Thunderbird 900 Sport MK1 won't start!

Hi Stevie and welcome to the Triumph Playground. The first thing I'd be doing is have the battery on charge for a couple of hours or more if you can. This may well cure the starting problem, but even if it doesn't you've eliminated a classic starting cause, for nowt!

 

with the low miles I would think the jets were a bit gummy. Over the summer while you used it did you try any carb cleaner in the fuel, redex, petrol magic etc?? I would have treated the bike to a couple of shots every tank and by 500 miles you would see some sort of improvement I think.
When you have tried starting a few times with no luck, try taking a plug out, can you smell or see fuel on the plug?? maybe the filters are blocked.
what is your starting procedure?? most of the carbed hinckley triples will not fire if you twist the throttle. the trick on my Sprint is to ,if it hasnt been used in a while, turn the fuel onto prime and press the middle of the the tap in for a couple of seconds to fill the carbs with fuel, choke on ( now some need full, some half and some none at all, mine is about a quarter). press the starter and do NOT touch the throttle and away she goes.
On my bike there is a drain pipe at the back, bottom of the engine by swinging arm, mine was unplugged but i found out in another forum it should be plugged so I have done so and it seems to start and runs much smoother tho i do not know why (probably all in my head but thought I would mention it).

 

Do you know when the valve shims were last checked? My Trident has never been a bad starter (except for when the battery was on its last legs) but was so much better after the shims were checked/adjusted.
And yes, as per sprintdave, my bike gets regular doses of Redex which has kept the carbs etc in fine fettle over the 20 years that I've had the bike ... so far ... touch wood!!

 

Good call stevethe goolie. I never thought of the shims but T say they need checking at 12000. Some have done upwards of 50000 miles and no shims needed, others have had one or two done and that is it for years. mmmmmmmm

Also I read on the USA RAT site that premium fuel is harder to ignite than normal unleaded but when it fires it burns hotter or summat like that. Sorry i aint a chemist. BTW I use super unleaded in my bike and petrol magic additive if that helps.

 

Mine has fuel {plugs get wet} spark and compression engine spinning over but won't start

 

StevieP
Try taking the plugs out warm them up and stick a cap full of petrol down each plug hole and try firing it up. you will know if it is carbs and it may get it running if it has enough will to suck the fuel through. If it starts then get fresh fuel and some Lucas fuel conditioner and it will clean itself up internally.
Regards
Joe.

 

I will try anything, it has new fuel. and the plugs are getting wet.

 

GypsySOHMC.
Seems we have two here using the same thread. You are losing spark or the filter is blocked or choke blocked. On your bike you really need to check the ht leads and caps the plugs make sure the gap is right and the plugs good. Then if that doesn't work check your filter and coil themselves. Your bike what is the miles and has it sat.
Ride Safe
Joe.

 

When was it last ok? Have you done anything at all to the bike since last used?
If it is a new bike to you it may have flooded and fouled the plugs. New plugs in and don't touch the throttle when you try to start it as this floods the engine. Try with and without choke as it could be sticking. Check it is sparking coz it could be electrical issue.
Don't try to start it with a low battery as it will shag the sprag clutch which is an expensive job. Fully charge battery and try again. Post back here and the boys will sort you out.
Were valves done at 12000 miles as ut may be a tight valve?

 

18,000 Miles it's sat for a few weeks. Plugs are new and I have gapped them, checked they have have decent spark. I've checked the plug leads and the coils.

 

18,000 Miles it's sat for a few weeks. Plugs are new and I have gapped them, checked they have have decent spark. I've checked the plug leads and the coils.

 

Bought it after 12000 miles
Battery is new and fully charged
sidestand switch cleaned
clutch switch replaced
Wiring connectors stripped and cleaned
coils checked
ht leads checked
plugs new and gapped and have spark
carbs stripped and cleaned
fresh fuel
and nothing at all

 

Carb vacuum blocked, try on prime if you have that position on your bike. I have a Sprint so may be different. Remember to turn it back after tho. If the engine turns over it won't be the clutch or side stand switch.

 

Starting System Symptoms:

Weak battery symptoms:
-- Slow cranking.
-- Stops cranking suddenly on compression stroke with button pressed.
-- Starts when starter button is released at end of cranking.
Repair:
-- Charge/Test/Replace battery.
Failure Modes:
-- Loss of capacity. Appears to charge, voltage good but no reserve for starting.
-- Won't hold a charge.
-- Low voltage/cell failure.
Preventative Maintenance:
-- Check fluid levels regularly
-- Maintain full charge: Regular riding, trickle charger.

Ignition Coil failure symptoms:
-- Hard starting/misfiring during cranking.
-- Rough idle that can't be tuned out with carb adjustments and carb cleaning.
-- Idle misfire clears with new sparkplugs, returns in a few hundred miles
Repair:
-- Replace: Preferably with Nology for higher reliability than stock Gill coils.
Failure Mode:
-- Shorted turns in secondary resulting in weak spark.
Preventative Maintenance:
-- None
Testing:

Pickup Coil failure symptoms:
-- No spark at all
-- Spark quits with engine hot, returns when engine cool.
-- Note: Pickup coil failure is total. There is no random misfire spark loss.
Repair:
-- Replace pickup coil
Failure mode:
-- Thermal intermittant with long (15-30 minute) period.
Preventative Maintenance:
-- None. Get a spare.
Testing:
-- Ohms checks hot and cold.

Worn starter symptoms:
-- Sometimes won't crank until the bike is rocked in gear.
-- Excessively noisy cranking with a grinding sound.
-- Click from under seat but no cranking.
Failure Mode:
-- Brush wear progressing to commutator damage.
-- Bearing failure related to brush wear.
Repair:
-- Rebuild or replace.
Preventative Maintenance:
-- Maintain battery in peak condition.
-- Follow proper starting procedures. Neutral, clutch in.
-- Crank 5-10 seconds at a time max., switch off for twice as long before cranking again.

Worn sprag clutch symptoms:
-- Very loud rattling when cranking
-- Starter spins but engine doesn't turn
Falure Mode:
-- Breakage
Repair:
-- Replace sprag clutch
Preventative Maintenance:
-- Maintain battery in peak condition.
-- Follow proper starting procedures. Neutral, clutch in.

Worn starter solenoid:
-- Click from under seat but no cranking.
-- Won't crank after rocking bike.
-- Starter continues to run after bike starts and won't stop until the battery is disconnected.
Failure mode:
-- Internal contact damage resulting in non-conduction.
-- Internal contact damage resulting in contacts welding shut.
-- Internal damage/wear prevents solenoid core movement.
Preventative Maintenance:
-- None.
Repair:
-- Replace starter solenoid.
Testing:
-- For no cranking, short across solenoid high-power terminals. Normal operation denotes failed solenoid contacts.