2015 Triumph T100 Boneville Overheating/idle Issues

Discussion in 'Technical Help' started by CRC1996, Oct 23, 2025.

  1. CRC1996

    CRC1996 New Member

    Oct 23, 2025
    0
    0
    Austin, TX
    I picked up my 2015 Triumph Bonneville T100 a few weeks ago. It only has about 1,300 miles, so it’s still basically new mechanically, but it’s spent most of its life sitting. The previous owner told me he hadn’t ridden it in a long time.


    When I took it for a short test ride (about ¼ mile), it ran perfectly. I then rode it an hour and a half home with no issues.


    The second time I started it up, things changed. It began having idle issues, it would die every time I came to a stop. I tried adjusting the idle knob, but now it overheats badly after riding for a while. I’m pretty sure it’s running too lean, but no matter how I adjust the idle knob, I can’t get it to stop overheating or idle consistently.


    When the engine is cold, it idles fine. But once it warms up and starts getting hot, the idle issues come right back.


    Here’s what I’ve done so far trying to get it running smooth again:


    • Changed oil and oil filter

    • Replaced in-tank fuel filter

    • Changed brake fluid and brake pads

    • Cleaned and lubed the chain

    • Replaced spark plugs

    Everything is stock, no mods, and the bike is EFI and air-cooled.


    Unrelated, but my speed sensor went out around the same time, it likely burned out from the overheating.


    At this point I’m pretty frustrated and running out of ideas. Does this sound like a fuel delivery issue, bad sensor, or something else? What would you check next to get it running smoothly again?
     
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  2. Samsgrandad

    Samsgrandad Senior Member

    Dec 15, 2019
    712
    243
    Somerset
    Sounds like the fuel system needs a good clean. As a start you could try adding some injector cleaner to the fuel and run the bike to see whether that improves things
     
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  3. Pegscraper

    Pegscraper Elite Member

    Jun 12, 2020
    3,785
    800
    Yorkshire
    It does sound like symptoms of lean running.

    Does the bike have an any sort of diagnostics capability?

    A faulty engine and/or intake air temp sensor could cause fuelling issues.

    A clogged/gummed up injector can give problems without actually showing a MIL light on the dash so, as Samsgrandad has said, try some decent injector cleaner in some fresh E5 fuel.

    Check for air leaks on the intake side of the cylinder head/throttle bodies.

    If nothing shows up and the problem persists, taking the injectors out and getting them tested would be my next step

    I can’t see how overheating would affect the speed sensor which should be on one of the wheels or the final drive somewhere.
     
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  4. Walter C Licker

    Jun 12, 2025
    25
    13
    Essex
    Have you checked air filter is clean, fitted correctly and not been upgraded ? Sometimes an ill fitted filter can upset the fuel mixture balance. This causes the fuel management to work overtime continuously correcting itself. I really hope this simple check will resolve your problem.
     
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