Plugs blowing fast!!!

[Phil_Dev]

Hi

Since renovating a 78 us custom XS650 I have had an ongoing problem that I have not been able to solve despite trying new ignition system, carb overhaul, oil changes, and continual adjustments of timing and carbs etc. My bike runs 100% for 20-30 miles on new plugs then backfires, starts running rough then stops running until a new set are fitted then all is fine again? I changed valve stem oil seals as the plugs were coming out oily and there was a bit of smoke but still the same problem even though plugs are not oily, I have tried hotter running plugs and cleaning the plugs but they are still not as good as putting new in, I now have 8 pairs of plugs and covered around 200 miles!

Has anyone ever heard of such a problem before?

 

[glennpd]

Check your air cleaner elements? If they are nasty they could cause the plug fouling.

 

[blackbetty]

My bike had bad valve stem seals, would foul both plugs overnight after a day of riding. Usually I'd pull them, wipe em off, and go out for the day. I just bit the bullet on a rebuild.

If you say you changed your seals though, you could be pulling oil in from the cam chain tunnel via a bad headgasket.

 

[DogBunny]

You say same problem even though plugs are not oily -- what DO the plugs look like? Post a good pic maybe.

 

[mouser]

I had the same problem but only on one side. It would foul a new plug after only a couple of days. Turned out for me that my throttle flaps were not set properly and sync'd. Since correcting the flaps and throwing away buckets of NGK plugs. They now give me a full season ...no problems! I have to order them in special....but I swear by Champion plugs.....wouldn't use an NGK if you gave it to me..

 

[yamaman]

yep, champion plugs, i wouldn't run anything else in my mower!

Posted via Mobile

 

[Phil_Dev]

Sorry but I am just getting use to the reply method so appologies to those I emailed directly!

Where do I start? thanks to everyone for your advice and I honestly can't rule out any of your thoughts as possible remedies. In obvious fashion I will try the easy 1st by getting some champion plugs as I have only been fitting ngk and take a look at the filters and throttle flaps. If I still have no joy I shall post a picture of my plugs before another engine removal to check my head gasket for possible oil transfer through the chain tunnel.

Another thought was given by Pete from Pamco as my rings letting oil pass so if I do go down the route of a top end dismantle I shall be asking for more advice an rings as I don't want to leave any stones unturned this time around.

 

[numnum]

Leaving stones unturned now and then, allows a busy man, more excuses for garage time .