Well, I don't have a Monster but I do have a Monster powered Multistrada (and air cooled Ducatis are basically all the same, right?). Multistrada.net just doesn't have enough traffic to answer some of my questions so I've used this site as a resource for a while and thought i'd finally say hi. So here's an introduction to my Monster 800 swapped Multistrada 620. Sorry, it's kind of long winded (and copied from another forum).
I am not the first person to do this swap. My real inspiration came from Dan (Dukerdr) here at Multistrada.net [url]http://www.multistrada.net/forum/viewtopic.php?t=30263[/url. He also gave me some good advice to help along the way. There is also a very old thread on that site by someone who did this way back when a 620 was a new bike. Overall I would say it's not a beginner project, but not all that complicated if you're adept at turning wrenches. Other than the machine work the rest was just removing and replacing the engine plus some other stuff I did, and there will be more to come. I started it for the first timea couple weeks ago and have commuted on it twice now, and it feels real good after riding my Sportster all summer. It certainly feels stronger than the 620, but until it's tuned and running properly I can't say too much because it coughs and sputters below 4500 rpm. I am not good at documenting stuff like this but here's my attempt at a build thread anyway. I still need to do the important stuff like set the TPS, sync the throttle bodies and then get it on a dyno and get the fueling figured out. The idle is low so I have to use the choke lever to keep it up. Revs great though.
I got a new phone so I don't have any recent pictures of the bike before I took it apart. It was really dirty. It ran OK but had a bent shift fork and sometimes fell out of gear or grinded going into gear. It ran strong but it also ran really hot. I have no explanation besides potentially being really lean due to the exhaust. When I put it together this time I used Permatex Ultra Copper gasket maker on the exhaust joints so it should be pretty tight. Besides that it was just a 620. Here is a picture that shows my home made exhaust (built from a Two Brothers for an R1) and a rack I made for a BMW top case. The picture is old so the bike looks significantly cleaner than it did when I took it apart. The only thing not in this picture is the Multistrada 1000 Showa forks.
The difference between a Multistrada engine and a Monster is the width of the case where the swingarm mounts. On a Monster the swingarm just mounts to the engine, therefore the part of the case that the swingarm bolts through it very wide. On a Multi or Hypermotard the swingarm goes around the engine cases and then inside the frame so it is significantly narrower where the swingarm attaches. But it does make for a stronger pivot point for the swingarm. To make the engine fit I had to machine the cases down. I did this by mounting the engine on it's side to a 1" aluminum fixture plate and bolting the whole thing to a mill, then flip it over and do the other side. The hardest part was finding something to measure off of to do the first side. Luckily, I work in a machine shop.
Here's it is ready to go back in.
All bolted up. With a bike jack and good adjustable straps it wasn't overly difficult to get back in by myself. Moving it around is a pain in the ass though. I'm not the biggest dude around. There are some intricacies to getting it in place that you just kind of figure out as you do it.
I had the PCIII on the bike before I did this swap, but I never liked how it was mounted. I have to use one for a Monster 620 so the ground wire on it is really short because on a Monster it would mount right on the battery, which it can't do on a Multistrada. I had to mount the unit strapped to the outside of the bike. It was never a problem but I never liked it there, so I found a way to move it. I also may go naked someday so took this opportunity to get some pod filters from Ca-Cycleworks. Chris is great and their customer service is the best. I cut up the airbox to keep the coils mounted in their stock location and give me a place to mount the PCIII. Someday I may fabricate something to make this prettier and mount the battery and electronics and stuff.
It gives a lot more room to work this way also, not having the big ugly airbox in the way.
Here's the breather for the crankcase.
I also took this opportunity to install the Multistrada 1000 Showa rear shock I've had on the shelf for like 2 years. I had to make a mount for the preload adjuster since a 620 doesn't have one. I used my favorite medium, 1/2" square tube from Home Depot and a piece of the original bracket. I am no expert welder, that's for sure.
My junkyard engine didn't come with an oil cooler, so I found one on ebay for $60 from a 750. The older bikes used different oil line threads so I got some -6AN to 14mm adapters from Jeg's. I bent up some mounts from aluminum bar just to get the bike together. These will be replaced. It's pretty crooked right now.
And finally, here it is all together. It basically just looks like a 620, but with my exhaust and rack. The oil cooler is the only thing to make it look different than a 620. I also Plasti-Dipped a few particularly ugly panels from a lowside. The whole bike will probably get that treatment to even things out. I need to move the forks down in the trees because it's a little high in the back now, but besides that it feels great and I hope to get some serious miles on it now.
