I recently aquired a box full of engines from a friend who has quit the hobby. Does anyone know the differece between the Magnum XL and XLS engines other than the XLS has a blue head. I have a .40 and a .25 that are the Xl model and a .15 and .52 that are XLS with the blue head.

Don

Not all the XLS models have a blue head. As far as I know, the .15 and .52 are the only ones. What they generally have, I think, is the head sitting flush atop the cylinder, instead of sticking down into the cylinder. I'm not sure I approve of this, but it does allow shortening the cylinder which saves some weight and makes the engine shorter and more compact. They also have a little bit of the "weedeater" look. I have an XLS .52, but haven't popped the head off. I've been running an XLS .36 this past year...nice engine. I haven't been keeping a log, but I had so many one-flip starts over the summer that it's just silly. Then there was the one start without the battery...on an official.  I hope they'll bring them in again (the XLS .36), but it looks like maybe the ASP version is still available via Just Engines in England. Same engine, different brand name.   Steve

FWIW, our local combateers tried an XLS .15 with a big venturi, 7-3 APC's, and high rpm, on "buy-tech" F2D combat models for NW's 80mph Combat. They didn't get quite the speed needed with the stock XLS .15, had Henry Nelson do a little work on it, and promptly puked the crank. Moral of the story is keep the revs down to about 20k. Probably not for Clown Racing...    Steve