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YZ144 is jetting so rich

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Just got back from my second day of jetting my EG 144.

Started with stock needle in middle, 37.5 pilot (40 stock) and 420 main (400 stock) = ran like crap and unrideable.

So far I've ended up at 40 pilot, 460 main needle in the middle = pulls like a damn freight train and that's with the 1 tooth large counter sprocket.

I got rid of any bogging  in the needle which was the big struggle to jet out (the pilot and main were really affecting it) but there is still more work to be done with the pilot and needle relationship. To be honest judging by the plug colour after some WOT runs the bike appears it could easily run a 470-480 main which surprises me, hell even the 460 surprised me but there was a slight bog at around 75% throttle so I went richer from a 450 to a 460 and man it pulled so much harder. Starting at 420 I'm very lucky I didnt melt my piston. A stock 400 would have made the bike completely shut off past 70% throttle. So much for these 144's liking to be jetted leaner.. for me at least.

Anyone else with a EG 144 experience having to go that rich on the jetting?

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So don't know if this will help much... I went with the Derek Harris 144 with a 36mm Lectron... Now I changed almost everything went to vforce 4 reeds, FMF shortly and the fmf fatty ... I did have to lean it out a tiny bit on the low end ... Similar to dropping a clip but other than that it made everything run better ... but man they do run like a raped ape getting raped by another ape it took me a while to know when to shift... It just pulls and pulls and pulls .. now I am a pretty big @ 210 so I was looking for more... So my gearing never changed.. I would for sure make sure the reeds are good and you compression is all good upon recieving it for a baseline .. but I have heard people going richer on big bores it just depends on the kit...

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Ya... I wish I had a stock 125 to try so I could know the difference... but i am very surprised how hard this bike pulls my 240lb frame around with an extra tooth on the front sprocket. I thought the stock jetting would be close enough where i could fine tune... I went with a 420 main from the stock 400 just to be 'safe'.. the bike ran like garbage and I was really not having a good time with it as I started the jetting process. The whole time it was the main the was ruining everything. Be careful when people tell you to jet this things lean... every bike is different. I was probably seconds away from melting my piston and with the stock 400 in it I probably would have. Going to a 450 'just to see' if it was lean up top (before dropping to a 400 to see if it was fat) was the best thing I did. The bike changed drastically and I knew I was on to the right path. The slightest hint of bog at 75% throttle was completely removed by going to a 460. With the 40 pilot and needle in the middle the bike became a dream to ride fast... almost. I still feel the needle is too rich also after an easy non WOT ride the plug came out pretty dark.

Tuesday I will mark 50% point on the throttle and do a mid range plug chop. Hopefully this will help me get the most out of the 1/4 to 3/4. Once I have that sorted I will adjust the pilot according to what it is doing off idle.. get rid of any weirdness off idle to 1/4.  After that is sorted I will get a new clean air-filter and do a full throttle chop to make sure it hasnt gone too lean. If my hunch is right I will be going richer on the main past the 460 that's in it now.

 

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If it needs a main that large to run right, I would be checking for an air leak.  Have someone hold the throttle part way open at a steady rpm while you spray down the intake boot and cylinder base areas with carb cleaner, WD-40, etc.  If there is a leak, the engine will stumble.

I would also check with EG.

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Hey I run similar jetting in my Gorr 144 mid top porting race gas head. 

50 pilot 450 main stock needle stock clip position stock float height. Trick 114 race gas 40:1 for 10 years now it's not an air leak. I knew of someone else who had him do a 144 to their 05 and they ran a 450 main too. 

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I wasnt able to test with carb cleaner.. just wanted to get out and ride a little but I ended up swapping the pilot a couple times. 37.5 runs like crap... 40 runs really well then i jumped to a 45 and it ran like crap again. I'll try a 42.5 this weekend hopefully but so far the 40 works well with the needle in middle clip and a 460 main and air screw 1.5 out. It idles better with a richer pilot but certainly doesnt run better.

Only thing that bothers me is that I have the idle screw adjust screwed in so far the end of it is flush with the nut that tightens it down and it will still die on its own sometimes. Leads me to think something is up.

Edited by YZ144FirstTimer

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just an update...

I thought i felt some pinging or missing when I was revving the snot out of the bike... so to be safe I went from 460 to 470 main and wow... it pulls so much better up top and this is with an old clogged up air filter.

I feel now, more than ever, there is a leak on this thing. I just got the pressure gauge to build my own leak down tester and will get that done this weekend... but gees it's running well the way it is.

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Hey, is that the EG 144 I sold a while back? Glad it is running strong. I will tell you that it ran perfectly for me with the stock main jet (410?) and needle and pilot = 40, so something seems different in your carb. Definitely do the leak test.

I ran 32:1 Yamalube 2R with pump premium. Stock pipe and silencer. about 800 ft altitude.

 

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Hey rjpjnk... yup thats the one... pulls like a freight train.

Now that I think about it I had better make sure it's the correct carb for the bike. I just discovered the bike has a swingarm from an early model so god knows what else has been changed on it.

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I have an 08 with an Athena 144, which I assume will be quite different from yours. I have another bike that is a stock 125.  I had a hard time getting the 144 bike jetted, and I'm still not 100% happy. The way I have the bike now it has more chug off the bottom, screams up top. The mid-range I wish was a bit more responsive and linear.  I have 14-52 gearing.  Just to clarify, I confirmed the Timing, squish, compression, float height, and air leaks via pressure and vacuum leak down tests. I ended up at:

30 pilot, 440 main, stock slide with JD jetting red needle on 4th(rich) clip for 80 degrees at 700 feet. I was getting bogging when the temps dropped in the 60's 

The low pilot is the only way I could get the bike to start on choke, and the air screw to not be turned all the way out. I was advised not to turn the idle screw so far in as it moves the slide off the idle circuit. I was following advice to start at the idle circuit and work my way up with the jetting. The interplay between pilot and needle shape and position and main jet seem to all have an effect on each other.  What I do know  is that the stock jetting ran like crap.

  Part of me wants to send the cylinder off to Harris performance to do some porting and get the lectron carb for it.

Edited by Drumgar
correct bad grammar

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That's a good point about the pilot and me having the idle screwed all the way in just to get the bike to idle. I thought about that a couple times over the last week.... what if I'm not even on the pilot anymore. I think during my initial jetting I ended up with such a large pilot because it was the only way I could get it to not bog coming onto the needle just a little up from idle.

So first thing's first.. I need to check and make sure it's the correct carb for the bike.. after discovering the swingarm is from an older model who knows what else was changed on this bike. After that it is time to do a leak down test before I start jetting again.

 

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