YZ blue

I went to 116 when I tried a taller rear sprocket,stock 114 was too short the rear wheel wouldn't move up far enough so I went back to stock size sprocket better performance. 114 O ring is stock

I have the 08 450 and use the FMF power bomb header with the power core 4 silencer. The PC 4 silencer has a removable spark arrestor for when I do trail riding but most of my riding is at the track. I don't know about you but I like the steel rear sprockets with the O ring chains I get more life out them. Rocky Mountain ATV usually has pretty good deals on the combos every once in a while.

I don't think it's an injector it would show up right away not after 5 hrs of riding.

I have an 08/09 450 with a FMF complete exhaust, I did put a power commander on it with the remap, I had issues with a mid throttle miss before the PC and remap which sounds similar to your problem, if you just do the FMF slip-on muffler with the stock head pipe does the problem still come up? Mine was ok with the stock head pipe and slip-on you might be too, other wise you may need the remap to cure the problem.

Suspension definitely first save the bod as much abuse as possible you'll have more energy at the end for any last lap charges. On the exhaust, I feel much happier with the aftermarket pipe than I did with the stock pipe, a lot of times the quicker throttle response and power to get over a jump or get around another rider has been the key.

Up date ; After the valves were checked ( no adjustment needed) fresh gas, and clean plug, bike runs great no starting problems, one kick and we're on the track.

Dealer wants $71.00 for the DIMR8A10, according to this thread I can use the DIMR8B10 which is half the cost or the CR8EIB10 the plug that Rocky Mountain says will work for the 08 RMZ450. I wonder has anyone had any problems with the B10 or the CRBEIB10?

The insulator didn't look right, towards the tip like a small piece had broke off or had cracked. I took it in to have the valve clearances checked and they told me I probably need to replace the plug as well. They said I could still run with the old one but needs to be replaced and since its the original ( 2 yrs old with 130 hrs on it) I tend to agree. With the hard start the first thing that comes to mind is valve adjustment and plug then if that doesn't help look a little deeper, hopefully these and a change to a more frequented gas station will cure my ills.

Thanks, they have one that will work -- says it does anyway I'm going to order one to try.

I tried cycle gear last weekend ,they didn't have it I even tried a Suzi dealer with no luck so whats the deal with the plugs on these fuel inj. motors?

I've had a couple times the bike had trouble starting 5 or 6 kicks, not the usual 1 or two kicks. I have about 120 hrs on the motor still plenty of power and holds its own on the track, frequent oil and filter changes, I checked the valves they are in spec. What I would like to know is if anyone has had plug issues? The only place to get them around here is the dealer and they want $70 for one. Any second choices? I guess they are a radium plug which is a high tech plug.

Love the 08 450, its been a great bike and it was the same way an 08 with the 09 motor. Like OTHG_MIKE posted if you don't like it sell it for and get another KX.

They all have a little bad luck now and then, Reed tends to whine a lot when things go bad.

I put a Powercore 4 slip on with a power bomb header(Mega bomb might have been a better choice), on my 08 and have been happy with it. The Powercore has a removable spark arrester so I can keep the forest rangers off my back when we do trails, then remove it when I ride the track which it most of the time.

Here in Arizona if someone gets hurt on your property you are responsible. That's why the tracks have us sign a release when we ride there.