Banshee and 87quadzilla_guy are both right- 87 had single bolt upper a-arm that was made of square tubing.
There are other differences between the 87s and the 88-90 that have not been mentioned. The 88-90 have different 4/5 gears than the 87s, and come stock with 13/40 sprocket sizes (the 87 was stock 13/42).
The 87 with a 6-bolt head does need attention. Some folks but in larger head studs, I chose to keep the original studs and have the head o-ringed. I now now longer have to buy head gaskets, just two high temp orings. This solution has been working for over 6 years now without a problem.
Another difference between the 87 and 88-90 is the reed cage and associated size of the reed cage cylinder casting. The 87's have a larger and different shape/configuration reed cage than that of the 88-90. So when you go to buy reeds for this machine, be sure to specify what year you have.
Holeshot posted some good information, but there is an error in the post. The front shocks are indeed rebuildable. Mine have been rebuilt and I had reservoirs added.
The swingarm is really not a horrible design, but it does crack and need welding. I finally threw mine away and bought a Laeger's +1 swingarm after having the stocker welded twice and having a break a third time.
It is important to keep an eye on the cases where the crank bearings live. The 500 has a lot of mass to throw around and the aluminum that the cases are made of is soft; where the crank bearings reside eventually gets hogged out and this can cause air leaks causing a lean condition. You know what that means.
The most important thing to mention is that these quads are old. Finding one in good shape is tough, and when you do find one know that you will have to check a bunch of things before you have a reliable rider. Mine has been running on the same top end for 4 seasons now with no failures. Don't get me wrong, I highly recommend one. This board along with macdizzy.com both offer much good information about this machine.  |