wider chain:safe on a narrower sprocket?

I like to use the narrowest chain possible that will fit the sprockets.
On my race bike, I'm running a #410H BMX chain for the engine side!

Also... those wider chains can grind on the side of the engine case (of 2-strokes) because the small sprocket is always so close to the case.

Running the proper chain for the sprocket is definitely ideal.
You can use that 41/420 chain without problems tho, as long as you have the clearance.

The worst that can happen is the sprocket will wear out quicker. If you're "fanatical" about chain alignment, you might want to run narrower chain like VMB said. I've also used 410 on the 2-strokes and the chain being lighter will translate to a noticeable power increase. You need to have dead-on alignment tho.

Well I'm having an issue that I think is related to how wide the #41 chain, I broke the 410 before I even got the bike started for the first time, went to tractor supply and got the #41, went a good 30 miles with no issues then the chain started coming off every 10 feet even if the engine is off, I noticed that the chain has been riding around the sprocket on one side and is now derailing itself, tried moving the stock chain tensioner and tightening it but then the chain would hit the frame and pop off, there is no inbetween or sweet spot, the chain is either riding on one side of the links or its hitting the frame, idk what to do at this point, my only idea is to try bending the rear swingarm out less than a half inch or setting up some sort of chain guide to keep it centered, they say in the instructions to keep the sprocket with the domed edge facing the spokes but mine would be perfectly in line if I did the opposite, has any1 had any luck flipping the sprocket around for better alighnment?

they say in the instructions to keep the sprocket with the domed edge facing the spokes

Built 7 bikes-----Never once has this offered up the ideal alignment situation. The closer the sprocket to the spokes (without chain hitting tire) the better alignment you'll get. lose the chain tensioner but get the #41 chain.

FWIW, I run the #41 chain on my HS 49cc, 4G bikw. I also run a home made spring tensioned chain tensioner. Between the two what I call improvements, I have not had to make any adjustments or do any service at all to my drive chain for300 miles and counting. The move to #41 chain was by itself a very positive change. The spring loaded chain tensioner maintains a constant proper tension and acts as a shock absorber for the chain.