Chasing a 300-400 RPM drop issue in Port motor!!
#111
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Thread Starter
I gain speed tuning either direction. I just pick up more when freeing up the port side for some reason. But yes, I did make a change to the tie bar. I tightened it up a few turns (drawing the props closer together)
#112
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Well, I swapped the drives and also adjusted toe to 1/8" in. Also adjusted the port throttle cable a bit. Not sure what exactly to say because the problem didn't chase to the other side. It basically went away. Port side was still about 150 rpm lower but that's a huge improvement I can live with. AFR was mid 12's all the pulls. I am against the 6400 limiter on the starboard now at around 6300ish. Port was about 6200. Very confused and don't know exactly what fixed it BUT I'll take it! Props need some more pitch added so I'll give BBlades a call and get that straightened out.
#113
Banned
Just going back to your words in post # 68
rpms off even in Neutral .
and open carbs up to the same position still off - 200 - 300 rpms
So what else changed ? or did you change ? .
rpms off even in Neutral .
and open carbs up to the same position still off - 200 - 300 rpms
So what else changed ? or did you change ? .
Last edited by BUP; 10-23-2015 at 10:33 AM.
#114
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Thread Starter
I checked throttle openings countless times. They were always the same. 2 days ago I simply adjusted the port cable a little tighter because the starboard cable was triggering the accelerator pump a little faster off idle. Other than that I swapped the drives and adjusted toe from neutral to toe in 1/8". That's it. I don't get it at all. Basically it will take another test to back it up but I do know I ran out of prop. Need a set of 34p Maximus 5 blades.
#116
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It's winterized now. More testing in the spring. I didn't expect the last test to result in that. Makes me almost think during WOT pulls the engine vacuum may be trying to pull the blades shut some on the port cable. I just can't feel it because the cable could be stretched. Would also agree with not having a difference with engine off... Just a thought anyway....
#117
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I just bought a 2003 30' Daytona a couple weeks ago, pretty stock with 525efi and bravo xr's. Similar issues yours.
The original owner told me the port motor always ran 200 rpm behind the starboard which I found was true. I have not had it long enough to start checking trim of the drive or toe in but can get the revs to match with a bit more port throttle say about 1/2" more and more port trim.
Is 200rpm difference within reason for you other guys running a twin cat?
The original owner told me the port motor always ran 200 rpm behind the starboard which I found was true. I have not had it long enough to start checking trim of the drive or toe in but can get the revs to match with a bit more port throttle say about 1/2" more and more port trim.
Is 200rpm difference within reason for you other guys running a twin cat?
#118
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I have a twin cat with Merc. 700's that has livorsi tachs and also mercury smartcraft display. I have been amazed by the discrepancy between the readings of the Livorsi gauges and the smartcraft display. The tach gauges are different than each other and different than the smartcraft. I thought I had 1 engine that was quite a bit different in rpm given throttle position, then frequent checksto the smartcraft, reveal error in gauge tack readings. Everything is different, fuel pressure, oil pressure, water pressure, temperatures.
Bottom line..........I do not think you can hang your hat on guage readings...... use them as an imperfect guide.
Bottom line..........I do not think you can hang your hat on guage readings...... use them as an imperfect guide.