LBZ,
sounds like your jetting is off, It sounds like your main is too lean. Check plug. It probably cuts out on you when you open up the throttle, but is fine at slow speeds.

 

I have done alot of research on this matter, the manual calls for 24:1, but all dealers and long time quadracer riders I talk to say 32:1. I used to have that black goop problem, until a dealer sugest I switch to KLOTZ semisynthetic/Castor based 2 stroke oil, this stuff is great no goop/residue, plugs never foul, and has the awsome castor smell.

 

20 TO 1 IS WAY TO MUCH OIL, IF YOUR BIKE RUNS GOOD ON IT THEN LEAVE IT, BUT THE REASON WHY THE MANUALS SAY 20 TO 1 IS BECAUSE OF THE LACK OF A SYNTHETIC OIL BACK IN THE 80'S. I HAVE RUN MINE AT 32 TO 1 AND HAD FOULED PLUGS AND GOOP. I RUN 50 TO 1 NOW WITH SYNTHETIC OIL AND LEADED GAS. THIS IS ALSO HOW THE GUYS GET AWAY WITH 100 TO 1 BECAUSE THE LEAD IS A LUBRICANT. I HAVE RAN MINE AT 100 TO 1 WITH NO NOTICABLE DIFFERENCE SO I STAY AT 50-1. IF YOU GET ALOT OF BLACK GOOP THEN YOU NEED TO CHECK YOUR JETTING IF YOU ARE RUNNING TO BIG THEN UNUSED FUEL AND OIL WILL BE DISCHARGED OUT OF THE MOTOR. THE DAY I BOUGHT MY FIRST ZILLA IN 87 THE REP (NOT A DEALER BUT A FACTORY REP) TOLD ME 32-1 IS THEIR RECOMMEND MIX BUT SAID I WOULD HAVE NO PROBLEMS WITH 50 TO 1 WITH A PREMIUM OIL. AND NOW THAT WE HAVE SYNTHETICS WE ARE EVEN BETTER. AS FOR BLOWN HEAD GASKETS, I HAVE HAD 3 87 ZILLAS AND HAVE NEVER BLOWN ONE YET. YOU HAVE TO CHECK THE HEAD NUT TORQUE AFTER EVERY COUPLE OF RIDES. I DO HAVE OVERSIZED STUDS JUST INCASE. YOU CAN ALSO RUN STEEL BASE GASKETS LIKE I DO AND A COPPER HEAD GASKET AND THERE IS NO WAY TO BLOWN A METAL GASKET PLUS THEY ARE REUSEABLE. THE O-RING SET UP WORKS VERY WELL TO. THIS MIXTURE HAS BEEN WHAT I HAVE USED IN THESE BIKES FOR THE LAST 14 YEARS WITH NO PROBLEMS AND NO BLOWN HEAD GASKETS. THE JETTING IS 100 TIMES MORE IMPORTANT THAN THE MIXTURE.

 

Thanks again for all of your replies!!! This is a great forum. I just filled it up again with a 40:1 ratio, but next time I think I'm going to buy a good synthetic oil (perhaps that castor stuff) and try it out at the same ratio. Right now I'm just using some Havoline oil that it came with, but thinking about it there is probably some synthetics that would do it much better. I'm also going to change my jetting to get rid of the sputter and black goop! I go mainly riding at sea level and the guy I bought it from rode it at mainly 5000' so enough said. I'll let you know how the jetting turned out! Thanks!!!