I have a chance to pick up an Lt500r 89 model cheap. The quad is in reasonably good shape except it was run lean and the piston and cylinder are history. It looks like it has a cast iron sleve so how much can it be bored out. Wiseco has piston assemblys available from 86mm up to 89.5 mm. Is this year and model worth the effort as a rebuild.??? Thanks for any input. Frank

They can be bored very far. Once you go over 88mm you have to buy a different head gasket.

There are a ton of mods you can do to them to make them more bulletproof. The ones that I would recommend while you are rebuilding is to get the combustion chamber squish fixed in the head, do an RM 250 wrist pin bearing and billet thrust washer mod, and a petcock mod. You can learn about all of these modifications over at quadracerhq.com No need for me to type all of the info out again. Dr. Q on that web site sells the billet wrist pin thrust washers, and does the machine work to fix the combustion chamber squish problems. BTW, these quads needed race gas in stock form.......that's why the cylinder is toast.....from running gas that was not good enough.

How cheap? Because you can pick up real nice running zillas for $3000 or less. Craigs list I think has a nice one in Hays,Ks. for $2800 Good parts are going to be hard to find. Check the # of head bolts first years had less then later years. Not sure when they changed them I think that was their only issue. Might be able to upgrad

Jerimah25,The piston that's in it is a 86.5mm with a part No. of 561m08750 which is the same # Wiseco has on their site for the Lt500. I had hoped to go to an 87.5mm piston if the bore works out. What size bore on the jug will it take for that piston or is that the bore size it self. The walls are scored pretty good so would boring it 1 mm likely clean it up? And Long travel would a hundred bucks be too much??
I got it real cheap... also... it is using a 380 main jet. is that about right for the LT500?
Thanks Frank

This message has been edited. Last edited by: Mountainbum,

That is the first size over stock. You have plenty of meat left to clean it up again. Going 1mm over should clean it up, but you can go to 88mm without compromising anything.

A 380 is the stock size main jet for an 89. It shouldn't have hurt anything, unless it has been ported or has a pretty radical pipe. Like I said, zilla's need race gas. When they came out, pump gas was leaded, and everything worked pretty good. The unleaded gas we run nowadays doesn't get along with zilla's at all. Almost all racing gas is leaded, which helps alot. When you add that to the higher octane of race gas you're golden.

As far as a little zilla history.......They were made from 87-90. The 87's made the most power. They had a larger reed cage and 6 head bolts. In 88 Suzuki had to respond, because the 87's were a warranty nightmare. So they reduced the size of the reed cage, and added an extra head bolt. They also made some changes to the transmission gearing to help mask the loss of power. There were some other minor changes to the chassis as well. The 88-90's have more frame gussets, and round tube front A-arms. 1990 was the last year of the zilla. Basically Suzuki still had warranty issues and was catching major flack over rider injuries and such from the massive amount of power on tap. To date the LT-500r is still the fastest factory production quad ever made.

Jerimiah, Hey thanks for the great info. I am taking the jug to a machine shop this morning to have them look at it. I probably should order the piston for it before I have the machine work done. It doesn't appear to have had any extensive port work done on it although it does have an aftermarket pipe on it. Again I appreciate the help. Thanks Frank

I just got the jug back today and had it milled .060 over. That will require the 87.5 mm
piston. Does any one have the torque specs for the base and cap bolts> appreciate some info.
Thanks Mtnbum