I recently installed an exhaust tip on my son's xr100r and since it has been having some bog issues. Today after starting up it began sputterring and eventually shut down, it then took forever to restart but ran fine after I took it out and really opened it up.
This is the tip i installed: http://cgi.ebay.com/ebaymotors/3D-CNC-B ... ccessories
The rest of the bike completley stock.
I was thinking that it may need rejetting, but have no idea where to start, any suggestions welcomed.