BMP Kit Is A Good One!
I installed my 5hp GP460 engine with 1.25" one-way bearing on the BMP kit. As anticipated the combination worked VERY well on "The Iron Dragon". Engine bolts' integrity is a nonissue, even with four times the power of a generic powerplant.
To provide clearance for the engine's vaunted Dominator pipe, I cut off a HUGE chunk of steel from the BMP engine housing with no adverse effects. Since I'm not fond of the quick-release bike axle as a rear support clamp, I discarded that and devised my own bulletproof strut mounts.
Now that I've discarded the LOUDDD!!! Dom pipe, the new exhaust clears the housing easily. The bike is no longer a cop magnet, since the highly-modified engine now sounds like a mild-mannered Mitsubishi engine.
The .125" steel housing is more than adequate to support 5 hp. A 1.5 liter goped tank mounts easily on the BMP's outboard face.
The 1.25" BMP roller spins the 460 engine to 12,200rpm at 40mph. It's no strain on the engine but nerve-wracking with a LOUD!!! pipe. Sooo to relieve engine and driver, I installed a STATON 1.375" friction roller into the BMP housing. The taller spindle installed EXACTLY as anticipated and did an outstanding job of decreasing engine rpms and relieving driver stress. Now the engine sings 11,000rpm at 40mph, which is where a stock 460 engine produces maximum rpm.
My next BMP project is a 10hp modified pocket bike engine, starting with a 1.5" friction roller. This pb engine might max out at a lower rpm, so I'll try this large roller first.