HELP!! Plug Color
Posted April 21, 2000 - 05:56 PM
I have a '99 WR400 with YZ timing. It has the stock exhaust w/o the baffle.
Jetting: 48 Pilot, screw 2.25 turns out, DVP needle clip position number 5, 185
main (0 to 1500 ft alt). Air box lid is in place without the snorkel (helps
keeps water out). Stock sparkplug NGK CR8E.
The machine runs great - it is crisp and hits hard over the full range.
However, the sparkplug looks rather odd compared to what I have seen on other
machines over the years. The very end of the insulator, the tip of the center
electrode and the straight end portion of the ground electrode are white (even
though the tips of the electrodes do not look white in the scanned image). The
rest of the plug is very black with carbon. Color goes from white to very black
with no transition.
How does this compare to other WR plugs??
Thanks for any help or ideas you can offer.
Eric in WA
'99 WR400, YZ timing, IMS Tank, YZ Seat, Acerbis Handguards, Yamaha Full
Skidplate, Devol Rad Guards, Dunlop 755F & 756R Tires
'99 Polaris 400 Scrambler
'99 Honda Z50R
'97 Honda XR70R
Kubota L275DT and an assortment of farm tools.
Posted April 21, 2000 - 07:43 PM
This is an curious looking plug condition...
Posted April 21, 2000 - 07:46 PM
A 185 seems really rich..... hows your top end?
Posted April 21, 2000 - 09:41 PM
Posted April 22, 2000 - 04:27 AM
My plug looks the same as yours also. I am running a 180 MJ. The other jets match yours. I have removed the octopus and gone w/ Clarks jetting suggestions for that. My problem is my bike will never start in any condition w/out the use of the hot start button. I have closed my fuel screw to 1.5 turns. I have not yet completed assembling my bike to test it yet.
99 WR, 84 Kaw 900 Ninja, '82 Honda CB750F clothes hanger, '84 Honda Z50 "Berm Destroyer". Always thinkin' "Hell, this worked on my 2 stroke!!"
Posted April 22, 2000 - 06:07 AM
To reply to some of the questions:
Altitude is about 0 to 1000 ft.
The plug looked the same when I cruised into the shop just above idle as it did with a full throttle run culminated by hitting the kill button.
About half the time the engine starts easily when hot without the hot start button at mild temps ~50-60 Deg F. Perhaps a larger pilot (50) as James suggested or going to the stock WR DTM needle would help richen the low end as James Dean had suggested?
Comparing the 180 to 185 main, the plug had slightly more carbon with the 185. Performance-wise, I could not tell a difference. In either case it runs very well throughout the range.
Posted April 22, 2000 - 07:36 AM
Posted April 22, 2000 - 07:49 AM
Option 2) looks rich midrange to topend - 180 main, DVP#4, and lean down low - pilot #50
Option 3) DTM is richer on both clip and straight diameter so - 180 main, DTM#3, pilot #48 (similar to option 2)
note: too many changes at one time may be misleading, I like option 1 as long as it's running great.
Posted April 23, 2000 - 05:29 AM
I am using pump unleaded 92 octane with STA-BIL at 1 oz per 2.5 gal.
I will richen up the low end a bit as a first step - one step at a time.
Are there any detriments to the engine running slightly rich?
Eric in WA
’99 WR400, YZ timing, IMS Tank, YZ Seat, Acerbis Handguards, Scotts Steering Damper, Renthal Bars, Yamaha Full Skidplate, Devol Rad Guards, Dunlop 755F & 756R Tires
’99 Polaris 400 Scrambler –“Trail Couch and Lunchwagon”
’99 Honda Z50R
’97 Honda XR70R
Kubota L275DT and an assortment of farm equipment.
Posted April 23, 2000 - 07:00 AM
Posted April 26, 2000 - 07:30 PM
With the 48 PJ go to 1.25 to 1.5 turns out
With DVP use #3 (perferred) or #4 from top 180 MJ max.
Remember a little poping on decelleration with good clean response everywhere else is OK.
This bike has a great tollerence to running in a rich condition right up to the point of "bam" a fouled plug. Plug readings are tough with unleaded gas and bike that runs a cleanly as this one.
Good Luck and keep us posted
Posted April 27, 2000 - 03:11 PM
I will be recieving a BigGun SDS sytem next week. I suspect that will require some further tuning.
Eric in WA
’99 WR400, YZ timing, IMS Tank, YZ Seat, Acerbis Handguards, Scotts Steering Damper, Devol Rad Guards, Dunlop 755F & 756R Tires
’99 Polaris 400 Scrambler –“Trail Couch, Toolbox and Lunchwagon”
’99 Honda Z50R, ’97 Honda XR70R, Kubota L275DT and an assortment of farm equipment.
Posted April 30, 2000 - 07:45 PM
Posted April 30, 2000 - 09:00 PM
But I can't agree that only the white areas would magically turn from black to white so quickly during a plug test run. I would think that if the bike ran lean (starting and warm up or just small thottle) then ran rich (WFO test) and turned off with the kill right after wfo, the richness would show everywhere on the plug-not just what is shown above.
So now I am starting to wonder if the plug is borderline too hot. Around the edge where it's black is what the head is like and what the overall mixture really is-too rich. But the insulated and hottest part of the plug are burning the carbon off very well- a good thing unless they hot enough to glow and cause pre-ignition. Unfortunately trying and even hotter plug may be risky to to this, especially with the high-compression and TPS.
Am I crazy? Have a had too beers wondering about this? Someone, anyone--any takers to this theory??
On the other hand, it would make sense that Yamaha would choose a plug that would agree with most gasolines, riding conditions, and bike variances and satisfy the "not too cold to foul and not too hot to pre-ignite needs- so the weird multi-color reading may be normal for some bikes. Rich, Clark, James, et all- what are your thoughts?
mcarp-3 month WR owner and learning everyday.