fouling a plug

[dwfranke1]

79 gs1000 bored out to an 1105, since the rebulid, that i had nothing to do with the bike has fouled a #3 plug, i inherated this problem with the bike and run a plug nonfouler in it to compasate for the problem, is there a way to tell if it is the rings or the valves that are the problem, it does smoke alittle but only at idle, not a smoke screen generator, the bike seems to run really strong so i dont think it is down on compression
thanks
dwfranke1

[Big T]

Could be any number of things:

1. Bad valve seal
2. Bad bore job - mine originally had a gouge in the side of the sleeve, it would pump oil like you wouldn't believe
3. Rings not properly installed - upside down, bad end ring gap or placement

You need to start with a compression test - dry and then with oil to see if the rings are sealing

1105? What piston set is that?

[dwfranke1]

no clue i was just told 1105, it was a drag bike and i know the rebuild was done then 3 days later it was being raced on 1/8 mile runs, so i dont think break in was done like it should have been

[chef1366]

That's the best type of break-in.

[Tarbash 27]

A non fouler, ugh. It could even be running too rich in that cylinder. I myself would pull the carbs apart but first do a compression test.

[SqDancerLynn1]

79 has the petcock on the #3 carb Check the petcock & check the vacuum hose for fuel
Most common was the wisco 1085 cc kit

[dwfranke1]

a non fouler is a sleeve that raises the plug up out of the head, and it is oil on the plug, the carbs are set with 120 mains, pod filters and megaphone open exhuast, and the other cylinders seem to be mixed about right, the plug checks show a lite brown color, and the inside of the exhuast shows a little pale white,except for the #3 and it is oily black, have not done a comp check yet, dont have the tools for it, so thats next, what do i need to look for with a comp check and can you tell a difference between a bad valve seat or seal and a bad ring?
thanks

[Jethro]

I don't know the specs for an 1105 compression test, but start by seeing if the cyls are all within 10-15% of each other. Healthy would probably be anywhere from 120-140 psi, but even 100 psi isn't a disaster as long as they are all within 10-15%.

The only way to tell if you have bad rings or valves is if you get a bad reading and then do a wet test- put about 2 tbls of oil in the low cyl(s) and if that brings it up then you have a bad ring... process of elimination is the only way to tell unless you have a leak-down tester (which would be ideal).