TDM 850 1998 Starting fault

[Wilskie]

Hi all , I have a strange fault with my TDM850, to start with it has been sitting for a while. I have replaced the battery and now it cranks over just fine but only on the first press of the button it sparks but after that no spark from the plugs. Any help would be much appreciated.[/list]
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R.Wilson

[jaffa90]

Does your (old) bike have any safety cut out switches that kill the spark only? Somebody on here may have the same bike.

[Wilskie]

Hi thanks for your reply , I honestly don't know . It does seem very strange as both plugs act the same way with only the initial spark then nothing.
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R.Wilson

[Easy-X]

Both sparks you say? I was about to use the phrase "wasted spark" but if this is the correct manual:

https://www.manualslib.com/manual/816356/Yamaha-Tdm850-99-4tx-Ae3.html

...then it has coil-per-sparkplug. It looks like the sort of "pre-ecu" affair I'd expect, the Relay Unit being the typical convoluted jumble to enable the safety features

Try turning it over with the clutch pulled in, see if it makes any odds
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Wilskie]

Hi again I think I will try another ecu on my bike to try and resolve this starting issue , are they compatible with each other or are they set for each individual bikes. Thanks
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R.Wilson

[Nobby the Bastard]

The only time ecus are specific to a car or bike is if there's an immobiliser as well and only if the ecu and immobiliser are set together in the factory.

The only time I've come across the two being linked like that was on a fiat bravo so i really don't think it will be an issue. Assuming the connections are the same swapping e us should be fine.

I'd still be looking at clutch and sidestand switches.

The way to tell if its wasted spark is to follow the ht leads. If they do to a single coil its wasted spark and you would expect both to spark at the same time.

Generally a twin would be a wasted spark in the same way that a 4 is two wasted sparks.

V2 and v4 are different, obviously, as are twins that are emulating a v.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Easy-X]

Trying out another ECU would only help if the bike has an ECU to start with AFAIK Yamaha didn't go fuel injection on this line till the TDM900.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Nobby the Bastard]

It will still have some sort of electronic ignitor box for the sparks.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Easy-X]

[Ingo]

Hi all
I’m using a phone so it’s hard to navigate.
I have the exact same problem re the single spark on just the left cylinder and no spark after that.
Was a solution ever found for this problem?
I am also not a everyday forum user.
Help would be much appreciated.
I have done all the checks
New plugs
New ht leads
Second hand cdi/ecu
I’m thinking it’s the pickup from the generator.
Thanks ingo
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Ingo

[stinkwheel]

Try swapping the coils over and see if the problem changes sides. Also if it's a similar problem where the bike has been sat fro some time, go through all the relevant connectors and give them a clean.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[WD Forte]

so what is it?
CDI or ECU ?
pretty major difference y'know
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bikers smell of wee