I'm looking at the 6.5 HP Predator engines at HF and I see them listed with 3 different part numbers - 69727, 69730 and 60363. I've noticed they do that stuff in their ads. They advertise one number then you get to the store and it's a cheaper model with a different number. What's the difference and is one better than the other for mini bikes???
Speaking as a HFT employee, they are all functionally the same. Each one will make at least 6.5 HP.
Speaking as a mini bike enthusiast, the differences lie in the cylinder head and emissions controls. The 69727 and 69730 are pretty much the same model, except 69727 is CARB and EPA compliant, for the California market, while the 69730 is EPA compliant for the other 49 states. Both the 69727 and 69730 feature a "wedge" style cylinder head and can be identified by the shiny stamped valve cover. The other model, 60363, is often referred to as a "hemi" style head and can be identified by it's dull gray cast valve cover. The combustion chamber forms a hemispherical shape rather than a wedge shape. Hemi head designs in the automotive world were lauded for having better flow and burn characteristics. Hemi heads can also accommodate larger valves than a comparable "wedge" design.
The 69727 and 69730 have been on the market longer than the 60363 and thus it's easier to find hop up parts for them, but the parts availability for the 60363 is quickly catching up. Many websites that sell hop up parts for these engines will specify if a part (if it's not compatible with both designs) is designed for "old style predators" (the "wedge" head 69727 and 69730), or "new style predators" (the "hemi" head 60363).
Now I may have missed something in my research, but I haven't seen anything that conclusively shows that, with the same mods, the hemi design on these engines makes more power than the wedge design. There is theoretically more potential in the hemi design, especially as you get up in the rpms. I believe the valves on the hemi are bigger, with the intake measuring 27mm and the exhaust 25mm, while the wedge head has 25mm intake and 24mm exhaust. This is conducive to top-end power, but may be detrimental to low end torque.
TL;DR: Ultimately I would recommend the hemi predator, 60363. It's a newer design and it theoretically has more power potential than the older 69727 and 69730 engines. Out of the box, I suspect you would not notice a difference performance-wise between the two.
Speaking as a mini bike enthusiast, the differences lie in the cylinder head and emissions controls. The 69727 and 69730 are pretty much the same model, except 69727 is CARB and EPA compliant, for the California market, while the 69730 is EPA compliant for the other 49 states. Both the 69727 and 69730 feature a "wedge" style cylinder head and can be identified by the shiny stamped valve cover. The other model, 60363, is often referred to as a "hemi" style head and can be identified by it's dull gray cast valve cover. The combustion chamber forms a hemispherical shape rather than a wedge shape. Hemi head designs in the automotive world were lauded for having better flow and burn characteristics. Hemi heads can also accommodate larger valves than a comparable "wedge" design.
The 69727 and 69730 have been on the market longer than the 60363 and thus it's easier to find hop up parts for them, but the parts availability for the 60363 is quickly catching up. Many websites that sell hop up parts for these engines will specify if a part (if it's not compatible with both designs) is designed for "old style predators" (the "wedge" head 69727 and 69730), or "new style predators" (the "hemi" head 60363).
Now I may have missed something in my research, but I haven't seen anything that conclusively shows that, with the same mods, the hemi design on these engines makes more power than the wedge design. There is theoretically more potential in the hemi design, especially as you get up in the rpms. I believe the valves on the hemi are bigger, with the intake measuring 27mm and the exhaust 25mm, while the wedge head has 25mm intake and 24mm exhaust. This is conducive to top-end power, but may be detrimental to low end torque.
TL;DR: Ultimately I would recommend the hemi predator, 60363. It's a newer design and it theoretically has more power potential than the older 69727 and 69730 engines. Out of the box, I suspect you would not notice a difference performance-wise between the two.
The latest 69730 has 27x25 valves but they are the 5mm stem with the split valve locks. The hemi has all of the same parts available that the non- hemi has. If you research the cylinder heads from guys who actually know what they are doing with porting and have flow numbers, I think you'll see the hemi head levels off and will require welding.re-shaping to hang with the RTC-6 head.
Again, I agree the hemi is the way to go but when getting into serious head mods, know what and who you're dealing with.
Again, I agree the hemi is the way to go but when getting into serious head mods, know what and who you're dealing with.
