Bonneville America Forums Forums Off Topic Discussion Forums Lounge 790 vs 865

For better overall driveability, power and torque what is better between a 790 and a 865 model?

I've found many different with good prices and for example a 2003 and a 2006 SM with the same miles but the '03 790 is $1000 less than '06.
I know with $1000 I can go for a 904cc. But it's not something I'll do soon.

So if airbox, AI, pipe mods have been done, what is a better bike?
I'm interested in driveability rather then peak power.
So low-mid rage torque and power is more important.

What results do you obtain from the same mods on those different bikes?

The 865 engine has different camshafts. The 790's cam breathes better at top end. I'm not sure if the ignition timing was altered as well, but I'm sure one of us can answer that one.

The 904 kit with 790 cams seems to be the best bet overall.

Save yourself the $1000 and get the 790.

Soren

Mechano, I have never been on a 865, however I ride my 790 Speedy on twisty mountain roads and the performance is amazing for a cruiser. On these roads I will out perform all of the heavier cruisers. I think you will be very happy with the 790.

Dave

Robert, I love my 790 America but from what you've said in your posts, I would recommend you pay the extra 1000. and get the 865. The bike is a 3 year newer model and with the "normal" mods they are close, but the 865 will have more torque in the lower rpm range.

I'll probably do the 904 kit, but I'm waiting to see what the 08 larger cruiser is like. Unless you're doing the work yourself, you also may find that a big bore mod will cost more than $1000. parts and labor. With the newer bike you would pretty much have what you want right away.

Pat would be the guy to answer this.
I know that I have an 865 and it seems the same as the 790. Right now the 790s have more aftermarket in the way of big bores etc. I bought the 865 thinking that it will have the support soon. I know talking to Pat the secret to the 865 looks like cam work.

Mechano, NATURALLY, the 790 is a faster bike, since it has a lot less weight to haul around, what with those bigger pistons and all!!!

But seriously, I've never noticed any lack of power on my 790, interstate, twisties or otherwise....

>But if a new 865 with the common mods will be closed a 790 with 904cc kit, I'll have a new bike with the same good performances of an old one modified.

I don't think it would.
The difference being cams & compression.
That said, your preferences indicate you might prefer the 865 "grunt" cams anyway.

i totally agree with dave. My 02 america 790 can keep up with much larger american v-twins all day long. drove 600 miles in one day to get to sturgis doing 80mph plus the whole way. never had a problem. besides the ability to cruise at a high speed, i regularly enjoy beating the pants off my buddies 1200cc sporty.

I would also say go with the 790 and save the $1,000

Maybe I can put this better than I did before. The 904 kit will boost the bottom end. The 790 cams will keep it from running out of breath at the top end. The best of both worlds.

The 790 with the pipes, jets, breathers simply is more useable in its power. The end grunt is for the first 20 mph, and who runs around in 20 mph all the time. The 790 has a nice sweet spot that is the mids and highs rpm, more fun.

I love my 790..

No issues with performance on my end

just my 2 cents

Trev

Small blocks rule!

The difference is that the 790 has more power at the topend and the 865 has more torque at the bottom end. This means the 865 will be quicker starting off and the 790 has a faster top speed.
BUT the reason for the difference in power is the valve timing is very mild on the 865, especially on the exhaust cam. If you start with an 865, open up the breathing at both ends of the engine, and install better cams, it would be a different bike.

I love them both, I wish I had 2 bikes

But can 865 use the 790's cams?

Cams are the same except for the profile.

the hard part will be finding a set of cams

Frank

While I was in the shop earlier this week to pick up my bike, I discussed the 904 big bore kit. They (D & D Cycles, Inc.) do their own using the Wiseco pistons but re-bore and nickel the cylinders (no dissimilar metal sleeves). They also have designed their own high compression pistons if you want a little more hp. The service manger said that to get the most out of the big bore kit with an 865 you need to install the 790 cams. I'm still deliberating about the future larger twin cruiser. If I stay with my 790 America I will definietly have them do the 904 kit, but not sure whether to go with the 10.5 Wiseco or their 12.0 pistons. You would need to burn premium and I'm not sure if there are other negative aspects. After all, I'm not racing the bike, but I do want more torque and hp.

As far as the way the cylinders are bored, they have done quite a few of them including all their own racing bikes. The owner's son is sponsered by them and Brent's company (NewSpeedmaster.com) and is probably the top Truxton Cup racer at this point. His name is Rob McLendon - look him up in some of your past Triumph (Torque) and other motorcycle mags.

I do respect their opinion and am greatful to have such a great service dealer. If I redo the bike, I'll get them to do the work. They also suggested I go with the adjustable needles they use on their racing bikes. I'm for letting them do the works, test it out on their dyno, and ride off with a HD killer.

Go 10.5:1 unless you want to carry octane boost everywhere you go.

No one mentioned this yet, so I'll throw it in; The new 865 has a far superior crankcase ventilation system.