Here are some remarks by ootscoot of the SYM forum. He is a dealer/rider/owner of a SYM shop in Santa Barbara. Interesting.
I often get asked if the warranty will be valid if " I do the maintenance myself".
I encourage my customers to take care of their own bikes and yes I do honor the warranty if the owner does his/her own maintenance. I teach my customers how to do an oil change, gear oil change, where the air filter is and spark plug...
The quality of the SYM product is excellent - hard to do much damage - though some have managed.
I do not cover damage caused by the customer - for example stripped spark plug threads, broken body panels ("I didn't know you had to undo those screws..."), and forgetting to put in the oil...
As far as modifications go, for the most part I am fine warrantying with mods if done correctly. - I had one customer remove all the smog junk - which is ok with me, but he also removed all the vacuum lines and could not get the bike to run...I had to charge him a small fee to put it back together. Another customer wanted to lower the seat height - I told him that he could have someone remove the seat cover, trim the foam and re-recover for $75. - he decided to do it himself, butchered the seat and wanted to claim the seat was defective due to lack of foam...
Many have changed from rollers to sliders - I still warranty if the weights are within a few grams...not if the job is done incorrectly.
Overall I have found that those who take care of their bikes do so out of care for the bikes, not just to save a few bucks. - a well cared for bike has less warranty issues.
Alliance has been very good about supplying warranty parts - they seem to like these bikes as much as I do!