yamaha468

Another thing. If the engine it way to rich, it can wash the cylinder out. In other words. If you are running so rich that the oil that coats the cylinder wall is being diluted too much, you could end up with worn piston rings or excessive cylinder bore wear. That's why I wanted to know smoke color. Just like DirtDemon said, color can help diagnose the problem. Another problem you could run into if your carb is dirty is the carb leaking fuel into the cylinder while the bike isn't running and causing the oil level to increase. If your oil level is too high, it will cause the motor to lose power due to the crank, rod, and piston having to move through excessive fluid. Anyone who has ever overfilled a 400ex can tell you that. Check your float to be sure there is no trash in the seat that would cause the float to stick. If your float sticks it could cause excessive smoking in low rpm.

If you have any kind of serial number you can bring it to a dealer and they should be able to tell you the year. Just make sure it has a clean past.

What color is the smoke, did you clean the carb, did you check the oil to make sure it doesn't smell like fuel?

Around here it runs about 45 dollars. To cut the valves and the seats you have to have the correct machines. You could probably get away with just lapping the valves if your in a crunch for money, but it will require knowledge on how to properly lap valves.

If you just replace the rings and hone the cylinder it may quit smoking, for a little while. There's no telling how long it will work. If you want the long term fix, bore it, hone it and put a new piston and rings. While you have it down it would probably be worth a valve job or at least replace the valve seals.

I would also go with the +6. There aren't to bad in the trails or dune ridding. I see your going 498, so I figure your going to end up going drag in the future. A +6 is a great start. If you ever want to go faster than the swingarm allows, just get a wheelie bar. There are alot of custom fabricators around that are fairly cheap, but you have to look at the weight issue if you ever plan to be competitive in drag racing. If you just plan on dune ridding, weight probably won't be that much of a factor.

Things aren't to clear for me right now. On flu medication:confused:

Yeah I know, I had blaster on the brain.

Have you checked your reeds?

The main reason for the change is pollution. 2 stroke engines go way back. Alot of diesel engines used to be 2 stroke. There is a plus side to it. This is the reason that 4 strokes have progressed so much in the last couple of years. The atv manufacturers had to come up with 4 stroke engines that would keep up with the power demands that motocross and other types of racing demanded. This wasn't a recent decision. The first I heard about the 2 stroke issue was around 1999. That's why the thumpers started showing up. Look at it this way. If they phased 2 strokes out and the riders had to start riding the 4 strokes that were around in 1998 the riders would have been really upset at the power loss that they would have seen. Not to mention the weight of the motors back then. So they started making motors like the 400ex, the 660raptors and the 450's. They used existing technologies to base these motors off of. For instance, You'll notice that the new motors have oil tanks on them. The reason for the oil tank is because with an oil tank the motor doesn't have to be as big and the less oil you have in the crankcase the less the crank has to move through. This technology has been around for years. Alot of race motors(v-8 motors) use a dry sump motor for the same reasons. So with less oil in the crankcase the cases don't have to be as big which equals less weight. Remember how big the old 350 motors used to be. That was partly because all of the oil was in the cases. But all this doesn't mean that the 2 strokes are gone forever. There are already people making all of the 2 stroke parts that you'll ever need. I like 2 strokes, but I also like the challenge of making the 4 strokes fast. We are catching up. Look at it like this, Take a banshee motor. A banshee motor fires and makes power 2 times per revolution of the crankshaft. A 4 stroke makes power 1 time for every 2 times the crankshaft makes a complete revolution. That's the reason they put out so much power. Now they have people making cases to put a 3rd cylinder on banshees. The 2 strokes are long from being extinct.

Thanks! The one in the far lane is our drag frame raptor on nitrous and the one closest is our drag frame yfz on nitrous. We also have a stock frame yfz with a turbo and nitrous. My bike is on a stock frame with nitrous and we have a trx on nitrous. We are currently building a 250r for drags and if you haven't guessed yet we will put it on nitrous to.

Thank you! I was going to post some more ,but the picture file size was too big.

New to this forum and saw the pictures. Got some of our bikes if I did this right. [ATTACH]61[/ATTACH]