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YZ jetting with pipe and silencer

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So my new to me 2003 yz250 bike has a spooge issue. Have not pulled apart the carb to see what jets are in it but its jetting is too rich because there is too much unburned oil. I put a pro circut 296 and an fmf gnarly pipe and I was wondering what you guys recommended for jetting that way I can buy new jets and get them coming and have them here when I pull it apart.

 

Bike is mostly a woods bike with some dune riding. Has a rekluse z start pro clutch and no toil air filter in it.

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My 03 with a PC pipe runs perfect in the woods with stock jetting at 32:1. The air screw sometimes needs some adjustment as the temperature changes.  I swap silencers a lot and never notice any effect on jetting unless it's a sparky.  My 06 runs better in the woods with the accessory needle that is a half step leaner, and an "8" plug.  I am a very high-rpm rider.  

 

Both the FMF and PC websites have jetting charts you can look at for a 32:1 mix.  For most years the changes are minor, if any.  

 

I doubt you are going to find a setting that works for both woods and dunes if you are a fast rider.  Woods may need to be a little leaner than stock, depending on how tight the trails are, and how you ride the bike.  Sand riding is going to need richer jetting for safety.

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So my new to me 2003 yz250 bike has a spooge issue. Have not pulled apart the carb to see what jets are in it but its jetting is too rich because there is too much unburned oil. I put a pro circut 296 and an fmf gnarly pipe and I was wondering what you guys recommended for jetting that way I can buy new jets and get them coming and have them here when I pull it apart.

 

Bike is mostly a woods bike with some dune riding. Has a rekluse z start pro clutch and no toil air filter in it.

My '03 had a huge spooge problem. Problem completely solved by repacking the silencer & using an exhaust pipe sealant (from any auto parts store) around the ends.

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40:1 with a clean burning oil will make a big difference, I suggest amsoil interceptor. Next up would be getting the head squish fixxed, these 2 changes would not only kill all the spooge but clean up the lowend power.

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Well  as far as oil goes the bike had Caster927 in it but I had a buddy recommend Honda HP2 pre mix. I am running at 32:1 like the manual suggests. The Honda HP2 seems way more oily and way more smokey. I really hate it.

 

Also I am not sure what pipe sealant would do other than trap it in the pipe, I am getting spooge out the silencer not at the connection at the head. Well im getting it kinda everwhere but im getting it as far back as the silencer. Its just too much oil something is wrong somewhere

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Well  as far as oil goes the bike had Caster927 in it but I had a buddy recommend Honda HP2 pre mix. I am running at 32:1 like the manual suggests. The Honda HP2 seems way more oily and way more smokey. I really hate it.

 

Also I am not sure what pipe sealant would do other than trap it in the pipe, I am getting spooge out the silencer not at the connection at the head. Well im getting it kinda everwhere but im getting it as far back as the silencer. Its just too much oil something is wrong somewhere

32:1 was too rich for my bike and the spooge was running to the lower (front) side of the silencer & blowing out of my silencer around the front silencer end cap. The exhaust sealant & re-pack fixed it all & I had massive spooge. It was blowing out all over the caliper, hub, wheel...I mean everywhere...and I have heard of a lot of people getting the squish corrected too. I need to look into that myself. Not sure what it's all about...i've been on CR's all my life, so the YZ I have now is my first YZ.

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Bike is mostly a woods bike with some dune riding. Has a rekluse z start pro clutch and no toil air filter in it.

 

You have the tricky situation of having to jet it lean enough at low / mid throttle so not to foul or spooge up from the low combustion temps of trail riding,

but yet still rich enough to properly cool the engine at high rpm / high engine load of wide open throttle dune riding.

Meaning a smaller pilot jet, a larger main jet. The needle will require the most fine-tuning, not only the clip position but also trying different profile needles.

 

To 711redrider, if you mostly trailride you also would likely need to re-jet leaner on the pilot jet & needle clip

A well jetted / mechanical sound (good compression) engine will not spooge up, even slow riding at 32:1

If you ride motocross / high rpm and your engine still tends to spooge that massively, apart from the jetting also confirm

than your RH crank seal isn't worn/damaged and sucking in gearbox lube.

 

Type of oil can also worsen the spooge issue, if you trailride/off-road, a 'race' type premix meant for sustained high rpms oil will not fully burn off.

Something like Lucas or Interceptor etc. that has a lower flash point is better suited for lower rpm / trail use / recreational MX'ing.

Edited by mlatour
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