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Tuning a carb after rebuild and adding a pipe, etc.

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Hey guys, I'm getting ready for riding season and I'm not really sure where to start with tuning my carb. I disassembled it last year and cleaned it but never got back around to tuning/riding it and it's been sitting ever since.

I'm setting it up for more of a woods bike so in the off season I got a 10oz FWW, Pro Circuit pipe and a throttle tamer. Weekend plans are to install everything and see if I can get her to run and not nuke the motor in the process. I hear 2 strokes are finicky when it comes to this. (I'm not super familiar with 2 strokes).

Is there a starting point to set your screws/needle? Any good rule of thumb to follow? 

edit: 04 RM250, stock aside from PC pipe. altitude ~460ft. Hot summers, lots of humidity.

 

Thanks!

Edited by FullTilt151
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Maybe start with telling us what bike you have,altitude and average temperatures. I'm not an expert but that stuff is pretty important.

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Ha! You're right. Sorry about that, I was on my lunch break at work and in a hurry. 

04 RM250. Bone stock aside from the PC pipe

I'm in Louisville and according to Google we're at 461ft above sea level. Spring/Summers are pretty brutal with humidity. Avg temps in the summer are high 80's low 90's.

Thanks again.

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When mine was a 250 I used a 45 pilot 168 main and a NECH needle. I can't remember if it was in the second or third position. And just played with the air screw if it didn't feel right. Might be a little rich for woods. I'm sure someone else will know a lot more than me about it

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Thanks. I'm guessing if there's lots of smoke it's too rich, no smoke it's too lean? There should be a little smoke right? 

These bikes should idle like 4 strokes eh? I've been reading and people seem to be in 2 different camps. Some say no, you have to keep blipping the throttle the whole time and others say the bike should idle normally when you're not on the gas.

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Ha yea a lot of people say different things. Mine idles fine. And weather or not it smokes can depend on a lot of things like when I was using motul 800 I would get shit loads of smoke if I sat at low revs. Ask kxrob he's a legend at jetting. That's what I did

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On 4/14/2017 at 3:17 AM, FullTilt151 said:

Hey guys, I'm getting ready for riding season and I'm not really sure where to start with tuning my carb. I disassembled it last year and cleaned it but never got back around to tuning/riding it and it's been sitting ever since.

I'm setting it up for more of a woods bike so in the off season I got a 10oz FWW, Pro Circuit pipe and a throttle tamer. Weekend plans are to install everything and see if I can get her to run and not nuke the motor in the process. I hear 2 strokes are finicky when it comes to this. (I'm not super familiar with 2 strokes).

Is there a starting point to set your screws/needle? Any good rule of thumb to follow? 

edit: 04 RM250, stock aside from PC pipe. altitude ~460ft. Hot summers, lots of humidity.

 

Thanks!

45 pilot ( 48 was standard)

necj clip 3 to start (standard)

165 main  (pro circuit recommends it ) 168 was standard

google spanky's jetting guide for correct airscrew adjustment

is you want it better then that then i would buy a neDj needle and run clip 2

and do a plug chop for the main ( explained in the jetting guide above ) you might end up at a 160-162 only the plug chop will tell the tale

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9 hours ago, kxrob said:

45 pilot ( 48 was standard)

necj clip 3 to start (standard)

165 main  (pro circuit recommends it ) 168 was standard

google spanky's jetting guide for correct airscrew adjustment

is you want it better then that then i would buy a neDj needle and run clip 2

and do a plug chop for the main ( explained in the jetting guide above ) you might end up at a 160-162 only the plug chop will tell the tale

Ah. Thanks! I took notes when I cleaned the carb but of course I can't find them (in the middle of selling my house). I'll check the docs. 

Thanks again everyone

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Sorry to bump an old topic but I wanted to reply with what I found so in case someone else runs into the same issue. The PC pipe would not mount properly. Nothing on the bike looks bent and nothing on the pipe either, but it just would not mount. I got a extra couple sets of eyeballs on it and they couldn't mate it up either so I went back to the stock pipe and silencer. 

Checked the main/slow pilots/needle clip setting. All stock for a 04 RM250.

Set the carb to stock settings per the manual.

Air Screw: 1.5 turns out (turn all the way in until it stops, then back out 1.5)

Bypass knob 12 turns out (the knob on top of the choke)

Idle knob. The manual says stock is screwed all the way in. This is bullshit and will scare you to death if the bike actually fires. (ask me how I know).

Tried kicking the bike over and it fired but I had to back the idle way out. Then it died and after the 10 thousandth kick I realized I forgot to put gas in the damn thing! Once that was sorted it fired right up. The throttle tamer helped a lot but there's still a little stutter/hesitation between cracking the throttle open until about 1/2 throttle. If I read the manual correctly that's the slow system, so that'll be the next thing I'll address. Haven't installed the FWW yet either. (Mother's Day stuff getting in the way of my fun).

 

Thanks again for the help guys.

 

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