Triumph Rat Motorcycle Forums banner
  • Hey everyone! Enter your ride HERE to be a part of December's Bike of the Month Challenge!
1 - 20 of 223 Posts

·
Premium Member
Joined
·
20,740 Posts
Discussion Starter · #1 · (Edited)
A cursory trawl through the forums shows this component to be responsible for no end of problems on Bonnies. I can't understand why this should be so. Similar devices have been used on all manner of bikes for donkey's years and they mostly last the life of the engine. It's a relatively simple, passive device with no moving parts. The working principle was worked out by Michael Faraday as long ago as 1821. Another mystery of British electrics...:)

WHAT IS IT AND HOW DOES IT WORK?

This simple component is just an assembly consisting of a metal bracket holding a plastic housing that encloses the two active elements in it: A coil of very fine enamelled wire wound around a magnetised iron core. It is in effect a tiny generator stator.

I have got hold of a spare one and close examination shows a well-built, robust and well epoxy-sealed assembly that should be reliable. I can't see the windings inside though, so this is where the troubles could stem from, cheap enamelled wire or faulty soldering or strain-relief of the many turns of very fine wire necessary to obtain the sort of resistance and inductance values required in such a small component.

On carbed models Triumph call it an "Ignition pick-up sensor" and on EFI models it's called a "Crank Position Sensor". Other manufacturers use names such as "Pulse coil" or "Pulse generator".

It's actually the same component on both: Part number T1290131 and costs £49.61 ($79).

On both models it's positioned inside the triangular cover on the right of the engine and fitted very close to the alternator rotor.

On carbed models the rotor has some metallic strips bonded to it called reluctors that pass very close to the magnetic core as the rotor turns. Everytime they do this a tiny electrical pulse is generated and sent to the igniter. This signal is processed by the program or map loaded into the igniter to work out the moment of ignition and the degree of advance and retard to be applied, depending on engine revs. The advance and retard function is entirely electronic, unlike the old centrifugal weights system. No moving parts, just time-delay circuitry that applies more or less delay to the received signal.

On EFI models it also sits close to the rotor but this is fitted with a toothed wheel. Everytime a tooth passes the sensor it also sends a signal to the Electronic Control Module (ECM) and it's used not only to work out the ignition timing but the moment of fuel injection as well. Between the signals sent by this sensor and the MAP sensor (manifold absolute pressure) the ECM knows exactly in what position the crank, and herefore the pistons, are at any given moment.




DATA, TESTING AND FAULT-FINDING

If the pick-up sensor is on the bench like the one in the photo the resistance can be measured using the multimeters probes. If however it's still fitted to the engine the connector can be difficult to access, being stuck between the right hand seat rail and the top of the airbox. Brilliant bit of engineering this...

Unplugging is often impossible without further dismantling. You can see the two wires that go into the connector though, so you could just use the following method:

Using a couple of pins prick the insulation of red and black wires under seat tube above the airbox. Drive the pins deep enough to pierce the insulation and contact the conductors inside the cable. Connect the multimeters probes to the pins and set the meter to the appropiate Ohms range.

The quoted resistance to be expected is 560 ohms +/-10% at 20ºC .This means you should see somewhere between 504 and 616 Ohms. If you measure it with the engine hot the resistance would be higher, as much as 640 Ohms or so.

You could even measure the voltage output with this method. Just ensure the two pins and meter probes are not short-circuited, set the meter to a low DC volts scale and start the engine. You should see at least 0.6 volts although at idle this would be pulsating and the digital readings difficult to pin down.

This nice drawing I've found shows how the pick up generates two pulses: one positive and another negative, the first one as the reluctor first meets the pick-up coil and the second as it leaves it:



A simple tester can be made using a couple of green LEDs that will detect any pulses above around 2.2 volts, both the positive and the negative pulses will show up as the LEDs light up alternatively as the engine is cranked:



The gap for the pick-up coil is quoted in service manuals as 1.0 mm +/-0.20 mm but was changed during production due to warranty issues. The following was sent out as a statement by the Factory in a technical release to dealers:

Affected Models: Bonneville/T100, America, Speedmaster, Thruxton and Scrambler.

Should a bike (see above) demonstrate faulty ignition coil type symptoms (most commonly an engine misfire), please initially check and adjust the ignition pick-up (IPU) air gap (we recommend an air gap of 0.8mm).

Since changing the IPU air gap in production to 0.8mm, we have had no ignition coil warranty claims.


As far as I know this only applied to carbed models with chronic ignition faults, often blamed on the ignition coil.

The 2008 service manual of which I have a copy, only covers bikes up to 2008, including EFI models, and the gap is still quoted there as 1.0 mm so maybe that technical note came out later than 2008.

The pick-up coil to rotor gap is set by positioning the alternator rotor with a reluctor strip facing the magnetised core and measuring the gap with a suitable feeler gauge. If found to be incorrect the fixing screws are loosened slightly, not too much, but enough to enable the component to move a bit, ensuring the feeler gauge is a firm sliding fit between the two points and re-tightening the screws to 10 Nm (7.3 Lbs/Ft). Re-check the gap after tightening.

 

·
Registered
Joined
·
1,433 Posts
ctrl+s... enter!

thanks..
have to check that on Davids bike.. he has allready changed the coil ones!
 

·
Registered
Joined
·
2,693 Posts
For someone like me who has no concept of electrical wizardry that was a good read, thanks Forchetto.

john
 

·
Banned
Joined
·
67 Posts
Always wondered how that worked. However, after a frustrating bout with intermittent spark, I dismantled, checked resistence and gap, found satisfactory, but the problem persisted. A dealer ultimately fit a new one and problem gone. Yup, those buggers cause some headaches!
 

·
Registered
Joined
·
1,296 Posts
Just happened across this post. Great write up, explanation and contribution Forchetto. The Bonneville library of technical fixes etc. in the stickies is really filling out much of it thanks to your well presented write ups. Thank you bro.
 

·
Premium Member
Joined
·
1,966 Posts
well done Forchetto, brilliant write up

have saved it for future reference. thankyou
 

·
Premium Member
Joined
·
20,740 Posts
Discussion Starter · #11 · (Edited)
Have you got a pic of the efi alt rotor?
Not yet. I've been looking for one though. I was surprised that they use the same sensor for the EFI bikes and I like to see that toothed wheel arrangement for myself. Really I don't even know if it has one, I'm just guessing from reading about it on other EFI bikes.

The part number used of EFI models has changed. It was T1300067 and now they use T1305501, so there's something different about it but on the parts catalogue there's very little detail and they are drawn the same.

As soon as I have a new gasket on me I'll wait for the next oil change, and probably take a look in there myself.
 

·
Registered
Joined
·
37 Posts
I found it!

Thanks Forchetto for a very nice explanation.

I dove in this morning in seach of the connector in order to measure the resistance.

After removing the tank and battery, I was able to coax the connector out of the cranny where it was stuffed out into the battery compartment and unplug the connector for testing. I left it where I could get to it in the future if needed.

It was on the right side as you said and my measured resistance was 593 ohms. I'll check the gap at the next oil change.

I've changed both coils now and found this pickup to be good. I had lost one cylinder intermittently while commuting but now have confidence restored and feel I know the bike a little better.

Now back to riding the silly thing!

Joe
 

Attachments

·
Registered
Joined
·
7 Posts
nice

u were able to give me more info than the dealer, my bike has only 3k on it, im guessing gap will be ok, although i should check, i did notice from time to time, rare but still happened, when the bike was hot and brand new, at a intersection i would stall at weired times, were i live can be as hot as 100 degrees and this winter was cold many days less then -18, the bikes in a garage, but still. my meter is trash, im going to get a new one and try my test again tonight, thank you for all your post on my ark delete issues, wen i find the issue ill let you know what it was
 

·
Registered
Joined
·
120 Posts
Service Bulletin

The following was sent out as a statement by the Factory in a technical release to dealers:

Affected Models: Bonneville/T100, America, Speedmaster, Thruxton and Scrambler.

Should a bike (see above) demonstrate faulty ignition coil type symptoms (most commonly an engine misfire), please initially check and adjust the ignition pick-up (IPU) air gap (we recommend an air gap of 0.8mm).

Since changing the IPU air gap in production to 0.8mm, we have had no ignition coil warranty claims.
You don't happen to have a complete copy of this service bulletin, or at least a bulletin number do you? I would like nothing more than to slap my local dealer around with it...

Thanks for the excellent post. I haven't had an opportunity to investigate on my bike yet, but somehow knowing what my problem likely is restores my enjoyment riding it, even when it misfires.
 

·
Premium Member
Joined
·
20,740 Posts
Discussion Starter · #15 ·
You don't happen to have a complete copy of this service bulletin, or at least a bulletin number do you? I would like nothing more than to slap my local dealer around with it...

Thanks for the excellent post. I haven't had an opportunity to investigate on my bike yet, but somehow knowing what my problem likely is restores my enjoyment riding it, even when it misfires.
News of that factory notice has been around as long as 2007. This is the first I've heard of it on this other forum thread:

http://www.bonnevilleamerica.com/forums/showflat.php?Cat=0&Number=234884&page=0&fpart=1&vc=1
 

·
Premium Member
Joined
·
20,740 Posts
Discussion Starter · #16 · (Edited)
Have you got a pic of the efi alt rotor?
Mike:

Sorry it has taken me six months to get a pic of the rotor showing the toothed wheel instead of the reluctor stuck on the rotor on the carbed bikes.

Don't worry, I still haven't seen the inside of my engine...:)

The photo was kindly donated by member "Philontheroad" from france who has also informed me that, at least the 2010 bikes, have a different part number for the pick-up or crank position sensor:

SENSOR IGNITION P/N:T1296505

When I bought my spare one, the partnumber was still the same as the carbed bikes: Part number T1290131

This sensor is also a different shape and has an internal resistance of just 217 Ohms rather than the 600 Ohms of the original.

 

·
Registered
Joined
·
8,881 Posts
thats interesting wonder how many teeth there are and if they go all the way around.The older one has 3 teeth best i rember.The ingiter must count 3 then fire ,the last tooth lines up before tdc ,so my guess is triumph has that figured into the total static timing and then go +or- with the box to change timeing.Makes one wonder how close one motor is to another with the slop in the pick up mounting.
 

·
Premium Member
Joined
·
20,740 Posts
Discussion Starter · #19 ·
More info on crank position sensors

After some lengthy research I've found out that the EFI bikes can have two sorts of pick-ups or crank position sensors:

On engine number up to 437492 the sensor required is Part number T1290131, (same as on the carbed bikes) as stated on the OP on this thread.

From engine number 437493 the part number becomes T1296505

Note that this new sensor is not only electrically different from the old one, but also mechanically not compatible. Different fixing centres, I believe.



Sorry to keep banging on about this, but I feel it's important to keep the thread supplied with up-to-date info.
 

·
Registered
Joined
·
69 Posts
Testing Ingniter

Hey Forchetto, have picked up much advice over the last few weeks with diagnostics and have found that my Igniter has packed it in. Tested all other components as for your instructions and just so happened that I have a spare igniter, fitted it and back on the road. When this first went it was when the engine was warm and just completly died. When I got the bike home it started and ran fine, riding into town today armed with many spares and a multimeter it did it again.
So my question is can you explain how I can test the igniter?
Regards,
Grinder
 
1 - 20 of 223 Posts
Top