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  1. #1
    Race, wreck, repeat delagem's Avatar
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    JS440/JS550 head question

    Can anyone confirm that the heads are different between these two models? Head I bought on eBay is supposedly from a 87 550, but looks exactly like my 89 and 90 440 heads. I would expect the chamber do roughly match the bore of a 550, at 75mm, but this one is 69mm, almost matching the bore of my 440. I know it will fit, and it might work, but it really isn't a 550 head, is it?


  2. #2
    Watcon's Avatar
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    heads

    No. The 440 head can be cut to the 550 specs, but the squish area will be different. The head I.D. must match the bore diameter.

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