20 Most Recent 2003 Triumph Speedmaster Questions & Answers

hi check and adjust valve clearance

bad ignition module or pickup coil...or wiring to the components could cause the ignition to fail... also check plug caps ,plugs and wires

The coil is marked with a plus + sign for positive and a - minus for negative.

You did not say whether or not this was a carburater engine but from the sound of it one of your jets may be sticking, a good cleaning of the jets will most likely fix the problem, the likely cause is a small build up or piece of debris on the jet.

right in front of the oil filter

Seems like the same problem my 2004 S/M had just before i brought it , Turned out the ignition module was faulty ..

Starter is starting to go out. Sounds like the starter clutch is giving up. The starter clutch is only supposed to go one direction. The winging noise is it's inability to hold under the torque needed to turn it over again. Or...... it could be a bad or low battery. Generally you should have over 10.5 volts at the battery when cranking the bike over. If it drops below that then the contacts can keep full contact to transfer the voltage need to keep in engaged. Even if the battery is the problem though , that same problem takes a beating on the starter and it will eventually need to be replaced. I’m happy to assist further over the phone at https://www.6ya.com/expert/robert_5bac37c3cb991fdb

replace the coil since it was loose and you had ran the cycle with it that way. It had a poor ground and now the coil has a very low resistance leaving the problem you have now

bad coil

Since the fault seems too evident when the engine is around a low RPM the back firing is seen, the two factors seems related to a poor timing setting or the AUTO- ADVANCE timing seems to have some errrors.
In the first place you must recheck with the timing of the firing, check this at idle and at high RPM . If there is a noticeable shift of greater accurancy at higher RPM then when the throttle is cut the residual fuel will ignite with the wrong timing as the enigne returns to lower RPM.
Also if there is residual fuel, clogging of exhaust can also cause the back firing when the engine shuts down from a higer RPM.
If so remove and clean exhaust- or replace- check timing , spark gaps and valve settings on the LEFT cylinder.
Hope these tips helps you.

You gave a great amount of info, But have the exhaust been modified? If so you will be needing to re-jet the carb.s If not try running Seafoam thru the carbs. Drain the tank down to about 1/2 gal and mix in the proper amount of Seafoam and run that thru the carbs. Seafoam can be found at most any auto parts store now.
Following is a list of symptoms, either of or a combination of which, one may experience because of a defective throttle position sensor: A TPS will effect the engines ign. system thru the computer.

• Bucking and jerking of the engine
• Idle surging
• Sudden stalling of the engine
• Hesitation while trying to accelerate
• Sudden surge in speed while driving on the highway.

These symptoms do not quite sound like your problem. Hope this helps Fix Ya up.

has the bike been sitting? take the air filter off and spray starting fluid into the carbs and see if she will fire up.

In UK, 2002-2004 speedmaster15w50 synthetic, SG/JSO MA3.8 Litres

I would run a compresion test on it first

It could be caused by a faulty coil, HT lead, Plug cap or Spark Plug. It may even be low on compression.
Check the plug gaps first. 25thou is recomemded.

You may have a clogged tank vent. Open the gas cap, then try to start the bike again. If your bike still does not start then replace your fuel filter. If the fuel filter is clogged, the sentiment will settle on the bottom and prevent your bike from starting.

Did you consider that when the bike was rejetted , maybe the jets were not put in tight enough ( you do have to be careful not to put them in too tight) and there is a possibility that one or more of the jets have come loose . They could be sitting in the bottom of carburetor bowls causing an overly rich condition on two or more cylinders.I have repaired motorcycles where the jets have come loose and fallen out . It is worth a check.

You can get an easy out tool from Auto Zone which will let you drill them out and remove the pieces and then re-thread the hole or drill them and put boss inserts in to replace them with the same size studs. These Easy out tools usually come with a drill bit and threader tool and run about $12.00

My first guess... it's a breather/vapor hose for the gas tank.