Allbon Javelin Diesels?
Thanks Mike. A lot of information! From your pictures and the descriptions you gave, one is a Javelin and the other is definitely a Dart. Both have the two-sided tommy bar. Neither has a tank attached. I gather tanks were extras as the picture on the box does not show one. I'll try to borrow a digital camera and post a picture of the engines and the box. Both engines look to have been mounted but do not look to have run much, if at all, as both pistons and exhaust ports look very clean. Unfortunately, there were no instructions in the box, although there still is a little glassine envelope which I assume held the instructions.