Thunderbird 900 Sprag Clutch Question

As long as you keep the battery in top form then you should be okay. Yes, they were uprated some time in 1994 I do believe (but will stand being corrected) and failures on these later bikes, whilst not unheard of, are unusual.
I'd like to think that a 2003 model would be a safe bet.

 

The problem wasn't the sprag clutch or the battery . All the early triumphs pre 1994 were, supposed to have an ECU that prevented spark/ignition firing until engine had done TWO full rotations, so engine was spinning over quickly, there was a stuff up from the ECU suppliers, and, this wasn't happening!! So what happened on some bikes(causing sprag clutch to break) was ignition firing when engine cranking speed was to slow(back firing) this put too much load on starter system and the weakest point broke (sprag bearing), ECU's were replaced @ services, problem solvered !!! I had 94 Trident with this problem. ECU was replaced @ 40 odd thousand klms.

Cheers capt

 

I fitted the later ecu and the starting was completly different. The early one starts immidiatly , fine if the battery is 100 % . The problem comes from if its not and as the engine turns over it cannot get it over compression , the engine goes in reverse and it is this that kills the sprag clutch. The later ecu has to see 200 rpm minimum before the ignition is enabled.

 

Hi
Where did u buy the later ecu and part no ? Thanks

 

I had a '96 sprint and still have a 1998 TBS and have never had issues.

Don't know if it is true but heard a rumour that the earliest models (pre 1995) could be repaired more easily / more cheaply as there was access within the cases to effect a repair, whereas with the later versions of the earlier engine it necessitated an engine out and split of the crankcases. Is that true?

 

Yes that is correct.

 

I think the original part number should get you the right ecu/controller, the problem was the early supplies. Was fixed late 94 early 95 so check dates of manufacture/supply on the ecu

 

Thanks chaps....I too have had an interest in the 900's but been put off by Sprague clutch problems.
Now I know the ' safe' years to look for.

 

You mean safer. They still can give probs if the battery is weak. Mine is a 95 and it needed the spray doing a few years back.
It isn't just a triumph issue either, many other bikes suffer the same

 

So in fact the easiest bikes are the safest to buy due to the cheaper fix

 

Earlier rather than easiest. Bloody predictive text.....

 

Oh dear...back to the drawing board then.....