Another eng swap thread:(Edit: no longer considering EFI, upgrading 750 engine

[LowercaseJake]

I'm not saying it isn't true, but the stock carbs on Monsters are BDST 38's. The spacing on the manifolds isn't foreign to Mikuni.

You're correct, and I've also seen people in the Supersport forums with really exotic spacing plus different angles of each carb to accommodate odd sizes intakes, so I know you can buy the correct rails and such., it can be done etc.  Apparently there's just no "off the shelf" kit.

[koko64]

You're correct, and I've also seen people in the Supersport forums with really exotic spacing plus different angles of each carb to accommodate odd sizes intakes, so I know you can buy the correct rails and such., it can be done etc.  Apparently there's just no "off the shelf" kit.

Those Supersport guys have the luxury of not having the frame cross members limiting manifold choice as us Monster riders. If the frame cross members were not in the way I would have tried short manifolds on one of my Monsters a long time ago. Anyway, over time I have reconsidered and realised that the extra low down grunt of long manifolds was better for a street bike in my highly regulated home State and well worth the top end power loss they impose. For a maximum effort motor I would go short manifolds (or buy an 1100Evo) . Long manifolds give the desmodue very good, real world, streetable power characteristics. However, with careful intake tract/airbox mods, you can mitigate some of the top end power loss of long manifolds. http://www.ducatimonsterforum.org/index.php?topic=75652.msg1389559#msg1389559

Good score getting a deal on the FCR39s. Going hi comp pistons and light flywheel, or waiting until you do the head swap?

[Duck-Stew]

Jet sizes?  I don't recall things THAT far back... 

[LowercaseJake]

Those Supersport guys have the luxury of not having the frame cross members limiting manifold choice as us Monster riders. If the frame cross members were not in the way I would have tried short manifolds on one of my Monsters a long time ago. Anyway, over time I have reconsidered and realised that the extra low down grunt of long manifolds was better for a street bike in my highly regulated home State and well worth the top end power loss they impose. For a maximum effort motor I would go short manifolds (or buy an 1100Evo) . Long manifolds give the desmodue very good, real world, streetable power characteristics. However, with careful intake tract/airbox mods, you can mitigate some of the top end power loss of long manifolds. http://www.ducatimonsterforum.org/index.php?topic=75652.msg1389559#msg1389559

Good score getting a deal on the FCR39s. Going hi comp pistons and light flywheel, or waiting until you do the head swap?

I read about your airbox mods way back as a lurker, Koko. Very impressive. I was considering stuffing the larger airbox from an S4R or other EFI bike in there, with a removed lid of course. I would just need to make sure the FCR adapters fit the rubbers. Battery is a teeny weeny Antigravity which can go pretty much anywhere, same with my ignition box.

For me the choice to get the 39's instead of just bolt on the stock 38's was pretty easy...new throttle cables (I HATE measuring and making my own), the (IMO) mandatory Factory Pro kit or at the very least the nickel plated emulsion tubes, scouring ebay for a choke + lever or again making my own..adding up the cost and time it just wasn't a significant savings. Plus, tuning of the FCR's is so linear, easy to understand, jets and screws easier to access and so forth. Plus once you feel the previously imperceptible difference in throttle response between a slide carb and vac carb it's obvious from that point forward. At least to me. And, FCR's are EASY to resell when you're finished with em.

For now I will just drop in a set of Ferraci pistons, except their website shows "out of stock". I hope they didn't discontinue them? maybe attempt a shadetree port + polish while I'm in there, cam timing and that's it. I've subscribed to eBay listings for 800 and 695 heads.

The logic behind Stu's comment regarding what he'd do to a 750 engine before calling it quits applies equally to a 900 based on my experience. Besides the extra gear and dry clutch I don't find it to be vastly superior, and it's lazier which I don't like. I also don't like dry clutches...blasphemy, I know.

Only question I really have now is who sells a light flywheel for a 2000 750 engine? there were only 2, maybe 3 years where there was even a carby motor with 3 phase alternator....the 900/750 in 1999 and the 750 from 99-01. I prefer aftermarket aluminum ones, because in my mind if tragedy strikes and the nut backs off, the softer aluminum will take the damage instead of the crankshaft. Regardless, I NEED a light flywheel.

BTW I emailed Chad @ Sudco (super helpful dude) and he responded with the FCR39 baseline for SS750/M750. The ONLY DIFFERENCE is an extra quarter turn of the fuel screws. Seems ridiculous to me.

I still would've liked to see if these fit:https://www.ebay.com/itm/Dellorto-PHM-NS1-ND1-38mm-PAIR-carburetors-Moto-Guzzi-Ducati-SS-4906-4907/172650522787?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

[koko64]

Nichols make 3 phase carb flywheels iirc, or you could have yours machined down. MPL (German company I think) also do flywheels.

FCRs win hands down.

You might find that hi comp pistons, light flywheel, airbox mods, FCRs and some porting are all you need.
That's what Nibor did and his M750 goes great. Imo, it's worth porting the intake manifolds as they can be pretty rough as cast with mirror shiny patches in some sections and then casting dags and ridges in others. You can radius the bends, open the volume, match the ports and finish the walls in a satin, honed texture.

[LowercaseJake]

Koko, what baseline do you suggest I have my local carb shop build these to? The baseline according to Sudco:

155 mains,
200 main airs,
EMT needles in the 3rd,
60 slows,
1.5 turns out on slow air screws
and 1 turn out on fuel screws.

My initial thoughts are since I'll be aquiring an airbox soon but presently only have pod filters is keep everything the same as above, except:

160 main jet
55 slow jet

Needle clip and slow air screws as recommended by Sudco.

I'm basing this on needing a HUGE jet change when I originally chopped my M600 airbox top and cored the cans, and the fact that 60 slow jets were so pig rich on my 900 that they literally soaked my spark plugs with petrol.

[greenmonster]

http://www.ducati-kaemna.de/schwungrad-alu-ergal-evo-superleicht-nippon-denso-lichtmaschine-ab-98.html

[koko64]

For a 900 for the same mods, I note that 39s need larger pilot jets, lower needle position and smaller main jets.
For example:    
                      FCR39    FCR41
Pilot               58            50-52
Needle          #3            #5
MJ                 160         165

That's just my experience with the half a dozen 900's I've tuned. Note, these are hi comp 900's with porting and fully open airboxes on premium kangaroo fuel.

Thats a fair "guestimstion" for your 750. I have only played with one 750 with FCRs but we strangely found the 60 pilot to work and are running 155 main jets with a half open, "expanded" airbox. The filter is a little larger than the holes from the snorkles removed so we used the 155s (baseline from a buddy). 160s would be a fair guess with a fully open airbox.
http://redirect.viglink.com/?format=go&jsonp=vglnk_150974634515312&key=7380040348cb056f0e988195afaf9852&libId=j9kfze8f01000c6m000MA6pxldmta&loc=http%3A%2F%2Fwww.ducatimonsterforum.org%2Findex.php%3Ftopic%3D75652.0&v=1&out=https%3A%2F%2Fwww.flickr.com%2Fphotos%2F150482584%40N03%2Fshares%2Fa4j6Dw&ref=http%3A%2F%2Fwww.ducatimonsterforum.org%2Findex.php%3Ftopic%3D75652.15&title=Modified%20Carbs%20and%20Airbox%20Mods.&txt=https%3A%2F%2Fwww.flickr.com%2Fphotos%2F150482584%40N03%2Fshares%2Fa4j6Dw


60 pilot jets in 41s on a 900 couldn't make a mile without fouling and stalling. The better the porting the worse it was, but thats our fuel too.

Speeddog gave me a good baseline from tuning his 750 so he might chime in.

[LowercaseJake]

http://www.ducati-kaemna.de/schwungrad-alu-ergal-evo-superleicht-nippon-denso-lichtmaschine-ab-98.html

GM those don't appear to have the ignition triggers I'd need. 99-01 were oddball years for the carby Monsters. Nichols might be the only source but they are hella pricey. I will email them tho, that's a fair price. Except they look identical to the SSR ones, I hope they aren't the same.

[Speeddog]

Here's Kaemna's flywheel for carbies:

http://www.ducati-kaemna.com/catalog/ducati/supersport-750-900-1000/motorenteile-engine-parts/schwungrad-ergal-900-ab-98-vergaser-monster.html

[LowercaseJake]

Here's Kaemna's flywheel for carbies:

http://www.ducati-kaemna.com/catalog/ducati/supersport-750-900-1000/motorenteile-engine-parts/schwungrad-ergal-900-ab-98-vergaser-monster.html

Thanks, that's a very reasonable price compared to Nichols... Finger is on the trigger. I already ordered a pair of MIVV X-Cones and am having some stock headers ceramicoated.

[koko64]

Vergaser flywheel.

I'm getting excited about this build (vicarious pleasure). Time to set up a build thread in the mods & accessories section.

[LowercaseJake]

Vergaser flywheel.

I'm getting excited about this build (vicarious pleasure). Time to set up a build thread in the mods & accessories section.

It won't be anything special for awhile. just a super clean, low mileage stock 750 engine with a light flywheel, stock heads until I decide on what recipe to use (Ferraci pistons plus 695 or 800 heads, need to determine which - I may even draw the conclusion that the Ferraci pistons are better off in the 750 heads. I refuse to get carried away with throwing money at this 750 engine, I loved everything about it while I had it EXCEPT the low low top end ceiling and the inability to power wheely - I love to power wheely and am not very good at clutch wheelies. If the light FW, flatslides and 14t sprocket give me at least first gear wheelies I'll be fine.

You guys will like the bike though...glossy black powdercoated frame, hard anodized S&P/Ducati Performance rearsets, TONS of Roadracing parts including alloy tank that I had hand finished to a brushed look (hate mirror/chrome finishes) Roadracing clocks, DP alu cowl, forged wheels, the trusty Brembo 4 pot/2 pad dual calipers were disassembled, coated black and rebilt, CORE MOTO stainless hoses, Penske shock, hard anodized AEM triples (lots of black, brushed raw aluminum, hard ano gray accents). What's odd is I'm oddly relieved that the 900 bit the dust...it was an aggravating engine from the very start and took my bike from rocksteady reliable to problem after problem.

Tho, since I'm already waiting on parts to arrive from Italy, the headers to come back from ceramiccoat, and the engine is on a stand...it might be rather silly to not to the headwork before installing the engine in the frame. I really need to learn how to be patient. If any of you guys get a lead on Ferraci pistons lemme know...the "currently unavailable" notation on the Ferraci website is concerning.

[koko64]

Sounds good. Some nice items there .

It is certainly a breeze doing engine work on the stand and out of the bike. Monsters are one of the easier motors to work on in the frame, however.

I am biased towards large capacity grunt, but the way Nibor's bike runs was a wake up call to my big bore bias.
It seems that these short stroke motors tolerate less flywheel mass than the long stroke donks. This all helps response (and wherlies).
If 695/800 motors or heads are cheap enough in your locale then cool, but down here 800 motors cost thousands of dollars so 900 V head 43mm inlet valves in 750 heads ported towards low lift flow and hi comp pistons would work quite well. If more cash was available then dialed in 900 V cams and diffrrent porting.
Nibor's bike has stock cams and valves and runs great. It hasn't been dynoed yet but I was impressed.

[Duck-Stew]

A guy I used to ride w/in SoCal begged and begged me to install 11:1 Ferracci piston in his STOCK HEAD equipped 750.  Finally, mostly to shut him up, I did it.  What a mistake.

The stock 750 heads lack the flow to get air in and out which is used to somewhat reduce the static compression ratio of the pistons.

The bike made more torque, yes.  But to do so, it took the highest octane fuel and the torque was over-and-done-with in short order.  Bike also ran very, very hot.  My stock headed 750 ran just as hard as his high-comp bike did.

I used to cut apart 750 heads to make "demo" units so that people could understand how desmo works (w/o the top of the head getting in the way).  That's about the most practical use for them.  There isn't anything about the 750 head that's good.  Nothing. 

695 heads run 7mm valves, same as the later 800 heads do.  Get them if you get the pistons.  Consider it a package deal.