2000 CR125 Mods

M

MCP486

~SPONSOR~

Dec 26, 2001

37

0

• Aug 19, 2002

• #1

Hi everyone. This post refers to the porting diagram for a 2000 Honda CR125 from Eric Gorr's Performace Handbook. First when it says to lower the outer edges of the exhaust port 8mm, it shows a drawing that shows cutting down the lower edge of the port, but it does not say how deep, only how long to cut. Second, When it says re-profile the exhaust valve 2mm, is that keeping the same radius as stock, just removing 2mm of material? Third, aside from raising the exhaust port to 27.5mm from the top of the cylinder, would rasing the transfer ports 0.5 to 1.0 mm serve to add more top end while keeping a good amount of rideability, or would they take off too much bottom? My final question is with these mods, would a Wiseco 707PS (no intake window) piston help regain some of the lost low-end, while still providing favorable power characteristics on top?

Thanks,

Matt

 

marcusgunby

LIFETIME SPONSOR

Jan 9, 2000

6,450

2

• Aug 20, 2002

• #2

Not easy questions these as im not eric but i have seen a few cylinder done to this spec.The outer edges of the exhaust port need to be dropped but im not sure what you mean by deep?you are trying to make the port larger by making it more oval.The powervalves need to be raised 2mm in the same profile as stock.To be honest im not convinced this mod really does much.I think its one of those things in theory works but in practice doesnt do much-if the powervalves were closer to the piston in the closed position it may have more effect.I would just raise the exhaust port for now as the 2000 had large transfers.Giving too much port time area i believe will give you a hole in the powerband at 9000rpm.

I would try the no-window piston to help give back a little pick up as it does have a small effect.

 

EricGorr

Super Power AssClown

Aug 24, 2000

708

1

• Aug 21, 2002

• #3

Theres a lot of different combinations of aftermarket accessories and machining mods that can be performed to achieve any type of powerband. What are you looking for? Perhaps we can give you some specific suggestions to meet your needs.

 

M

MCP486

~SPONSOR~

Dec 26, 2001

37

0

• Aug 21, 2002

• Thread starter
• #4

Eric, I am looking for the bike to retain the same bottom end power, if not gain a little, but rev further on top. I realize its hard to make a motor better at both ends of the powerband, but that is what I would hope for. It feels like my 125 has engine-braking after riding my 450, and I would like it to rev further in each gear so it is easier to switch bikes.

Thanks,

Matt

 

Y

yzeater

~SPONSOR~

May 21, 2001

1,995

0

• Aug 21, 2002

• #5

Wait a second...you're in Alexandria...where do you ride? (BTW, I live in Fairfax)

 

M

MCP486

~SPONSOR~

Dec 26, 2001

37

0

• Aug 21, 2002

• Thread starter
• #6

Yep, I am in Alexandria. Pretty much all the local areas have been shut down, so right now I am going to The Landing MX in Easton, MD a lot. I also race at Budds Creek and Antietam. Maybe Seaford this weekend.

Matt

 

steve125

LIFETIME SPONSOR

Oct 19, 2000

1,252

0

• Aug 21, 2002

• #7

Then yer in my neck of the woods. I live near Mt. Vernon and go to the Landing on sat or sundays :cool:

 

M

MCP486

~SPONSOR~

Dec 26, 2001

37

0

• Aug 21, 2002

• Thread starter
• #8

Steve, I live near Mt. Vernon too. Is there anywhere else that you practice at besides The Landing? I wish there was somewhere else to ride near here that was half as decent as The Landing

 

Y

yzeater

~SPONSOR~

May 21, 2001

1,995

0

• Aug 21, 2002

• #9

A track builder told me there's an older track next to Budd's Creek, I haven't looked into it yet

 

M

MCP486

~SPONSOR~

Dec 26, 2001

37

0

• Aug 21, 2002

• Thread starter
• #10

Hmm, I actually heard a rumor about that from some redneck guy who rents a room at my friends house. I know there is that Southern MD ATV park, but it was closed as of a few months ago. So the closest decent practice track you know of is The Landing?

Matt