'71 Bonneville 650 Airbox Alignment Off From Carb

Discussion in 'Vintage Classics' started by tc80211, Dec 12, 2023.

  1. tc80211

    tc80211 New Member

    Dec 12, 2023
    2
    3
    Boynton Beach, FL
    Howdy all!

    I just bought my uncle's 1971 Bonneville 650 that he has owned for 25 years. In replacing everything that is cracked and broken I noticed that trying to fit new carb boots to the airbox is hilariously difficult because the carb is not aligned with the hole on the airbox. See this pic attached.

    I did my best to fit the new boots, but this isn't how it came from the factory... I hope. Any insights would be awesome. Very excited to get this old girl back on the road.

    IMG_6058.JPG
     
  2. Iron

    Iron Elite Member

    Dec 29, 2021
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    Bob Ross Studios
    #2 Iron, Dec 13, 2023
    Last edited: Dec 13, 2023
    Yoiu may have the wrong connecting rubber, here is the 1971 parts catalogue showing
    part number F12626, notice there's also a connector adaptor that screws onto the carb part number E11860.

    Screenshot 2023-12-13 173937.jpg

    Screenshot 2023-12-13 174200.jpg

    Screenshot 2023-12-13 174111.jpg

    Screenshot 2023-12-13 175207.jpg
     
    • Agree Agree x 1
  3. tc80211

    tc80211 New Member

    Dec 12, 2023
    2
    3
    Boynton Beach, FL
    I have that rubber, too. But the alignment is so far off, there is no way. I have removed the boot so you can see the alignment and how off it is.

    IMG_6060.JPG
     
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  4. tc80211

    tc80211 New Member

    Dec 12, 2023
    2
    3
    Boynton Beach, FL
    I know the boots in my first photo are from later in the 70s, I got them because the '71 boots don't even come close. so something is def incorrect as based on everything I can find, the carb inlet and the airbox should align
     
  5. Iron

    Iron Elite Member

    Dec 29, 2021
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    Bob Ross Studios
    #5 Iron, Dec 15, 2023
    Last edited: Dec 15, 2023
    Looks like you have a later year cylinder head. The inlets for a '71 should be the threaded kind:

    71 head.jpg

    while later years have the bolted on version:

    72 onwards.jpg

    I wouldn't have thought that would make too much of a difference. However, if you have the early '71 frame (oil tank) rather than the later oil in frame version then that may be the difference as the side panels would be further apart on the oil in frame.
    I always bin the standard side panels and air filter so have never come across this issue.

    71 air.jpg

    72 air.jpg
     
  6. tc80211

    tc80211 New Member

    Dec 12, 2023
    2
    3
    Boynton Beach, FL
    Well I'll be damned. Yep. That is too funny. Well I will be giving my uncle an earfull of shit. Thanks so much for helping! If this was your bike would you source an earlier cylinder head or just figure out an elegant solution to hookup the airbox?
     
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  7. Iron

    Iron Elite Member

    Dec 29, 2021
    2,589
    943
    Bob Ross Studios
    I'd be binning the airbox and sidepanels, fit the older style sidepanels and screw on some polished bellmouths.

    7.jpg

    Second hand heads are pretty expensive and even then may require work on the valves, guides and any damage from previous owners overtightening of the head bolts. If you really want to keep the side panels then cobbling something up by cutting and welding/sticking some ally/rubber pipe should look and work ok. .
     
  8. tc80211

    tc80211 New Member

    Dec 12, 2023
    2
    3
    Boynton Beach, FL
    Beautiful bike!!
    I just ordered those pipes. Question: What size jets are you running with your velocity stacks? Or were you able to keep the stock size for the amal 930's?
     
  9. Iron

    Iron Elite Member

    Dec 29, 2021
    2,589
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    Bob Ross Studios
    Just running standard on everything and it runs rich - probably due to just pootling around not doing much mileage or making it work hard. Every one I have or have sold runs fine on the standard sizes and adjustments.
     
  10. tc80211

    tc80211 New Member

    Dec 12, 2023
    2
    3
    Boynton Beach, FL
    That's great news. My first Triumph but not my first classic by a mile. I had an airhead that was very temperamental. Appreciate your insights. Happy Holidays!
     
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