Airflow question from a great 2 stroke moto-x aritcle

[Longtrail23]

http://twostrokemotocross.com/2009/05/budget-racer-2001-honda-cr125/

In this link is a great write up on building up the 01 CR 125.  I have this bike, and have a few quick questions about this article..
- If you go down to "step one" modify the airbox do they mean the side number plates? If so are you just supposed to make the factory opening bigger & by how much is safe?

-At step 2 replacing the stock intake boot with a 2005 intake boot, do they mean the black boot that goes to the carb?

-At step3 I believe the larger valve limiter is the one they made for this bike to replace the smaller stock one (if im correct). How did they figure out what size to make it/where could I get one? How does this achieve more "blow down" and what is blow down?

*I know these questions may seem a bit ridiculous bc they are going to be such simple answers but I need to clear this up 100% and make sure im doing the right thing, so thank you so much for all the help!!

[2T Institute]

http://twostrokemotocross.com/2009/05/budget-racer-2001-honda-cr125/

In this link is a great write up on building up the 01 CR 125.  I have this bike, and have a few quick questions about this article..
- If you go down to "step one" modify the airbox do they mean the side number plates? If so are you just supposed to make the factory opening bigger & by how much is safe?

-At step 2 replacing the stock intake boot with a 2005 intake boot, do they mean the black boot that goes to the carb?

-At step3 I believe the larger valve limiter is the one they made for this bike to replace the smaller stock one (if im correct). How did they figure out what size to make it/where could I get one? How does this achieve more "blow down" and what is blow down?

*I know these questions may seem a bit ridiculous bc they are going to be such simple answers but I need to clear this up 100% and make sure im doing the right thing, so thank you so much for all the help!!

Yes drill some more holes in the air box lid. probably 2 X 25mm holes would be ideal.
Yes
Depends if it's an RC or HPI type valve, if it's a RC valve it will sit higher in the cylinder at full open. If it's a HPI they have no real idea what blowdown is.

[Longtrail23]

- Thank you for the response 2T Institute but just to make sure, if you (or anyone else here) wouldn't mind looking at this picture I'd like to know if drilling two holes by the air inlet would be best or cutting out the whole or part of the "triangle" would be better.
http://www.google.com/imgres?imgurl=http://upload.wikimedia.org/wikipedia/commons/7/7b/Honda_cr_125_2001.jpg&imgrefurl=http://commons.wikimedia.org/wiki/File:Honda_cr_125_2001.jpg&usg=__A1C-yY7Xg1be0tATGE-RICsiylA=&h=1200&w=1600&sz=694&hl=en&start=1&sig2=SkyO3IGZKzEiz0VQWcNyuQ&um=1&itbs=1&tbnid=63HaO1AmOGJYDM:&tbnh=113&tbnw=150&prev=/images%3Fq%3D2001%2Bcr%2B125%26um%3D1%26hl%3Den%26safe%3Doff%26rls%3Dcom.microsoft:en-us%26rlz%3D1I7GGLL_en%26ndsp%3D20%26tbs%3Disch:1&ei=dNoWTJe8GMH78AbPhL33CA

-As far as replacing the stock intake boot for 2001 I'm definitely going to pick up the one made for 2005 (is that the best year to get or has any other year a better choice?) and as far as the valve types and blowdown goes I am going to do some reading about that.

Thank you so much once again, I appreciate the help!!

[JohnN]

Longtrail23 - If you have questions about the article, my suggestion would be to contact the author, Derek Harris at HP Performance. I'm sure that he could guide you because he is the one that built that bike.

Derek does post on occasion on this site, but he is very busy, so it would be best to contact him directly. There should be a link in the article and his site has a contact page.

Good luck and let us know how you make out!

[Longtrail23]

Thanks, I may do that to have some work done in the future but I wouldn't want to bother the shop. If he posted on here that would be great but Im sure someone else here may be able to point me in the right direction.

[mrhp]

the boot is from the airbox to the carb.

The bigger stop holds the powervalve at a slightly higher height on this bike.  Quite honestly you could skip this mod if you didn't want to spend the time getting it right.

The 01 actuates like most other 125's did, with a ball and ramp system.  Holding the powervalve slightly open (it's a rotary style on this bike), or higher in the port gives the engine what is called more blowdown.  Blow down is the time when the exhaust port opens to when the transfers open...and is the most critical period IMHO in a two stroke.

[2T Institute]

Blow down is the time when the exhaust port opens to when the transfers open...and is the most critical period IMHO in a two stroke.

True and one of the least understood to