Starting: is this normal

What's the details of the bike in question?

 

Should get a spark when turning over (the engine, not you!).
If you are getting a spark with the engine still turning after trying to start it and it is still spinning, then the battery is not supplying enough power to spin the engine AND fire the the plugs at the same time. This is not unheard of (apparently). Don't know where I saw this nugget of information but it now lurks quietly in my memory banks amongst much high class rubbish!

 

Hi Craig, as a check to see if the battery is the problem why don't you attach another battery with jump leads, then see if you have spark when turning over the motor?

 

+1 what biglad says, sounds like a weak battery or perhaps bad earth connection to engine (or other dodgy connections)?

 

Hi Craig, I had a 1994 trident from new did 161,000 klms on it, the T300 range were all fitted with electronic ignition which was programmed not to supply spark for at least the first 3 full rotations of the motor, to stop backfires killing the spray clutch in the starter motor !!! The engines were known for holding compression fuel charge in a cylinder that stopped near top dead centre before ignition occurred. This charge could fire anywhere up to 1/2hr after switching off the motor and restarting, it would hold it that long. Even longer on some!!! So its normal if it is within the first 3 turns. You need to take all plugs out and do a longer crank over so if it starts sparking after 4 turns ?

Some earlier models 93 and before possibly didn't get the factory recall to replace ignition model for 3 sparkles rotations before startup would occur! It was a known fault causing start system failure's.

 

I always use Yuasa's and never had issues with them and they are used by bike manufacturers.

 

Again +1 the biglad, I've used Yuasa in the past and they are good, but more recently I've gone for Motobatt and would recommend them also, manufacturer claims a "power balanced" design. Anecdotally they seem to be superior at holding charge on bikes that are not always used frequently but I've not seen scientific proof or indeed any claims from Motobatt.
Just don't bother buying a cheap unknown brand, unlikely to last more than a year or two (personal experience ), it seems you get what you pay for in batteries.

 

Motobatt installed some 18 months ago and despite lack of regular useage over that time is still showing north of 12.6v whenever I check it. Rated at 190CCA means that it spins the engine over quickly and easily every time (I believe Yuasa have a battery to fit which is similarly rated) even when not used for a couple of months - e.g.early August to mid October, and it fired straight away after using the 'prime' setting on the fuel tap.

 

had this problem on an old jap bike about 20 years ago..turned out to be starter button draining all the power
not sure how to test it i'm sure someone will know

 

If she runs fine once started on your existing plugs then I doubt that's where the problem lies. It's sounding like either a faulty start switch (as bogg suggests), or relay, or perhaps most likely, corrosion in one of the connector blocks. Unless you're a dab hand with a multimeter and the wiring diagram it's going to be a bitch to find.
Have you tried posting on the Thunderbird section of the forum, these sort of problems are often not unique if another Thunderbird owner (or your friendly Triumph dealer?) has had the same problem he might be able to point you in the right direction.
Otherwise - I don't know your bikes wiring in detail but I would expect there to be a relay in the start circuit I would suggest starting with that, try cleaning the socket it plugs into and/or replace the relay (not unheard of for them to go faulty). Still no better? - next check the start switch, take it apart and check for bad contacts, if that's ok then trace back the wiring loom and check each connector block you come to for corrosion, clean and re-connect as you go.
Good luck!

 

Definitely pointing towards that switch then Craig, with a 10 year old bike you can bet water/corrosion related problems will raise their ugly head sooner or later.

 

I just use a quality aerosol can of Contact Cleaner. Cleans really well and leaves no residue to block electrical flow.