Luca, thanks. I've ordered the M&P ones. I've looked at the R&D but at 20 quid plus 20 to get them here I'll go with the M&P, especially as you say you haven't had a problem with them. Spike, thanks for the tip on the orientation, I'll pay particular attention to that when I remove the carbs to fit the fuel screws. Thanks to both of you.
Well the carbs are now off the bike, and sitting on my workbench waiting for the mixture screws to arrive from M&P. I counted how many turns they were, http://www.ducatitech.com/2v/img/fuel_screws.jpg 6 turns from fully wound in! 5 1/4 more than the california cycleworks ducatitech page recommended. Just out of interest, what do you guys have them set at? (running bigger inlet valves, hi comp cosworth pistons and flowed heads with a full spaghetti system.)
What? Default is 1.5 full turn (6 quarter turns) I have 5 quarter turns. At 6 it floods all the time.
It was waayyy more than 6 quarter turns, which explains a hell of a lot, especially with the woolly running and the flooding. I think the rear cylinder was around 8 quarter turns. So if I set them at five, I should be ok I guess.
As lucaz said default is 1.5 turns, if you look in the manual it tells you that any more out and the pilot is too big and any less the pilot is too small. i found that the american pilot is too big and opted around 45, this gives the screw 1.5 - 1.75 turns on mine, it should not matter about the spec of the motor for tickover unless you have a set of radical cams like the st2 cams, these have a load of overlap and can cause reverse pumping at low speeds as in tickover. on a seperate note, just look at the weight of an st2 flywheel (about 3kg) that was used by ducati to get over the bottom end stumble. i found best tickover around 1200 rpm with these cams and fcr carbs, i just could not dial out (or tinker) this particular problem but it went like a shot from a gun. Jet size too big possible cause of flooding at two turns? For tinkering real "loads of dyno hours".
On a seperae note: i saw some settings on here for the ignitech dwell values, any one direct me to them as i have lost my way.
Following on from Lucazades links and advice I ordered the fuel screw adjusters from M&P. Bit unnerving that the pin is not the same length on each, but there we go. I though I'd stick a small guide to aid anybody thinking of doing the same thing. Things i've learnt: Take the carbs off the bike for easier access. Also remove the bottom cover plate. Don't do what I did, and think that they'd drop out when you've unscrewed them all the way! Luckily I didn't strip the threads. As Laca says in his notes, the hole in the cover which you've just unscrewed needs opening out or else the thread can't pass through. 6mm diameter drill bit did the job. You can see that the hole for the fuel screw isn't round. Clever really as it essentially provides a lockstop to stop the screw from falling out entirely. Retrieving the spring, retaining circlip and O-ring, I assembled the new fuel screws. Assembling the carbs and inserting the new screw, and dialled 5 quarter turns out from fully seated. I took the opportunity to tighten up the spigots that the mounting rubbers clamp on to as I found them to be loose, and I sat the mounting rubber home properly as they were on the piss. And finally she's back on the bike. I've done the twistgrip and checked it wasn't tugging or strained on full locks. Tommorrow I'll turn on the fuel tap and pray that all is good! In case you're wondering, as you see here and on my 900ss Ressurection thread in the projects forum, there's a blob of yellow chowder on most of the bolts. For those of you that don't know, its called Torqueseal, and is a resinous gloop which dries and provides you with two things, a visual mark as to what bolts have been torqued and tightened (very handy when you're doing a rebuild and can't remember if you've tightened the bolt or not), and also a visual torque break detector, as you will see the seal has broken if the bolt has moved. Invaluable I reckon. F900 Torque Seal - Vibration Detection - Anti-Sabotage Lacquer | eBay A Domani!
The adjuster screws look like a good idea. I took my carbs off to swap the main jets at the weekend and turned those screws out a half-turn whilst in there but it would be very tricky to adjust them in situ. Off to the dyno this afternoon and hope I don't need to turn them! How far do the adjusters stick out of the carb base? as I'm not sure how much clearance I've got on my carbs.
Yes, I really need to book some Dyno time as I'd like to have them set up properly. The trough they sit in is approximately 25mm deep, and so a further 20mm beyond that.
I had been looking at finding a way to extend the OEM BDST pilot screws to make adjustment easier.......Factory Pro sell them as well. However, I gave up on the idea for the time being.....they need to be quite long and I wondered if the extra length would cause vibration and loosening...... ......but fortunately with the half fairing fitted, I can get at the OEM ones quite easily.......with a short screwdriver and the occasional burned fingertip. AL
Good point AL re: vibration - it's a good idea in general apart from that but would prefer if only the extention were plastic. A slightly longer than standard brass 'fuel screw' with an Allen-key head would suit me fine. (Keihin or Mikuni)
I pretty much agree here, i think they are a little too long and may encourage the loosening effect that some have already mentioned. i use an extended screwdriver tip thats about 25mm long in a short handle that snapon do thats a couple of quid, it makes the overall length about 35mm, the handle is just a blob of plastic with a hex in. once adjusted i had no problems with mine but i wonder if there is an issue with the spring length not giving enough tension allowing these to back out. And i think the burned fingertip statement is just perfect!
Chris, the extended part has an O-ring down the shaft which acts as dust seal and AV damper. I'll see how this goes in practice. Personally I can't see why the casting in the housing needs to be so deep, or yes a better engineered tail on the screw. I'd welcome an allen head on it as well.
Because I have the high level oil cooler, I also get a burned underside of my forearm from the front header pipe if I am not careful when laying on my back to get at the balance screw........the throttle stop/idle screw was dealt with by using a spare trip meter cable attached to a spare throttle screw...... I agree about the spring pressure.....five turns out and you are in danger of losing the screw. AL
I looked at extending it with a plastic rod, but joining the two wouldn't be easy.....they would have to butt joint to the screw because the casting is too tight to the screw to be able to bond a slip over onto the screw head. I have also looked at the idea of carefully drilling the brass head, but I doubt if a drill bit over 2mm diameter would be safe enough.......but I do have a 2mm diameter stainless steel rod from a car aerial........unfortunately it isn't threaded and I can't find my BA taps and dies. .....brass rod just pushed in and solder might work though AL
if you're going to go to that trouble you might as well look to have a version of the screw machined up with a suitable tail. "T"-Handle FuelscrewAir/Fuelscrews Mikuni BSR Jetting Tips Requested - DR-Z 400 - ThumperTalk
The one with the dog leg won't work on the BDST..........and the others are too long if the T is to clear the float bowl. AL
Question - The thinnest part of the mixture screw, is that a needle or a locating pin? the reason I ask is because on the screws I have fitted as replacements this is not the same size, one is lightly shorter. If its a locator, then no probs, but if its a needle then I may well revert back to the original brass items.
