Getting more HP

[The ModFather]

I love my 2005 Monster 620 Dark and have it modded exactly how I want. Really dont think I'd ever sell it but I'd like to get more HP out of it. Especially now that I got the Diavel. The 620 is super fun to ride but I need more power out of it. I was thinking of opening up the airbox and picking up a Power Commander 3 then getting it Dyno Tuned. It's got Boom Tubes so I'm pretty sure there's no stock mapping for those. Not sure how much that would give me in terms of HP. Anyone have any idea? 
My other concern is do these type of performance modifications shorten the lifespan of the engine. Thoughts?

[Dirty Duc]

Compared to the diavel... Turbo it.

[Kopfjager]

Not gonna get much out of the that engine. Put an 800/900 or 1000 in it.

[The ModFather]

I was thinking of putting a post 2k 900 in there. Need to find out the fitment for the frame exhaust etc. Hoping 900 Monster engine will fit. I think it will.

[Howie]

The engine fitting the frame will not be a problem, bigger problem will be computer compatibility.  2001 will be a problem, though doable.  2002 up to whenever they went to the stepper motor for idle speed, probably easier. 

[Speeddog]

An 800 is going to be the best bang for the buck, your exhaust will fit, a reflash of your ECU to 800 DP spec and you'll be set.

[Rudemouthsky]

An 800 is going to be the best bang for the buck, your exhaust will fit, a reflash of your ECU to 800 DP spec and you'll be set.

Thorn14 went this route so he'd be a good person to ask.

I think you might miss the 620, espec since you already have a Diavel for insane power. I know I miss(ed) my 750. I dunno if it was the shorter stroke or what but it was just "fun" around town and in the back roads in a way my 900 and Jap bikes of the past never were.

[The ModFather]

Thorn14 went this route so he'd be a good person to ask.

I think you might miss the 620, espec since you already have a Diavel for insane power. I know I miss(ed) my 750. I dunno if it was the shorter stroke or what but it was just "fun" around town and in the back roads in a way my 900 and Jap bikes of the past never were.

This is real good insight as I've also been thinking this could happen. The 620 has been bullet proof and is loads of fun to ride. I should probably accept it for what it is. With my luck I'd swap the engine and have nothing but problems.

[Duck-Stew]

This is real good insight as I've also been thinking this could happen. The 620 has been bullet proof and is loads of fun to ride. I should probably accept it for what it is. With my luck I'd swap the engine and have nothing but problems.

620 is 61.5mm stroke and an 80mm bore.
750 is 61.5mm stroke and an 88mm bore.

Ferracci sells 750 hi-compression pistons for $420.
You'll have to buy either 695, 800 or 2002 only 750 barrels and do an upper-end swap.

You get to keep your original short-stroke small-case motor (I miss mine...) but punch it up quite a bit.

620 heads are good (certainly better than 750 heads), but 800 or 695 heads are better still.

ECU & mapping?  You're on your own there...

Another side note:  620 intake and exhaust ports are in the same place which means you get to keep your Boom Tubes w/o modification.  900 swap will need to have minor changes there.

Another fun idea is that 696 motors (796 too) are starting to come available for cheap $ (if you watch long enough) and those have MUCH MUCH MUCH MUCH better cylinder heads.

[thorn14]

800 is the largest you can go before exhaust headers change in length as others have pointed out. I love mine, but headers can be had relatively cheap, so just get a 900 or larger if power is what you want. The 800 is difficult to upgrade with less power options than 900/1000's with big bores, and cylinder kits etc.

[Duck-Stew]

...but headers can be had relatively cheap...

Headers:  Yes.

BoomTubes: No.

[thorn14]

BoomTubes: No.

Forgot about those.

Isn't it just adding a small amount of exhaust pipe on the horizontal? Does the vertical need it as well?

[Rudemouthsky]

Forgot about those.

Isn't it just adding a small amount of exhaust pipe on the horizontal? Does the vertical need it as well?

Yep. The Roadracing exhaust I fitted to my 750 needed about 4.5" to fit my 900 and it was no problem.

[brad black]

i sent this reply to someone on the ducati.net mailing list on a similar theme to the 620 - 800 - 1000 question:

i kind of like the 696.  i'm not so big on the 796.  the 796 is a bit too
tweeny for me.  the 696 isn't powerful enough to lift the front wheel
without a big effort, whereas the 1100 will throw it round willy nilly with
precious little.  but the 796 is in between and i find that a bit
frustrating.  tempting more easily than delivering.

the 696 is just fun in a slow way.  as long as you don't want a fast bike,
it's cool.  i've had a couple of slow bikes that are fun to commute on: kr1s
250 and then m600.  but i always had another bike at the same time, as you do.

[jduke]

3 bikes don't take up much more room in a garage than 2, get a new Monster 821.
After all, what kind of story would it be if Goldilocks ran into just 2 bears???