Speedmaster Engine Heat

Discussion in 'America, Speedmaster & Rocket' started by Dr. Mark Bohn, Aug 26, 2025.

  1. Dr. Mark Bohn

    Dr. Mark Bohn Member

    Joined:
    Mar 22, 2024
    Messages:
    16
    Likes Received:
    30
    Trophy Points:
    13
    Location:
    Mountaintop PA USA
    I have read on other threads that speedmaster 1200s run very hot. I have found this is the case. Is there anything that can be done to help the engine run cooler? I had my 2020 speedmaster decatted but haven't noticed any difference in the engine heat. The bike has never actually overheated. Can the radiator be modified? Is any brand or type of coolant better than the other? How often should the radiator be drained and the coolant changed?
     
    #1
    • Useful Useful x 1
  2. joe mc donald

    Subscriber

    Joined:
    Dec 26, 2014
    Messages:
    10,255
    Likes Received:
    15,581
    Trophy Points:
    1,000
    Location:
    slough / burnham
    @Dr. Mark Bohn Welcome to the family. Can't help but i am sure someone will be along soon. Do tap the upload a file button and show us all the bike
     
    #2
  3. Dr. Mark Bohn

    Dr. Mark Bohn Member

    Joined:
    Mar 22, 2024
    Messages:
    16
    Likes Received:
    30
    Trophy Points:
    13
    Location:
    Mountaintop PA USA
    1000000110.jpg

    1000000120.jpg

    IMG_8632.jpg
     
    #3
    • Like Like x 4
  4. joe mc donald

    Subscriber

    Joined:
    Dec 26, 2014
    Messages:
    10,255
    Likes Received:
    15,581
    Trophy Points:
    1,000
    Location:
    slough / burnham
    #4
    • Agree Agree x 1
  5. triumph900

    triumph900 Active Member

    Joined:
    Dec 24, 2017
    Messages:
    219
    Likes Received:
    130
    Trophy Points:
    43
    Location:
    US
    Heat is an interesting, and very subjective topic.
    I have two Bonnevilles, and while they do put off some heat, they are nowhere near as warm as Tiger 900s I've demo'ed, or as my wife's Indian Scout! The Bonnevilles really only get warm while stopped and the fan is on. I personally have no issues while moving, but that's me.
    I would consider removing the fork bag to allow maximum airflow. Probably won't help much but at least can say you tried.
     
    #5
    • Like Like x 1
  6. Fork Lock

    Fork Lock Crème de la Crème

    Joined:
    Feb 5, 2021
    Messages:
    1,761
    Likes Received:
    2,959
    Trophy Points:
    1,000
    Location:
    South Jersey, The 51st State
    I have a 2018 Speedmaster. Bought new as a leftover in 2020. Why no one snapped up this pretty baby for two years I can't imagine. Anyhow, I have never noticed any heat issues. I have never even heard the fan kick on. She is decatted.

    I installed this oil temp gage that replaces the original oil cap when I first got her. I have never seen it go above 150 degrees F. Not all that hot. You might want to consider investing in one of these. You can monitor the temp and note if any particular condition results in a spike in temp (idling for long periods, flogging her hard in summer heat, taking on steep hills, etc.). As for the coolant. I've never changed it. It's a closed system and I see no need to. Maybe when I hit 10k miles I'll look into a drain, flush and refill.

    oil2.jpg
     
    #6
    • Like Like x 1
    • Agree Agree x 1
  7. Pegscraper

    Pegscraper Elite Member

    Joined:
    Jun 12, 2020
    Messages:
    2,807
    Likes Received:
    3,783
    Trophy Points:
    800
    Location:
    Yorkshire
    I have a Scrambler 1200 and noticed the fan cuts in at 103 Deg C and it will do so readily in traffic but never has a problem controlling engine temp. Personally I can’t see why the other models using the 1200 twin should run any hotter. The headers on these bikes do radiate a lot of heat being quite large and exposed and not shielded behind bodywork.
     
    #7
    Last edited: Oct 20, 2025
    • Useful Useful x 1
    • Agree Agree x 1
Loading...

Share This Page