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Discussion Starter · #1 ·
Hi all.
I just got my 2002 monster 750 in April, it's fuel injection and was just through it's 15k check up at the dealership. It's been running great up until a week ago. I was out riding in town and got on throttle to get away from a car that was coming into my lane. Once that happened the bike started to running unevenly it wouldn't hold a even speed, sounded like it was bogging down then would be fine. I checked the spark plugs and they were pretty black so I changed them out. She ran great for a about 30 miles and then started doing the same thing as before. I checked the plug again and the vertical plug is black and the horizontal plug looks fouled. I put new plug wires on today hoping that would fix it, but it didn't and now she'll only idle with the throttle advance on about halfway. I not sure if I messed up the valves or if it's something electrical I should check out. Any ideas would be great. Thank you.
 

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Check to see if both cylinders are actually firing. remove one plug lead and try to start. It should start and run with offbeat note and you may have to hold some throttle on.
Replace lead and repeat with other lead removed, if it does not start or run then you have found the offending cylinder. You can also try with engine running using insulated pliers. If you have new plugs and leads then a coil check is next. also, check you have installed correct type of plugs. If one is in fact not firing, swap coils and see if it changes to other cylinder... replace faulty coil.
30 miles before plugs foul is a bit strange.

A compression test will tell you if there is a problem with valves.
Sounds to me that one cylinder is not firing. Possible that throttle body sync has gone out, I doubt that as it usually is gradual over time.
If plug is fouled, ie. wet and black, then at least you know injectors are working.
Check air filter, blocked air filter will foul plugs very quickly.
When was the fuel filter changed?
hope this helps.
 

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Discussion Starter · #4 ·
I think I may have fixed it. The plug wires I put on had weak spark, so I switched back to the old ones and it's stronger. When I took the air box this time, I took the boots off the throttle bodies and discovered they were full of black build up. It's all back together and now the idle is around 1200 to 1500 rpms, and it's smoothed out a lot. Just did around 20 miles on it and the plugs are nice and tan, no thick carbon. Thanks for the responses.
 

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Hi all.
I just got my 2002 monster 750 in April, it's fuel injection and was just through it's 15k check up at the dealership. It's been running great up until a week ago. I was out riding in town and got on throttle to get away from a car that was coming into my lane. Once that happened the bike started to running unevenly it wouldn't hold a even speed, sounded like it was bogging down then would be fine. I checked the spark plugs and they were pretty black so I changed them out. She ran great for a about 30 miles and then started doing the same thing as before. I checked the plug again and the vertical plug is black and the horizontal plug looks fouled. I put new plug wires on today hoping that would fix it, but it didn't and now she'll only idle with the throttle advance on about halfway. I not sure if I messed up the valves or if it's something electrical I should check out. Any ideas would be great. Thank you.
Hallo Mr. Origin. The deeper I get into this malady (Duzification) the more I'm convinced that nothing other than OEM (Original Equitment Manufacturer) parts will do. The only alternative would be something just close to the specs, but then better have good luck. We left behind the Honda / Suzuki in line 4, or Yamaha Sr 650. Compounding your problem is the fact that you're amongst the first to go with fuel injection, advanced technology and inevitably and unintentionally a Guine Pig
Ps: the way out in desperatin is simple
Flamethrower
 

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The traditional, seat of the pants test, to check fuel injection systems is be driving along in the car at about 130 kph or 80 mph, release the throttle or lift the pedal quickly, then mash down the gas pedal and IF THE car does not respond accordingly then the suspect item was dirty fuel injectors. Now, just for the record, I was never a car mechanic.

The first question I would ask is if the speed up event was normal driving for you or ... oops gotta do this to evade?

Why the sputtering reaction after acceleration?
1. some chunk of crud dislodged on the last bump in the fuel cell and it clogs delivery line?
2. some wiring connection or connector is loose and pertinent to spark production
3. it was a warm day and you put your scarf under the seat and plugged the airbox ( yes, I have seen that ....lol)

I think that the proper approach is to do a complete check on every element that you can without a Ducati DDS computer hooked up ....

I wonder, if your bike is 2001 ish ... then I would ask if the fuel cell/tank is steel or plastic .... If not plastic then a thorough fuel tank inspection is needed simply for ruling an issue out of corrosion or dealing with corrosion accordingly.

Once that is sorted you can check the fuel pump and if possible fuel pressure. Apart from dealing with fuel the work is straight forward ... if you have a place to work on it.
 
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