Bimota Forum

[brian]

So here's what I've done and replaced to date...

Replaced the following -

Carburettors
Fuel lines
Fuel pump
Fuel filter
Battery
Ignition coils
Plug leads
Plugs (many!)
Pickup coils (genuine Ducati)
All wiring between ignition modules and coils etc

Checked/ cleaned the following -

All connectors
All earths (grounds)
Cleaned and applied dielectric grease to ignition switch and kill switch
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[brian]

I'm convinced that it's weak spark only because of the symptoms that the timing light show and the fact that it misses/ backfires every now and then and fouls plugs.

Is it possible that it's not weak spark??? If so why does the timing light do what it does?

The only thing that I havn't replaced is the ignition modules. I haven't replaced them as I think it would be unlikely that both of them are playing up. I might see if I can borrow a set of ignition modules from someone to check.

I'll try to link a video of it running showing the timing light doing its thing
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[Bud977]

You've been trying to solve this one for quite a while now. I've got to admire your persistance.

Backfiring is just about always related to ignition or valve adjustment. WR450s set you know when they need a valve adjustment when they backfire on decelleration.

[brian]

It's really trying my patients Bud. But I don't really have any alternative than to keep plugging away at it. There's not much I haven't replaced now
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[brian]

Front ( horizontal) cylinder. Rear is much the same. [img][IMG]http://i1252.photobucket.com/albums/hh562/meeko68/th_IMG_0432_zpskycr6awq.mp4[/IMG][img
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[brian]

If someone could confirm this I for me I'd be very greatful.

I've tested the voltage on the GREEN wire and YELLOW wire on the 3 pin connectors at the ignition modules and found the following...

With the ignition switch ON but engine stopped I get 1 volt.
With the engine running I get about 10 volts.

I can't find any info on the ignition modules in the manual.

Many thanks
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[2bims]

The only thing I have Brian is the Haynes Manual for the Ducati 900SS....and this gives Pick up coil resistance (the small black boxes) of 96 to 105 ohms...air gap 0.6 - 08mm...Tested using the multimeter set to ohms x 100 scale


and for the ignition HT coils...Primary winding resistance at 3.8 to 5.2 ohms...with secondary winding resistance at 10.8 to 16.2 KOhms...

Primary iginition coil winding the meter is set to ohms x1 scale...and fed off the back of the 2 pins on the back of the unit...for the secondary windings the meter is set to K ohms...and tested off the plug lead connector and the corresponding pin on the back of the unit on the same side

[brian]

Thanks for that Steve. I've got most of that info. I was just wondering if anyone has got the r/h side bodywork off their db4 any time soon if they could put a multi meter on the 3 pin plug yellow or green wire and measure the voltage on theirs for me. (On the ignition modules)

Just trying to work out if mine is normal (10v running) or the voltage on mine is low. That might help put me on the right track.

Thanks again
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[brian]

I've now ordered an inline spark tester so I can hopefully determine once and for all if it's spark or fuel related.
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[brian]

I'm a little reluctant to post an update on this one, but here goes.

I got an adjustable spark tester and have tested the spark. I had to put another brand new spark plug in the front cylinder to get it to run as the other 'new' plug had now fouled and died.

The spark tester shows strong and consistent spark on both cylinders. Even with the spark tester adjusted to its widest gap of 9.5mm (3/8"). I ran the bike for quite some time but couldn't get it to play up, it ran well with no missing or backfiring at all.

So I put it all back together and took it for a ride to fill the tank with fresh 98 octane juice and had about a 100 klm ride with no hint of any trouble.

So I've now riden the bike 3 days in succession and its run perfectly. Something that I've never been able to do before. I'm not all that confident that I've fixed it yet as I haven't done anything different since it fouled the plugs after I replaced all of the electrics.

Anyway, I'm not going to complain about it running good . I'll ride it and enjoy it while I can
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[Bud977]

Let's hope it's permanent Brian. I suppose it's too soon to take it on a Tassie holiday?

[brian]

[2bims]

Fingers crossed for you Brian that all the love has come together to create a bike that wants to work...Italian electrics always a strange one....they do much prefer to have juice running through them rather than sitting idle.....my restart of the DB2 after 7 years lying idle was similar...so many little items not quite right...yet magically sprang back to life after several good runs...dash lights, kill switch etc etc....inbuilt corrosion working loose and juice flowing properly...ride and enjoy...she obviously appreciates all your efforts.....

[brian]

Thanks Steve. I really love riding the db4 when it running right and this is the best it's ever run since I've owned... it must be over 2 years now I think.
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

[brian]