2009 21X3 questions

[MattVT18]

I searched for all the 21X3 threads and found some useful info but thought I'd ask a couple of questions of my own. I posted about a suspected engine issue in the 3.0 Merc forum but wanted to see if this could be more of a setup/hull issue.

I'm currently running a 25P Tempest Plus. Can spin it to upper 5900s RPMs and today it ran 66 MPH with my partner, most of a tank of fuel, tourney load and extra water from rain. However, I have to get to full speed trimmed all the way down before I start to trim up or I seem to be limited to about 5k RPMs. Today was kinda rough with wind and lots of tourney traffic, several times I'd be running along and hear the engine change. When it changed, the RPMs drop. Most of the time I could hold it WOT and it would come back when I hit a wave a little later. I can also come to a stop, trim all the way down and start over and run full RPMs again. Has anyone experienced this? I'm going to reach out to my mechanic when he gets back from vacation to have him see if he can find something but it seems strange how it happens.

Second, I have a 27P Tempest Plus and a 26P Fury 3. I've tried the 27P when the engine was acting up so I don't really have good data on it. Any one have success with a 27 Tempest Plus or 26 Fury? Thinking I might take the 27 and get it repitched or sell it and the Fury to buy something else.

[jbh3]

Sounds like it's is intermittently dropping a cylinder. Are your plugs pretty fresh? Known, good, BIG battery that's fully charged? Might also check under the "hood" to be sure all electrical connections (cannon plug, spark plug and coil wires, battery terminals, etc.) are securely connected. From what I remember, the X3 hulls were not known for high speeds vs the "X" or "XHP" hulls that were speedier, but required more driver input. I believe a good 25 Tempest may wind up being the best prop. Would also be interested in the contact info for the tech you're using. Have a good one!

[MattVT18]

jbh3 - the 25 is a solid performer so far. Was hoping someone had some experience with other props to help me decide what to do. I'm planning to try the other 2 props once I get the intermittent issue figured out. The battery meets all specs and seems fine. I haven't spent much time with it looking for issues yet. I just bought it a little while back and it was not able to get above 5k RPMs so I just took it my mechanic to check it out. We thought he had it but this issue pops up occasionally. I'll check around under the cowl to see if anything looks out of place but will most likely just take it back. He wasn't sure it was "fixed" after the initial inspection. I'll PM you his name and number. He's been great to me and many others when it comes to Optimaxes.

[MattVT18]

Update in case someone else finds this in a search (honestly fixed it a while back and forgot!). Found two different issues: one of the keeper clips on an injector plug was not fully seated and one of the spark plug boots was torn just a bit allowing it to short to ground occasionally. Once those two were fixed it runs great. The 26 Fury 3 blade is the best prop I've tried so far. 70 ish with just me, 67ish with partner and tourney load.