[sai5]

Hi all! I recently bought an 03 Ducati Monster 620ie and I'm a complete novice to any mechanical work. I've been having issues where my bike was bogging down on full throttle or quick acceleration (but not when I was gradually accelerating). It only has 1500 miles per the previous owner. Bike turned on fine before i did the following.

The air filter is fine. I used the hex tool in the bike to take out and inspect both the spark plugs. I took the top/vertical plug out, inspected it (was black and had an orange gradient) and screwed it back on with my hand and then tried to use the hex tool to do a half turn but it wouldn't turn more. I turned on the bike and it seemed like it was misfiring. So I checked the bottom spark plug (it was black and had black oil in its threads - thinking this is related to the bogging issue?). I put it back with the hex and then after it sat snug, it wouldn't do the half turn that the manual recommends. When I tried to turn the bike on, it would take a long time to turn on even with choke on high and would crank but there wasn't any spark.

I'm getting new plugs tomorrow. I'm hoping the new plugs would help but I would love to hear y'alls thoughts on what could've gone wrong. The bare minimum I want with the bike is to have it work for 15 mins so I can take it to the closest Shop.

 

[Bushyeyed1]

Sounds like the plugs are fouled. Hope your correct in your diagnosis and the new plugs start it up. There is probably another issue to address if it has oil on the plug. Does it smoke when it runs? It could just be running too rich and may appear to be oil.

 

[sai5]

It has never smoked when it ran. Though I've smelled gas multiple times when riding and when parking it in the garage.

The bike started up fine before I pulled out inspected the plugs.

When I change the plugs tomorrow, I'll also reseat the relays and fuses tomorrow and see if that helps (based on a youtube video and another thread).

Is it likely / unlikely that the plugs are under or over screwed and this is the reason why the spark isn't catching?

 

[Jason Duerr]

Did you set or check the spark gap?

 

[sai5]

Did you set or check the spark gap?

I didn't do anything to the spark plug at all -- just pull out, visually inspect and put it back in.

If you mean whether the spark plug went in correctly into the cylinder, I believe so -- cuz I tightened it as much as I could but wasn't able to do the half turn recommended in the manual.

 

[ronski]

Well, apart from some coincidental mystery, the only thing is the plug leads, are they sitting correctly on the plug, some bikes have no, 'rounded' screw on end cap on the plugs, just a threaded end, and it clicks when you push lead cap on. The other possibility is where the leads screw into the coils, Not sure on your bike, but the older ones screwed into coil and can work loose.
Make sure all leads and end caps are secure.
Worth following both leads path, any other wires nearby that you may have disturbed.

Don't panic if you don't follow manual about exactly half turn after fully in, you can wreck the threads if over tightened,
just snug them up reasonably tight. Plugs should spark even by loose contact, as long as they earth to the head.
hope this helps,

 

[sai5]

Well, apart from some coincidental mystery, the only thing is the plug leads, are they sitting correctly on the plug, some bikes have no, 'rounded' screw on end cap on the plugs, just a threaded end, and it clicks when you push lead cap on. The other possibility is where the leads screw into the coils, Not sure on your bike, but the older ones screwed into coil and can work loose.
Make sure all leads and end caps are secure.
Worth following both leads path, any other wires nearby that you may have disturbed.

Don't panic if you don't follow manual about exactly half turn after fully in, you can wreck the threads if over tightened,
just snug them up reasonably tight. Plugs should spark even by loose contact, as long as they earth to the head.
hope this helps,

Thank you!

I got new plugs and I removed the nut off of them to expose the threaded end -- because my older ones had them off too. After hand installing the new plugs - the 1/2 turn with the hex was possible! That was exciting to see.

After this, I tried to follow the plug wires but couldn't find where exactly they were going. I reseated the two relays by my battery and started the bike -- a little resistance but voila! It turned on and caught the spark. I rode her around in my apartment's parking garage for ~1 mile and she seemed good. Tried full throttle but I could only do so much in the garage.

I'll take her out tomorrow and see how she behaves on full throttle on the streets of SF.

I'll share pictures of both the removed spark plugs but I remembered that I had to jumpstart my bike once with this heavy duty portable jumpstart kit (used for cars) and may have used the boost option. Kinda read somewhere that this spike in electricity could damage spark plugs. Is this a real possibility?

 

[QLDs4]

I've only seen spark plugs die from old age or impact.

 

[Dvy3178]

Taking hits of large power spikes is kinda what they get off on.

 

[sai5]

Haha.

I took her out for a spin and she rides great! No more bogging down on full throttle -- there's a slight lag before she takes off but it's been there since I bought her in Oct 2020.

I may have been going full throttle when the temp gauge still shows "LO" -- "LO" goes away once the temp hits around 123 degrees. Is going full throttle on "LO" detrimental to the engine?

 

[notdeutsch]

Haha.

I took her out for a spin and she rides great! No more bogging down on full throttle -- there's a slight lag before she takes off but it's been there since I bought her in Oct 2020.

I may have been going full throttle when the temp gauge still shows "LO" -- "LO" goes away once the temp hits around 123 degrees. Is going full throttle on "LO" detrimental to the engine?

Yeah man, that's not a great idea for lots of reasons, not least of which is the calculated thermal expansion needed to seat everything within expected tolerances so that it runs smoothly and reliably under anticipated conditions.
Other than that, you've got quite the steep learning curve ahead of you and I'm only slightly ahead, having done only a bit more on mine than you have on yours.
As such, I think one of the first things you'll want to do is figure out how to balance your throttle bodies, since my 800S2R also had a big difference between spark plug residue and balancing fixed that right up, made for steady idle and better mileage.