Well, I bit the bullet and chopped my DP Remus hi-pipes yesterday. I ended up shortening them 3 inches, and boy does it ever look better paired with a tail chop. Problem is the bike now sounds pretty weak, and though I haven't ridden it, it definitely seems off on power (takes a good bit more throttle to rev it now). A buddy of mine suggested that I'd need to rejet the carbs to account for the shorter cans - Now, I was kinda half planing on doing it anyway since the PO didn't do anything after installing the DP cans, but is that really all I need? I find it hard to believe that going from a restrictive stock can to a high-flow aftermarket one hardly effected the bike, but taking a few inches off the effective length of the can would totally throw it off - especially considering that the overall length of the system is probably still longer than with the stock low-mounts.
The cans should not make much of a difference on a carbie Monster. The OEM mufflers actually flow pretty well. the big source of restriction is the crossover. The problem is weight and ground clearance. Oh, of course add to that aesthetics, both visual and audio.
Ok, started it again this afternoon - Oh boy. Wouldn't run without a good amount of fast-idle dialed in, and it had a tendency to die even then (though it is about 30 outside right now). Exhaust smelled quite lean. Rev response was painfully slow. But perhaps the most disturbing thing (for me) was the sound. Uhg! Not only does it seem quieter (after removing 3 inches of muffling?!?), but the tone itself is just depressing - sounded a lot like a dirt bike [puke]. I shot a quick video, though it actually sounds better in the video than in person.
Crap (http://www.youtube.com/watch?v=nDIC4LebuRU#normal)
Any thoughts? I know it's lean, but I still can't bring myself to believe just taking a few inches off the cans could have such a dramatic effect! It ran beautifully before...
Real hard to tell from the video, but to me it sounds like the bike is running on one cylinder. Are both getting hot?
I had had the same thought, since it's all puttery like a thumper. Didn't really run it long enough to tell though. Perhaps I'll have to try again...
Ok, acquired the proper socket to remove plugs (A deep 18mm? Really?), found the vertical to have no spark. Pulled the coils, checked both (A-OK), replaced in opposite positions. Still no spark vertical. Swapped plugs, now no spark horizontal. DX: Bad plug.
Ironic how it happened in lock-step with the pipe chop. Now it's off to the dela' to get me some plugs, hopefully that will do it.
How'd you go with the new plugs?
Can you post up some pics of your shorty pipes/tail chop. I've got high mount remus pipes also and was going to the tail/can chop next week. Just want to see what it's going to look like first :D
All went swimmingly post plug replacement!
Excuse all the odds and ends missing / hanging / taped on / etc - She's a work in progress.
(http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs1357.snc4/162953_10150348544700467_853020466_16305507_8044518_n.jpg)
(http://sphotos.ak.fbcdn.net/hphotos-ak-ash1/hs750.ash1/164123_10150348544545467_853020466_16305501_3066299_n.jpg)
And a little YouTube action:
Ducati Monster 750 with chopped Remus DP hi-mounts (http://www.youtube.com/watch?v=JZZWfn_Wmtg#normal)
Looks 1000x better, and not just because the cans line up with the "fender" either (I took off exactly 3" FWIW) - I feel like the proportions are much better now, and that the whole back end looks much more balanced. For the first time since I picked the bike up a few weeks ago, I can look at it from every angle and not feel that something major is detracting from the appearance. Also of interest: The sound registered 1-2 dB louder (at ~1500 rpm fast idle) about 2 feet directly behind the bike (100 up from 98), though I'm not sure how far back my original reading was so it may just be a function of distance. Subjectively, it isn't any louder or even really and different sounding.
They look great. Since they are free flowing they may require rejetting for optimum performance. Since you have shortened the mufflers there is even less back pressure now.
Jetting becomes very necessary when you modify the air intake, like running an open air box or pods. As someone else said carbed bikes have a good tolerance of free flowing mufflers, but yours are even shorter now. It's worth considering a jet kit. There are quite a few carb jetting threads here.
You can email Dynojet and tell them what you are running and they may recommend a particular kit.
The kits available from Dynojet and Factory Pro cater for a range of modifications including free flowing pipes and if you wish, air box mods. Their websites let you preview the jet kits for the mods you have in mind.