Bonneville America Forums Forums Technical Forums General Tech Newbie; "does size matter" question

I have a question about the 790 vs 865 engines. From what I can find, the 790 makes more horsepower (61 vs 54bhp), but less torque (44 vs 50 lbf). How much of a difference is there between the two when actually riding? Since I do not own a Triumph yet, I was searching for a Speedmaster '05 and newer due to the larger engine, but wasn't set on it. Doing some homework though I found this info, and don't know how much it matters. I have used this site as a basic reference (http://www.triumphtwinpower.com/triumphspeedmasterspecs.php). I know there are big bore kits and such, but thats a whole other thing. Or are you guys just going to tell me to get out and buy a Speedy regardless of engine?

I like the 790 myself, mostly due to the cams. Thought about the 865 parts that were for sale cheap not long ago with the high compression pistons that are available for that top end and keep my 790 cams with it. Sort of a cheap BB. But if I had to choose I would say the 790 over the 865.

to be old school you have to have a 790.

or at least start with one

When you're discussing street machines, there's no substitute for midrange torque. Additional torque is also useful if you ever decide to gear up the front sprocket to reduce cruising RPM.

The 865 is fine, if you replace the cams with those from a 790 or an aftermarket set from Thunderbike. With no other changes, you will get about 65 HP and any changes to the intake and exhaust will be about as effective as on a 790.

i would go for the 790---i rode an america and a scrambler with the 865, but i think the 790 in my bike has alot more power and pulls harder in the higher revs----cliff

I would think with basic mods (pipes, intake, AI removed, and carb adjustments) there probably isn't much difference between them. I would suppose Triumph "updated" the engine for a good reason - not sure exactly what that was.

If you plan to eventually put in a BB kit, you are better off with the 790. If not, it doesn't matter much. The performance figures on the Triumph literature are measured with restricted air flow, stock pipes, etc. The differences get less after both bikes have all the normal changes done.

The new '09 865 Americas and Speedmasters have 61bhp and 55ftlbs torque and at lower revs than the older bikes so you get the best of both worlds (specs from the Triumph site). So I don't see how an older (790) bike is better.

the '09 gets those good numbers because of fuel injection

Thanks for the replies so far.