78 90 hp Rebuild pistons

[Joe Fisherman]

I blew a 78 90 hp john due to bad impeller on top cyl my other 3 comp readings are 125-123-125 and the bad cyl 40 p.s.i.. What is a reasonable cost for a shop repair. Could i just machine that side head both cyls and replace pistions and rings???<br /><br />If so can an amautuer do this with shop manual or are there to many various factors involved??? Thanks

 

[wilde1j]

Re: 78 90 hp Rebuild pistons

If you've never rebuilt a powerhead, the learning curve can be steep. Reworking the bad cylinder only is OK, but you need to know the reason for the failure. A water pump failure will usually destroy all cylinders, not just one. I would consider cleaning/rebuilding all carbs. <br /><br />You may be ahead getting a rebuilt powerhead, although the age of the motor makes this an expensive decision and probably not worth it.