plug fouling

[jfligg]

Hi guys
  I just got my A7ST out for the first time today.  Its starting to foul plugs.  Its running alittle rich.  I am going to try a hotter plug and go from there.  Last season the bike ran great but started to get a bit rough in October.  Any other ideas.  Thanks Jeff

[admin]

Hi, well, lots of possible & interesting causes, the elimination procedure may be the way to go. Btw, which carb is it? Some ideas that comes to mind: Black smoke? then definitely running too rich, not a plug problem. Is it only at low throttle\idle, or do you get a black plug\rough engine on a ride with open throttle as well? Check the plug after a high speed run. Any petrol leaking from float chamber\carb? Check float level & float needle. If you have an airfilter, is it better without it? Jet(s) are correct size?, or are they worn? Needle jet clip at correct position & not worn?

Regards
E.

[jfligg1]

Hi E
  Its a monobock carb.  It has a tiny bit of smoke just off throttle.  It is running without an air filter.  It starts to foul a plug after a couple of miles of running.  All the carb jets are the same as when I got the bike 2 years ago.  So they could be worn.  I know there is play in the carb body but I would have thought that that would make it leaner not richer.  Jeff

[BrianDallasTX]

Have you checked the timing and points?  It can cause a weak spark that won't burn the gas well.  How fresh was the gas?  I would think play in the throttle body of the carb would make it run leaner and very rough/uneven.

Brian

[jfligg]

Hi Guys
  Heres a plug fouling update.  I set the points, dropped 2 main jet sizes, installed a new needle jet. So its still running rich.  I am off to get a hologen bulb for the headlight so I'll get a new needle today.  I am also looking for a 276 carb to try.  The monoblock is a real tight fit.  Onwards and upwards.  Jeff

[BrianDallasTX]

What plug are you using?  I currently have NGK B8ES and I am finding them a bit sooty after 100 miles/tank of gas.  I have been running 93 and lately I have noticed a bit of pinking.  Previoulsy I had B7ES and there was only slight fouling and very little pinking.  I think I may try B6ES next go round but they were out when I bought the last four.  I usually commute so the traffic could be a factor.  Let us know how it goes.

[dpaddock]

I run B5ES's in my A10 in order to get a light tan on the center electrode nose. That's the primary result you want for your riding style.

The dark and sooty stuff around the plug, is any, is the result of fuel richness, oil in the combustion space, or just plain failure to reach operating temperature because of idling, low speed, etc. It has nothing to do with the heat range of the plug as long as you're getting the nose color stated above.

Don't worry about "holing the piston" or other dire old wives tales associated with "hot" plugs, unless you're running a racing Bantam.

[fido]

I have 2 pairs, one pair on the head and one pair in the tool bag. I still get hot starting problems sometimes so I swap the plugs and it seems to start on the cold ones. One set are NGK B6HS, other are Nippon Denso W20FS-U. Both have the light tan deposit on the centre insulator.

[BrianDallasTX]

The B7es seem to be a good choice for my sickle, and I have been using RPX gas additive.  The pinking hass all but stopped.

[jfligg]

Hi Guys I got my A7 put away for the winter know.  Next spring I am gonna try the twin 275 carb set up.  It'll be sure to be troublesome.  Jeff

[BrianDallasTX]

Aw man it is finally cooling down nicely here!  Been riding as much as possible.