Well Ausie, I had nothing but the worst luck with my '87. I bought it for $1,500 and thought I got a steal. Though it needed much work and I would have been way far ahead if I had bought a $4,000-$5,000 Zilla. Anyway like I said I had terrible luck with every part of that quad, I finally said forget it and sold it. Before I sold it though I did have the crank case decked to flatten it out because it was warped. I'm sure a cool head would definently be a good investment and help any head gasket problems too. I will probably end up buying one for my '88 soon.

 

Aussie,
You can see one of my Zilla's at www.Quadzillathon.com, my new alchol turboed Zilla is still not finished, it is boating season and the Baja needs to be in the water with those 550 horses sucking fuel, so I am behind on it. As for your leaking problems, I have had 3 87 Zilla's and have never blown a head gaskets in 13 years. I do recommend you send out your cylinder and have the oversized studs installed, then either get the an o-ringed cool head or use a copper head gasket. I also use a flex steel base gasket with a thin coating of 3 bond 1104 sealant. Due to the compression I am putting out I did blow the factory base gasket out twice when riding hard in the dunes. Now that I have the copper head gasket and the steel base gasket I have not had any problems. You can get these gaskets from tudors performance you can get his link from the site where my Ride is. Most of the time the guys who complain about the 87's don't realize there are very cheap and permanet fix's to these few problems. Plus You can buy an 88 cylinder for around 300 bucks and put it on the 87 lower end if you want to, but the oversized studs and gaskets have never let me down. Oh and by the way after every couple of rides check the head stud nuts for torque setting, alot of people don't do this but it does help.

 

I'm going to repeat myself here since apparently it didn't get through the first time. Stock LT500R's DO NOT have more compression than other atv's. In fact, they have less than most. A compression gauge reading taken from the big LT will read around 125 psi. Take this same reading from a stock LT250R and you will get a much higher 175 psi. A stock Honda 250R has around 145. For the most part, larger cylinders have lower compression than their smaller counterparts.
There is, of course, a larger volume of air in a 500cc motor and thus more force against the piston but not necessarily more pressure in the combustion chamber. A Pressure is force per area (ex: pounds per square inch). You could take a 10,000cc engine with only 20 psi of compression (theoretical only) and you will still feel a great deal of force resisting your efforts to kick start such a beast.
The reason that older stock LT's blow head gaskets has nothing to do with compression being too high. Suzuki spaced the small head bolts too far apart. Thus, each bolt was responsible for holding in a larger volume of pressurized air than it reliably could. Since the 125 psi in a stock 500 is already relatively low, I wouldn't recommend lowering it further. Fuel ignition becomes worse with decreasing compression ratios. Also, the small amount of reduced compression you will achieve through the use of two head gaskets probably will not significantly reduce your likelyhood of a blown head gasket. The air volume will still be high and the head bolts will still be spaced far apart. Hopefully, rectifying the ignorance on this simple subject will help people understand their engines better.

 

One of the previous owners of my '88 (or its mechanics) had an innovative idea. To keep the intake side of the basegasket from blowing out, someone added dimples to the cases in that area. It looks as though an all was used to dimple about a two inch strip along the cases where they meet the cylinder directly underneath the reed cage area. This creates a slightly rough portion that the gasket is unable to slide across. It apparently works on my quad because I haven't had a blowout in the six years I have owned it. Has anyone else heard of this strategy? I know if somebody told me to try it, I would be afraid of creating a problem rather than solving one.