Black and White Spark Plug

dps650rider

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Looking for some opinions on these spark plug pics from the right cylinder. Plug is black on the intake valve side and white on the other side. Left plug looks normal but a tad rich. Bike runs great with a fresh bore job, pistons, rings and valve seals. Valve stem to guide clearance was in spec when I put it together and compression is good in both cylinders at around 150 psi. At the start of the season plugs were good but this seems to have gotten progressively worse. Never see any oil smoke and exhaust smells clean if I give it some revs. Seems like it must be a valve seal problem but they only have about 2500 miles on them.
 

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No mention of what spark plugs -- the obvious would be install BP7 ES se what happens
No mention of intake --- some filters can be problematic
 
Bpr7eix plugs... been using them for several seasons. If I swap plugs the problem stays on the right cylinder.

Stock 78 air boxes with kn filters. Have been using this setup for many many years and miles. Filters have been cleaned and swapping them makes no difference.
 
Bpr7eix plugs... been using them for several seasons. If I swap plugs the problem stays on the right cylinder.

Stock 78 air boxes with kn filters. Have been using this setup for many many years and miles. Filters have been cleaned and swapping them makes no difference.

Stock 78 boxes ..( points to ) well points and these can be individually set slightly
I would recheck timing Both sides and points operation. Maybe replace points

And then it is the Carburetor Boys
 
Engine is rephased and has 2 Boyer systems, timing was set and with thus system rarely needs adjustment. Carbs have new oem needles and seats and have been gone over. Also tried another set of good carbs (all are stock bs38s), rebuilt peacocks and same thing. I'm thinking this is oil from a crappy replacement valve seal, a bad valve guide o ring or head gasket. Never saw a plug that looked quite like that.

Still hoping for more insight from cliff on possible fuel washing.
 
Difficult setup
How is the Boyers set up it is a waste spark system the box with electronics want 2 signals in from rotor and want to fire 2 spark plugs at the same time Coil need some time for that To short weak spark to long heating the coil ( Jim)
coil needs time and the normal setup is most likely programmed into the box
 
Boyer is a waste spark system, for the rephase I have 2 independent Boyers one pickup mounted on each end of the modified cam. Just for ha ha's I checked the timing and it is right where I set it at about 38 degrees. Swapped back to my better set of carbs after checking the right choke plunger and linkage yet again. In the process I eliminated the inline fuel filters I added a while ago, maybe the excess fuel volume in the line is resonating with the vibration at some RPM and pushing extra fuel past the float valves? Really clutching at straws here... having a hard time explaining all of the black on the plug as oil since I don't ever smell or see oil smoke and the oil level doesn't seem to be going down.

Keep thinking about Cliff's response on fuel washing, maybe it is happening under some condition.
 
So if I get this right you have replaced the Carburetors and gets the same result appearance on the plugs
Then it is not likely any washing .. I have had problems and had black sooty plugs and never seen differences on different sides
of the plug .

Assuming the intakes + exhausts look the same .filters and channels .I am still at weak spark.

If one takes the plugs out and ground them to the block please google here how it is done .. so the ignition don't gets damaged ---kicking one can se if the spark looks different left or right.
Having 2 Boyers there can be weak power or ground on one side.
 
Yes remarkable contrast on the plug.
Glazed black is oil coking.
Light brown/white crusties on ground electrode is phosphorous from oil burning.

cliff
 
Back to the better set of carbs, eliminated the filters, cleaned and swapped the plugs and checked the spark. Runs great, gets close to 60 mpg but right plug is black and white again after a ride. 500 miles on the oil change and oil level may have dropped just a bit. Went down a long hill with the throttle closed, stopped at the bottom and gave it some revs. No smoke or smell of oil burning
 
Back to the better set of carbs, eliminated the filters, cleaned and swapped the plugs and checked the spark. Runs great, gets close to 60 mpg but right plug is black and white again after a ride. 500 miles on the oil change and oil level may have dropped just a bit. Went down a long hill with the throttle closed, stopped at the bottom and gave it some revs. No smoke or smell of oil burning

Not --the Carbs --> Back to the better set of carbs,
Not the filter --> Eliminated the filters,

I would test stock spark Plugs with the corresponding caps some are resistor caps and others are not And check right side Boyer wiring and replace spark plug cap ( or shift cap left to right ) ensure connection

I hear you saying you have used the plugs before but that is the way electronics faults The TV set working 5 yeas ago might not work today ..

Boyer Bransden also have a support which is rare in these days a good support

http://www.boyerbransden.com/faultfinding.html

Further Help
If you still can't find a solution from the information above and continue to experience problems please contact us:

Fax: 0044 (0)1622 730930
or Email: help@boyerbransden.com

I am still at poor power and ground supply to the Boyer .Not having seen the wiring
 
May have finally found the problem here. I took a closer look and made some measurements of the needle jet where it protrudes beyond the bowl gasket surface, and the recess in the bowl where it sits and found that the bowl contacting the needle jet was preventing good pressure on the gasket in the middle of the bowl where the jets in the bowl connect to the carb body. Not sure where I got the gaskets but the needle jets came from Mike's.

I measured some used gaskets I have laying around and there was one set that was thicker but there were dried out and stiff so I didn't use them. Note with that additional thickness there would have been no problem. Instead I removed the needle jets and took 0.010" off them in the lathe so there is now a bit of clearance when the bowl screws are tightened using the thinner gaskets.

Now all I need to do is run a tank of gas through it to test, hopefully in the next day or two. :)
 

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Problem apparently solved by replacing valve seals. Took it for a test ride after replacing them and cleaning the plugs and no signs of black deposits after the ride.

The valve seals that were in it were low profile seals from Hoos that I installed last winter. The ones I put in this week came from Mike's bought a while ago. Seems to me like I more recently bought some from Mike's and they were the same as the ones from Hoos. The ones I just put in fit my shortened guides more securely and the seal itself seems to be of different composition. Just to be sure they don't move I filled the grooves in the guides with gray engine sealer before installing the seals and let the sealer cure for a day before reassembling the engine.
 

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Eye surgery 3 weeks ago but is the Hoos Spring smaller in diameter or is it oil
 
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