Bought A 2001 Triumph Thunderbird After Not Having A Bike For 20yrs. My How Things Have Changed.

Hi.
How long have you had it?
How long has this been happening?
Did you properly clean the carbs?
Have you run an engine/carb cleaner through the system?
How old is the petrol?
Have you taken it out and rode it for a hundred miles?
Do you have cake?

 

Your post is up twice, your going to split the responce, as you cant delete it, change the name to "please Ignore This Post "and youll be fine, honest.

 

Sounds like the pilot circuit has a problem, either blocked airway or most likely the jet itself, also if they are CV type could be the diaphragm has damage or hole.

 

First - Welcome to the forum! I wouldn't expect surges like you're describing from a bad crank position sensor. I would expect a really rough idle where the motor is cutting in and out due to a failing sensor or a short in the wire. Once it progresses, the motor should just stop running. As mentioned above, I would rethink what you did when cleaning the carbs. The surge could be due to 'crud' blocking and/or moving through the jets or fuel screens and causing the motor to run lean and then run normal. Did the bike sit for a while before you bought it? It could also be an air leak, or even minor amounts of water in the fuel. I'm a big believer in Lucas Fuel Treatment. It will 'sort out' some really aggravating problems. If the bike will stay running when you ride, I would put Lucas in the tank and take a long ride. If that doesn't solve the problem, I would look at the jets and fuel screens again.

 

With a bike that age I would firstly,

Change the carb to head rubbers ( air leaks will cause idle issues )
Clean the carbs paying extra attention to the idle jets, readjust the pilot screws to 2 turns out from closed
Check the float heights & float valves.
Drain the fuel tank into a clean bucket and check the bucket ( t300's have a habit of collecting water in the bottom of the tank )
Remove the rocker cover and check the valve clearances ( unless you have written proof they were done in the last 3-4000 miles )
Next time you remove the airbox remove the screws and cut the back in half to make it easier to remove & refit the carbs and filter in future.

 

My TBS is very similar.
Lovely bikes, with lots of character.

 

Sounds as said on here carbs are to blame. I take it you have new plugs and all that so carb seem to ring true. If the bike has been laid up then I would have the carbs ultra sonic cleaned as people go in there with carb cleaner and the likes and it does more damage than good. I am sure you will get it running again and you will love it. My old t140 I work at it every now and then and it seems that each time I get it closer to the way I want it. Ten more years and it will purr. Can't wait.
Regards
Joe

 

bump

 

I know I'm going to be the odd man here but, when you say you cleaned the carbs, I take your word for it. I own 2 of these engines. One 900 Legend and.one 900 Sprint. The thing that has given me the most grief with BOTH of them is ignition coils. Take a look at the coils. If they say."GILL" on the side, throw them in the bin and get some new ones, before you do anything else. You have already been through the carbs. Time to look elsewhere. Thier ignition is CRAP! That has been my experience with these bikes. Take my advice or not. I have had T-3 Triumphs for 17 years. ...J.D.