First 450r. Some questions.

[B.Rich108]

Hey guys what's going on? So I had a 2007 400ex that I just traded away for a 2005 trx450r. The guy didn't know very much at all about the bike. The HRC kit was installed. He said it was just rebuilt about a month ago. It has a lexx exhaust on it. That's all I know for sure about the bike. He said he thinks it's a big bore but he was not sure. The quad is very clean and it runs very well. However, when I got home with it I noticed there is oil leaking out where the clutch cable meets the motor. Any Ideas on why this could be? Also, It backfires slightly on decel. I know this could mean it is running lean among other things. I was just wondering what size jets some people are running on their 04-05s with the HRC kit and an exhaust. I plan on taking it to a place and have them check it out and have them make sure everything is good on it and it's not ready to blow on me. I have not checked the oil filter yet for metal shavings but I will be doing that before I ride again. Also, how often should I be changing fluids and what kind of each is best to use? Sorry for the long post and all the questions but any kind of input would be great.

[B.Rich108]

Is there any way for me to find out if it is bored out or not?

[blacknblue#2]

The popping on decel sounds to be a lean pilot jet. The oil leak where the clutch arm goes into the motor is more than likely the seal around the clutch pusharm shaft which shouldnt be a hard fix. Big bore kits can be identified easily or hard depending on what kind it is. Athena and some other big names are stamped right on the side of the jug which would be a dead give-away. Cylinder works is a stock appearings jug so the only way to identify one of those that i know of would be to pull the head. Pulling the oil filter before the deal woulda prolly been the best bet but either way yes i would pull it now and inspect it. As for oil changes that differs between everyone. If im riding in muddy conditions ill change mine after each ride. If im riding mx and really running the crap out of the motor ill also change every ride. If im just out casual trail riding for a stretch ill let it go a little longer.

[B.Rich108]

How about for the tranny, can you change the oil or just add to it? If you can change it, how often? The same time you change your motor oil?