I first got my 2006 YZ85 in January. It didnt have any problems with the spark plug until a week later after I got it. But now it has bad spark plug problems. Every time I ride it the spark plug goes bad with black spooge all over the tip of the spark plug. I am going to try some of the tips that all of you guys have provided me with and I will tel you if they worked. Well I really hope they do and thanks to all of you that have provided me with info on what I should do because the manual doesnt tell you everything.
YZ 85 fouls spark plugs
- Thread starter KE100
- Start date
Jasle
Sponsoring Member
- Nov 27, 2001
- 1,358
- 0
I noticed that someone mentioned using the B8ES plug. DONT!!!!! There have been several reports of the electrode breaking off at the weld and dropping in the motor. The ES plug is not that great with vibration. Use the EG plug. If you do a search there was a NGK apps engineer on this list that posted this info as well.
As for 40:1 not being good enough for small bores...I'd disagree but have to qualify that statement. If you use a good quality oil like Bel-Ray Si7 or Motorex Cross power 2T you'll be fine at 40:1. We use 40:1 exclusifley in our Cobra 50's, KTm 65's and yamaha yz85's. With riders that ride hard getting top 10's at nationals including one national champ.
As for 40:1 not being good enough for small bores...I'd disagree but have to qualify that statement. If you use a good quality oil like Bel-Ray Si7 or Motorex Cross power 2T you'll be fine at 40:1. We use 40:1 exclusifley in our Cobra 50's, KTm 65's and yamaha yz85's. With riders that ride hard getting top 10's at nationals including one national champ.
Would going to a different drive ratio help you at all.If your son uses less throttle than required and is comfy at that speed,increse front sprocket or reduce back sproket by 1 tooth and see how that goes.He will open the throttle up more to go just as quick and might clear the plugs
Two steps higher compression dome Y03 5.9cc (Phathead Racing)
V Force 3 Reed Valve
FMF Pipe w/ Turbine Core 2 silencer (spark arrester)
VP race fuel (straight)
NGK B9ES
Timing stock
Steahly Flywheel weight
48 Pilot
NAPE needle
3.5 Slide
135 Main
This is what I have done to my son's bike for offroad use. It now has some low end where there was none before. It still has a upper powerband rush but is also a nice trail bike.
Advancing the ignition timing to 1.2mm BTDC is also supposed to help. This will be my next mod.
The NAPE needle and 3.5 slide are stock KX85 items.
Stock 2006 KX85 jetting:
Slide 3.5
Needle NAPE
Main 140
Pilot 45
Stock 2006 Yz85 jetting:
Slide 3.0
Needle NBKF
Main 138
Pilot 45
With my current jetting the exhaust pipe no longer has oil dripping all over the pipe and swingarm
V Force 3 Reed Valve
FMF Pipe w/ Turbine Core 2 silencer (spark arrester)
VP race fuel (straight)
NGK B9ES
Timing stock
Steahly Flywheel weight
48 Pilot
NAPE needle
3.5 Slide
135 Main
This is what I have done to my son's bike for offroad use. It now has some low end where there was none before. It still has a upper powerband rush but is also a nice trail bike.
Advancing the ignition timing to 1.2mm BTDC is also supposed to help. This will be my next mod.
The NAPE needle and 3.5 slide are stock KX85 items.
Stock 2006 KX85 jetting:
Slide 3.5
Needle NAPE
Main 140
Pilot 45
Stock 2006 Yz85 jetting:
Slide 3.0
Needle NBKF
Main 138
Pilot 45
With my current jetting the exhaust pipe no longer has oil dripping all over the pipe and swingarm
