Bonneville America Forums Forums Technical Forums Performance Mods Horse power

A few questions that have probably been discussed, but I cant find the answers too. What is the stock horse power for an 02 BA? Also, I have short silencers on my bike, the AI removed, airbox drilled, and the snorkel has been shortened significantly. I just had somebody do these mods for me(I'm not too mechanical) Also, I have 150 mains. When he dyno'd it my hp was 52. Is that good or bad? My bike seems to run stronger now and I'm not unhappy with how it feels, but I want to continue to head in the right direction without spending tons of money(yet). What should I do next? As always, I appreciate any advice.
Thanks,
Gapper

The bench is 61HP I think. Dyno readings seem to be all over the board on this stuff. You loose at minimum 10-15% putting it to the rear wheel so I think you are not really that far out. Available torgue (forward push) is the key. If the torgue line stays relatively consistent with the HP line you are good to go. You also have to look at the air fuel mixture at the diferent RPM checkpoints. Back pressure and the lack of it on louder pipes can really mess with the lower end of torgue and increase it at wide open throttle.

Do a search on dyno in the board and you will find many that have posted their results with similar setups. The tech vault also has references to this.

Many on this board are getting good HP at high end but its all over the place on its way up. In my humble opinion that is air fuel mixture.

In normal riding, you don't drive wide open throttle all day so the real question is if it is zippy enough for you. If so, the HP to the asphalt is incidental.

150 sounds way to big for tors and still haveing your airbox

Frank

Yes, 61 British Horse Power (bhp measures engine power at the flywheel, not counting drivetrain losses.)

Effective horsepower (ehp) is the power converted to useful work. In the case of a vehicle this is the power actually turned into forward motion.

In automobiles, effective horsepower is often referred to as wheel horsepower. Most automotive dynamometers measure wheel horsepower and then apply a conversion factor to calculate net or brake horsepower at the engine. Wheel horsepower will often be 5-15% lower than the bhp ratings due to a loss through the drivetrain.

Begging your pardon Moe, but BHP actually stands for Brake Horsepower, because power used to be (back in the days when Men were Men, and livestock lived in fear)measured by means of a hydraulic prony brake attached to the output point.

150 mains are a bit much for your bike. With the Freak and short offroads I run 145 mains with 45s and one shim. The bike resgisters 64hp/49ftlbs on the dyno (averaged over 3 runs).

If the bike runs well now, is there a benefit to reducing the mains from 150 to 130, 140 etc..? Also, is there a benefit to completely removing the snorkel? Mine has only been shortened? Thanks for all the info.

Could run better....

My service shop says stock units run 50-54 hp at the back wheel when tested.

The "800" engine is rated at 61 BHP (62 DIN PS) at the crankshaft. Rear wheel power will be less because of losses in the primary drive (more so because it is gear driven), gearbox, and final drive.
Dyno HP will also vary a lot because of altitude and atmospheric conditions.
52 - 54 HP is about right for a stock or near stock engine at sea level, 68F and under 35% humidity if he chain is in good condition and well adjusted, and the rear tire is in good contdition and properly inflated.
On your bike, you might be able to get some 3 to 6 more HP if you work on the jetting. Only an exhaust gass analysis while on a dyno can tell you exactly.
At any rate, try adjusting the idle jets for best idle speed. On mine, I gained better than 15 MPH topend by doing this, and that translates to a good power increase.