Thermostat housing hole.

[Sea Rider]

I flush many Yam/Tohatsu large HP motor with posted ear muffs with 0 issues at all, don't need to flush them in a barrell to compensate back pressure. All these motors have had their exhaust covers, cylinder heads removed and all their water passages mechanically desalted and decarboned to factory conditions. Check if possible to find out if your motor has been used in salt water by previous owner.

If suspect the motor has stuck rubber pieces or whatever in the water passages, remove lower leg, remove thermo, put cap back on and connect a water hose on the water pick up tube, flush the motor at wide open faucet for 10-15 minutes. Would be much better to test the motor at open water, rather than on muffs, plane the boat at reduced throttle and check if everything is working ok.

Happy Boating​

 

[Douglasdzaster]

I flush many Yam/Tohatsu large HP motor with posted ear muffs with 0 issues at all, don't need to flush them in a barrell to compensate back pressure. All these motors have had their exhaust covers, cylinder heads removed and all their water passages mechanically desalted and decarboned to factory conditions. Check if possible to find out if your motor has been used in salt water by previous owner.

If suspect the motor has stuck rubber pieces or whatever in the water passages, remove lower leg, remove thermo, put cap back on and connect a water hose on the water pick up tube, flush the motor at wide open faucet for 10-15 minutes. Would be much better to test the motor at open water, rather than on muffs, plane the boat at reduced throttle and check if everything is working ok.

Happy Boating​

Owner has moved and I can’t get in touch. He said he was fresh water only and the person he brought it from had a jet drive on it for the river here and were to far away from the coast for brackish water. It looks like scale build up like in a coffee pot. The outside of the engine has a few paint chips but no corrosion that looks like salt to me anyway. A few bolts with some rust. Other than that it’s the aluminum vs the different metal in the bolts (can’t think of the name). I saw on a Yamaha page where they flushed the scale out with vinegar and a circulation pump. Takes 1 to 2 hours then flush with fresh water. I don’t mind taking it apart and cleaning it I just don’t want to end up at the shop in town with more broken bolts. I’m going to have to do something. Knowing it’s in there will drive me crazy now until it’s cleaned. I have to have everything perfect or I worry myself. That’s why I’m still paranoid about what I did with the air hose the other day even though the lower unit seems fine with no leaks and some pressure even came out when removing the top bolt. That should tell me it’s not leaking if holding pressure. But what i saw come out the water pickups was the same green as the gear oil. Where did it come from? I’ll feel better after a successful lake run. With all the work I’ve done I definitely have more confidence in the boat I’ll have my tools with me. If it doesn’t run smooth at wot what should I try adjusting. The linkage is flaps open at wot and open just a little at idle after adjusting to spec rpms. Sorry I wrote you a book to read again. Just excited and anxious. Hey, no fuel leaks this time. Lol

 

[Sea Rider]

A fresh water motor due to constant On/Off cycles will build up scale along water particles adherences on the entire water passages but less worse than salt water motors. Vinegar which is at the most only 5% pure won't do a thing if the motor has highly reduced diam water passages. don't worry, that motor should run smooth at open throttle. Carb's butterflies must remain fully closed at idle/neutral and wide open at full throttle, if so there's nothing to adjust. Report the motor behaviour after fully warmed up at the lake at idle with all 3 pilot's crews adjusted to 1.5 in/out turns.

If interested in descaling internal water passages check this : https://forums.iboats.com/threads/m40d2-water-system-question.742500/page-2 (last post).

Happy Boating​

 

[Douglasdzaster]

A fresh water motor due to constant On/Off cycles will build up scale along water particles adherences on the entire water passages but less worse than salt water motors. Vinegar which is at the most only 5% pure won't do a thing if the motor has highly reduced diam water passages. don't worry, that motor should run smooth at open throttle. Carb's butterflies must remain fully closed at idle/neutral and wide open at full throttle, if so there's nothing to adjust. Report the motor behaviour after fully warmed up at the lake at idle with all 3 pilot's crews adjusted to 1.5 in/out turns.

If interested in descaling internal water passages check this : https://forums.iboats.com/threads/m40d2-water-system-question.742500/page-2 (last post).

Happy Boating​

Just got in from working on the trailer. It should be easier to launch now I hope anyway. Still planning on the trip tomorrow so I’ll let you know how it goes.

 

[Douglasdzaster]

Just got in from working on the trailer. It should be easier to launch now I hope anyway. Still planning on the trip tomorrow so I’ll let you know how it goes.

Just test ran it before I head out. Kind of hard starting and it’s developed a cough at about 1500 rpms bring it back down to idle speed and no cough. Guess I’ll find out at the lake. First time I ran with the silencer on. Could that have any effect? Oh I put the new muffs in my vise and squeezed them. They fit tight and the engine peed like a champ and no overheating.

 

[Sea Rider]

I guess that motor has had enough being run too much on muffs. Check if the new spark plugs have been darkened/fouled too much on muffs. Run it on the lake after being fully warmed up at different throttle settings . By "silencer on" you mean the top cowl or the carb's tall air silencer ? All motors must be run with both sitting in their respective place. There's nothing that can resist to a vise grip LOL!!

Happy Boating​

 

[Douglasdzaster]

I guess that motor has had enough being run too much on muffs. Check if the new spark plugs have been darkened/fouled too much on muffs. Run it on the lake after being fully warmed up at different throttle settings . By "silencer on" you mean the top cowl or the carb's tall air silencer ? All motors must be run with both sitting in their respective place. There's nothing that can resist to a vise grip LOL!!

Happy Boating​

I was speaking about the intake when I said silencer. Made it to the lake but running late. Forgot my life jacket and had to rent one from the office. To return it In time gave me about an hour on the water. Engine didn’t cough or cut out any. Idle as low as 600 rpms and 400 in gear. Wot boat seemed to be running good but I think it could be better . I don’t know if it’s the cheap tachometer or what but it only showed 2040 rpms at wot. Every now and then I would feel it and it dropped to 1910 rpms. Like I said though I was trimmed out and moving pretty good. I can’t imagine it going twice as fast. Anyway since my time was short I just ran it the whole time. I’ll be making another trip soon and I’ll double check that the tachometer is set correctly for the engine and make adjustments to the idle. I’m wondering if the cdi is set correctly it’s not even on the scale of lines there for it. I don’t know much about them. I feel like it should be putting out more but I don’t know about twice as much. Maybe so. Everything else worked well. Water pump was good. Well, except for the winch on the trailer. It’s worn out and the latch gave way and the handle spun back and hit me in the shoulder. Made me not talk nice for a second. Today I feel like I was hit with a hammer. So it WILL be replaced before the next outing. Lucky I always carry extra straps and tied the boat down to get it home.

 

[Sea Rider]

That tach as installed seems is reading 1/2 rpm of the true rpm the motor is achieving. Aside setting the unit for 1 or 2 sparks per revolution need to set the tach to 3 cylinder as well. Have you tried running the motor with trim set to 90º ?
​

The idea is to run it that way and if the motor sits at the sweet transom height go for a prop maximization to run towards its max wot rpm range as loaded.

Happy Boating​

 

[Douglasdzaster]

I would have tried lowering it yesterday but I was short on time. From looking at it at the dock it only needs to go down a notch maybe two. The bow rises just a little at take off and keeps the boat trimmed about half way out the way it is. It did better the first time I took it out though. Before doing the carburetors. I’m wondering about the cdi. If they had it adjusted due to the carburetors being so bad. The needle on it isn’t on any of the settings. I can’t find specs on my engine anywhere. There should be a setting for idle and wot just don’t know what that is.

 

[Sea Rider]

That I know CDI's are solid state non adjustable electronic devices.. Has nothing to do with carbs, are married to the exciter and ignition coils as well. At 90 trim setting, spot on motor/transom height matched, well propped to run towards max wot rpm, the combo will literally jump on plane near instantly while the boat runs parallel to the water level. BTW, motor's physical height has nothing to do with trim settings, has to do with the angle of the motor sitting on transom. Try that setting whenever possible and report if performed much better than previous two runs...

Happy Boating​

 

[Douglasdzaster]

That I know CDI's are solid state non adjustable electronic devices.. Has nothing to do with carbs, are married to the exciter and ignition coils as well. At 90 trim setting, spot on motor/transom height matched, well propped to run towards max wot rpm, the combo will literally jump on plane near instantly while the boat runs parallel to the water level. BTW, motor's physical height has nothing to do with trim settings, has to do with the angle of the motor sitting on transom. Try that setting whenever possible and report if performed much better than previous two runs...

Happy Boating​

Maybe I called it the wrong thing. It’s a black box with an arrow on it that is moved by the throttle linkage. There two different adjustments on it.

 

[Sea Rider]

Maybe I called it the wrong thing. It’s a black box with an arrow on it that is moved by the throttle linkage. There two different adjustments on it.

For clarification post a pic to check that out. Does the adjustments mentions anything ? Must be posted in the Service Manual for sure.

Happy Boating​

 

[Douglasdzaster]

Here’s a picture of that box. I found my missing rpms today. When I last messed with the linkage making sure all three carburetors where in sync. I didn’t check the throttle I guess. Today I looked at the carburetors and opened the throttle to wot and they were only opening maybe 3/4 of the way. So I adjusted the throttle. They now open exactly level not to far as so they’re closing again. Now I bet I get the ride I’m looking for. Just need another calm day. The tachometer has a default setting for 4 stroke. I set it for 2 stroke the first time I used it. Maybe I’ll have to set it each time. It does not have a setting for how many cylinder.

 

[Faztbullet]

That is your CDI engine control box. Your magneto is fixed and timing is controlled thru linkage settings. With engine off, shift into gear and open throttle to WOT. The needle should point to the top cast in line on plastic of CDI box. The lower three cast lines are idle timing and usually the middle line is close. And also engine height does matter to trim settings...

 

[Sea Rider]

If you bought a Runleader Ind Tach like the one below...

Must adjust the firing pattern to 3P1R (2 Stroke/3 cylinder) or the idle and wot displayed will read false rpm's. To my particular taste that tach has too many settings to play with. With patience find the Programmable Firing Pattern and adjust it to that precise setting. Good Luck!!

To know if that motor sits at the sweet transom height apply the second pic parameters seen in post 189; go for a wot run on flat calm water cond and visually check at which lower leg is the water flow passing by out transom, that's soon after the motor has been spot on CDI/carb timing synched and running strong as a champ.

Happy Boating

​

 

[Douglasdzaster]

That is your CDI engine control box. Your magneto is fixed and timing is controlled thru linkage settings. With engine off, shift into gear and open throttle to WOT. The needle should point to the top cast in line on plastic of CDI box. The lower three cast lines are idle timing and usually the middle line is close. And also engine height does matter to trim settings...

Thanks for the knowledge. Always appreciated. It’s not running bad but I was concerned if this isn’t set correctly could it cause damage. I worry about everything I touch on this engine. I’m surprised Searider is still talking to me with all my worries. Lol

 

[Douglasdzaster]

If you bought a Runleader Ind Tach like the one below...

View attachment 336122Must adjust the firing pattern to 3P1R (2 Stroke/3 cylinder) or the idle and wot displayed will read false rpm's. To my particular taste that tach has too many settings to play with. With patience find the Programmable Firing Pattern and adjust it to that precise setting. Good Luck!!

To know if that motor sits at the sweet transom height apply the second pic parameters seen in post 189; go for a wot run on flat calm water cond and visually check at which lower leg is the water flow passing by out transom, that's soon after the motor has been spot on CDI/carb timing synched and running strong as a champ.

Happy Boating

​

All mine ask for is how many times it fires per revolution. I think I paid around $10 bucks for the thing.

 

[Sea Rider]

All mine ask for is how many times it fires per revolution. I think I paid around $10 bucks for the thing.

You're always welcome to dispel your technical doubts, nobody was born with boating knowledge, it's a slow learning curve we've all been through. Can you post a pic of the tach you bought ? If the thing is limited to just 1-2 cylinders and 1-2 sparks per revolution, don't know if will read half or double rpm when at wot ? The Runleader tach shown sells for round $ 17.00, don't know what you bought for around $ 10.00 ? LOL!!

Happy Boating​

 

[Douglasdzaster]

If you bought a Runleader Ind Tach like the one below...

View attachment 336122Must adjust the firing pattern to 3P1R (2 Stroke/3 cylinder) or the idle and wot displayed will read false rpm's. To my particular taste that tach has too many settings to play with. With patience find the Programmable Firing Pattern and adjust it to that precise setting. Good Luck!!

To know if that motor sits at the sweet transom height apply the second pic parameters seen in post 189; go for a wot run on flat calm water cond and visually check at which lower leg is the water flow passing by out transom, that's soon after the motor has been spot on CDI/carb timing synched and running strong as a champ.

Happy Boating

​

All mine ask for is how many times it fires per revolution. I think I paid around $10 bucks for the thing.

You're always welcome to dispel your technical doubts, nobody was born with boating knowledge, it's a slow learning curve we've all been through. Can you post a pic of the tach you bought ? If the thing is limited to just 1-2 cylinders and 1-2 sparks per revolution, don't know if will read half or double rpm when at wot ? The Runleader tach shown sells for round $ 17.00, don't know what you bought for around $ 10.00 ? LOL!!

Happy Boating​

its settings are for once per revolution, twice per revolution, and once every other revolution. Information about it is on Amazon.

 

[Sea Rider]

One, two and once every other revolution it's OK, that tach is missing half of the equation which is the number of cylinders the motor works with. That tach is useless. Return it to Amazon, tell them it's not for your type of motor and get the one posted above....​

Happy Boating