Dry black soot

[Mr.Freeze16]

Hello again, I used to know a few things but it seems I'm having brain freezes, lol. Anyway, the sparkplugs are getting black soot on them, can anyone tell me what that is a symptom of? Thanks

[Capn Ron]

Cap'n Ron. . .

[movenon]

Hello again, I used to know a few things but it seems I'm having brain freezes, lol. Anyway, the sparkplugs are getting black soot on them, can anyone tell me what that is a symptom of? Thanks

Soot.. First impression is to rich ? Just for fun, do a few blip tests and see how the tach settles.  Where are your needles set ?  How many turns out are your fuel air screws ?
Sooty then there is oily....? Pictures ?  
George

[Pat Conlon]

Isn't life a funny old dog?  I *just* went through this....like just last week.

That was happening to me. Black soot on my mufflers and #3 plug. My mileage was terrible ~30-31mpg.

What to do? Call in the pro....I rode my bike up to Oakdale for a shop visit to Randy at RPM for his advice.

My '84 has a new set of carbs, clean carbs......jetted appropriately. The motor is new.
After removing the rack of carbs and studying them closely, Randy saw some abnormal wear on the tips of the choke plungers. The part of the plunger tip where it touches the actuator rod. The wear was abnormal because in the normal riding position the actuator rod should not touch the plunger tip. The only time the contact is made between the tip and sliding actuator rod is when the choke was on, durning warm up.

Randy's diagnosis was that somehow the choke remained partially on...just a smidge...a tiny bit. This was just enough to draw excess fuel through the choke circuit, causing the rich condition.

Here's what he did:
1) made sure the choke cable had extra slack where it connected to the actuator rod. On the choke cable holder, there is a small tab that holds the end of the choke cable sheath a set distance away from the carb linkage...Randy ground that tab off so as to slide the choke cable thru the holder, increasing the amount of slack.
2) on the horizontal sliding choke actuator rod, Randy installed a soft compression spring (from Ace Hardware) to assure the the choke circuit remained closed. The spring fit around the rod and was positioned between carb#1 and #2. When the choke is on, the spring is slightly compressed, when the choke is off, the spring is in it's relaxed position.
All this happened last weekend....on the ride home (400 miles) I knew things were looking up...mileage went up to 41mpg.
I had some carbon on the tips of my Cobra F1 slip ons, but that was from the all the built up carbon blowing out. Since I got home, I cleaned the tips, I've put more miles on the bike and the carbon is gone.
I haven't checked my #3 plug yet, but I suspect it will be clean. I'll report my finding.

So, long and short of it: check your choke linkage. Make sure you have plenty of slack in the choke cable when the choke is in the off position. If your choke actuator rod can slide back and forth freely, consider adding a soft compression spring to assure that it stays closed. It only needs to be open a little bit for things to turn dark.

Thanks to Randy @ RPM for this little nugget.   Cheers, Pat

[Mr.Freeze16]

Thanks, I'll try that choke trick. but will that make it sound like its missing and is the 105-110 compression ok?

[Pat Conlon]

Uuuuh, no that compression is not ok. Did you do the test correctly? Warm engine, throttles open?
Squirt some oil in the cylinders, see if the compression readings come up. If so, it's the rings. If not, it's the valves

Speaking of valves...Are your valves adjusted?

Remember: A tight valve on a cold engine, is a open valve on a hot engine.

Maybe that's where your compression is going?

[Mr.Freeze16]

I'll check everything again george and let you know. I don't know if valves have been done Pat, I haven't done it.  I'll do that comp. check and reply. I really appreciate t :wacko2:he help everyone.

[movenon]

Nice write up on the choke problem Pat. All those little details we over look...... I will inspect mine tomorrow.
George

[Pat Conlon]

Yep, like Steve (mr freeze) posted earlier with his #2 plug sooting up...mine was happening on #3

I was taught a good lesson...I would have never noticed the abnormal wear on those brass choke plungers....never put 2 and 2 together.

Left to my own device, I would have been dicking around with different jets and carb settings, trying to figure it out...going crazy.
I mean, come on, all the carbs are jetted the same. They are new. Motor's fresh, compression good, valves adjusted, good spark on the ignition, no missing, why on earth is just 1 plug sooting up?

Only a person with a lot of experience with those carbs would have noticed the wear.....I sure couldn't.

Moral of the story: Some things are best left to the professionals.

[Mr.Freeze16]

Well, I'm going to take bike to a excellent mechanic I know on may 16. I told him about it and he said that the vakves need adjusted and right now I don't have the equiptment to do that job. Anyway I just wanted to say "THANKS" for all the input from everyone.