Ok -- so here's my plan -- now that my 848 has sold I waited a whole week before I started on my next project. I put in a cheeky low bid and got a 2015 scrambler frame. I also picked up a snazzy 1000SS DS rear swingarm. I plan to mate the two together (I've done this kind of stuff before).... hack off the rear subframe and come up with something lighter. Big question is engine. I have a line on a reasonable, low mile Monster 800 ie engine. I'd like to run the bike with a simple set of carbs. Problem is, what kind? I think the scrambler frame is too narrow to fit a set of BST carbs or racked FCRs: I also think the top of the carbs will foul on the underside of the frame, although I won't know for sure until the frame arrives and I can measure it up. So I was thinking that as the scrambler and 797 run a 2-1 with a throttle body, could I do the same thing with a carb? Behold the cocktail napkin sketch below: Something like a downdraft 41FCR should mate to the OEM scrambler 1-2 intake manifold: I would "plug" the fuel injector ports -- the nipple could even act as a vacuum to power a wee mikuni fuel pump if needed. A custom build shows how it would look (although they are using the stock throttle body with a foam filter: A downdraft carb would be required due to the angle of the float bowl in this orientation. A shop in Japan did put split FCRs on their project, and it appears to have plenty of room and they used a gravity/vaccum fed tank...but that's a very expensive proposition: It also results in 4 (2 pull, 2 push) cables being routed from the throttle, and the trickiness of keeping split carbs synched. From what I've read, the stock scrambler throttle body is 50mm, so a 41FCR should fit, or a 50mm spigot can be used. I'd run an ignitech or even retro-fit carbureted ignitors to the bike for a super-simple wiring system. A fella in the states did that with an 800 FI engine, and it ran well. Now, I realize that the best thing you could do to an old 1990 ducati sport 750 was put twin carbs on it; however, an FCR is better than an old single weber(?) or bing carburetor. Thoughts? Dumbest idea ever? I realize it may lose some power going to a single carb, but how much do you reckon? Of course, if a set of twin BSTs will clear the frame, I'll go that route as I seem to have a knack for setting those up to run properly...
I just saw this in the FB group and am glad you've started a thread here too as it will be easier to follow it than on FB . If you've not already seen them you should look for threads by @buzzer who's built a fair few bikes along the lines of what you're intending. Here's the latest one, but several others precede this (as you can tell, this being no.#10). https://www.ducatiforum.co.uk/threads/ducati-1000ds-custom-build-10.94299/
Check out Steve Hilary he does lots of trackers and stuff, his 748 one is interesting…he builds them so sells things like seat units etc that are for Ducatis
I don't understand why you'd think Carbs are simpler or easier to work with than the injection set-up. Carbs are far bulkier than the Throttle bodies, getting round which is what most of your post above is about. The Ignitech unit or original ignitors are roughly the same size as an OEM ECU. But the biggest issue with Carbs, especially in a build like this is adjusting them. Half the bike needs stripping each time you want to change a jet, needle position etc. You’ll soon get fed up with it. With an original Injection set-up a couple of hours on a Dyno costs less than an aftermarket set of Carbs. Or do as I’ve done several times and have hours of fun learning how to get the best out of a Power commander. Plugging the laptop in is far easier than stripping the bike down each time, and it’s really satisfying to embrace and learn about mapping.
Good one @bradders - Steve supplied me with a few bits for my Triumph tracker. Lovely bloke. https://redmaxspeedshop.co.uk/
But but think of all those hard to start days that you will miss out on and no iced carbs to heat either!
As this is primarily intended for a trackbike, the compromises of developing a 1-2 intake, and the likelihood that it will result in less power, has me abandoning the idea. I'll proceed with the project, with the intent of using either the BST racked (if they fit) or split FCRs. I appreciate the feedback on FB and this forum! I'll post progress pics as they come!
