2003 RM 250 ----- Reed valve modifications?

I just bought this bike, its real slow!

So I am putting a new top end, port and polish, mill the head.

I am not excited about spending $150 just on a stupid reed valve assembly right now, so...

Is there any cheap tricks to modify the stock reed valve?

$30 buck for the boysen power reed or spend $60 the pro series. If you have a slow 03 RM250, then something is wrong with it. Jetting realy wakes the 03 up. Also what type of expansion chamber makes a big differance in how the bike pulls.

Example: I do not like my FMF SST pipe at all. It will change the bike to be very smooth power from just above low rmp and it will hit a peak and falls short of full top end power. My PC pipe will rev to the moon and still give you more. Just my 2 cents. My FMF is hanging on the shop wall now.

Would it be a big difference between the:

1 ) boyesen power reed or the pro series

2 ) v- force reed assy the $150 one


I rode the bike at the track to tune the suspension and figure out any bugs before I tore it down. It has a FMF Gnarly pipe on it, with a fmf spark arrestor. (this bike will be used to race enduros)

The jetting should be ok, per the spark plug color...

I am just suprised at how slow it was. The jug is getting ported / polished and head milled now. The piston didn't look bad but the rings were worn enough to get a little blow by deposits on the side of the piston.

I am looking to get more mid to top end power with these mods. I guess we'll see after it gets put back together...

get the boyesen RAD valve. port the block to match the cylinder porting. i did all of the porting and head work on my 04 and it absolutely screams! PM me for more info on porting your bike and/or rad valve.

Bro, you need to ditch the gnarly pipe. Those pipes put all the power down low and rob the top end power blind! You're going to really enjoy the fmf fatty or pro circuit pipe compared to the gnarly. Make sure you're jets are to spec for the pipe you choose. I have a hard time thinking any 250 two stroke is slow unless IRS (It's, stupid iPad auto type) got problems. All thatvengine work is awesome but should absolutely not be necessary! The 03 is a clone (mostly) of theY 250 too, a great bike with even in stock form. Good luck!

Edited by moto_xmayhem21

HOLD-UP! If your 03 is slow, something is wrong. As stated before, ditch the Gnarley! Those pipes are horrible for desert/enduro on every bike I have tried it on, unless you are strickly woods tight twisty at all times. Second, my 03 is stock with a Rad valve and Bill's pipe with a PC spark arrestor. It fricken rips! My 01 and 02 are ported and special tuned by Bill's and my stock 03 is more powerful. I think your top end was ready for an overhaul. Before you go and port it, I recomend a fresh top end, new pipe of your choice, and a good powervalve cleaning. Also dissasemble your muffler, bet it is all clogged up. I used a beed blaster to clean all the carbon from the krizman and core. fresh packing will help too. Start off with it stock and fresh, then if it isnt enough build it. Remember, when you mill the head, Race gas will be a MUST. I run 91 in mine with a bit of predetonation. I am gonna relieve the head a bit to control that. What elevation are you riding at too? Maybe you will need to run a hotter motor to get the feel you desire since the higher the elevation the less power your bike makes. Regardless, try it stock and fresh first. As for your reeds, try the Boyesen set.

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