I did what research I could here and could not find the answer. As long as the bore and stroke are the same, and they should be, then you should be able to use the same cylinder head, pistons and cam on any of the bottom ends, since those three items are engineered to work together. Whether you can use a combination of parts from pre-81 and post 81-bikes I honestly do not know, and I don't have either the parts fiche or the shop manual for the 81 nd earlier bikes to check.

If you have access to the cylinder head, bolt it on to spec and turn the engine over by hand. The engine won't turn over all the way if there is any interference. This is not to say there may not be some light "kissing" of parts when the engine is running at certain speeds, but the forces involved should not be enough to damage anything in the engine -- many a race engine has been run this way for a long time without trouble.

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| 1990 Kawasaki Zephyr 615 (Daphne) -=- 1986 Kawa Ninja 250 (stolen) |
| The Motorcycle Fuel Injection Handbook -=- http://tinyurl.com/297abo |

As far as I know, the engine mounts are identical on all the air-cooled 550 Kawasakis. The only isue you are likely to run into is getting the length of the output shaft correct so the front sprocket is spaced correctly. The easiest way to do this is by stealing the output shaft from the donor boke, but the problem there is that you have to split the cases on both engines to make the swap, meaning new seals and gaskets, and yhou know how it goes... "While I'm in here, I'd might as well blueprint the bottom end and swap out the rings and..."

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| 1990 Kawasaki Zephyr 615 (Daphne) -=- 1986 Kawa Ninja 250 (stolen) |
| The Motorcycle Fuel Injection Handbook -=- http://tinyurl.com/297abo |