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Jetting 08 YZ144 by Eric Gorr ????

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Who has a good starting point for jetting a 08 YZ144 by Eric Gorr, ported low/mid stock reeds and pipe/silencer @ 1000ft 70°F either with 98 pumpgas or racegas

I have a head cut for both. The bike will used in the woods.

Thanks

Bob in MN

Edited by Treesmacker

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my gorr 144 it ported for mid/top with race gas head I run Trick 114 in it I currently been running two pilots larger over stock, stock needle in 3rd pos and a 460 main.

I would say at least 1 or 2 on the pilot and a 440 main should be good starting points.

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my gorr 144 it ported for mid/top with race gas head I run Trick 114 in it I currently been running two pilots larger over stock, stock needle in 3rd pos and a 460 main.

I would say at least 1 or 2 on the pilot and a 440 main should be good starting points.

I had the stock 40 PJ in during break in and it was too lean, I will go 2 up and try that and bump the MJ from a 430 to a 440. So far I have just gone up and down the street, too much snow! I have the pumpgas head on now.

Thanks for the info!

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I had the stock 40 PJ in during break in and it was too lean, I will go 2 up and try that and bump the MJ from a 430 to a 440. So far I have just gone up and down the street, too much snow! I have the pumpgas head on now.

Thanks for the info!

Rode today it was 60° F jetting is at MJ440 PJ 45 #2 clip A.S. 1-1/2 out

92 pump gas 32:1.

The idle still wants to hang like it's lean so should I try a larger PJ or clip position #3??

Bike sure is fun in the woods! :thumbsup:

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Wait a minute, what happened to all the people who said you had to jet the big-bore leaner due to increased vacuum through the carb? You guys are both jetting richer. Of course if you are using race fuel with a lower density, I guess you would need richer jetting. But everything else being equal, do you need to jet leaner or richer for the big bore?

I am so confused.

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Hey guys, whats going on? Most think BB's need to go leaner. Don't get me wrong just an observation. I will be running my 144 richer for sure based on what my engine builder's experience and my own.

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Its very confusing and both sets of logic seem to make a bit of sense (less or more jetting for big more). I have played around a bit with the jets in my 07 YZ. I started with a 440 and it ran OK, but power was down compared to a stock 125. Jumped straight to a 380 (only size i had with me at the time), jumped out on the track and it ran perfectly for a little less than a minute, then is started to Ping VIOLENTLY. If you do not know what Pinging sounds like, just imagine gravel in your exhaust pipe and that sound would be about the same. I jetted one larger (390) and started running 50/50 mix of race/pump gas. No more pinging and nice brown plug. All bikes will be different, but dont be afraid to lean it out a bit, just dont keep riding if its pinging.

07 YZ144 (Eric Gorr)

stock reeds

PC pipe and Shorty

750'

37.5/390 main jet

Bruce

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Would it just be better to call Eric yourself and have him talk directly to you about your set up??.I've called his shop a few times and he alway;s seems willing to help out.

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I'm running stock pilot and needle with 470 main, ported for mid -top, 144 HGS pipe, V- force 3 reeds and a powerblade and this thing is a rocket.

I have yet to race it against 250 4t but seat of the pants tells me I should have them on a rolling start.

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