125m tranny noise

[lonnie]

Hi I just replaced the sub transmission on a 1985 honda 125m. The problem I'm having is that it makes a sort of kinda grinding or gear meshing noise when I put it in gear, it sounds the worst in first. When its idling you can still hear it but its not bad but when I start to ride it, it sounds terrible. Its not a constant sound but kind of a grump grump grump. When its in the other gears it sounds alot better. Everythings works good. It had sat for 6 or 7 years, could a bearing make it sound like this?
Sorry for this mess of a question but I don't know how to explain it.
Thanks,
Lonnie