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Not getting full RPM at WOT

B

BAS

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C40TRLX
Compression: 115/115/114
New ignition system (CDI, Pulser Coil, Lightning coil, Charge Coil, 3 Ignition Coils, Rectifier)
Rebuilt carbs, new fuel pump, filters, fuel lines with mechanical clamps no bleed down with vacuum gauge. (Carb needles adjusted to 1-1/4 turns then fine tuned using inductive tach on each cyl)
All DVA readings in spec. (Via CDI manual and Yamaha Factory Manual for C40 & C50)
Performed link and synch and verified timing adjustments correct.
Idle: 8 degrees ATDC, WOT in tank in neutral: 26 degrees BTDC (In spec via Yamaha Factory Manual) (Cant test in gear at WOT due to tank limitations and danger while running on river, tiller drive)

This motor is pretty dialed in and runs well with no obvious tell tales of poor parts are settings. When in the tank, in neutral and WOT it will hit 3200 rpm. Under load with me (210#) 15gal of fuel, 2 life vests, two paddles and two padded seats (total weight about 450# with boat) the WOT is 2600 and it seems to be a tad slow to get up to speed. Hole shot seems OK with no stall or lope. Top speed on flat slack water is 25mph via GPS)
Boat is a flat Monarch aluminum.
Prior to new ignition and carb rebuild the boat would hit WOT-4000 rpm with a top speed of 34mph.
Im concerned that the motor not hitting spec ( 4500-5500 via Yamaha Factory Manual) may wear down crank bearings.
Any suggestions on if this is the norm for an aftermarket CDI or maybe I missed something? I have scoured the prop sites and they all suggest a 10-5/8 x 12 prop and that's what's on there. Im not a prop scientist, would a prop change be in order? To be fair the boat is a tad overpowered when running correctly, however, as duck boat it is usually weighted down during the season and I like the extra wattage for 15+ mile runs into the marsh.
 
While underway under load at WOT does the engine sound like it's at peak power? If so I would test engine with a different tach.
 
Thanks ClassicAQ. Just for the record, My other boat is an Aquaspot 201 with a 209 yamaha.
I was thinking the same thing. It has a Marpac analog tach set on the 4 pole setting. Manual sez it is a six pole but at idle, 6 pole is about 400 rpm higher and I know it aint at 1200 rpm idle. 4 pole seems right. That said the speed is is off by 6-8mph which regardless what the tach sez, is lower than normal or at least what was
 
As you continue to troubleshoot, I wouldn't rely on speed as a means to gauge engine performance. This is because there are numerous environmental variables that affect speed. Rpms are the looking glass, so to speak, of engine performance. I'd first find means to confirm accurate rpms, as speed is just the byproduct of rpms with influencing environmental and load factors.
 
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