IMO you are being advised by a bad dealer. One who does NOT like doing warranty work.
He does have a point though, if you don't do your research and install too large a sprocket on the front and create an issue with the chain making contact and rubbing on something. But it sounds like he may be the type of dealer that will blame everything on the mod you made to your stock bike, rather than accept a potential defect and resolve it.
Warranty work is flat rate, they get paid a certain amount to complete the repairs. if they run into problems, or have a slow mechanic, it will cost them more to repair the bike, and the shop will lose money.
That being said, do your research, and do any mods correctly. Many on this forum, including myself have changed the gearing with no issues.
He does have a point though, if you don't do your research and install too large a sprocket on the front and create an issue with the chain making contact and rubbing on something. But it sounds like he may be the type of dealer that will blame everything on the mod you made to your stock bike, rather than accept a potential defect and resolve it.
Warranty work is flat rate, they get paid a certain amount to complete the repairs. if they run into problems, or have a slow mechanic, it will cost them more to repair the bike, and the shop will lose money.
That being said, do your research, and do any mods correctly. Many on this forum, including myself have changed the gearing with no issues.