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JBL Dragonfly Project

John W

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Need help finding any literature pertaining to rebuild of HAPI 75 Magnum engine, and sources for parts.  Have book “Engine Assembly Manual” by Steve Bennett.  Looking for Top end gasket kit, Rings, and Valves, etc.  Tried contacting Grate Plains Aircraft but they must really be busy as getting no response. My local VW guru tells me HAPI must have used special valves as he can not locate.  Looks as if engine has very low hours but has valve damage, most likely from running hot.  Can not find any postings on this topic - or did I overlook??  Any insight into rebuilding this engine appreciated.  Thanks

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1 hour ago, John W said:

Need help finding any literature pertaining to rebuild of HAPI 75 Magnum engine, and sources for parts.

I don't know anything about these but they are mostly VW engines.  I imagine VW parts would work and there are PLENTY of VW parts houses and VW rebuild books.  This site says that engine has reliability problems and had to be rebuilt straight from the factory.  https://hugheskr2s.yolasite.com/   There is a link there to the Yahoo VW conversion group.

Also not very complementary:  http://www.buildagyrocopter.com/vw-engine-maintenance/

A chap named Bob Hoover wrote a lot about VW engines.  He is deceased now but his legacy lives on.   http://bobhooversblog.blogspot.com/2007/05/hvx-mods.html

Another thread   https://www.homebuiltairplanes.com/forums/threads/bob-hoovers-hvx-vw-engine-mods.31359/

If you can determine the URL for the old hapi engine website, you might go into the internet archive and find pages  https://archive.org/


  • Thanks 1

Cozy IV N13AM-750 hrs, Long-EZ-85 hrs and sold

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