Honda Dirt Bikes Forum

I just bought a 2004 CR250 and I have been having a lot of oil coming out of the exhaust connections and I have been fouling the plug too. I have set all the jets to stock (pilot 32.5  main 420) and set the air screw at 1 and 1/2 turns out. The air filter was dirty so I replaced it and I also changed the oil in the transmission.

I'm thinking maybe the next step is to screw around with the air screw and try to lean it out???? Any help would be really appreciated. I'm new to dirt bikes but am a mechanic. So this 2 stroke stuff is all new to me.

k_rok  

Thanks for including the bike info as well as the jetting sizes. go to a 400 main. repack the silencer (its full of spooge)warm up the bike and ride for a while. with the engine running (at idle or @1000 rpm) turn out (counterclock wise) the air screw until the rpm peaks. reset your idle and go ride. pull your plug out and take note of the color. we want a tan or very light brown color. this reading will not be accurate with a new plug, you will need to put a few hours on a new plug before the readings are usable.  

          post count means nothing
06yz125,kx60(2)

A 400 main jet??? ok I'll try that. Repacking a silencer... is there any tricks to doing that or do I just take it apart and replace the stuff inside?


Thanks  

MJP is right again.  When taking apart your silencer you will need to take a razor and cut the silocone seal around the gap before the core will seperate from the cylinder.  Resealing with a high temp silocone is recommended but not nessesary.  

Bill H. 2000 CR250R

Nothing to add but would replace the silocone seal and do not get carried away with leaning out the air/fuel screw.
Better safe then sorry.  
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Ruff!

Sorry just also wanted to add I have been riding at sea level.  

Even better.  You don't need to adjust for altitude.  

Bill H. 2000 CR250R

Would you recommend changing the pilot jet also. The reason I ask this is cause the parts guy at the dealer had the same bike as I do and he mentioned that he put his pilot down to a 30. Any opinions on this? He had also put the main at 400.

I changed the main but have not had a chance to ride it for a test ride yet. Also when I pulled the silencer apart the inner tube was broken into 3 pieces. So it looks like I'll be needing a new silencer as well.  

is there an aftermarket pipe on this? any other aftermarket work? someitmes this can throw it off a bit. and ussually the exhaust companies will tell you what to do in order to get the bike going good again after a new pipe ~pat  
PEACE GUYS ITS BEEN A BLAST!!!!! ~patrick

Normally if the core is broken it's a sign the packing wasn't changed as often as it should have been.  Keep the stock pilot jet for now.  See how it runs before making any more changes.  

Bill H. 2000 CR250R

no it is stock exhaust on the bike. Everything else is stock.  

ok will do. Thanks a lot everyone so far.  

Get a Pro Circuit nature friendly or FMF Q type silencer.  Both are trail legal, and quieter without costing any HP.  I always run mine except when my friend borrows it.  

Bill H. 2000 CR250R

Ok guys I changed the main jet to a 400 now it seems to be a much better color then before. I also adjusted the air screw and idle screw and it seems to be running better. I took it out for a bit today and pulled the plug and it is a nice tan color.

I have noticed that it runs alot better at higher rpm. Like it seems to take a bit before it really starts to pull. Is there a way to check the lower end to see if it is jetted correctly?  

your jetting should be fine. if anything else needed to be changed your spark plug would be black

what kind of silencer are you looking for. the fmf titanium 2 is best out there. the fmf shorty and fmf powercore 2 are good. procircuit r304 and 304 are good too. the best nature friendly silencer is the fmf Q.

i suggest you take a look at their websites        fmfracing.com        procircuit.com  
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Ride 2 strokes, buy 2 strokes, save the 2 stroke.

1998 cr125
2002 cr80