Keihin FCR Carburetor Kit 1991-2002 Ducati 750SS 900SS M900 Nomnomnomnom. :biggrin: Somebody hide my c/card ffs...
Just Pulled the Barrels off and have found why the rear cylinder was leaking see O ring bttm RH corner as removed ! View attachment 5627
After puuling the barrells off I also noticed that this built using No base gaskets , just permatex or the like , the pistons are Arias and have 908 dotted into the underside, I assume running no base gasket meant is was running a Higher Comp ratio ? also the pistons and bores are spotless , you can still see cross hatching from the honing tool on the bore ! and thankfully no cracks in the web or gudgeon pin area of the pistons. The Rods also look like they have been balanced as this pic shows some work to the front of this rod , I assume Ducati just left them as cast. Also the top two oil plugs in the crank appear to have been centre punched and the side gallery one is not visible so hopefully a good sign ! View attachment 5628
Took off the alternator cover and look what I found :biggrin: It does look like someone went to town on this motor , its def going to get some FCR41's now !! View attachment 5629
Good work! Mines got Arias, were secondhand off a forum member who went up to 94mm 944cc hi-comps a few hundred miles after fitting these 92mm ones? Skirts were good tho? Persistent redlining will kill one of these motors more than anything else? :wink: Lack of base gasket - may have been done deliberately to set the squish correctly? Can't remember but I think there is a cutout in the alloy base gasket to hold the o-ring in place whilst you drop the barrels down?
Presuming with all the work its had done on it the studs got changed, sorry if this sounds obvious just noticed them in the pictures. Cheers, Gaz
I do not think all had base gaskets, I think some older one's did not have it hence issues with oil whipping out around that area on older m900's. In mine base gasket and silicone sealant was needed to not uzz oil.
I am not sure what the new ones look like because I have not bought any yet and they could be different depending where you get them i.e. silver or darker or black, but I believe mine to be original ones which are bright silver and which have snapped and have an "M" stamped on the end. Have a look at following article: Good Studs vs Bad, Head Studs that is - Ducati Monster Forums: Ducati Monster Motorcycle Forum I would have a guess, but please check that if they are silver but don't have the "M" you're ok. Just checked mine for info they are 7.95 dia so although silver the ones you have are obviously different. Sorry to unnecessarily harp on about this, just don't you to be caught out. Cheers, Gaz.
Gaz Dont apologise I want to rebuild this engine once ! interesting whovever assembled it after the mods mashed an o ring up , maybe the person who spent the money on it was a wee bid fed up at the time and lost interest ? with oil persintently flowing out of the rear pot.
Baines put hi-comps in my Imola rep, and they didn't use base gaskets on the rebuild. When I pulled the motor apart earlier in the year I used Threebond on the cylinder base with no issues at all ;-)
Thanks I spoke to Geoff earlier this morning and he recomeneded Three Bond , I already have some at home, if I use the base gasket he reckons it might be a bit easier to start but just lose a little on the top end speed , something I'm not to bothered about , so will probably opt to use a base gasket. Thanks
The silver studs are the early ones, are the ones prone to breaking! The later black ones are thicker (but not by much & still break??) I would recommend APE studs, those are 10mm all the way down and aint breaking for no-one!
Hi Si I would dry build the top end and check the squish. 0.8-1mm. You can buy different thickness base gaskets to get it spot on from anthena. I bought .9mm ones for my stroked st4/851 motor and got the squish set to 1mm
From what I've read this issue with the studs breaking is not the thickness/dia but they were made from the wrong material - not enough elasticity. The studs get hot then cool suddenly, I am guessing cooler air or water, they then contract and not having enough elasticity break. Look at the Nichols studs (wish I could afford a set) they are quoting elasticity and they also neck down quite a bit in the middle. Well that's my story and I am sticking to it (unless some with "senior member" in their title says different.) Thought I had also read the APE ones were a bit of a loose fit could anyone confirm. Cheers Gaz
Nichols studs - quite a lot of other FILTH in their other items! Ducati Cylinder Head Studs (Qty. 8) | eBay Expensive though... $280 + $126 postage??! Fakkin giraffe mate! Would agree with Gaz's longterm metal fatigue answer for the original studs, too many hot/cold cycles and stud snappage... Had no probs re: fit or quality with my APE ones? (pic below) Note condensation rusting on the original studs shaft - can be troublesome removing the barrels if they get too gakky?? I degreased & painted my APE stud shafts with hi-temp paint to try to stop any future rot? Search results for: 'studs' | ca-cycleworks.com Cycleworks studs - $99.04 for eight?
No not snapped the O ring was half up the tunnel, there was a fair bit of oil around the rear pot, not surpising !
