Hi Dirtrider
It all depends on the particular alloy that you have. If you have a non-heat treatable alloy, then there should be little problem in performing the heating cycle. If you do however have a precipitation hardened alloy, then you will cause over-aging, resulting in strength loss.
This is not a streight answer, but is as good as I can give under the circumstances. If you can give the alloy designation or composition, then we will probably be able to give a better answer.
Regards
Niekie Jooste
Fabristruct Solutions
6061 is not available as a casting alloy.
However, most castings are silcon based and as such may be heat treated.
In reality, however, many castings are not. Even when wewlding on heat treated aluminum like 6061-T6, we find little problem when interpass temps stay in the 350 degree or so range.
Most motorcycle parts are basically lo-buck castings (there are a few exceptions).
In my experience, the powder coat temp you anticipate shouldn't hurt much.
If you want a real authoratative opinion that you can show your insurance guy, get the alloy type you are doing. Then contact thhe Aluminum Association in Washington,DC.
They ARE the final word in aluminum!
Hope this helps!
Good Luck
brande