Dont know about this type of engine as i havent worked on one but the discription of symptoms you have described sounds like a valve issue to me . Once it gets hot either to big , or small , valve gap .
Thanks ducati2242 as that may very well be the issue since I have installed new timing belts but haven't tackled the Desmo valve train yet. I have never adjusted Ducati valves before but have watched many videos and believe I have the skill level but do not have the shims or special tools to do the job right so it will probably be a trip to the dealer once I get it driveable and registered...here is a video clip of the old Duc running!
Just check them to see where they are first . May not be that . Just has that ring to it. Vid not there by the way
Good point and advice. I will check the valves first for proper gaps before going further. I will try to up load a shorter video as it was probably too long and too large a file.
If your valves are out of spec, replace the 1/2 rings (retaining clips) and recheck, often this brings them back to spec.
Thanks NZDave for the tip and I will do that and report back. Here is a link to a video I posted on Facebook after getting the old beast running for the first time: Facebook Curious what you guys think if you can access the video and listen to the engine at various speeds.
Thanks NZDave for the tip and I will do that and report back. Here is a link to a video I posted on Facebook after getting the old beast running for the first time: Facebook Curious what you guys think if you can access the video and listen to the engine at various speeds.
With the original mileage stated I wouldn't be going anywhere near valve shim adjustment yet, they will often get to 20,000 and more before you need to touch them on a 2 valve. More likely get on those carbs again – but could be many carb-related things. Possibly balance between the two bodies comes to mind first but certainly float level is another/air leak(s) /idle mixture screws not seating or need adjusting/idle galleries partially blocked.
Hi Chris and thanks for the input/advice. I am more inclined to believe this idling problem is carb related and likely either one or even all of the possible problem-points you listed. I almost want to pull the carbs back off and break them down again part by part and do an ultrasonic cleaning and start over with baseline "bench" synchronization, needle and float settings, and idle mixture screw seating & adjustments. I wish I had the funds to slap a set of 41MM FCRs on this old beauty as I have read nightmares from several longtime Ducati carby owners going through rebuild after rebuild on these OEM carbs to throw in the towel and slap on a FCR 41MM Kit and never look back! Any thoughts on the FCR conversion over continually fiddling with these OEM Mikunis?
I know what you mean regarding the FCRs but even that route isn't all plain sailing as they need to be meticulously maintained. I.e. if you 'fitted them and forgot them' on a road going Ducati they would be fraught with more problems than the Mikunis. It is a labour of love with the standard carbs (I have about 8 or 9 pairs) but they are brilliant for the job when working properly. You will see the odd low mileage/good condition pair turn up on eBay for around £75 and if you like a gamble, sometimes this is the best route. Answered questions and high-quality pictures from the seller are vital of course. As far as your current carbs are concerned, you can only persevere and try one thing at a time. When you are happy with grovelling around behind the front wheel finding the slow running/mixture screws/ balance screws you can try raising the idle to 1500 approx ( sounds like you might not need to!) and then try running the bike on one cylinder at a time. Quickest way is to get a slave plug and then plug it into the appropriate lead and rest it on earth to save the exciter etc circuit from damage while running. By running each cylinder separately you will hopefully get a clue as to how each cylinder is performing and if one cylinder is "lagging" or "leading" (revs wise)
if i mind right you can do a balance test if you can find a way to measure Kv's at your ht leads anyone got an old krypton tuner? :smileys:
That really sounds like a solid plan to isolate the cylinders and carbs for detailed tuning. With the K&N pod setup I can reach the idle mixture screws, sync adjustment screw, and the idle adjustment screw pretty easy so this may get me started on locating the issue one carb at a time - thanks! I do have a watch going on several listings for these carbs on eBay some look really good and others are just junk. I saw a dealer listing a new old stock set for $350 but they are jetted for a 350 Duc and would need upgraded for the 900SS with pods & open exhaust cans. Much to ponder....
Ideally that would be the way to go certainly a garage might do that, or other ways of conventional balancing but in reality it just takes too long and is a pain in the backside and isn't really an improvement if you know what you're doing.
Even I was tempted on another spare pair at £75 recently! The description and pictures looked really good but then I promptly forgot about it
Factory Pro make a float height measuring tool that is easy to use and gives a certain result. It is fairly expensive but you can replicate it for free in cardboard or similar if you don't mind it being fixed rather than adjustable. Just take a look at their website. Here's a 14 mm one I made from the hard-back of an old diary. Worked perfectly.
Thanks Old Rider! I saw the Factory Pro tool on their website awhile back when I was rebuilding the carbs but decided to us my digital calipers instead of buying one of theirs (price did seem a bit high). I like your template and will make one like yours set the floats using it to see if it makes a difference and report back. Again, thanks!!!
