OMC looper top end surge

[Machinist76]

Purchased this boat in March. Cyl #2 had 80# compression. It had lost piston ring locating dowel, woodpeckerd the head.
I personally bored all 6 to .020 over.
Removed all six sleeves, #4 and #6 we're turned slightly (incorrect orientation maybe 5-10 degrees.
I epoxied idle relief holes.
I measured, cleaned inspected everything.
The only port work I done was smoothing rough casting edges, glue marks.
I didn't have clear direction as to changing port hight so I left all that stock.
I want a reliable fishing motor, if it's a tad stronger then great...

Here's the kicker.....

The only improvement from this entire rebuild is much better holeshot.

Again guys/gals...it starts, idles, and planes the boat great. It simply bogs at 4500-4900, approx 40-45mph regardless of prop!

That's a 21P aluminum 4 blade, rough 24P Raker, or a 27P shooter. Earlier I said the shooter was 25, it's not...

So, what I haven't yet done is the following.

Gut antisiphon valve in fuel tank.
Change plug wires, coils, trigger or stator.
Rebuild/calibrate carb assemblies.

My problem must be one of those three above statements!

Tach wiring circuit runs through the controls box, being a 94 motor on 89 boat the wire colors didn't match
Whoever installed this engine never hooked it up. Three wire plug under keyswitch was cut about 12" long, shoved into grommet next to seat.
Took way too long to discover that issue, but now tach works and I've verified it very close to accurate!

Maybe this boat isnt as waterlogged as I think!

Any new ideas/help much appreciated

[Machinist76]

With some time to kill this morning, I'll type a little more...

Stator and R/R seem to function correctly.
Trigger moves and timing light on indexed flywheel shows correct fire all cylinders.
Quickstart stays on for 30-45 sec when motor is cold...seems way too long for me.
It's only active for a couple seconds when warm.
My problem is above the S.L.O.W mode limit, right?

Oh yeah, and the damn trim unit has a bad check valve internally....if I give it fuel in reverse engine tilts out of water!

It's a project boat I got cheap, didn't realize I was going to need absolutely everything looked at/fixed! LOL...lesson learned.

I've ran a 2L 1987 Merc XR2 since 1997. Rebuilt it twice about 1999 then again in 2002. My fault in 02, ragged edge high timing,little lean,last year's water pump impeller...POW! 18years and counting its still a great gas guzzling engine. Maybe someday I'll replace it with a 4 stroke....done spent $17,000 in gas in that 2stroke!

Needless to say, I'm starting to think less of OMC stuff.... Had. a 48special 93 model or so and a XP200 88 I think that were fine engines....didn't have either more than a summer though....

Dad's a Vietnam Veteran and they are done cutting skin cancer off of him so I gotta go for now. Hope you enjoyed my story

[FMP]

Solid core, NO resistance lead and boots. Check end to end continuity while gently bending and twisting the lead boot to boot. If you find a bad end remove boot , cut off 1/2" and reset the clip and boot.

http://www.marineengine.com/newparts...num=OMC0582365

[warriorcookie]

How do you know it's not a bad powerpack? What test did you do?

I had a similar issue that ended up being the power pack... Test it before you throw parts at it though.