gofastlvr

I have twin 500 efi's and through the rpm range therer is a 100-200 rpm difference between engines. I am running B1 drives and they are turning out. Engines have 300 hrs. I am at 5200 @ wot on star and about 5050 on port. Down around 4000 it is about the same. Even as low as 3000 there is a difference and its always that motor. I've checked trim settings varying each drive with no change. Ive changed props and nothing. The motors run strong up through the range pulling well running 80-82.

What else could it be other than a sender or gauge issue. I guess there could be resistance in the drive looks like that would make some kind of noise. The drive oil looks great. The engine fluids look fine.

Any ideas?

Dkahnjob

I have virtually the same boat as you, mine is a 2000 classic 35' single step with 500's. I am running B1 drives, turning in with 28P Bravo 4 blade props. my rpm's stay pretty much together until top speed. As I trim the drives up the starboard drive will start to blow out and over rpm before the port. I end up running the starboad about 1/2 lower than the port side. I assumed it is a rotational thing with the props. But that is just a guess. Around 5000 rpm and 78 mph at lake Havasu, AZ 115 degrees and 600' elevation.

John Worthing

On my new 2007 38 Lightning the port motor was about 100 to 200 RPM higher than the starboard. At WOT it was around 250 higher. After adjusting the throttle cables, having the prop's labbed (BBLADES) it was a little better.

I then installed a Smartcraft Monitor gauge to each motor, Guess what? My Monster tachs are not all that accurate.

My motors are running withing 3/10's of each other at all times (according to Smartcraft). At times they fluctuate within 1/10 at cruising RPM's.

My port monster tach is NOT ACCURATE! The starboard tach is OK at best.

I suggest installing the Smartcraft Monitors or at least use a pair of digital tachs for dialing in props and such. And have BBLADES true up your props for a perfect match.

Good Luck,

John

woodington1

GOFAST had same problem with/525's tried props checked cables drives ect. chased it for year next season got a little worse took out injecters had them cleaned,replaced one, problem went away !!! keep those injectors clean the way gas is today HOPE THIS HELPS

woodington1

GOFAST had same problem with/525's tried props checked cables drives ect. chased it for year next season got a little worse took out injecters had them cleaned,replaced one, problem went away !!! keep those injectors clean the way gas is today HOPE THIS HELPS

MikeyFIN

Friend has the same problem with a 35 ´07 and it´s 425HO´s----port engine is lagging 200rpms.

techman

I agree with John. The Livorsi gauges look great, but analog gauges leave a bit to be desired for accuracy. My smartcraft readings are pretty darn close on all parameters compared to larger fluxuations in the monster gauges. I think the digital signals from the sensors to the ecms are much more accurate.

Tinkerer

The engine with the power steering pump will usually run a little slower.

John Worthing

BOTTOM LINE! If you do not have an accurate tach reading on both motors your guessing at best. Dirty injectors, bad prop, whatever, your guessing!

On the new blue motors there is an interface module that converts the true digital signal from the Smartcraft to the Livorsi (Analog) Monster Tach. If the Livorsi Tach were
perfect you would have the same reading as the digital output from the Smartcraft Module.

I installed a Smartcraft Monitor directly above each Monster Tach. It looks fine, and now I know what my RPM's really are. Having all of the other info available on demand is very nice. I highly reccomend this option.


John

Back4More

ignition module?