I finally bought a Ducati, after years of wanting one I did something about it. I was looking for an early 90's Supersport or Monster (love the Cagiva era stuff) and this one happened to pop up first. A '94, fairly original condition M900 with aftermarket cans and a tail tidy. Oh and no service history Pickup day
First job was a belt change, I went with some Exact-fit ones as they were easy to source locally. Install was straight forward apart from a hiccup when I tried to fit the vertical belt and found a collar on the end of the cam pulley preventing it from sliding on. None of the guides mentioned it but I found an old post somewhere saying they can be removed easily. I assume it was an early model thing that was left off later years. After yanking it off the rest of the job went well.
Next up there was some weirdness with the carbs, rich and surging down low and the odd backfire. When digging into them I found a few things; like a drilled airbox lid, K&N filter, dynojet kit, rtv goop in the bowls, ovalled needle jets, one mixture screw wound all the way in till it bent the tip and someone had been adjusting idle speed using the throttle cable adjuster. So I bought a full rebuild kit which included new slides/diaphragms and Mikuni jets, cleaned the whole lot in an ultrasonic bath then reassembled with all the nice new bits. Straight away there was a massive improvement, probably due to the new needle jets mostly. After balancing them they were better again. I still need to fine tune the jetting but will get to that later. Another fun thing I found was an Ignitech ignition unit and aftermarket pickups. After sourcing a serial to usb cable I hooked up my laptop to see how it was setup and found it was still running a generic map for a GSXR. After creating my own map based on Ducati Performance specs and setting the base timing correctly it now starts a lot easier.
Blimey interesting "tuning on it" I wonder if it was setup properly, then some monkey screwed it up, otherwise seems odd to get all the kit on... and then just totally abuse it ?
Great thread - I'll be following with interest! I'm building an early Monster this winter from a box of bits that have had kicking around for something like 10 years now with the following spec on top of standard; 900ie engine (original in bits and rusty but with 944 JE kit to go in one day) Ignitec ignition unit which fits the ie lump to the carb loom Exactfit coils Mikuni 40mm TDMR carbs MWR airbox lid Silmotor 45mm headers SP Engineering (generic cans) 2/3 length oval cans in carbon fibre 916 forks by Maxton Maxton rear shock
Waiting on some minor engineering (fatbar risers) and then its off to powder coating before starting the build. Just got my spare clutch cover back today as well all milled out Corse style - lovely! Got a few bits to figure out along the way such as fitting a Multistrada mosfet reg/rec etc so it will be a slow and steady build before paint and probably some dyno time to set it all up. Ben
After getting the carbs back in I needed to balance them and set the idle. I bought a cheap set of gauges and after calibrating them I found that lying on the ground was the best position to adjust the carbs so this was a good place to hang them where I could see them. The idle screw is not too bad to access but the butterfly sync screw is a right pain Anyway, job jobbed so onto the next thing. The jetting I have now is a mix of recommendations I have seen online and what I had available, Mikuni 150 main (155 was unavailable at the time), DJ jet needle with clip 3rd from top, DJ spring, Mikuni needle jet (new), Mikuni 40 pilot jet, mixture screw 3 1/2 turns out and factory float level. It seems pretty close with no bogging or hesitation but I suspect it is rich down low at least. I have gone back to the stock cans but want to keep the swiss cheese airbox lid (I love the sound) so to get an eye on the situation I dug out a wideband kit I used to use on my old cars to see if I could fit it. I considered a few ways but in the end some spare air fittings and an unused o2 sensor spacer cut and tacked together allowed me to use the factory boss in the header. Some jbweld also slapped on for strength and sealing as I mig welded the stainless bits with mild steel wire The hose vents the gas and was a recommendation I found for getting better readings on big twins. Normally for tail pipe clamp setups, the idea is to have a long bit of hose to stop fresh air reaching the sensor due to the large pulses present. Initial tests on a private test track *ahem* are showing it's a bit lean at WOT with 15:1 and a touch rich in the middle and bottom. I'm not an expert by any means but I'll try and get it a bit closer and then leave it as is.
Following on from above, I ended up sourcing some 155 main jets and they were spot on at WOT. I also fiddled with the needle a bit, I tried the stock one out of interest (5C19) but that was too lean even on its richest setting so ended up with the Dynojet needle on the 2nd from top groove and fuel screw 3.5 turns out. I switched the sensor to the rear cylinder and other than being a bit leaner at idle (14ish vs 13ish for the othe cyl) everything else looked the same so will leave it there for now. After that I did a bit more reading of the FBG Ignitech manual and tweaked the dwell settings to match my coils which made a noticeable difference. The coils I have are 5.3ohms on the primary side so like more dwell time than the 6000ms that was set. Went out for a nice ride Got back and decided I'd had enough of the crappy feeling in the forks so I pulled them apart to see what was up. The oil looked good and level was about 110ml, the spring seemed weedy so I cobbled together a thing to measure the rate. Made from a bit of scaffolding I found when out walking the dog, some misc washers and top hat spacers held together with a couple tacks and some all thread. An unopened 15kg roll of mig wire provided the load for measuring. The 15kg weight compressed the spring 25mm which makes the rate 0.60kg/mm Online calculators suggest 0.85 for me so I have some of those on their way.
Went with 916 forks in mine and flatslides because the carbs were totally shot - be interested to hear how you get on with your low cost fixes
I'm hoping the new springs make a good difference, it's the only part of the riding experience that I dislike. I'm also going a bit deeper now as per my other thread. I found I had the dry spaghetti cylinder studs, not a big deal but I also had aluminium swarf on the strainer so I'll pull the engine and sort those soon hopefully. It will give me a chance to clean some of the bits up while I'm at it.
Great thread with some intresting stuff - crack on, can't wait for the rest. Bike looks great. Cheers Gaz
What's the dry spaghetti studs? Are they the early ones which often snapped? I have 2 engines for my build - a 900ie one that's complete and going in this winter and the original one that's been in pieces I believe since it snapped a stud maybe 15-20 years ago. Unfortunately it was then left in a damp shed by the previous owner and all the bearings are rusty
Yeah just meant the old studs that break I bet a few engines met that fate, I saw an M900 recently that was going cheap, engine was apart needing broken stud removal, a few more questions and it turned out it had been apart for a few years and passed through a few owners too, who knows the state of the bearings let alone if all the bits are still there
I'm only making a little progress at the moment, just doing small jobs as I wait for parts. One of those is making all the special tools I need. First up is a wheel bearing driver An old screwdriver heated and bent then ground to fit the notch in the crush tube. Allowed me to clean up the wheels and get some new bearings installed. Next tool is for the head nuts. 15mm spanner cut and welded to an imperial socket I have owned for 23 years and never used Then we have something to help lift the rod in the forks when assembling them. It'll be helpful now that these have arrived. Some 0.85kg/mm springs to replace the 0.6 ones. A quick go in my spring rate measurer shows they compressed about 18mm which is spot on. 0.85 marks on the left and 0.6 on the right. The spring is a bit longer so I'll need a shorter spacer but will leave that and sag adjustment for later.
A bit more progress, I have four studs out so far, these didn't give me too much grief. Repeated heating and doses of atf/acetone mix and they eventually came out. The vertical cyl studs feel like they may give trouble though. After getting the vert cylinder off I was keen to see the state of the crank plug but found it well seated and nowhere near touching anything. This was surprising as it means the ally bits on the strainer came from somewhere else. Something has happened to this engine at some point as the horizontal head has marks from something banging around but the piston and cylinder don't so maybe the bits on the strainer were just leftovers from an earlier failure.
Looks like you may have been lucky there then. Is that gasket sealer I can see in that lower picture?
