Bonneville America Forums Forums Technical Forums Performance Mods Stock Rear Wheel Horsepower

Does anyone know the rear wheel horsepower of a stock BonnevilleAmerica?
I am going for a dyno soon and would like to know, since my bike was received in a slightly modified condition TOR shorts with 125 mains, AI in, stock airbox and filter. Of course I've modified some more. After removing the AI with TOR shorts, I bought some stock Speedmaster pipes on ebay for 99 cents (cool, i love long pipes on the BAM & SM. I drilled out the rear plate with a 3/4" rotary file, broke out the tube and ground out the second plate with the same 3/4" rotary file. Then drilled a small pilot hole followed by the 3/4" rotary file in ALL the remaining plates, just beside all the remaining 1/2" tubes (i think there are 4 plates & 2 remaining tubes. I tried 132 jets. The bike pulled hard but sputtered early in the upper power band. I put in some 138 main jets and found a working point, and all was well except for the flat spot in the middle of the power band, and some backfiring on deceleration.
I remembered seeing some of you removing the snorkle, so I yanked it. WOW! I can't believe the difference. I didn't think that restriction would even be significant. She pulled like a 1200 sportster and when power shifting into second, the front wheel bounced off the ground with an 18T counter sprocket. Now I think I need to shim the carb or use TBird Sport needles, since I am sputtering at first roll on of throttle.
Current Settings:
Stock Pilot
138 Main Jets
Fuel Mix = 2.5 turns out
AI removed
Modified airbox with UNI filter
Snorkle out
Totally defiled stock Speedmaster long pipes
(i plan on SpecialtySpares long cannons or Raask pipes in the future).
Any suggestions are welcome, and I will not be offended if you laugh at me.
Blessings!!!

Hey Demilo,
Sounds like you've got it just about right!!! The TBS needles will make a positive difference in rollout. Something else to consider is the Thruxton needles....supposedly they are a litle more aggressive than the TBS needles.

DK the rear wheel stock hp of an America, but Motorcycle Consumer News (Jan 2005) listed the rear wheel hp of a stock Speedy at 53.1 and the torque at 40.3.

A stock Bonneville - from the same issue of MCN - posted 53.9 rear wheel hp and the torgue at 40.8.

Hope that helps.
Roadie

Thanks TonyG & Roadie,
The only dyno around here is a ChromeShop that specializes in Harleys ONLY. I asked the chief mechanic one day if he'd run my bike. He said, "I wouldn't, but since you've got the best looking stock ride in town, I'll do it for $50. I rode a Triumph when I was younger". He's a pretty good guy and helpful finding parts to interchange with my bike.

Yur probably overjetted on the mains, however, turn the air screws to 3.25 and consider 130 mains. Depending on how open yur pipes are now, but many people unknowingly overjet which wastes gas. Remember, yur trying to set yur bike up the way u ride, which aint wide open all the time. Stock RWHP is from 49 to 53HP dependant on the bike. I went to 64.7HP with pipes and airbox elim. Now runnin CR II carbs and am over 70HP / 52.7 torque. Next stspe you can get rid of the airbox but removing the snorkel is a start, with the airbox you are overjetted, wannna bet??????

souds good gusser!! BTW where did you get your CR's and how much do they cost, if you mind me asking..

thanks,
joker-