New Bonnie in the shedprevious

Hi AK, it seems to me like the first thing you should do is to take out the bellmouth and filter and then take it for a ride. It should feel like revs more freely.

In my opinion 62bhp dyno result seems to disappoint but bare in mind that the dyno result shows power at the back wheel whereas the manufacturers power figures are always given 'at the crank'. Just to show the difference : an 865cc fi engine has a mfrs power figure 67bhp (from memory) whereas it will have a dyno 'at the wheel' of perhaps 58 bhp. Transmission losses account for the difference, in broad terms.

The other thing to consider is that if you take the same bike and put it on 3 different dyno's you will get 3 different max. bhp figures - due to the differing dyno configurations. Dyno runs are not really there for providing single figure outputs - they are there to provide 'before and after' numbers, to show the effects of engine modifications.

 

Big bore conversions tend to only give you more torque and thats no bad thing on a bike, to get the most from it you would have to fit a better cam and up the compression ratio.

 

I would go for new cams and a pair of 36mm Mikuni flat slide carbs

 

You'll definitely need to check your carburation if you remove the airbox as there will be loads more air going into the motor.

 

The Jenks Bolts guide to tuning Bonnevilles may help you:
http://www.bonneville.se/nedladdning/Hur man jettar.pdf

 

that's a good one Steve

 

Not sure why folks get so hung up on horsepower numbers. Is the bike fun to ride?
Guys who want "just a little bit more" tend to never be satisfied.
(Bikes & life!)

 

Don't blame you there. I've modded every bike I've owned, mostly cosmetic, lights, & functional items. The only engine mods I've ever really felt necessary were things to improve breathing & get a bit more noise/MPG. If I upped the HP in the course of it , all the better!