125-200cc Port work on a 144 or 125

[rockdancer]

Just wondering if anyone has had theirs ported and wanted to share their experience and knowledge of the benefits of getting it done
eg
Is there a noticeable increase in performance ?
Is there a loss in low down performance ?
Is over rev increased ?
What was actually done ?

Thanks in advance

 

[firedog55]

I sent my 144cc cylinder to MaxPowerRPM. They're easy to work with and have a quick turnaround. I first heard about them from Grass Roots BMW when they ported their Italian Husky CR125 race bikes. They were every bit as fast or faster than the KTM's and YZ's at our local MX tracks.

http://www.maxrpms.com/

They can do any porting from mild to wild, or big bore it. I went with a simple clean up and flow. Helped a little from bottom to top with the biggest increase in the mid range. And works best with the 36mm Lectron and 8oz. FWW/CR ignition. I'm pleased with the set up for tight single track here in SE Missouri, lugs down low better than I expected and still rips on top.

 

[justintendo]

thats the best port job, a good mid boost with no loss on top or bottom. takes some good skill and know-how to pull that off.

 

[rockdancer]

Thanks - I am familiar with them . What do they do to make it flow better ? Polishing ?

What did it cost ?

 

[justintendo]

altering port heights, and or dimensions. ive read many places that polishing does little if anything especially on modern engines that are already quite smooth.

 

[rockdancer]

Some info I got from a 2 stroke cylinder tuner below

I think matching the transfer ports to the cylinder is something I will look into - measure


The best value for money mod will be setting up the cylinder head correctly... always knock that off the list first before going down the route of porting.

I havent measured up the husky 144 ports so i cant comment on the exact timings and design they use but in general there are two stages for porting... the first is to clean up any casting issues, alter the shape of ducts, match the cylinder to the cases, etc and tidy up the port windows. this sort of porting usually gets a bit more power everywhere but just how much is gained depends on how bad the starting point is.
The next stage of porting is to actually measure up the port heights, widths and angles and then cut in a new set of port shapes, widths, heights, etc. Sometimes the changes are major and other times they are minor. Usually doing this will end up with a focus of gains in the midrange and top end, however in most cases if youre clever you can make good gains all the way through the rev range and still manage extra gains up top. If you actually make a loss down low then as far as im concerned youve stuffed the job up... it is possible to gain everywhere when doing it right.
Basically you can do whatever you want with the ports if you know what youre doing. You can aim for more bottom, more mid or more top. Usually for an offroad setup i would aim to gain in the bottom end and midrange as much as possible as well as gain some up top or in the overrev. The only way to do all that though is to work the ports and head at the same time.

 

[justintendo]

on the older swedes matching the cases to the jug and cleaning up irregularities makes a very noticeable difference...my 360 is my first and only italian and was really impressed with how well everything was matched at the factory and the casting was nice. being plated instead of sleeved helps that out quite a bit as well.