MB clubman
JL3
Taffspeed copy