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Anonymous (not verified)
Edited Date/Time
10/30/2020 6:02pm
It seems to run well, but a little lean on top(says the plug). The rad valve instructions say to lean it out, but is already a little lean. Should I up the main jet? I'm new to this and trying to learn, but I'm spinning my wheels. Not really sure what to do. I have had this thing about 6-7 months and have not taken it out. I'd really appreciate any help you guys could throw my way. Thank you.
Stock jetting:
#178 main
N3EW 2nd clip
#50 pilot
Screw out approx 1 1/8th
*Running 92 non eth pump gas @ 50:1 Motul 800
She has a Fatty pipe, Turbine Core 2.1, Radvalve, twinair with cage.
Stock jetting:
#178 main
N3EW 2nd clip
#50 pilot
Screw out approx 1 1/8th
*Running 92 non eth pump gas @ 50:1 Motul 800
She has a Fatty pipe, Turbine Core 2.1, Radvalve, twinair with cage.
I see you're in WA, so if you're riding moto, we probably go to some of the same places.
I haven't run straight pump gas in a two-stroke in over a decade and 50:1 seems way too lean for MX if you care about crankshaft longevity. If you're super slow, 40:1 is about as light as I would go on a track.
I run a 50/50 mix of Trick 114 and 92 ethanol-free, so my jetting setup will be a little lean for your fuel.
Also I run Yamalube 2R @ 32:1.
My jetting is:
M = 175
N3EW - 2
P = 45
AS = 1-3/4
PJ = Stock
I run a milled head (20.5cc with ≈0.045" squish clearance) VF3 reed and a couple of different pipes, usually the FMF Factory Fatty.
Getting the head milled on your YZ is one of the best ways to make it run crisp and easy to jet. If you don't want to splash a little race gas in there, get it milled to between .045" and .055" squish, but keep the stock 21.5cc volume.
Guys who are riding in the woods seem to like a larger slide cutaway and less oil (I have a #8 slide in my box of parts, but have never felt the need to test it out). There are also a lot of guys who like the Suzuki needles, but you have to switch your main jet down a couple sizes to run them.
Here's a plug from last week:
The Shop
Main - 178
Pilot - 48
Needle - 2nd clip
Air screw - 1 turn out
FMF Factory Fatty & Shorty
Vforce3
R&B head mod
VP c12/ pump 93 from Shell 50/50 with Klotz oil. Here’s my plug
50:1 is also pretty lean. I've been running 40:1 for years with no trouble but premix ratio is an argument that has been going on for years.
OP I would start with mixing your fuel at 40:1 minimum, 32:1 preferably. and bumping up the main to a 180 and see if that helps.
As for jetting, you wouldn't wanna know my jets as I go a bit nuts with carb slides, and get the pilot size down, and the needle up to add fuel at the right throttle
Openings
178s main
Stock needle in the 4th clip
And a 45 pilot and 45 slowjet
With a #6 carb slide
Wouldn't recommend a richer carb slide with the stock pipe, tooooo herky jerky off the bottom, but for a setup like pc, it helps with low end and off idle response. If you want some tuning tips for the yz, it's easy to make a lot of power for next to no cash with just the stock components and a set of small files, don't need any cylinder mods, unless youve done everything else, and are hungry for more snot, but just massaging the stock parts to work, is easy, and cheap, just adjusting your pv governor spring tension can add so much power a pipe couldn't ever hope to add in the important part of the rpm range, the low to mid. I'm not saying that adjusting the governor will add just incredible amounts of top end, its not what's needed, but it will take you from needing 2nd in corners to a weee bit clutch in 3rd for slow corners, and effortless roll on from bottom To top anywhere else. My 06 yz250 was ported, with just about the same mods as my 2015, my 2015, stock jug, with a rb designs head, a ported stock reed block, and a retimed pv governor, and it was way faster around the track in every situation.
Go up to a 180-185 possibly, depending
I dont have an issue going 40:1, it was just what my last yz used and it ran well. Was how i got it. Also, what would you recommend instead of motul? How do you feel about Redline and/or Amsoil?
I run the turbine core because i need a sparky and was told this flowed better than the older version. They all are restrictive correct? Just the nature of what it is?
Also, what does the NECJ needle do exactly?
My bike is jetted with a 175 main 48 pilot N3EJ needle #2 groove 1turn on the air screw.
rocketship.
...i believe that's exactly what Pro circuit recommends for stock bikes
Dep pipe shorty silser
110 octane race fuel for the head work done
Sporting to cylinder
Rad valve system with carbon dual stage
Holes in nber plate to allow.more air to filter(top end)
Retarded time 1/8 inch
40 deg this weekend running
195 main
50 pilot.
Air screw 2 turns
Race j day off road. Always ran much bigger jets and prefer them over 178-182 ranger
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