Hi, I know this forum is mainly for road bikes, but i'm hoping you'll forgive me if i ask a question about the cylinder of my ktm300 that i bought back in december. The head gasket is a silicone o-ring type, and a few months back it tore in one place.. don't know how it happened, but the engine got very hot, and i had to have the cylinder replated because of chipping around the top (coolant went inside the cylinder). After taking the head off, i noticed a couple of the bolt threads had been stripped before and re-threaded (on the cylinder), one was sticking up a bit, and was pinching the o-ring by narrowing the groove a little (not sure if this caused the problem in the first place), which the shop told me they would fix up with a new helicoil threading. They put in a new threading but the groove where the o-ring sits is still a little narrow. Here is a pic: [img:806:531:d4a19c2030]http://members.optusnet.com.au/jonoburt/KTM-cylindertop.jpg[/img:d4a19c2030] So i took it back and they shaved it down and put another helicoil in so that it looks like this: [img:681:422:d4a19c2030]http://members.optusnet.com.au/jonoburt/KTM-cylindertop2.jpg[/img:d4a19c2030] Now they've told me it should be fine like that, just to put some sealant between the bolt threading and the o-ring... That to me sounds pretty risky considering how much i've already spent trying to get this thing going again, around $1000 including piston kit, replating, tools etc. The bike cost $3000. Do you think sealant will do the job? What other options are there?