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Thread: Same engine '82 GS650EZ and GS650GL?

  1. #1
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    Default Same engine '82 GS650EZ and GS650GL?

    I just picked up an inexpensive, non-running, partially completed cafe racer build on a 1982 GS650GL. Not running at purchase. Came across an inexpensive '82 GS650EX motor and trans running. I know the GL is shaft driven and the EX is chain. Question is, can I poach the engine from the EX for the GL? Don't want to complete the build only to find the original motor is junk.

  2. #2
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    There are a few parts that will cross over, but forget about switching engines.

    As you have noted, the GL is a shafty, the E has a chain. The frames are different to accommodate the different drive systems, as well as the swingarms.

    The cylinders and heads will interchange, but the cams need to remain with their original crankshaft. The sprockets have different number of teeth, so they don't stay in sync. It might be possible to simple change the cam sprocket, but I had no way to verify the cam timing when I did this, so I simply used the other cams.

    .

    mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
    hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
    #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
    #2 son: 1980 GS1000G
    Family Portrait
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    Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
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  3. #3
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    Non running is typically not an issue with GS motors, save the Gen 2 750.

    Adjust the GS valves, then do a compression test. If they're relatively even, it should be able to be revived

    The G and E cranks are totally different
    1978 GS 1000 (since new)
    1979 GS 1000 (The Fridge, superbike replica project)
    1978 GS 1000 (parts)
    1981 GS 850 (anyone want a project?)
    1981 GPZ 550 (backroad screamer)
    1970 450 Mk IIID (THUMP!)
    2007 DRz 400S
    1999 ATK 490ES
    1994 DR 350SES

  4. #4
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    Quote Originally Posted by Steve View Post
    There are a few parts that will cross over, but forget about switching engines.

    The cylinders and heads will interchange, but the cams need to remain with their original crankshaft. The sprockets have different number of teeth, so they don't stay in sync.
    Quote Originally Posted by Big T View Post
    The G and E cranks are totally different
    As we both have hinted, there <are> a few pieces that will cross over, but the engines are totally different.
    The E has one-piece rods, roller bearings, a pressed-together crank and a low-pressure oiling system.
    The G (and GL) has two-piece rods, plain bearings, a solid crank and a high-pressure oiling system.

    Some time during the '82 production run, there was an extra bolt added to hold the valve cover to the head. Of course, the head and the cover were both affected, they do not interchange. You can install an '83 head and cover on an '81 bike, but you have to move the head AND the cover.

    Valves, springs, buckets and shims are the same. Cam chain tensioner is the same. Stator is the same. Ignition is different on the '83, the advance is electronic and is built into the ignitor, not using the mechanical advance on the end of the crank.

    .

    mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
    hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
    #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
    #2 son: 1980 GS1000G
    Family Portrait
    Siblings and Spouses
    Mom's first ride
    Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
    (Click on my username in the upper-left corner for e-mail info.)

  5. #5
    Join Date
    Apr 2004
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    Ignition is different on the '83, the advance is electronic and is built into the ignitor, not using the mechanical advance on the end of the crank.

    The 83 engine is identical as far as far as ignition advance. I swapped an 81 for an 83 without issues.
    1981 GS650G , all the bike you need
    1980 GS1000G Power corrupts, and absolute power corrupts absolutely

  6. #6
    Join Date
    Sep 2019
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    Quote Originally Posted by Steve View Post
    The cylinders and heads will interchange, but the cams need to remain with their original crankshaft. The sprockets have different number of teeth, so they don't stay in sync. It might be possible to simple change the cam sprocket, but I had no way to verify the cam timing when I did this, so I simply used the other cams.
    I have to replace the head on my '82 650E, bought a used head that came from a 650G that I was told "would work", the cams look the same but the cam sprockets are very different:

    Camshafts - The cam shafts from the E are the same size and orientation to the G, but the E shafts are stamped with "R6" and the G "R4" (opposite side of the shaft and sprocket to the EX or IN stamps)

    Camshaft Sprockets - The sprockets from the E are smaller and are stamped with 470, the ones from the G are larger and stamped 342.

    I tried installing the cams from the G which didn't work, but I can't seem to find a pic that shows the proper size for a 650E sprocket? Comparing photos from Ebay the 342 sprockets look like they are the proper 650G size, and I did find a pic of an '81 550 sprocket was stamped 470, did the 650E use 470 sprockets instead of the 342 used on the 650G?


    As an FYI from my searching:

    '81 550 - 470 Sprocket
    '83 550 - 434 Sprocket
    ? 750 - 454 Sprocket
    ? 1100 - 490 Sprocket
    1982 GS650e - Cafe or Scrambler...that is the question...

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