Reduced Speed

[Banditgrrr]

The altitude at Lake Mead is 1250 ft. I just launched the boat for the first time on Friday. It got up to about 45mph for the first mile and about 7200 rpm. Then all the sudden it was like an immediate loss of power and it dropped to about 35-37 mph and 6500 rpm. I didn't think it would be a heat soak issue as I let the boat sit over night and it would still only get up to about 35mph/6500rpm when I first took off in the morning. The prop was pretty chewed up but that shouldn't affect the RPM's either. I'm going to go out in the garage tonight and check the connections at all the hoses. Maybe disconnect each one and reconnect it. I also just installed new plugs but the ones I removed still looked pretty good.

 

[swatski]

It got up to about 45mph for the first mile and about 7200 rpm.

Well then, will need to get you back up to those RPM - that's not bad for Lake Mead I would think. But it should not be dropping!
There is a pretty good thread on 192 mods started by @SamCF - long read but if you have the time it may be worthwhile, there is a ton of good info there on SC 1.8s.
https://jetboaters.net/threads/sx-192-mods.6550/

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[haknslash]

Hmm that almost sounds like the time I was out testing the RIVA ribbon spacer and my upper intake hose coming from the supercharger to the IC came loose. I had removed all of that crap when I did the ribbon delete and just didn't tighten down the clamps as good as I should have. The clamps just slide up and off the tube when it was hot and under boost. It was a major PITA to get it on and tighten with a crap screwdriver while out on the water because it was one hot mofo and I kept having to touch the hose!!! I swear I got like 2nd degree burns that day . Limped it back to the dock so I could get to better tools in my truck and tighten down all the clamps so the hose wouldn't pop off or come loose again. When the hose came loose it was immediately felt and power/top speed dropped like I wasn't getting boost and driving around N/A. I knew exactly what it was from previously having a modded turbo car running moderate boost and it would occasionally blow off an IC tube. same feeling but on water. You'll want to check the clamps using a nut driver or socket. Don't use a flathead screw driver as you can't get a good bite.

 

[haknslash]

I heard back the guy I bought my SVHO intercooler from and he said he can't remember the size either but he said Rick or WFO on greenhulk would likely know.

 

[Banditgrrr]

Thanks for the info. I'll double check ALL the hoses. I made measurements on the SVHO IC cap and ordered these from Amazon and going to pick up a tap set from Harbor Freight tomorrow.

NPT barbs
https://www.amazon.com/gp/product/B077D3TFLM/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1

1/2" Y connector
https://www.amazon.com/gp/product/B017UXEF0A/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

[d_coyne1984]

I didnt see anyone mention this yet so if somebody did, sorry for playing repeater. One of the first things you should check when you aren't getting the RPM's you would expect is the throttle cable. Make sure (with the engine off) that when the throttle lever is all the way forward, that you are hitting the hard stop on the throttle assembly in the engine compartment. If not, you can adjust it.

 

[swatski]

I didnt see anyone mention this yet so if somebody did, sorry for playing repeater. One of the first things you should check when you aren't getting the RPM's you would expect is the throttle cable. Make sure (with the engine off) that when the throttle lever is all the way forward, that you are hitting the hard stop on the throttle assembly in the engine compartment. If not, you can adjust it.

Good point! And easy to check this. There is a Jet Boat Pilot quick video on how to do this. It could have loosened up after that initial run at 45mph.

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[Banditgrrr]

Thanks for the advice. I just checked the throttle adjustment. I had about 1/8th of an inch that wasn't hitting when I put the throttle forward. I adjusted it now so it's fully hitting the stop. This adjustment now prevents the limiter from hitting in full reverse but that's not near as important as forward. It's going to be a little while before I can take it out and test it because I still have several things I'm doing before I get back out on the water. Impeller replacement as mine is pretty beat up, IC upgrade to an SVHO and I plan on doing the ribbon delete.

On a separate note, I ended up purchasing the 1/2" Y connectors for the IC upgrade. They only come in a bag of 10. If anyone needs one, shoot me a PM and I'll mail it out.

 

[Banditgrrr]

So the latest in the saga. I was just reinstalling the pump after changing the impeller. Like a jackass, I put too much torque on the bolt to the right of my thumb and it ended up breaking the cable you see in the picture. It's actually more of a stiff metal rod with threads on the end. This is the cable that moves the gate up and down. Not sure of the name of it. I've looked on Partzilla at the link below. I'm not sure if this is the part being shown between items 13 and 14. If it is, I don't see a part number for it. I'm not even sure if this is the right diagram. I'm hoping this isn't one long cable that goes from the pump to the throttle. Any advice on how to get a part number for what I'll have to replace?


Is this it on Partzilla?
https://www.yamahapartshouse.com/oemparts/a/yam/540dcc06f8700217e452cd0a/control-cable

 

[swatski]

I'm hoping this isn't one long cable that goes from the pump to the throttle. Any advice on how to get a part number for what I'll have to replace?

Hmmm... I think it is the long cable... Damn.
@Bruce and others - can you chime in?
There is an FAQ on replacing the throttle cable, albeit most will be for the MR-1 boats the cable system is the same I think.

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[blacksapphirez]

the bucket cable has like a spring loaded part at the end that keeps it attached to the bucket ball socket, should not need any "tightening"

 

[Bruce]

It's actually more of a stiff metal rod with threads on the end. This is the cable that moves the gate up and down. Not sure of the name of it

That is the reverse cable. It does go all the way to the trottle.

Lots of info on the part at https://jetboaters.net/threads/seastar-teleflex-steering-systems-and-cables.10706

There are several posts on changing the steering cables.

I would consider changing both steering and reverse cables while you are in there. Next time you are on the water you will be glad that you did.

 

[swatski]

So the latest in the saga. I was just reinstalling the pump after changing the impeller. Like a jackass, I put too much torque on the bolt to the right of my thumb and it ended up breaking the cable you see in the picture. It's actually more of a stiff metal rod with threads on the end. This is the cable that moves the gate up and down. Not sure of the name of it. I've looked on Partzilla at the link below. I'm not sure if this is the part being shown between items 13 and 14. If it is, I don't see a part number for it. I'm not even sure if this is the right diagram. I'm hoping this isn't one long cable that goes from the pump to the throttle. Any advice on how to get a part number for what I'll have to replace?


Is this it on Partzilla?
https://www.yamahapartshouse.com/oemparts/a/yam/540dcc06f8700217e452cd0a/control-cable


View attachment 69566

@Neutron, @jcyamaharider, @bronze_10, @itsdgm, @Scottintexas Do you guys think this could be saved without replacing the entire cable? I seem to remember someone has done it here...

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[jcyamaharider]

You could probably die the end that has the broken threads farther back on and then put a coupler on the end of the newly threaded rod. After that get a threaded stud and screw into the other side of the coupler and reattach your quick connect carb end. Remember to use man nuts against the coupler also and maybe thread locker.

 

[swatski]

You could probably die the end that has the broken threads farther back on and then put a coupler on the end of the newly threaded rod. After that get a threaded stud and screw into the other side of the coupler and reattach your quick connect carb end. Remember to use man nuts against the coupler also and maybe thread locker.

That's kind of what I was thinking but was afraid to say it, it's much better coming from a talented machinist!
In a newish low hours boat that has not been wet slipped the cables could be fine for a few more years.

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[Banditgrrr]

After reading the info that Bruce provided, I called the local Yamaha dealer to get some info on the cable. It turns out they had the cable in stock. I asked them what it would cost for them to replace it and they quoted $70 for the part and 3 hours labor @ $120/hour. OUCH! The guy told me if I bring the cable in, they'll match it up. I decided to tackle this myself. It literally took me all of 15 min to remove the entire cable. I took it to the shop, paid $70 for the new cable and I was out the door. Going to install the new "reverse cable" tonight and it looks like it will be no big deal. The biggest issue will be to make sure I use quite a bit of silicone to seal the cable where it goes through the transom. If it's as easy as it appears, I can't believe they were going to charge me $430 to do this work.

 

[Neutron]

If you reattach the end to the cable, you will have a shorter cable so it will only work if there is room at the other end to lengthen it

 

[Bruce]

It is not worth trying to salvage.

 

[Neutron]

It is not worth trying to salvage.

Not if a cable is only 70 bucks

 

[Bruce]

Not if a cable is only 70 bucks

$35 a side https://www.marinepartssource.com/control-cable-assy-3300-tfxtreme-18ft-ccx63318?gclid=Cj0KCQiAieTUBRCaARIsAHeLDCTs9x4j0_3D4eF8UPEK5P6qr3iUn65REbxH9xmlWrvv05l-SRkUSU4aAncQEALw_wcB