My recently acquired ST3S is brilliant except when on small/trailing throttle. It seems unable to ‘decide’ whether to add fuel or not. No issues under load at all, but makes life awkward in the wet/narrow lanes.....Seems really quite snatchy? I was told by a dealer this can be mostly tuned out - is this the case? - I don’t want to add Power Commanders or after market cans, just for it to work in standard format. Any thoughts? Thanks.
Eminently possible — my ST3 is serviced by Ray Petty, as was the ST2 that preceded it. Ray had both bikes set up such that they fuelled smoothly right down to tick-over. With a (very) light hand on the throttle it's possible to bimble along at 2000 rpm in the lower gears (not much acceleration, but ideal for unobtrusive progress in built-up areas).
Thanks - that’s what I’m after! I understand there is a Ducati expert in Dunchideock near Exeter - does anyone have contact details? I believe he may be called Westlake, but not sure....
Bud Westcott. He's like an enigma to get hold of. Probably easier to give redmax at Dunkeswella call. A good setup is critical ( factory emission standard ruins the bike) I wouldn't write off the idea of a remap or power commander. What part of Devon are you in? Good luck with your quest!
Just going to throw out an alternative thought here. Have you considered putting a larger sprocket on the back wheel? (Or maybe a smaller front sprocket, which is not as good an idea IMHO?) As a touring machine, a larger rear sprocket is not ideal ... but for low speed situations, it can smooth things out, by placing the gearing for the 10-20mph travel in a "sweeter" (smoother) part of the rev range for 2nd gear. This has worked a treat on my 750SS and 999S bikes. The ST3 has a different engine config from either (3 valves per cyl IIRC) but who knows? Changing the effective gearing might help.
People have sold perfectly good bikes due to them still being on factory settings. Pull a sparkplug out and have a look yourself. It will be very pale / lean.
Thanks, cycled along the lane where he is supposed to be and could only see some old vehicles behind some fencing.... Spoke with Redmax and hopefully going to take it up soon. He is ordering in a fuel sender unit, mine gets to a quarter and stays there until you run out of fuel. I guess with a new sender and hoses and filter things may improve anyway? It’s the fact fuelling seems to go to over run cutoff and then jumps back in even on a steady throttle around 50mph in 5th. Surely that can’t be right, as it still takes a fair bit of energy to push the bike along at that speed? Based in Exeter BTW....
Interesting comments re sprocket size. I understand the 3 is lower geared than the 4 anyway. Is it the case that correct chain adjustment is also critical - mine was slightly too tight (20-25mm) so have set to around 35mm as per the label which may help with snatchiness?
An overly slack chain would adversely affect smoothness. I suspect an over-tight chain would provided maximum smoothness but obviously it's not a good idea.
Does anyone know if the Matheson? analyser is essential for correct tuning alongside throttle body balancing? Also, does Bud Westcott have one? Thanks
CO needs to be raised to about 4 to 5% some people might be able do this by smell!!! You still chasing bud? I'm sure he has all he needs.
Have new fuel sender and lots of water etc in tank/filter. However still awful at moderate throttle openings with surging and lurching. Is blowing back through the rear throttle body as this is sooty. Does this in all gears (even 60+mph) but particularly bad accelerating out of corners or when trickling through 30mph zones when there is hesitation, then acceleration! Any ideas on specific problem? Could it be the throttle body balancing/inlet seals/air screw/valve timing/other?? I have vacuum gauges but no Matheson and Bud Westcott not answering!!!
Got to first sort the fuel tank before anything else. Empty it clear the filler overflow and new filter. You know how to set up the co% and tps reset? My 4 was an early ecu and a bit different to yours. Redmax no good?
My ST4S suffered from this when i first had it. It drove me mad and in hot weather made the bike almost unrideable in traffic. High octane petrol helped slightly and i had fitted the lower gearing front sprocket as well. Nelly sorted it at a service. No mention of what he did but it was perfect from that day onward.
Thanks both, injector cleaner working well, but managed to book in with Bud next week to tune. Fingers crossed.....
After a lot of cleaning and a tune up......even worse....blowing back through the throttle bodies and generally terrible at low speed/throttle. After a lot of head scratching we tried a good used fuel pressure regulator. Problem pretty much solved....
