I performed the Desmo service on my Ducati Monster 797, and my valve clearances were very good, meaning they were all correct according to the workshop manual. I aligned the crankshaft to the TDC position and marked it. Then, I installed the new timing belts and bearings, making sure that I didn't disturb my marks. The spark plugs were replaced. The air filter was cleaned and oiled (K&N KU8015).
I manually turned the crank 6 times, and I didn't encounter any scraping or sticking. Then, I set it to TDC 3 more times, and on the third time, the marks were aligned.
Before this, I had a slight issue, but now it has become a bit more noticeable. The issue is as follows: When I first start the bike, the idle is normal, there's no issue while riding, and there are no problems with acceleration or top speed. However, when I stop at a red light, there's a shaking that feels like the bike might stall. This issue also occurs at idle. Sometimes, it disappears after a few hours.
For example, the problematic engine behavior videos:
Sometimes, it runs perfectly:
The issue started here: I bought this bike around 10,000 km and have had it for about 40,000 km now. The first Desmo service was done at the shop, and since I didn't see any issues with the valve clearances, I did the second one myself. However, the issue actually started before I did the Desmo service. There's no error in the ECU, but there were 1-2 fuel sensor errors, which I cleared, and the error didn't come back. I suspect it might have been caused by bad fuel, as the problem was worse before—I could feel it was about to stall when I gave the throttle, and it stalled a few times at red lights. My quick reaction was to try Motul's fuel cleaner, so I added it to the new fuel on top of the old one, and the stalling issue at red lights was solved. However, the idle fluctuation still persists. If I remove the air filter cover, the issue seems to go away, even though the filter is clean, and there is sufficient airflow.
The ignition is working, and the spark plugs are firing correctly.
Now, I can't think of anything else. I plan to measure whether the ignition coils are supplying the correct energy, as it could be causing the idle irregularity when releasing the throttle due to insufficient energy.
I'm using DCPR8E IX iridium spark plugs. I also tried the nickel ones, and the issue is the same.
I think the belt frequencies are correct. The workshop manual indicated 140 +5, and I believe I was able to get a range between 138-142. I may have over-tightened them a bit; I wasn't able to get the exact data. I'll check the belt tension again, but my marks seem to be correct.
The spark plug in (Horizontal) the cylinder head has carbon buildup, just carbon buildup. There’s no oil or other substances. This makes me think there’s an issue with the fuel-air mixture, which further strengthens my theory about bad fuel.
Thank you..
I manually turned the crank 6 times, and I didn't encounter any scraping or sticking. Then, I set it to TDC 3 more times, and on the third time, the marks were aligned.
Before this, I had a slight issue, but now it has become a bit more noticeable. The issue is as follows: When I first start the bike, the idle is normal, there's no issue while riding, and there are no problems with acceleration or top speed. However, when I stop at a red light, there's a shaking that feels like the bike might stall. This issue also occurs at idle. Sometimes, it disappears after a few hours.
For example, the problematic engine behavior videos:
Sometimes, it runs perfectly:
The issue started here: I bought this bike around 10,000 km and have had it for about 40,000 km now. The first Desmo service was done at the shop, and since I didn't see any issues with the valve clearances, I did the second one myself. However, the issue actually started before I did the Desmo service. There's no error in the ECU, but there were 1-2 fuel sensor errors, which I cleared, and the error didn't come back. I suspect it might have been caused by bad fuel, as the problem was worse before—I could feel it was about to stall when I gave the throttle, and it stalled a few times at red lights. My quick reaction was to try Motul's fuel cleaner, so I added it to the new fuel on top of the old one, and the stalling issue at red lights was solved. However, the idle fluctuation still persists. If I remove the air filter cover, the issue seems to go away, even though the filter is clean, and there is sufficient airflow.
The ignition is working, and the spark plugs are firing correctly.
Now, I can't think of anything else. I plan to measure whether the ignition coils are supplying the correct energy, as it could be causing the idle irregularity when releasing the throttle due to insufficient energy.
I'm using DCPR8E IX iridium spark plugs. I also tried the nickel ones, and the issue is the same.
I think the belt frequencies are correct. The workshop manual indicated 140 +5, and I believe I was able to get a range between 138-142. I may have over-tightened them a bit; I wasn't able to get the exact data. I'll check the belt tension again, but my marks seem to be correct.
The spark plug in (Horizontal) the cylinder head has carbon buildup, just carbon buildup. There’s no oil or other substances. This makes me think there’s an issue with the fuel-air mixture, which further strengthens my theory about bad fuel.
Thank you..
