Can anyone tell me what this means

Create New Tag

8/3/2022 6:09 PM

I picked up a 2005 Honda CR250R a month or so ago and have just started digging into it.

Noticed "BF158" etched into cylinder above the exhaust port. Does anyone have any idea what it means?

Thanks in advance.



8/3/2022 6:21 PM

Probably a mold number or something for parts tracking in the oem world


8/3/2022 6:24 PM

slowgti wrote:

Probably a mold number or something for parts tracking in the oem world

No, that's etched by the guy who did the head.


Go for it! Don't let a little thing like fear, or common sense hold you back.

8/3/2022 6:27 PM

Probably work done for a BF #158 so the part didn’t get lost in a hop up shop.


8/3/2022 6:47 PM

Big Frank?


2021 KTM 350 SXF
2006 KX250

8/3/2022 7:24 PM

158 Beef Franks.


8/3/2022 7:38 PM

Buck futter 158


8/3/2022 8:19 PM

After you make love to it, the cylinder will read 159 BFs


8/3/2022 9:20 PM

Billy Franks ?

Barney Fife ?


8/3/2022 9:37 PM

You are waaaayy good with a BF158 head. Now if you had a BF73 , , BF116 or the rarest of all a would be putting your life at risk by riding that thing. This is common knowledge by the way.


" And there goes Jeffro. One of God's own prototypes. A high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die.”

8/4/2022 5:54 AM

The ‘05 CR250 engine was updated with a new cylinder that featured a removable exhaust spigot casting. They did this to allow better placement of the exhaust valve and better sealing. The cylinder and exhaust spigot casting are a matched set, hence the etching. The etching is factory to identify them as matched set. Some engine cases are also matched sets and have similar etchings. You cannot take an exhaust flange from another ‘05 and mate it to your cylinder. As you tear the engine down, you will find the same etchings on the exhaust spigot casting.


8/4/2022 10:36 AM

I'd be more concerned with that severed hand someone shoved in there then the etching on the exhaust port....thats just me though.


8/4/2022 3:58 PM

If anyone knows or suspects they know what company did the porting or yet to be determined engine work based upon where and how they engraved it I would appreciate the info.

I'm wondering if others (obviously who purchase used bikes for projects or personal use) might find it handy if there was a thread that had examples of or descriptions of how various hop up shops identify parts they've done work on.. ...IE if ProCircuit engraves their work in a certain location using a particular identifying standard. etc. etc. to help ascertain if, and by who, any work had been previously done to an engine/bike.

It could help prove or disprove claimed performance mods as well as finding out what was done based upon the shop's records, the serial number and/or what's engraved.