1986 Honda Shadow 1100

750 horsepower question - Honda Shadow Forums : Shadow Motorcycle ...

I admit to being ignorant when it comes to mechanical issues so I thought I would ask the experts. I was reading that the 750cc Harley XR750 engine produced about 90 HP. I also read that the 750cc engine in my Shadow produces about 40 HP. I know the Harley was a racing bike but how can two engines of the same size produce such drastically different amounts of HP? Also are their techniques to increase HP in the lower HP engines? I think back in the day they used different criteria to measure horsepower. My 1100 is more powerful than the 700 I had, maybe not by 15hp or so, but it's a solid 10hp more. According to specs, it's only 4hp more. Also, most dyno graphs for Harleys seem to be off modded bikes. A factory 1200 Harley is only putting out about 75hp. Ironically, that's the same amount as a Shadow. Granted, Harley has more performance parts it seems, but still, any of those items can be mounted onto a jap bike. Intake design and flow, valve size, exhaust flow, compression...lots of variables. Also, does it make the horsepower only at a certain RPM range? An engine can have a lot of HP and very little torque. I think if we could see the detailed engine specs side by side we could figure it out. There are ways to increase HP, the most common way is to get the engine to more more air through it from the intake through to the exhaust. These are conditions that your 40 hp Shadow vt750 doesn't have. Instead your compression is 8:1. The cams are mild and conservative with very little overlap. The timing has very little advance. You have a single carb that is jetted lean for emissions. If you would like to make hp, install 10:1 pistons, radical cams, ignition computers set up to advance the spark, carbs with rich jetting and large capacity to deliver the mix. (Or better yet, FI.) Etc. My 1986 Shadow 700 has more power than the modern 1100s. This is because in 1986, Honda was designing bikes for performance. It turned out that the American market better preferred bikes that sounded better, so Honda de-tuned the engine, change the intake and exhausts, changed the compression ratios and engine timing so that you have a bike that sounds more powerful, yet makes less power.

Hannibal and the King

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