Fitting a Crankshaft Ignition Sensor

Replacement of the Crankshaft Position Ignition Sensor (Pulse Generators)
by John Doak of Baltimore, with due acknowledgement to Rider Magazine Q&A section for additional information.

These are little electrical gizmos that sit at one end of the crankshaft and tell the black box when to spark. When one dies, it's not so bad because you can diagnose its departure with an ohm meter. It should be said that carburated Triumph pulse generators are notorious for croaking, stalling the bike, and suddenly springing back to life as the engine cools down.

Most of the failures seem to occur after about 13,000 miles. To check this is the problem, remove the right lower fairing so that you can quickly gain access to the round engine cover at the base of the cylinder block. Take a ratchet with an 8mm socket and an aerosol can of brake cleaner and ride around your neighborhood until the bike quits. Remove the engine cover and give that black cube – the crank sensor – a long blast of icy brake cleaner to cool it to down. Touch the starter button and I'll betcha the bike fires up. Don't worry, engine oil will only spit out with the cover off. The only thing about Triumph crank sensors are that compared to the Japanese equivalent, they're quite affordable-under 80 bucks.

When planning an 8,000-mile or so trip from Baltimore to Seattle via San Antonio, and since I have an extreme aversion to breaking down and being stranded far from home I bought a new crankshaft ignition position sensor for my 2001 Trophy 1200 to carry as a spare in case mine fails en route. An experienced Hinckley Triumph mechanic told me these sensors are prone to failure if they get overheated, and that's why the bike will usually restart after sitting a few minutes and the sensor has cooled down.

I bought the sensor for my 2001 Trophy 1200 from my Baltimore Triumph dealer: part number T1290022. The list price from my dealer was $67.07 and he gave me a 15% discount, for a net price of $57.01.

Last night I did a 'dry run' to install the new crankshaft position sensor in the comfort of my garage with all of my tools handy. In case anyone is thinking about a roadside replacement, I STRONGLY recommend you do a 'dry run' at home in advance. Here is what's involved:

1) Remove the 10 x 5mm Allen-head bolts that hold the fairing 'belly pan' to the fairing on both sides, and put the belly pan aside.

2) Remove the right fairing pocket cover and also pop off the two small plastic 'tabs' on the dull gray/black top section of the fairing behind the pocket. This exposes the 4 x T30 Torx head bolts that secure the painted right side fairing to the dull grey/black fairing top section.

To remove the small plastic tabs on the top section, insert a dull thin-bladed screwdriver, putty knife or other dull knife blade in the center of the tab closest to the gas tank, and push GENTLY outward until the tab pops out. If you try to pry it out starting from the fairing side, there's a good chance you'll chip the paint on the edge of the fairing. Don't ask me how I know this. Remove the 4 x T30 Torx bolts.

3) Remove the 8 x 5mm Allen bolts that attach the right side fairing panel.

4) While holding the fairing panel, GENTLY disconnect the wiring connector for the turn signal on the fairing. Having three hands here is very helpful. Now the crankshaft end cover that covers the crankshaft position sensor can be removed.

5) Remove the seven 8mm bolts that hold the crankshaft end cover.

In my case the gasket come off without tearing and was reusable; you may not be so lucky. In any event, carry in your repair kit a small tube of gasket sealer, preferably Permatex Hylomar gasket sealer, which is far and away the best gasket sealer I've ever used in 50 years of working on cars, motorcycles, and trucks.

Have a rag or paper towel handy to wipe off the small amount of engine oil that will ooze out when you remove the crankshaft end cover. Amazingly Hylomar will seal even if the surface is not perfectly clean and dry.

6) Remove the 2 x T30 Torx bolts that hold the crankshaft ignition position sensor. In my case, these bolts were VERY tight and must have been installed with heavy-duty Loctite. Don't try to remove them if you don't have a good quality T30 Torx L-key or better still a male T30 Torx bit to use with a ratchet or breaker bar.

7) CAREFULLY and SLOWLY wiggle out the insulating block on the sensor's wiring harness where the wiring harness goes through the engine case.

Now the toughest part:

The wiring harness from the position sensor loops up in back of the cylinder block and then loops back toward the back of the engine where there is a snap connector into the mail wiring harness. There are two black plastic tie wraps under the carburetors at the center of the engine that hold the crankshaft sensor wiring harness to two other wiring harnesses; you can barely see these tie wraps, much less get access to them. It took me a good 15 minutes of experimenting with various pliers and cutting tools before I could cut off these two tie wraps and free up the crankshaft sensor wiring harness and trace it back to its connector. I STRONGLY recommend that anybody contemplating a roadside replacement of the crankshaft position sensor to cut off these two tie wraps before you leave home, since removing these two tie wraps is a real bear and by far the toughest part of the job.

8) Unclip the connector from the old crankshaft sensor harness and plug in the connector from the new harness.

9) Install the new position sensor, and rotate the engine with the rear wheel in second gear to line up any of the five or so teeth on the crankshaft rotor with the sensor's protruding metal tip. The manual calls for 6-8 mm clearance here. You can set that with either a metric feeler gauge or a precision wire spark plug gauge. I found the handiest gauge for jobs like this is a Craftsman #40801 spark plug gauge which has feeler gauges at one end and precision-wire spark plug gauges at the other end, with everything marked in both inches and mm.

If you don't have metric gauges, any spark plug gauge will work to set the crankshaft sensor clearance using the following conversion table:

I used the .028" wire spark plug gauge as a "go" gauge and the .030 gauge as a "no-go" gauge, so I know the gap on my sensor is between 7.1 and 7.6 mm.

Does anybody out there know if it makes any difference between setting the clearance at 6mm vs. 8mm? If so I'd appreciate your telling me.

10) Put a light coating on Permatex Hylomar or other gasket sealer on the crankshaft cover, reinstall the seven 8 mm bolts, reinstall the fairing, and then, most important, drop to your knees and pray to the Gods of British motorcycles that the damn bike starts!!!

Is this a roadside repair? It's certainly doable if you carry the right tools including a T30 Torx bit or L-key, 6-8 mm spark plug or feeler gauges, and the gasket sealer. If your sensor fails you can wait 5-10 minutes until it cools down and hopefully the bike will restart and hopefully you can make it to a gas station, motel, etc. where in an hour or two you can replace the sensor and be on your way. Having a spare sensor in the saddlebag sure beats the hell out of being stranded and trying to find a Triumph dealer who will courier a new sensor to you. And $57 in my opinion is cheap insurance for an 8,000-mile journey.

I hope the above helps, and if anybody has any questions on this, please feel free to e-mail me.

P.S. Since I've read so many horror stories about Triumph COILS failing I also just ordered a pair of Nology coils direct from Nology in San Marcos, California (www.nology.com) for $142.24 plus $11 for 3-day Select UPS shipping: Nology part number 152 001 070, item number PFC-06D 0.6 Ohm dual outlet coil, and you need two. I'm going to replace my stock coils for the peace of mind of not having to worry about a coil failure 1,000 miles from home. Also my Trophy is surprisingly hard to start from time to time with no apparent pattern or explanation: sometimes it fires right up and other times it takes its own sweet time before firing, and hot or cold makes no difference. When I replaced the stock Honda coils on my 1981 CBX with Accel Supercoils, it was amazing how much easier it started, and I'm hoping a 'hotter' spark from the Nology coils will make the Trophy easier to start as well as relieve any fears of the stock coils failing far from home.

The folks at Nology told me that Nology coils do NOT accept the stock Triumph plug wires, and they include with their coils new end terminals and boots to crimp onto the Triumph spark plug wires after you cut off the stock Triumph wire ends that connect to the stock coils. Also I'm told the Nology coil mounting brackets are not a direct bolt-on relacement to the stock coil mounting bracket, and some coil mounting bracket fabrication or modification is required. As such, replacing stock coils with Nology coils does NOT sound like a roadside repair to me.

Peace.

John Doak in Baltimore, MD