2006 YZ250 Jetting Rad valve, PC full exhaust

WileCyot
Profile picture for user WileCyot
Posts
458
Joined
9/23/2014
Location
Katy, TX, USA
WileCyot
Edited Date/Time 6/4/2015 2:30pm
Alright guys, so I'm trying to figure out my jetting and I think it seems a bit screwy to me. Wanted to get some additional feedback from the peanut gallery.

I'm running 100L with Maxima Castor 927 32:1

Stock

Main: 178
Pilot: 50
Needle: N3EJ

Pro-Circuit recommends

Main: 175
Pilot: 48
Needle: N3EJ

I'm currently running

Main: 168
Pilot: 45
Needle: N3EJ

I feel like these jetting specs are WAY too lean. I know on the Rad valve I was going to lean out my main circuit but I didn't think it would be this much..... and then the pilot seems very lean as well.

My idle screw seems like it's screwed in damn near all the way and I'm at about 1.5 turns out on the air screw.

The bike seems to run really well but I'm not the best to ask as I've not been involved heavily in 2-strokes as I have been with 4-strokes.
|
mxrose3
Profile picture for user mxrose3
Posts
2360
Joined
8/17/2006
Location
Delmar, DE, USA
mxrose3 6/2/2015 1:07pm
6/2/2015 1:07pm
What does the spark plug look like after riding out on the track?
WileCyot
Profile picture for user WileCyot
Posts
458
Joined
9/23/2014
Location
Katy, TX, USA
WileCyot 6/2/2015 1:28pm
6/2/2015 1:28pm
I'll take a pic this evening when I get home of the plug I pulled out. This was when it was jetted with a 48 pilot but the air screw was out almost 3 turns O_o.
WileCyot
Profile picture for user WileCyot
Posts
458
Joined
9/23/2014
Location
Katy, TX, USA
WileCyot 6/3/2015 6:44am
6/3/2015 6:44am
So last night I screwed with it some more and enriched the main jet to a 170 while leaning out the pilot jet to a 42. This allowed me to back down the idle screw some but my choke still doesn't raise the idle of the bike. It causes the bike to run super rich and flood out so to speak. Bike runs crisp though or at least I think it does.
keeptwostrokesalive 6/3/2015 7:05am
6/3/2015 7:05am
I'm not very good at jetting, but I know that when I switch to the N3EW needle I believe, my 2006 yz250 ran SO MUCH better!! Everything else is stock if I remember correctly. I have an FMF gold series fatty pipe, pro-circuit r-304 silencer, boyesen super stock reeds, and I run 93 octane with Klotz octane boosters. Everyone that rides my bike says its a monster, I call it my "four stroke two stroke" only because it never bogs but still hits very hard.

The Shop

See All »
WileCyot
Profile picture for user WileCyot
Posts
458
Joined
9/23/2014
Location
Katy, TX, USA
WileCyot 6/3/2015 7:09am
6/3/2015 7:09am
keeptwostrokesalive wrote:
I'm not very good at jetting, but I know that when I switch to the N3EW needle I believe, my 2006 yz250 ran SO MUCH better...
I'm not very good at jetting, but I know that when I switch to the N3EW needle I believe, my 2006 yz250 ran SO MUCH better!! Everything else is stock if I remember correctly. I have an FMF gold series fatty pipe, pro-circuit r-304 silencer, boyesen super stock reeds, and I run 93 octane with Klotz octane boosters. Everyone that rides my bike says its a monster, I call it my "four stroke two stroke" only because it never bogs but still hits very hard.
I'm almost on the verge of going back to 93 octane..... Avgas is a great fuel but it's a bitch to jet.... I also have some C12 but I don't even want to switch to that.
keeptwostrokesalive 6/3/2015 7:12am
6/3/2015 7:12am
keeptwostrokesalive wrote:
I'm not very good at jetting, but I know that when I switch to the N3EW needle I believe, my 2006 yz250 ran SO MUCH better...
I'm not very good at jetting, but I know that when I switch to the N3EW needle I believe, my 2006 yz250 ran SO MUCH better!! Everything else is stock if I remember correctly. I have an FMF gold series fatty pipe, pro-circuit r-304 silencer, boyesen super stock reeds, and I run 93 octane with Klotz octane boosters. Everyone that rides my bike says its a monster, I call it my "four stroke two stroke" only because it never bogs but still hits very hard.
WileCyot wrote:
I'm almost on the verge of going back to 93 octane..... Avgas is a great fuel but it's a bitch to jet.... I also have some...
I'm almost on the verge of going back to 93 octane..... Avgas is a great fuel but it's a bitch to jet.... I also have some C12 but I don't even want to switch to that.
I personally have never used race gas(mainly because it cost too much for me) and will most likely never use race gas. The way my bike runs right now its absolutely perfect, I can't imagine needing any added HP from race gas or AV gas. I also have never had any detonating problems thanks to the Klotz octane booster, that stuff works surprisingly well. If I were you I would definitely give 93 octane a try again with some octane boosters
Jakes Dad
Profile picture for user Jakes Dad
Posts
1864
Joined
6/22/2009
Location
Brooksville, FL, USA
Jakes Dad 6/3/2015 8:20am
6/3/2015 8:20am
Run Motul 800T at 32:1
Squish is at .042

175 main
48 pilot
EW needle 2nd from top

I could go 172 on the main but I do run MRX02 at races and it runs fine with the 175 any cooler or drier air I would need to go to the 178 main though. But summer is here and this jetting will be fine.
WileCyot
Profile picture for user WileCyot
Posts
458
Joined
9/23/2014
Location
Katy, TX, USA
WileCyot 6/3/2015 8:33am
6/3/2015 8:33am
Jakes Dad wrote:
Run Motul 800T at 32:1 Squish is at .042 175 main 48 pilot EW needle 2nd from top I could go 172 on the main but...
Run Motul 800T at 32:1
Squish is at .042

175 main
48 pilot
EW needle 2nd from top

I could go 172 on the main but I do run MRX02 at races and it runs fine with the 175 any cooler or drier air I would need to go to the 178 main though. But summer is here and this jetting will be fine.
I unfortunately don't know where my squish is at.... I'm trying to wait till I rebuild this ol' girl before sending the head off to be machined.... I guess I could go ahead and check it...

What's your elevation? Temps?

Wait, you're in FL. Odds are similar to mine here in TX.... God this jetting is pissing me off....
HackMan162
Profile picture for user HackMan162
Posts
534
Joined
2/16/2007
Location
Austin, TX, USA
HackMan162 6/3/2015 9:38am
6/3/2015 9:38am
Might want to check with CamP, but I seem to recall him saying not to run the 927 with the 100LL.

In my RM250, I am running 100LL with Motul 800T 40:1
170 main
45 pilot stock needle in #3 position
air screw about 1 1/4 out

That is with VForce Reeds and FMF pipe/silencer
FGR01
Profile picture for user FGR01
Posts
6137
Joined
10/1/2006
Location
USA
Fantasy
908th
FGR01 6/4/2015 12:39pm
6/4/2015 12:39pm
WileCyot wrote:
So last night I screwed with it some more and enriched the main jet to a 170 while leaning out the pilot jet to a 42...
So last night I screwed with it some more and enriched the main jet to a 170 while leaning out the pilot jet to a 42. This allowed me to back down the idle screw some but my choke still doesn't raise the idle of the bike. It causes the bike to run super rich and flood out so to speak. Bike runs crisp though or at least I think it does.
Your jetting sounds ridiculously lean to me. I have a 2006 YZ250 also and even with riding at 4,500 feet I would expect my engine to seize in the first 100 yards with that jetting. At your elevation? I'm surprised the bike is still running.

At 2,500-4,500 feet my bike runs perfect with stock jetting and 100 octane pump race gas. I tried 100LL for a bit and had to go 1-richer on the main and 1-leaner on the pilot for it.
WileCyot
Profile picture for user WileCyot
Posts
458
Joined
9/23/2014
Location
Katy, TX, USA
WileCyot 6/4/2015 2:30pm
6/4/2015 2:30pm
WileCyot wrote:
So last night I screwed with it some more and enriched the main jet to a 170 while leaning out the pilot jet to a 42...
So last night I screwed with it some more and enriched the main jet to a 170 while leaning out the pilot jet to a 42. This allowed me to back down the idle screw some but my choke still doesn't raise the idle of the bike. It causes the bike to run super rich and flood out so to speak. Bike runs crisp though or at least I think it does.
FGR01 wrote:
Your jetting sounds ridiculously lean to me. I have a 2006 YZ250 also and even with riding at 4,500 feet I would expect my engine to...
Your jetting sounds ridiculously lean to me. I have a 2006 YZ250 also and even with riding at 4,500 feet I would expect my engine to seize in the first 100 yards with that jetting. At your elevation? I'm surprised the bike is still running.

At 2,500-4,500 feet my bike runs perfect with stock jetting and 100 octane pump race gas. I tried 100LL for a bit and had to go 1-richer on the main and 1-leaner on the pilot for it.
Well, that's what I thought as well but I'm following the procedures for jetting and this is where it's putting me O_o

Post a reply to: 2006 YZ250 Jetting Rad valve, PC full exhaust