[Bob22]

I have a 2001 M750 with 10,800 miles on it. No upgrades other than a 14 tooth front sprocket. The bike is not under warranty. I am not a newb when it comes to maintenance and repair, but I'm no mechanic either. I would like to fix the problem myself but lack a good place to perform any kind of maintenance (crazy apartment management) but will find a place to do so if any of you can help diagnose the problem . So on to the issue:

Lately while riding the bike to work, about 20 miles/minutes I have felt the bike almost die for a few seconds. When this happens the tach indicates 0 RPM but he speedo still indicates the "correct" speed. The engine will still respond to throttle input but only with about 1/10 of the usual power. The sound also changes to a muffled/restricted air flow sound. Then the bike will all of a sudden kick back in and work as advertised. The problem will last for a few seconds at most. Yesterday the same problem popped up and lasted for much longer, long enough for me to slow down and get off the highway. I checked the tach cable and other superficial stuff, found nothing. The bike started up fine after sitting for a couple of minutes.

I was wondering if anyone can give some insight as to where to start. I thought it odd that the engine and tach would react this way togeather. I did use the search function and did not find anything with the same type of problem. Thanks in advance for any input.
Bob

 

[test-reg]

You are having a loss of primary ignition if your tack is loosing it's signal at the same time. The tow most probable causes are the safety (sidestand) relay or a break in a wire coming down the stearing head.

 

[needtorque]

The loss of power on his along with the loss of tach would say a bad coil to me. One of the coils sends that tach signal adn the connection on that coil for the tach is bad about falling off. If it does it will also loose that cylinder fire and you will be running on only the other cylinder.

I would say either that coil is bad or the connection is loose.

 

[ducpainter]

Welcome to the board. The electronic tach is fired off the igniter box of one cylinder. I would check the wiring to the boxes. If all looks good try swapping the igniter boxes. Be careful. The boxes and their connectors are very fragile. They are also stupidly expensive.

It is also possible that one of the ignition pickups in the left side case is bad, or the wiring from it. Those generally are more reliable, but some members have had problems with them.

 

[test-reg]

The loss of power on his along with the loss of tach would say a bad coil to me.

I'm with Howie on this one - the tach feeds of the low voltage side of the coil so a bad coil is unlikely to be the cause given the stated symptoms.

big (besides, I've got first hand experience with broken wires in the loom at the steering head...)

 

[test-reg]

Duckpainter also has a good point about the ignition module connector. It could also be that module. Knock out one cylinder and there is the symptom. Check the connector. If the problem still exists, switch modules. Same symptom but the tach now works, bingo!

 

[Mdriver]

Myself and many others have been through similar problems with 01ish 750s.

Not suggesting that it couldn't be, but before you get to involved with searching for a bad wire or testing for bad coils, you should head over to NAPA and get a replacement "safety relay" NAPA# AR-634. It shouldn't cost more then $10 and even if it isn't the culprit this time, it will eventually need to be replaced anyway.

The safety relay is the smallest of 3 relays that are under the seat just forward of the fuse box.

If you don't have a NAPA near you check this thread for other suppliers part numbers
http://www.ducatimonster.org/smf/index.php?topic=22522.msg513105#msg513105

 

[needtorque]

I'm with Howie on this one - the tach feeds of the low voltage side of the coil so a bad coil is unlikely to be the cause given the stated symptoms.

big (besides, I've got first hand experience with broken wires in the loom at the steering head...)

How is a bad coil unlikely if there is a significant loss of power. Bad wiring at the steering head would not explain a loss of power.

I was speaking from personal experience with my 01' 750. Sitting on the bike the coil on the right will cause loss of tach and one cylinder from a poor connection on the bottom of the coil.

 

[test-reg]

How is a bad coil unlikely if there is a significant loss of power. Bad wiring at the steering head would not explain a loss of power.

I was speaking from personal experience with my 01' 750. Sitting on the bike the coil on the right will cause loss of tach and one cylinder from a poor connection on the bottom of the coil.

If you loose electric supply to the bike through the wiring in the steering head you will have no ignition or tach since...well...there is no electricity. It is basically the same as hitting the kill switch. There may also be no lights, but the operator may not notice this during the day time. No tach signal means no low voltage signal to the coil so that coil would not function. Could a bad coil or connection at the coil cause a loss of a tach signal? Possibly, if this would cause the module to malfunction, ie. the transistor nit triggering due to an open circuit. I can't determine this without a schematic and maybe more for the module.

 

[test-reg]

How is a bad coil unlikely if there is a significant loss of power. Bad wiring at the steering head would not explain a loss of power.

My reasoning is that the loss of power is due to a loss of sparks, but that if that's caused by a bad coil then you're assuming the low voltage side of the ignition electrics is still working properly - if that was true you'd expect the tach to work as normal. Since the tach isn't working normally, that could be explained by problems in the low voltage side of the ignition.

I was speaking from personal experience with my 01' 750. Sitting on the bike the coil on the right will cause loss of tach and one cylinder from a poor connection on the bottom of the coil.

Yep yep - you're talking about a connection problem on the 12v side of the coil, not an actual "bad coil".

I'll defer to your experience here, my '99 M750 has no tach, I'm just theorizing and trying to deduce likely problems... Bob22 - here's a good first place to start looking.

big

 

[Bob22]

Wow, thanks for all the info. This is more than I could have hoped for. I will start into the bike as soon as I have a chance, new job and all.

Bob ;D

 

[tsd345]

I have an 00 750, and had similar problems you describe, but at the time I did not have a tack. In my case, the bike was firing on one cylinder and almost stalled at a complete stop once warmed up.

As it turns out, the carbs were WAAAAY out of balance and the plugs were old, fouled and basically spent. When you come to a complete stop after the bike is warmed up, does it idle way low and stall sometimes?

www.ducatisuite.com, a $12 vacume gauge, some plugs, and some patience and I was on my way to trouble free riding. Later I installed the dynacoils from Cycleworks and I would recommend that upgrade to any carbed bike owner.

Of course, I could be wrong that the 750's went to FI in 2002, and you, in fact have an FI bike, in which case, posting this response would be alot like pissing into the wind......

 

[Aguacate]

What do the dynacoils do? (that is, what did they do for you)

 

[tsd345]

AFAIK the theory is they produce a better spark, i.e., stronger, more consistent, etc.

As for the bike, they shortened warm-up time (important in NE) and smoothed out the power deliver through the entire rev range and improved, to a small degree, throttle response. No more bucking or burping while put-put-ing around a parking lot.

That's my experience, there is more here http://www.ducatitech.com/2v/aftermarket/dyna_kit.html