Smallbore, How do you think the brochure I posted compares to what you said here. I think in it it calls it a 6hp. But maybe it's a different ride.
I looked at that sales brochure / price list and you have to look at the fine print. The basic engine for the smaller Jr. Sportsman, model B & C is a Series 1100... 175cc rated at 4.9hp.
That was the smaller engine option on the Senior Sportsman. That engine was fitted with a larger carburetor and manifold to boost it to 6hp. The photo in the sales brochure is a bit deceiving. At the top it does in fact say 6hp, but it is showing a Red Seal engine which is 7hp. The AU-10 Red Seal was a true race engine. Throughout the ‘50`s and into the ‘60`s it was the hot ticket if you wanted to run a 4-Stroke in your Kart. Over built with Roller and ball bearings they gave the Westbend 820 a run for the money.
Perhaps I should have elaborated more on Models / engine options. The Senior Sportsman had 4 official versions, and a few other “Special order” ones.
SENIOR SPORTSMAN:
MODEL
A- Briggs & Stratton 3-1/4 hp
B- Continental Series 1100 6hp
C- Continental AU-10 Red Seal 7hp
V- Villiers 200cc 4 speed
Those were the standard engines. By late 1965 business was getting difficult for treen and by then a few bikes rolled out with Tecumseh 3.5hp (Valiant) and I have seen both Tecumseh and Clinton 2 strokes. Both 2 strokes would have been Customer Request or Special Order items.
If I can find the time I will post some of the photos and sales brochures I have in my 40+ years of collecting this stuff. I have been dealing with health issues the last year and a half, so its getting harder to get stuff done. I have been gathering parts & supplies to get my ‘65 Senior Sportsman done this year but im torn on what engine to drop in it. I have been kicking around the idea of building a V-Twin out of 2 Honda XR75 or XR80 engines. I have not turned on my Laths or mills this year, so I need some therapy time !