EG YZ144 Jetting

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#1
I am in the process of getting my 2005 EG yz144 jetted properly and need some help. Went on my second ride Sunday and could not be happier with the engine. I am running FMF fatty, Turbine core2, V-force3, with Eric Gore ported 144. When I had the engine done, I was instructed by Eric to go up one on everything. I also was instructed by somebody what had this done to start with a 450 main jet. Right now I am running the stock 40 pj, 06-07 needle in the 3rd clip, and a 450 main. The bike runs clean in all throttle possisons. There is not a stumble or bogs anywhere, but it is smoking a good bit and there is a lot of "spooge". I think I need to go one leaner on the pilot, raise the clip one, and go to a 440 main. I am going leaner than stock on the needle and pilot. I am just looking for some input from others that have had done the 144, and got their jetting correct. I am mainly a woods rider so it is more important for me to get the low and mid clean, and have the main be just slightly rich for protection . Thanks in advance.
 
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#2
I have the same setup, using 110 octane fuel. I am using the Yamaha 43-74 needle in the second clip with good results. Stock pilot, adjust airscrew to suit conditions. Try a leaner pilot, see if it runs better.

It's not unusual to have some smoke and spooge while running the woods. I do. When I hit the track, the TC2 spark arrestor is bone dry. Be careful when leaning the main jet.
 

SpDyKen

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#3
PT cr said:
It's not unusual to have some smoke and spooge while running the woods. I do. When I hit the track, the TC2 spark arrestor is bone dry. Be careful when leaning the main jet.
Especially when your jetting is rich!

burgunder, read one of the jetting threads, then go down on your pilot jet. You'll like the results!
 
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#4
I have ready every jetting thread there is on the internet, twice (and there is a ton to read), but I am just looking for some insite and conformation that my discision is correct. The bike starts very easily without the choke and the rpms stop raising at about 2 1/4 turns out, so that is an indication to me that i need to go from the 40 pj to the 37.5. I am looking for the rpms to stop rising at around 1 1/2 turns out. And, from what i have read, the pilot jet does contribute to the jetting through every circuit, although mainly the 1st 1/8. If that doesn't clean it up, I will try the 2nd clip (I am on the 3rd right now.) After riding the plug is wet and black all over. I know that may indicate that I need a hotter plug, but with the riding I do in PA, the terrain changes so much -from very fast open conditions like a mx track to very slow trials type riding- I would rather error on the side of caution. It is not fouldling the br9eg(S) so I will stick with that, and try to clean up the jetting.

PT cr - what is the 43-74 needle. I am running the 07 needle (forget the number) but, is that leaner or richer.
 
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#5
Spydyken- would you agree jetting is load dependant? Is there a reason to use a bigger main jet when running in sand WFO compared to a hard pack track, all other variables the same? I think so.

Burgunder - I believe the 43-74 needle is 1/2 clip richer than the 42-74 needle. Sounds like your pilot could be leaned out. There's one way to find out, try it.

I'm just saying what works for me. If you want to be on the razor's edge and dig into your carb every 3% change in humidity or temp, you can do that too. I'll just deal with a little spooge now and then.
 

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#6
Hello burgunder,

Without a doubt, you are doing your research, (between here & TT.) As you have learned, go ahead with the pilot jet change to 37.5. i'm sure you have read to not move on to changing anything else until you get the pilot circuit right. That means, despite your thoughts on the needle change, leave it alone for now. From my experience on my '03 YZ125, and from reading your posts on both forums, I suspect you may even need to go to a 35.0, or possibly even to 32.5 before you are done.

I'm in the middle of doing the same to my stock '06 YZ125 now; I'm down to 37.5; going to ride it this afternoon, a 2nd time, then try the 35.0. It will take some time, but your low-end that results will be worth it! :cool: :ride:

Good luck!
Ken W.
 

SpDyKen

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#7
PT cr said:
Spydyken- would you agree jetting is load dependant? Is there a reason to use a bigger main jet when running in sand WFO compared to a hard pack track, all other variables the same? I think so.

Burgunder - I believe the 43-74 needle is 1/2 clip richer than the 42-74 needle. Sounds like your pilot could be leaned out. There's one way to find out, try it.

I'm just saying what works for me. If you want to be on the razor's edge and dig into your carb every 3% change in humidity or temp, you can do that too. I'll just deal with a little spooge now and then.
Hi PT cr,
To the best of my knowledge, I have not discussed anything relating to the main jet circuit, so far. But YOU may want to consider this; when in the sand you primarily run on what circuit? Now how about in the woods? When do you experience spooge the most? :whoa:

The beauty of it all is that we all get to choose how we want our bikes to run, ourselves, right!
 
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#8
You are also correct. I have found it safer to be on the rich side than lean when trail riding due to changing temps and conditions versus the track where you can make changes easily.

Happy trails. :)
 
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#9
That is why I want the pilot and needle to be as clean as possible, while I would rather have the main on the rich side. I am not racing, and do not need an insane amount of top-end (alot is good-but don't need a ton) but I do need snap on the bottom and mid. Before some body says that I should have bought a 250, I am not complaining. My bike is close, and was just looking for some advise. I will try the 37.5 and let you guys know how that goes. Thanks for the help.
 

SpDyKen

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#10
I rode my '06 hard this afternoon/evening on my usual tight wooded 7.5 mi. trail. I started out smooth & easy, but riding with about 10 other guys led to som pretty agressive riding. It was dusty, so I rode hard to stay near the front. Oh yea, good thing I had an extra bike to rob a radiator from, after veering 90 degrees left, and wheeling into a tree, in the middle of a hill climb (when I wasn't aggressive enough at the bottom.)

This bike is incredible, especially compared to my '03. Fantastic low end, for a 125; great turning,, etc.

I'll be going down from the 37.5 pilot to the 35.0 before my next ride. It runs well, now but it is still rich and is spooging, as well. I'll also be raising the forks in the clamps to 8 mm height above the top clamp. I'll report back. Ken
 

lwsmithjr

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#11
I'm running a 420 main and 42 pilot in my 05 YZ144 with the stock needle, 2nd clip position. A 450 main is seems to be way too rich. I think if you drop the main down a couple of sizes, it'll make getting the bottom right a little easier. And yes, I realize that the main jet is for 3/4 to wide open throttle, but all other things being equal, if the main is larger then you are going to get more fuel flow at any throttle position beyond 1/8 open. If the needle is moved off its seat, then a larger opening will flow more fuel.

I would also watch for detonation very closely. We have stock compression, but still ended up mixing 1/2 race gas with pump. You may have read my other thread but the indicator was the spark plug was unscrewing itself. This bike is really unbelievable for a 125!
 
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#12
I tried the 37.5 and 35 pilots, and for me it is better.

I have an 06 YZ144 for race gas, factory fatty, V-force 3, turbine core 2.
For around 70° with Torco 110 gas:
460 main
43-74 clip 2
35 pilot

Could be a shade lean on the needle now. The main seems ok. Need to do more testing.

Post your settings as you go?
 
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#13
I put together a cr134,had carb issues,was running a 460 main and 50 pilot!New carb and a 420 with 35.7 pilot is pretty close,may try the 35 pilot for sure.The type of race gas makes a big difference off bottom,I will dig up a link later.THIS BIKE RIPS! Talk about exploiting potential power!I can not wait to try his 280 mod!
 
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#14
When you are done messing with misinformation and companies that are after your wallet,check this stuff out,and you would not believe what you can do with this companies product line for state of the art technologies!The CR134 loves the 537 with a splash of boost!http://www.precisionautoresearch.com/Fuel.pdf
 

SpDyKen

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#15
Interesting company, it would appear. I'll be doing more reading of their website.

Just a ride report after re-jetting. I went down to a # 35 pilot today, everything else stock, except for FMF "Q" silencer. Ran excellent; of course I was happy with it after last ride. It finally rained last night, so I made good use of the improved low-end! Less spooge, air screw at 2 1/4 out, cooler today, (mid 60's) elevation 800 - 950 ft.

Tomorrow I'll try a # 32.5 pilot and switch to 75% 93 oct. / 25% 110 oct. race fuel