125-200cc 2011 WR 150

I bought a used 2011 WR150 (very clean) with 850km for my 15 year old son this summer. It starts first kick, idles and runs great no problems there... (my WR 250 is a different story for a different thread on starting) My primary problem with the 150 is the it fouls plugs after a couple hours of running. My secondary problem is it has a slight bog when starting to roll and a big bog like it's starving for fuel just before powerband. It seems to have less bog or lack of fuel when you roll the throttle as oppose to crack the throttle during the higher revs. I've had my Husky mechanic who use to own at WR125/144 check the jetting and he claims it's as lean as we want go on the stock mikuni carb. I've had a local mechanic do a simple carb clean with solution and blow air through it. I'm running a B8 plug rather than a B9 - 50:1 Klotz and recently switched to Amsoil an still I foul. My son doesn't rev it like it should be but should it foul a plug every couple of hours?

My thoughts...
- keep rejetting
- get a Lectron
- change gearing to 12/51
- the mikuni needs to be properly cleaned

I don't mind throwing a bit of money at it but I want to make sure my issues are fixed.

Has anyone had the same issues?

Thx

If its jetted correctly you should never foul plugs. Try lifting the needle and see if that makes a difference before going to a bigger main. Where is your air screw at?.
Read up about jetting a two stroke as going to a mechanic to jet would be expensive and its a skill worth having.

The fix for my mikuni was the oem 2004 rm125 needle. Do a search here. It's worked for others too. I'm very happy with the results. Before I had the dreaded off idle bog. After the needle swap, it was gone.

Open the carb and list the jetting along with float height

Thanks Dirt Addict! I got a handful of needles and jets with the bike. Would the same RM 2014 RM 125 be part of my handful as long as the needle numbers match or are they different altogether?

Kan3 - The bike's put away for storage right now for the winter. I'll see if I can pull the carb off and list what I have. might be a day or two...

I pulled the mikuni off today here's what I've got.

I run at about 800 ft elevation
Main - 460
Needle - 6DEY15-74
Needle clip position in the middle (3rd position)
Pilot - 4.0
I'm not positive what you meant by the float height but I took a picture of the float thinking that was what you're after.


Thoughts?

that bog shat me to tears too! lectron sorts it! rich bog thought(too much fuel)? shouldnt foul plugs even at 25-32:1 just cruising around but will still want a bit of a clean out(good hard rev every now & then) to run totally clean. 50:1 pretty lean for the small bore isnt it?

I was having same issues...2013 yz250. My bike is stock...except for an FMF Gnarly. Never fouled till I put on the Gnarly. I think the JD jet kit is the way to go...they do the homework for us. Just got the kit...my bike runs crisp and clean. I'm happy with the purchase.

Jetting for WR 144.

Hi we have two and one is the 144 and the other is a 165.
The pilot jet is probably still a 30 or even larger size. The correct size for the pilot jet is anywhere from around 15 thru to 20 and that is probably the biggest issue with fouling plugs and poor running at idle. Suggest you start at 15, we are at 300m above sea level so around the same elevation. When you try this the bike will idle amazing and be four strokish it will pull at minimal rpm thru trees and over logs and transform the whole bike.

As another improvement.
The RM needle is the go, search this site but # is 6CHY17-62 its an 04 RM 125 and it may pay you to also get the washer that is a half a notch for needle metering more accurately they are a couple of bucks as well Suzuki part #s are 13383-36FRO and 13382-19E00 respectively. The DEY needle should still work just try dropping into seat further after you have changed pilot.

By the way the "slide" is probably the #4.0 referred to not pilot.

Pilot jet change is the key here.