Hello all. After restoring my bike to stock after a botched rejet, I realized my spark plugs were badly fouled and caused shotgun-like backfiring upon startup. After replacing them, everything ran fine. The haynes manual suggested being able to use three different types of plugs, of the ngk variety. Either, NGKxx7a, NGKxx8a, or NGKxx9a. I don't know the exact labels, but you get the idea. The last number is what's important and it suggested using the "9a" for high speed riding. Being the optimist I purchased these and the bike ran fine for a while. After a short trip, I pulled my plugs to check lean/richness. They seemed fine. After putting plugs back in and starting it up, she sounded funny. As if she were still cold even after I had the choke on for a while and she was idling at 1200 no prob. She seems to go up and down in revs slightly. When i roll on the throttle, she stumbles at low rpms as if she is starved for fuel or something. Higher rpms yield no stumbling. There is also small backfires at low rpms, and every once in a while, a medium sized one that sounds like i ran overa soda can or something. Any ideas guys? haha, sorry about the long post, but I wanted to be as specific as possible.
~Facio
You're referring to this spark plug info from the Haynes manual, right?
(http://www.bbburma.net/Scans/Haynes_EngineSpecs.gif)
Perhaps "extended high speed riding" means "racing"? I have always used the "Standard" heat plugs, and they have worked fine so far.
Correct Kerry, I am referring to that info and I used the 9EA-9. Might this be causing the stuttering problems and backfiring at low rpms?
~Facio
Hotter or colder plug only means the temperature the plug attains and the rate at which it dissipates heat. No effect on performance unless your plugs are fouling with carbon after it gets hot ... then a hotter plug will stay at a higher temp and burn it off a bit better ...
Your problem is likely somewhere else ... bad connections etc ...
Cool.
Srinath.
check your plug boots as well and the connection inside of them might have been something as simple as getting a bit of crud in them when you were taking them in and out.
Mike
thanks to everyone who replied. turns out that i must've tightened the spark plugs way too tight because upon removing them, i noticed that the left one had its gad clearance way too small compared to the other one. a pair of needlenoses bent him back into shape and now she runs like a dfream again. note of caution to others when checking plugs: don't screw them back in too tight!
~facio
You screw it in too much and the plug gap is smaller ... OK that's a load of crap ... Your plugs are getting gapped by the piston if that is the case and tightening too much wont be even close to being enough to have that sorta contact ... my guess ... they were too close to begin with and you didn't measure it right ...
Cool.
Srinath.
well i had just bought them brand new when i first put them in. i pulled them after riding for a little while to check fuel mixture. after putting them back in, problems happened. after taking them back out and fixing the gap height, no problems anymore.
~facio