rpm big difference twin engines

[Seadeals]

One day when I am not entertaining the kids and wife on tubes and beaches, I will run YDS at WOT to prove the engine is running at only 8000 RPM and not the 8500+ the tach likes to show. I believe 1.69 hours out of 284 (.6% of running time) between 8000-10000 RPM is from the very rare instances of cavitation, rapid acceleration and catching air where the ECM takes a second to kick in and rev-limit.

As for speed @Billtex2000 , I know you hate for me to tell you this; but that is real and has been repeatable trip after trip for five years (except when we have four adults and five kids on board). You can see I was fairly full of fuel and GPS verifies the speed closely with the speedo. Unless you have a wicked ballast system that you keep full (cool) or a stereo system that takes six batteries (cool), definitely look into the impellers (confirming model/pitch/condition) and wear ring clearances. You are probably overdue for a refurb. It should get mid 40s with properly pitched, good condition impellers and tight wear ring clearance.

 

[Billtex2000]

Oh, believe me @Seadeals , I know I'm overdue! I do plan on a trip to the service department in the Spring. My wallet is already starting to weep softly. lol Thanks for the advice/input!

P.S. - I pulled her out of the slip and into the driveway this passed weekend. Her bottom was pretty cruddy. I'm sure thats contributing to the speed isue at least a few mph. She'll get cleaned next weekend and waxed really well after the cleaning and in the Spring.

 

[gmtech16450yz]

Hi Guys, first post here. I grew up with boats, but haven't owned one for many, many years. Dirtbikes and cars are my main things. (Yeah buying a Yamaha boat was a no-brainer! I've got 3 Yamaha's in my shop at home already.) I'm no forum newb though, I come from car forums mostly, a lot of engine mods and tuning stuff. I'll put a video in my sig that will give everyone an idea of what I do. (Don't forget to turn on your speakers if you watch it!)

Happened to see this and thought I'd start off my first post with a knowledge contribution...

First off, the engines in these boats run differently because of the way they pull water in around the hull. Basically both engines turn the same direction, but they're pulling from different sides of the hull which effects the pump loading. It's normal for the port engine to run faster because of this. If they had counter-rotating engines it wouldn't be an issue.

Secondly, the issues you guys mentioned with the throttles not being synced all the way through from closed to WOT are absolutely adjustable. I know because my '17 212 was pretty far off in the middle of the throttle travel. If you take the black plastic cover off of your throttle housing, you will see 4 set screws with nuts on them. Those adjust the full throttle forward and the full throttle in reverse. So basically what you do is set both throttles around mid throttle and get the cable adjustments right on the TPS's. Then move the levers to full throttle forward and reverse. If they aren't the same or one isn't opening all the way, adjust the set screws to move how much travel each throttle lever has at the ends. It IS possible to get everything synced up perfectly, it just takes a little time.

I've only had this boat for a month or so but I've already made a TON of discoveries. I'll try to share them here or on the YJB forum. Yesterday I made my own ribbon delete spacers that should work a ton better than the ones you can buy. Not sure why they designed them the way they did but they certainly aren't optimized for smooth airflow that's for sure. Here's a couple teaser shots of what I've done on this boat in the month I've had it...

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Video...

 

[swatski]

I'll try to share them here or on the YJB forum.

Man, this is one awesome-est first post!!!
I certainly hope you stay here! LOL. We call the other forum a "dark site", go figure. But seriously, way more traffic in here.

Yesterday I made my own ribbon delete spacers that should work a ton better than the ones you can buy. Not sure why they designed them the way they did but they certainly aren't optimized for smooth airflow that's for sure.

There has been a lot of confusion with those RIVA spacers, but I think you got the wrong set. Yamaha has changed the intake manifolds in the 1.8l engines back and forth, kind of hard to follow which model got what, and some have the more narrow passage and ribbons (and smaller spacers to replace the ribbons).

Q: Did you also remove the "snorkels" from the air filter boxes? I really like those cut-outs, never seen anyone doing this before!

Are you considering a reflash? I think that with the N/A engines there not much to be gained on top (for speed), but in my limited experience throttle response (throughout the range) and especially low end can be improved dramatically.

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[Benny Sibbitt]

follow

 

[swatski]

First off, the engines in these boats run differently because of the way they pull water in around the hull. Basically both engines turn the same direction, but they're pulling from different sides of the hull which effects the pump loading. It's normal for the port engine to run faster because of this. If they had counter-rotating engines it wouldn't be an issue.

Correct! There is an old but pretty awesome literature from "Group K", these guys have figured a lot that stuff out in early twins http://www.groupk.com/yjetboat.htm.

Secondly, the issues you guys mentioned with the throttles not being synced all the way through from closed to WOT are absolutely adjustable. I know because my '17 212 was pretty far off in the middle of the throttle travel. If you take the black plastic cover off of your throttle housing, you will see 4 set screws with nuts on them. Those adjust the full throttle forward and the full throttle in reverse. So basically what you do is set both throttles around mid throttle and get the cable adjustments right on the TPS's. Then move the levers to full throttle forward and reverse. If they aren't the same or one isn't opening all the way, adjust the set screws to move how much travel each throttle lever has at the ends. It IS possible to get everything synced up perfectly, it just takes a little time.

That is a great tip!
I wonder, however, if you have had a chance to look at the RideSteady system for twin Yamahas - works basically as an electronic "splice-in" fly-by-wire - with any model that comes with APSs.
It is fantastic, and synchs the throttles electronically across the range. https://jetboaters.net/threads/new-...nch-for-twins-ridesteady-by-hydrophase.12590/

--

 

[gmtech16450yz]

Yeah the Riva spacers I got were obviously the wrong ones, but I didn't really like the way they did them anyway. I ordered them before I took anything apart just so I'd have them, but I should have just known I was going to make my own anyway. The way I made them, it's a smooth transition through the throttle body and into the intake, with the bore opening up as it goes to meet the "bump" in the manifold. I would have liked to port out that bump, but it's part of the strength of the manifold where it necks out for the throttle body mount. I did open up the "bump" a bit to match the inside diameter of my insert.

As far as a reflash, I'm still trying to gather info on that. If you guys know about the HPTuners or EFILive tuning software/hardware, go on the HPTuners forum and you'll see my screenname pop up. I've taught a lot of guys how to tune GM engines. So there's no way I'm paying for a handheld "tuner" with preset maps on these Yamaha engines. I haven't gotten around to it yet but I'm going to play around with seeing if I can read and edit these ECM's myself. If all else fails and I want to go big with adding turbos, I might actually just buy Motec ECM's for them! (yikes!) For now I'm just doing cheap, easy mods.

Thanks guys! And yeah, I copied/pasted this as my first post on the YJB forum and it wouldn't even let me post without a mod approving it! Not a good first impression. haha. I own a Cadillac CTS-V Wagon. The main Cadillac forum is HORRIBLE. The CTS-V Owners forum is AMAZING. Probably the same situation with these very similar jet boat forums?


Oh and yeah, I ripped those snorkels out of the intakes right away! As with the huge plastic "mufflers" in the exhaust. Those went bye-bye after my first time out with the boat. Along with the 4 feet of extra engine flush hose and about 6 feet of extra battery cables. WTF??? I'm from the auto industry. I've NEVER seen this kind of shoddy workmanship as I've seen so far on the building of this boat. Thankfully the engines are "pure" Yamaha.

 

[swatski]

As far as a reflash, I'm still trying to gather info on that.

Yeah, very little info on reflashing N/A 1.8s, but a ton of research on SC (SHO, SVHO available only in 192/195 models of Yamaha boats) - @SamCF just did his 192. Most of the research of course done on skis - with the same engines - so those guys tend to post on greenhulk.

--

 

[zipper]

@gmtech16450yz WELCOME to this site. That was a pretty jaw dropping first post. Wiping drool off the computer now. Glad to have you on board. Your shop looks complete and pretty amazing, but it would all just be eye candy if you did not have knowledge of how to use it. YOU obviously do. Well done...cant wait to see what you can do with a Yamaha. In the near future, I will be playing with my mechanical throttles to get them to sync. thru the full range of travel, if it is possible. I do like your "ribbon delete" mod. I have 4 per engine on my MR-1s and have been told available products do not gain any advantages. Nice work!

 

[gmtech16450yz]

Thanks again guys! You're all too kind.

I just thought of another tidbit I think I've seen mentioned as a problem...

The second time I had this new boat out I got a battery low warning on the dash. Both batteries read 9.5 volts, exactly. Connecting both batteries didn't change the voltages. That right there told me they weren't reading two different batteries but actually they must be reading both voltages off one battery. The engines ran and started fine so I knew the starter battery was charging fine.

Got home and did a little troubleshooting. Yeah, there was NO COMMON GROUND between the two batteries. Evidently there's a ground connect cable that the dealers are supposed to hook up during the prep. It's obviously sitting on somebodies tool box because it didn't get put on my boat. I made a ground connect cable and cleaned up the ridiculously long battery and ground cables at the same time. I also added a Samlex 1215 onboard battery charger/maintainer. That fixed the fact that the house battery wasn't getting charged at all.

Next was figuring out why the Connext display wasn't reading both batteries. I had an idea of how they would wire the display, I expected they took one of the voltages internally and the other had to come in by a separate sense wire. I found a small gauge red wire hooked to the battery isolators and disconnected it. YES! One of the voltages stopped reading. It was hooked to the same battery as the display itself was hooked to, the house battery. Idiots! I hooked that sense wire to the starter battery and guess what? The Connext display now reads both batteries. Amazing. haha. Not really. Just another example of the shoddy workmanship at the dealer prep level and also the boat assembly level. Pretty disappointing.

So if your Connext display doesn't read both batteries, simply move the little red wire from the house battery to the starter battery.

The Connext display will read the house battery as "System" since that's what it's getting it's power from. The starter battery will be the "Auxiliary" battery voltage.

 

[swatski]

Thanks again guys! You're all too kind.

I just thought of another tidbit I think I've seen mentioned as a problem...

The second time I had this new boat out I got a battery low warning on the dash. Both batteries read 9.5 volts, exactly. Connecting both batteries didn't change the voltages. That right there told me they weren't reading two different batteries but actually they must be reading both voltages off one battery. The engines ran and started fine so I knew the starter battery was charging fine.

Got home and did a little troubleshooting. Yeah, there was NO COMMON GROUND between the two batteries. Evidently there's a ground connect cable that the dealers are supposed to hook up during the prep. It's obviously sitting on somebodies tool box because it didn't get put on my boat. I made a ground connect cable and cleaned up the ridiculously long battery and ground cables at the same time. I also added a Samlex 1215 onboard battery charger/maintainer. That fixed the fact that the house battery wasn't getting charged at all.

Next was figuring out why the Connext display wasn't reading both batteries. I had an idea of how they would wire the display, I expected they took one of the voltages internally and the other had to come in by a separate sense wire. I found a small gauge red wire hooked to the battery isolators and disconnected it. YES! One of the voltages stopped reading. It was hooked to the same battery as the display itself was hooked to, the house battery. Idiots! I hooked that sense wire to the starter battery and guess what? The Connext display now reads both batteries. Amazing. haha. Not really. Just another example of the shoddy workmanship at the dealer prep level and also the boat assembly level. Pretty disappointing.

So if your Connext display doesn't read both batteries, simply move the little red wire from the house battery to the starter battery.

The Connext display will read the house battery as "System" since that's what it's getting it's power from. The starter battery will be the "Auxiliary" battery voltage.

Wow, man, you move fast!!
The voltage reading error issue has previously been reported in the new 240s with the Connext and a patch/fix was developed by the resident electronics guru, @Mainah.
https://jetboaters.net/threads/fix-for-connext-battery-voltage-issue-confirmed.11381/
It is a long thread...
Some of us have done it and it definitely works, but I can't tell right now if it is the exact same issue and solution that you found.

--

 

[gmtech16450yz]

Hmm. My "fix* is to simply put the sense wire where it belongs, literally move it from one battery terminal to the other. The guys putting the boat together simply can't follow directions or the directions are wrong.

Sounds like that thread makes it a lot more work. "System" and "Aux" would end up being "Starter" and "House", but to me that's not exactly right. The "System" voltage should be exactly that, the battery that's powering the Connext display.

Some of you guys can look at which battery the small gauge red wire is hooked to on your boats. Imho it's supposed to be on the starter battery. That way the Connext display reads it's own voltage internally and the starter battery externally. BTW make sure you put the red wire directly on the starter battery post.

 

[buckbuck]

Thanks for joining us @gmtech16450yz . You already have made a fantastic contribution and we look forward to more of what you have.

 

[Billtex2000]

If you take the black plastic cover off of your throttle housing, you will see 4 set screws with nuts on them. Those adjust the full throttle forward and the full throttle in reverse. So basically what you do is set both throttles around mid throttle and get the cable adjustments right on the TPS's. Then move the levers to full throttle forward and reverse. If they aren't the same or one isn't opening all the way, adjust the set screws to move how much travel each throttle lever has at the ends. It IS possible to get everything synced up perfectly, it just takes a little time.

Soooooo... @gmtech16450yz when you say "Mid-throttle", do you mean mid-throttle forward of that first detent? And once there, how do I know if the TPS adjustment is "right"? They won't be on the stops if I'm only at mid throttle, correct? They only hit the stops at WOT. Sorry, I'm just a bit confused. And if what you say rings true, do I definitely have an issue because my port engine is slower than my starboard? At least @Seadeals port engine is spinning faster than his starboard, like you say it should be. Best case scenario, I'm hoping now that if I can do something with throttle adjustment I can get back the missing RPM's on my port engine and maybe run 8900(P)-8500(S)...closer to what @Seadeals runs. BUT, right now both of my throttles are "on the stops" in the engine compartment with full forward throttle levers. So wouldn't my "adjustment" be between where the throttle stops are (forget what you call it) and the engine itself? How do I get the port engine to rev higher if it's throttle is on the stop? Is that even adjustable, or is that a loaded question? lol I read something on here once about a Throttle Stop Screw on the engines to adjust idle for No Wake Mode issues. Or am I just back back to my port engine, pump or impeller having an issue.

 

[swatski]

Hmm. My "fix* is to simply put the sense wire where it belongs, literally move it from one battery terminal to the other. The guys putting the boat together simply can't follow directions or the directions are wrong.

Sounds like that thread makes it a lot more work. "System" and "Aux" would end up being "Starter" and "House", but to me that's not exactly right. The "System" voltage should be exactly that, the battery that's powering the Connext display.

Some of you guys can look at which battery the small gauge red wire is hooked to on your boats. Imho it's supposed to be on the starter battery. That way the Connext display reads it's own voltage internally and the starter battery externally. BTW make sure you put the red wire directly on the starter battery post.

I'll need to look into this again as I have already forgotten what it was about. But I am pretty sure the issue in the 2015+ 240s was with continuity within the SPU (black box inside the strbd rear compartment) that made both starter and house voltages read the same.
You may have found a different way to fix this (serious, IMO) issue or the two models have two different issues.
At any rate - you rock, man.

--

 

[swatski]

Sorry, I'm just a bit confused. And if what you say rings true, do I definitely have an issue because my port engine is slower than my starboard?

I would check if by any chance your port and strb impellers are not "switched", which has happened before. The port impeller has distinct markings on the "neck" and it is also pitched more aggressively especially on the leading edge:
(not my pic, I had it saved for reference from somewhere)


You should be able to see the markings through the intakes (with a flash light), I would start there. Also possible that your starboard impeller (or wear ring) has some damage, or you have sealant missing in the strbd tunnel/wear ring/transom plate - and suck air causing some cavitation - which would allow it to spin faster (albeit not in a productive way, just less resistance on the blades due to air intrusion).

--

 

[Seadeals]

Great discussion and sweet post @gmtech16450yz. To @swatski point, it wouldn't be that far fetched for a previous owner to pull both pumps and swap them (accidentally) going back in. I don't have near the technical background; but understand each engine to be electronically controlled by one of these:

The above is shown with the throttle cable at neutral and idle detent.

Here it is at full throttle (on the stop). So my only point is seeking confirmation that in this configuration (on the stop) the rpm is fully controlled by the ECM and has nothing to do with throttles at the helm as long as they are rigged to get you to the stop. I can't speak for other newer models. Also from my earlier post, I believe the tachs to be a very approximate representation of actual engine/ECM-reported RPM. Please let me know if I am missing something.

 

[swatski]

@Seadeals I think @gmtech16450yz was adjusting the throttle levers (under the black cover), albeit the APS cable adjustments also help - if you have any slack and are not hitting the "stops" you are not getting full RPM at WOT.

BTW - In the pictures your posted above - those are accelerator position sensors (APS) - so your boat can be fitted with the RideSteady, unlike the MR-1 HO models, which have a mechanical throttle connection to the throttle body (and are not compatible with RideSteady).

--

 

[Seadeals]

I have been drooling over ridesteady. No downside except spending the dough. I now understand the rigging of the throttle levers for alignment up until they hit the APS stops "click". What I struggle with is making any adjustments based off indicators (tachs) I believe to be inaccurate (up to 750 RPM at WOT on my port). If it were really 8750, the ECM would be logging tons of hours in the 8,000-10,000 band as reported on YDS and I would have seen that in the port to starboard hour log comparisons. I think I may play around with YDS on the water a bit and then possibly play around with the throttle lever assembly (+ finally fix the port lever slip back) if I feel there is an actual rpm split (per ECM YDS output and sound). Truthfully I don't mind the indicated rpm/lever split; but tinkering is part of the fun. Too bad YDS disables the tach. It would be nice to compare both in real time.

 

[Mainah]

Wow, man, you move fast!!
The voltage reading error issue has previously been reported in the new 240s with the Connext and a patch/fix was developed by the resident electronics guru, @Mainah.
https://jetboaters.net/threads/fix-for-connext-battery-voltage-issue-confirmed.11381/
It is a long thread...
Some of us have done it and it definitely works, but I can't tell right now if it is the exact same issue and solution that you found.

--

Sounds like swapping the red “sense” wire at the battery isolater the better way to go. Can’t say that I recall seeing that wire on my boat but I was not looking for it.When I tackled this I never traced beyond the SPU. I knew that something had to be sending the voltages to the display and figured out that the SPU was handling that so that is where I started and did not dig further when I figured out how to fix it there.

As for rpm display. There is a tach pickup on the engines that goes to the ecus and then to the analog gauges and connext from the ecu. The refresh rate of the connext gen 1 display is not great which is why you see the rpms jumping so much on the connext display. If you observe the analog tachs or ridesteady (tee off the pickup during install and higher refresh rate) you will see the rpms displayed much smoother. First step if you are not getting full rpms is to adjust the cables so you get to full stop just before the throttles max out and then balance the left and right side. If that is not the issue then it is something to do with the pumps or in rare cases the engine.