Tt 900 From 2000 Sputters, Stalls And Hacking

Hello!

I've just purchased a 2001 Triumph Thunderbird 900, and I managed to get it at an incredibly low price. This is my second bike, and the previous owner was extremely helpful. It's a fantastic bike, but there's one issue I'd like to address to make it perfect.

Video of issue: https://imgur.com/a/XG8x1PO


**Bike Details:**
- Model: Triumph Thunderbird 900 (2001)
- Battery Type: AGM
- No visible damage.

**Issues:**
The motorcycle occasionally jerks, sputters, or even stalls when running at low RPMs. It feels as if it's losing either electrical power or fuel. The best way to describe it is like when a fuel tank is running low and the bike starts to jerk before you can switch to reserve tank. But sometimes it completely dies.

**When I've noticed it happening:**
- Primarily occurs at lower RPMs, especially in 1st and 2nd gear, but also in 3rd.
- Engine sometimes dies at red lights or in traffic queues.
- Occurs when using the clutch, but also when applying very little throttle.
- Dying when pulling in the clutch at low RPM (not always).
- It stalled four times in a row in a recent traffic jam. It's fine when giving a little more throttle, but nobody enjoys high RPMs in a traffic jam right?
- It doesn't seem to happen in higher gears or when the RPMs go over 4000.
- It appears to happen both with a cold engine and after 20+ minutes of riding.
- One of the speedometer (RPM reader) backlight flashes a little. It can be constant but also when applying throttle it gets worse. (this might indicate something, I don't know).
- The idle seems fine otherwise, steady at 1000 RPMs after a few minutes of running choke.
- When it suddenly dies, there's a high-pitched sound, somewhat like a tiny rocket taking off, but I'm unsure where this is coming from (not the exhaust)

**Additional Information:**
- I recently used fuel injector cleaner (somethings similar)
- I've used fresh fuel.
- I checked the vacuum packs on the carburetor.

**Previous Owner's Input:**
The previous owner mentioned that the bike worked fine last season but started experiencing issues this season. Initially, the issues affected higher RPMs, he took it to a mechanic and now it seems to be primarily at lower RPMs.

**Solutions Tried by the Previous Owner:**
- Installed new spark plugs.
- Had a mechanic shop clean the carburetors (no new jets, just cleaning). This initially improved the situation, but the lower RPM issue returned.
- A new AGM battery (unsure if this was done last season or this season). Could this effect anything?
- He used fuel injector cleaner.

**Possible Causes Considered:**
- Dirty carburetor, especially the jets: exhange it all!
- Battery issues. - I read that a bad battery can cause similiar issues. But as it was changed pretty recently, i don't think it is that.
- The kick-stand – I've read that some bikes have an automatic kill switch built into the kick-stand which could have bad connections. I tested this by moving it during a test drive, and nothing happened.
- Air leak – I'm not familiar with this, but I read somewhere that it could be related to bad air filter or a leakage.


Thank you for taking the time to read this somewhat lengthy post. English is not my first language but tried my best.

Now, what should I do or check first? I'm still new to this and learning!
I tried recording a video today but the video stopped half way when it started happening. I'll try again tomorrow.

 

Thanks! This might me it!