201 porting

[bmp01]

3 hours ago, Crocky said:

I cut it off when I’m cutting the base on them too. It does no harm. Crank case still feeds the transfers the same. 

 Emmm.... whats if for then ?

Obviously that transfer port extension makes the cylinder more difficult to make, more expensive, you wouldnt make it like that unless there was a reason...

I've not really thought about the length of a transfer port as being critical for tuning to a particular engine speed, but I wonder if thats what its about (these modern transfer ports are a lot different to those on pre strato saws).   

[Crocky]

On 22/07/2023 at 14:26, bmp01 said:

 Emmm.... whats if for then ?

Obviously that transfer port extension makes the cylinder more difficult to make, more expensive, you wouldnt make it like that unless there was a reason...

I've not really thought about the length of a transfer port as being critical for tuning to a particular engine speed, but I wonder if thats what its about (these modern transfer ports are a lot different to those on pre strato saws).   

Maybe something to do with transfer velocity. Not sure though. I was a bit wary of cutting it off but after porting one with it off I have no problem binning it now 😂

[Dan Maynard]

Came across this guy who builds saws and also puts them across a dyno. Significant gains from porting both 200 and 201, not that much between the two.

https://youtu.be/lcX6yAFTZEo

[Crocky]

4 hours ago, Dan Maynard said:

Came across this guy who builds saws and also puts them across a dyno. Significant gains from porting both 200 and 201, not that much between the two.

https://youtu.be/lcX6yAFTZEo

Yeah Joes a good guy, does some good work. I’m planning on getting one of my 2511s over to him to get it on the dyno. 

[bmp01]

I like Joe's approach, throws everything at the saw and backs it up with some before and after facts. The only thing missing is the transient response of the saw which can get a bit messed up with fueling.

Given that he has the dyno to measure the improvements he will continue to Iearn though...

 

Unusual power curve shape on that 201, something's a little out of tune with the rest of the saw timing.