1985 gpz 900 lunges foward and makes a grinding sound in neutral

[smithintl]

Hey everyone thanks for any help in advance. I have an 85 gpz 900 I bought used and it wants to lunge foward in neutral. I also noticed today that when I hit 3rd gear which is all the faster I got foing it started making a grinding or clanking sound. Im not sure if it is the clutch or the transmission any help would be greatly appreciated. Thanks again everyone.

[zoro]

Sounds like the "Transmission"...If you dont get any relief here you might try the "Vintage Section"...Welcome to the forum by the way! St. Joe is only a skip away from me! You can plan on inspecting the clutch assembly first, and if you find nothing there,you can plan on "splitting the cases." I would change the oil and add a 16oz bottle of Marvels Mystery Oil and run it a bit to clean and loosen the clutch plates. Drain that oil and add straight oil and then see if she quiets down a bit. Inspect the oil that comes out first! Any fleck or silvery metal flake residue will indicate that somethings busted and wearing in the transmission and/or crankcase. Clutch Baskets can break and clutch plates can crack and fragment so do inspect the clutch closely.

[smithintl]

Hey thanks alot for the reply I opened up the clutch case and checked the assembly it all looks ok the friction plates are a little worn but not too badly. I took it out for another spin yesterday and realized that theres nothing after 3rd gear. I shift into 4th and its like im back in neutral so I am thinking the transmission is very likely. Do you know if the transmission repairs are going to be costly if I do the work myself? I have a clymer book for the bike that has alot of detail for the repairs but it doesnt have much for diagnosing problems. Thanks again for the help and any more advice would be great.