Rocky Mountain Dirt Riders

Here's my latest jetting:
440
42-75 clip 2
S4
32.5 pj
5.75 slide with reed side filed with a chainsaw file

Works really well!

For any of you who may have torn the top o-ring like I seem to have from jetting in the bush, here's the part number:

2001-2006 Suzuki RM125 part - 13258-36F00

1999-2015 Yamaha YZ125 part - 5ET-14147-00

Dobi wrote:I have run JD kits in the past with good luck, especially when running an SX head

162 main and a 38 pilot. L needle in the 2nd from top position (I can never remember how to label them)
I have gone as low as 158. but it hurts the top end run out at lower elevation and heavy loads.

Curious is the L needle a Suzuki NECL needle? Got the bike running decent but it could still be a little bit better.

BigD wrote:

Dobi wrote:I have run JD kits in the past with good luck, especially when running an SX head

162 main and a 38 pilot. L needle in the 2nd from top position (I can never remember how to label them)
I have gone as low as 158. but it hurts the top end run out at lower elevation and heavy loads.

Curious is the L needle a Suzuki NECL needle? Got the bike running decent but it could still be a little bit better.

I believe it is... I have a pile of jets and needles from years past

I did drop down to a 160 main and changed my needle again recently for better gains (can't recall what I stuck in, I was eyeballing them in the parking lot at Panorama before the race). The bike is now running great. I did buy a JD kit for the set up I am running but have yet to drop their needle in. Perhaps I will do so before heading to Vega to race this weekend. I do like to fatten it up for the sand drag races on Saturday night

Dobi wrote:

BigD wrote:

Dobi wrote:I have run JD kits in the past with good luck, especially when running an SX head

162 main and a 38 pilot. L needle in the 2nd from top position (I can never remember how to label them)
I have gone as low as 158. but it hurts the top end run out at lower elevation and heavy loads.

Curious is the L needle a Suzuki NECL needle? Got the bike running decent but it could still be a little bit better.

I believe it is... I have a pile of jets and needles from years past

I did drop down to a 160 main and changed my needle again recently for better gains (can't recall what I stuck in, I was eyeballing them in the parking lot at Panorama before the race). The bike is now running great. I did buy a JD kit for the set up I am running but have yet to drop their needle in. Perhaps I will do so before heading to Vega to race this weekend. I do like to fatten it up for the sand drag races on Saturday night

Ok thanks! I’ll keep testing I am starting to get a collection of needles also.

BigD wrote:

Dobi wrote:

BigD wrote:
Curious is the L needle a Suzuki NECL needle? Got the bike running decent but it could still be a little bit better.

I believe it is... I have a pile of jets and needles from years past

I did drop down to a 160 main and changed my needle again recently for better gains (can't recall what I stuck in, I was eyeballing them in the parking lot at Panorama before the race). The bike is now running great. I did buy a JD kit for the set up I am running but have yet to drop their needle in. Perhaps I will do so before heading to Vega to race this weekend. I do like to fatten it up for the sand drag races on Saturday night

Ok thanks! I’ll keep testing I am starting to get a collection of needles also.

I had to pull my carb apart last night to confirm my needle setting for another gentleman and thought I would document it here for when I forget... My current setting is below. This thing is jetted great. Pulls ski hills like mad and is clean off the bottom. i run Opti oil at 80:1 and recently ran a jug of Liquid Moly through at 50:1 with no difference in jetting

PJ - 38
MJ - 162
Needle - N2Zk (from an 09 300XC) part number 54731134800

Dobi wrote:


I had to pull my carb apart last night to confirm my needle setting for another gentleman and thought I would document it here for when I forget... My current setting is below. This thing is jetted great. Pulls ski hills like mad and is clean off the bottom. i run Opti oil at 80:1 and recently ran a jug of Liquid Moly through at 50:1 with no difference in jetting

PJ - 38
MJ - 162
Needle - N2Zk (from an 09 300XC) part number 54731134800

So the 2016 keihin bolted right in? Neither rubber boots needed to be upgraded? I would love to do this upgrade and just want to confirm on parts.

There have been fixes discovered to make the Mikuni just as good as the Keihin. I wouldn't waste your money if you intend to buy a new carb. Filing the slide and installing a jet block gasket kit form Cometic/JD Jetting seem to cure all the issues. There's also a few other mods Graham Jarvis' mechanic has done which seems to also improve things.

You can fix the carb for about $15 for the gasket, and everything else it DIY mods.

Mine runs great, and I have another friend who has the same jetting as me who says it is just as good as his old Keihin 300's.

I tried the "fixes " for the stock mikuni carb after running a 36mm keihin with a jd kit. The mikuni was ok but the mid range had a rough spot I couldn't get rid of. Elevation 3,000 to 5,000 feet for the winter. But will go up to 9,000+ feet in the summer. the keihin was hands down better and very simple to jet. I did the usual 4 force reeds and milled the head down .015. I left the airbox alone.
I grew up on 2 strokes switched to 4 strokes in 01 then rode a 2017 tx 300 and switched back to 2 strokes. I've also switched from primarily riding mx to more of a 50/50 split between mx and trail riding the tx 300 does it all! I even like the air forks

218Norton wrote:I tried the "fixes " for the stock mikuni carb after running a 36mm keihin with a jd kit. The mikuni was ok but the mid range had a rough spot I couldn't get rid of. Elevation 3,000 to 5,000 feet for the winter. But will go up to 9,000+ feet in the summer. the keihin was hands down better and very simple to jet. I did the usual 4 force reeds and milled the head down .015. I left the airbox alone.
I grew up on 2 strokes switched to 4 strokes in 01 then rode a 2017 tx 300 and switched back to 2 strokes. I've also switched from primarily riding mx to more of a 50/50 split between mx and trail riding the tx 300 does it all! I even like the air forks

When you say "tried the fixes for the Mikuni carb" that included the JD Jet block gasket kit, Jarvis mods and filed the notch in the slide bigger ?

"Trail guy. No I didn't do the JD jet block gasket kit but I did the Jarvis mods and filed the slide

I rode yesterday at Wild Rose with all the mods, bike ran great with the Mikuni. I know woods riding is a bit different, but I think all of those mods were another step forward from already dialed in jetting.