1. Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

Carburetor rack heat shield.....

Discussion in 'XJ Technical Chat' started by LarryMc, Dec 8, 2018.

  1. LarryMc

    LarryMc Active Member

    Messages:
    349
    Likes Received:
    206
    Trophy Points:
    43
    Location:
    Lakewood, WA
    I'm in the middle of a comprehensive overhaul on a set of Mikuni BS28 carbs for a XJ550 Seca. Does the heat shield located underneath the rack actually need to be there? I'd like to run without it if possible. Is there anyone who has removed it without negative consequences of doing so?
    If I'm correct, the XJ550 Maxim doesn't have a heat shield, right?
     
    Last edited: Dec 8, 2018
    LarryMc, Dec 8, 2018
    #1
  2. XJ550H

    XJ550H Well-Known Member Premium Member

    Messages:
    13,199
    Likes Received:
    3,855
    Trophy Points:
    113
    Location:
    Great North Woods
    both the Seca and Maxim 550 Have the heat shield. the heat shield is not needed.
    if you have it I would use it but If you do not have it you do not need to buy one.
     
    XJ550H, Dec 9, 2018
    #2
  3. Colin 85 700

    Colin 85 700 Active Member

    Messages:
    487
    Likes Received:
    131
    Trophy Points:
    43
    Location:
    Thunder Bay, ON
    Im sure it the same principal on a bike, heres my two bits.
    Many ATVs run a heat shield near the carb. The purpose is that at very low speed, or idling for long periods, engine heat doesnt try to "boil" the fuel in the float bowl.
    Also if its super hot out, and the engine is at temp when its shut off, the shield serves that same purpose, if the fuel boils out it makes it bitchy to restart hot as the carb goes low or empty.
    Also for emissions, this prevents raw fuel evaporating out into the atmosphere under these conditions.
    In any case, the shield is generally not required, and wont affect performance, other than the odd hard hot start, when the carbs get a bit low on fuel.
     
    Colin 85 700, Dec 9, 2018
    #3
    Stumplifter likes this.
  4. XJ550H

    XJ550H Well-Known Member Premium Member

    Messages:
    13,199
    Likes Received:
    3,855
    Trophy Points:
    113
    Location:
    Great North Woods
    a quick prime for a few seconds will fix that issue if it arises. there are a few posts on the subject stating that it is not needed.
     
    XJ550H, Dec 9, 2018
    #4
    Colin 85 700 likes this.
  5. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,635
    Likes Received:
    5,014
    Trophy Points:
    113
    Location:
    near utica, new york
    The heat shield is not needed. Plus, there is an inherent problem in trying to install it. The bolts that holt the rail in place are also want holds the shield in place. You can't remove or reinstall the shield without loosening the lower rail. If the rail is loose, then the rack isn't necessarily going to be tight and square. So, if you put it all together, then go to wet set, you're stuck....how are you going to wet set when the shield is in place? How are you going to wet set accurately when the whole rack is not tight?
     
    hogfiddles, Dec 9, 2018
    #5
  6. LarryMc

    LarryMc Active Member

    Messages:
    349
    Likes Received:
    206
    Trophy Points:
    43
    Location:
    Lakewood, WA
    Based on the great advice above and the other posts I've read on the subject, I'm going to leave the shield off.
    I appreciate your feedback.
     
    LarryMc, Dec 9, 2018
    #6

Share This Page