Bike Dies @ Speed. Ignition????

[matt4wheels]

The local trails in my area are just a quick 1/2 mile ride down the road. Yesterday while traveling about a constant 50mph down the road my bike just dies and starts the exhaust brake sound created by the turning cylinder without combustion. This isn't the only time this has happened. I've been changing out spark plugs about 1 every ride lately b/c this has been happening. I had assumed that I had a "running rich" issue b/c the bike has started to smoke a noticeable amount more. I didn't think a faulty ignition could cause smoke until I spoke to a GasGas dealer the other day. He said tha an ignition that is on it's way out can cause a weak spark and result in smoke. Is this true? Everytime I change out the plug it fires right back up.