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NISSAN 40C NO POWER HELP

timinator

Member
"I am stumped! I just bought a

"I am stumped! I just bought an Adventure SE with a 1988 40C nissan on it. Everybody else runs big props, but this one barely gets on plane with a 9" prop and will only run 3900-4000 rpm. It was owned since new by an old couple that I bought it from that hadn't used it for 5-6 years. A while back someone tried to make it run and gave up. The carb was full of white corrosion, so I thoroughly cleaned it in the cleaner, and rebuilt it. Running in the test tank I had to remove and clean it out several times and each time it got better. It now starts and runs well in the tank even with the 14" and 16" new props that the local dealer said that it would want. I can run it in gear for an hour at any rpm, but at the lake it just barely planes with the 9" prop. Tested ign output, timing at idle and at rpm, fuel flow (new pump and 2-4 psi), new plugs, got the manual, but it starts at a year newer than mine. Manual lists all the air bleed and jet sizes for all the carbs, but none are even close to what I have in it. Anybody have info on what size carb, jetting/bleed info,or any other places to look. The air box has a 2" hole cut in it in front of the carb inlet,I have covered it and removed it, no change.I tried running with no cowl too, no change. I have heard of other engines having exhaust tuner breakage, does this engine have this problem? Thanks for any info anyone can provide. I build jet and I.O. performance engines for a living, but this has me stumped. Mebbie the guy that tried to start it put two carbs together to make one? I just don't know what I have. Thanks again. TIMINATOR"
 
"Since my first post I: checke

"Since my first post I: checked the reeds, 3 out of the 12 are up about .040 from closed, ordered new ones and don't have them yet, pulled off the lower to see if the tuner was ok, it is, and nothing clogging it. Pulled the head , walls look fine, ports are all open and fine, no headgasket issues. No-one on any board has posted what size the mainjet is supposed to be. It seems big to me. Had the carb apart again and rechecked and everything seems normal. Might have to light it on fire.... TIMINATOR"
 
"You have a 22 year old engine

"You have a 22 year old engine with a dubious history. The main jet sizes are listed in the parts and service manuals. The parts manuals are available as a free download from www.internetoutboards.com. My best guess is that your problem is still the carburetor. The water damage almost certainly damaged the inner passages."
 
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