Hi all,<br /><br />I have 75 model 40hp Johnson electric start (40EL75) I have the Johnson workshop manual. When I purchased this motor it was running poorly and compression on the lower cylinder was zero. Some WD40 (at my father-in-laws suggestion) down the plug hole didn't improve anything and I have since pulled the powerhead off but not apart. Having gone over these forums I realise that the WD40 probably wouldn't have done much anyway and I should have used some decarb spray. I have 2 questions:<br /><br />1. With the powerhead off can I still try the decarb spray, pop the flywheel back on and turn it over by hand to see if it improves things or do I need to get the motor hot to get some results. Also - if I can do this - how much do I use ?<br /><br />2. If I do pull the powerhead apart and provided no bearings need replacing, cylinder bore and pistons are in spec and no other major problems exist. Can I get away with minimising costs by doing just the rings, a decarb, getting a powerhead gasket kit and cylinder head gasket to put it all back together again ? The prices from my local outlet put these parts and the kit at just $160 total which sounds too cheap compared with other posts discussing powerhead rebuilds. Am I missing something here ?<br /><br />Many thanks,<br />Darren.
