Set Timing and lost RPM

[rdfkentucky]

1986 Black Max XR2 150 OB122507

Using OEM Manual 90-97658-3

When I bought this boat it would turn 6000 RPM's. I few years ago I removed the Advance Timing Module and re-set the timing, Sync-n-Link done. Rebuilt the Carbs.Replace all fuel lines, and Still didn't run like before, but did 5400-5600 RPM's and little slow till it reach 2000 RPM, then it took off. Play with it some more and left it alone.

I didn't get to use it much, just a few times a year due to work. Decided to try again this year.

Checked compression both cold and warm motor, 115-120 psi on all cylinders, check spark, was good on all, Install new plugs NGK NU8H, Fuel filter. Check TDC with timing pointer alignment at .462. Adjust throttle pickup timing at 4 degrees and WOT timing at (cranking) 20 degrees. Adjust idle RPM in gear in the water, 700-800 RPM.
Still slow till 2000 RPM, then takes off, but only got to 5000- 5200 RPMs. About 4 seconds to get on plane. Motor runs good, starts and idles good.

What should I check now?


Thanks
Rick

[luvdmymerc]

Check your tach with a good shop tach that you KNOW is accurate. The in dash tachs are famous for being iffy...Double check those spark plugs too. I know they update them every now and then. The last XR2 I rebuilt called for NGK-BUHW but then I was told to change over to NGK-BU8H... so it wouldn't hurt to double check.

[JOE54]

ya killed it that module was an idle stabilizer and advance module both in one box it advanced the timming 6 drgees at 5600 same as early 200 ,set timming at 25 or replace module you can use BR8HS-10 also in it, 4 sec not bad for plane check linkage for advancement no lag on spark arm make sure bleed system is working right idle timming is right or lil faster (rich)fiber reeds will help that one don't use dual stage , remember its a 2.0L mtr with a big tuner ,old bell shaped they weren't real spiffy outa hoe , don't over prop it good luck

[rdfkentucky]

Thanks for the reply, just now got a chance to get back. Going to try checking everything this weekend. Not sure about "bleed system is working right", I have a Tempest 23p prop.

[rdfkentucky]

I got to try it out Sunday, Max cranking timing @22 degrees. Idle RPM in water & gear around 600 RPM, ramp and dock was busy. Running better on top end, up to 5800 RPM by trimming higher, but water pressure drop below 10 psi, I need to lower my Jack plate and try again. Prop to Pad @ 3.25".

[JOE54]

roll at timming up lil more, TEMPEST may be lil big in JULY/AUGUST loaded for that 2.0