How to adjust and prepare for 1st start after power head swap

[Eddie Rivera]

Just completed the power head swap from my 1989 50hp 507X9B to my 1991 50 hp 508F91C. It's ready to be started how ever I see that my tower shaft has everything out of adjustment and I don't feel comfortable starting it this way.

1) spark control/timing link seems too short.
2) top idle or fill screw is not touching.
3) shift arm at tower shaft don't quite line up.
4) when I pull the control box lever out for neutral start, it feels too loose and doesn't really push on throttle roller.
5) when I shift to reverse, it seems to stay in and out of gear and neutral.
6) at wot, the butterfly is not fully opened or flat, it has like 1/4 more to go.

Note:
I'm using tower shaft that came with power head. Its a 91 carbie. When I installed it the throttle cam was a bit more than 1/4 inch away from roller and the line was up above it. Shift arm wasn't really staying in the center of the interlock switch.

Adjustments I did:
I stretched out the throttle link to close the gap. I adjusted the throttle roller. I stretched out the shift cable and the throttle cable.

I don't want to cause any damage by a premature or anxious start. I got the manuals but I don't fully get it and I'm too frustrated and exhausted and feel a brain block. I need to be explained like a 5 year old, could anyone be merciful, patient and help me??? I've included pictures. And will not move a finger till I hear from you guys to prevent more of my dumb mistakes.

 

[Nordin]

Re: How to adjust and prepare for 1st start after power head swap

You got PM.

 

[Jiggz]

Re: How to adjust and prepare for 1st start after power head swap

On pic #1, the eccentric roller or screw slot (with the idle screw fully backed out as shown in pic#3) should line up with the scribe on the cam. If not loosen the eccentric screw, make it line up with the cam's scribe and make sure the throttle valve is fully closed. If the throttle is not fully closed, then adjust the cam linkage so it is not pushing against the eccentric roller but make sure the scribe lines up with the eccentric screw slot. Keep doing this until you achieved both, slot and scribe lined up and throttle fully closed.

Next, double check the control lever in full forward position will move the throttle in full open horizontal position. If it doesn't adjust cabling or control lever as required. If it does, then double check reverse to make sure it also fully opens. Then the next move is to do static timing. Watch the static timing video in the sticky. When done with static timing, then set the idle rpm by adjusting the idle screw. Do this my loosening the locking nut, screw in the idle screw until it pushes against the block (it if is too short get a longer screw but I doubt it will be) with idle rpm of 800~1000 in neutral. At this point, the cam's scribe line will not line up with the eccentric screw slot anymore since the throttle is now slightly open to maintain idle rpm.

 

[Frank Acampora]

Re: How to adjust and prepare for 1st start after power head swap

Based on what you are describing, everything is out of adjustment. You can not get where you are going without knowing where you are to start.

So: The basic adjustments are the same for the two cylinder engines as they are for three and four cylinder engines. Watch the video at the top of the forum and set the carb and timing synch. This is the baseline and is (or should be) "where you are at"

You did mention that the idle stop screw at the top of the timing tower was not touching the block. At the end of the throttle control cable should be a spring- loaded quick-connect. This needs to be adjusted so that in neutral, with the idle stop screw touching the block, the center spring-loaded portion is pulled out about 1/4 inch. This keeps pressure on the timing tower and ensures that it returns to the idle stop as you shift back into neutral. If the engine has multiple holes for the mounting ball, you may need to adjust its position. you also should have the quick-connect screwed about halfway down the threaded end of the control cable. The connection inside the box should be about the same.

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

Ok guys, I did screw up again by not marking everything as a starting point therefore not knowing what to do first or where to go, so I put everything back as I found it or as I transfered it.
Remember I have 3 motors. My original 89 my parts 89 and my new/good used 91 that came only with nothing but I did get the carbie. So I will take another picture I how everything looks now and even te gears work fine.
Frank, I did notice a bit if play at the end if both te shift cable and the throttle cable. So -
1) I am using the cam from my original 89. As well as the link to it. I will check on the size of my "89 parts motor" to compare in case one is bigger than the other as that is the only extra one I have.
2) can someone help me understand what is a "WB" carbie and a "TC" carbie?
3) my 91 carbie uses the same choke solenoid set up and apparently seems to be the same " length" as both my 89s
4) I found TDC - it does not line up properly with the flywheel marks on the calage - please help me by confirming this - I'm guessing I'm supposed to make "a new mark" on the flywheel aligned with the calage's "0" mark?
5) both flywheel and shaft are clean and key fits great.
6) after putting everything how it belongs or as close to it I adjusted the shift rod and shift cable and the throttle cable so now everything is back to its original form or best possible and the gears are set properly cuz they were not and the only thing that is not touching is the cam on the throttle roller.
7) the manual's specs says this motor needs to be set at 30 at cracking for it to be at 32 when running.
8) my boat does not have a tachometer.

Based on Frank's advice now I know where I am and stand, so I can know which way to proceed. Pictures coming up first thing in the
morning (pacific time)
My most humble thanks to everyone for finding in their hearts the time to help me. Be blessed!

 

[pnwboat]

Re: How to adjust and prepare for 1st start after power head swap

1) I am using the cam from my original 89. As well as the link to it. I will check on the size of my "89 parts motor" to compare in case one is bigger than the other as that is the only extra one I have.

Which ever one works with your tower shaft set up and allows for proper adjustment of idle screw and cam position at idle.

2) can someone help me understand what is a "WB" carbie and a "TC" carbie?

WB = Walbro manufactuer carb. TC = Tillotson manufacturer carb.

3) my 91 carbie uses the same choke solenoid set up and apparently seems to be the same " length" as both my 89s

This is good.

4) I found TDC - it does not line up properly with the flywheel marks on the calage - please help me by confirming this - I'm guessing I'm supposed to make "a new mark" on the flywheel aligned with the calage's "0" mark?

This is not good. With #1 piston positioned so that it is at the closest to the head itself, the timing mark on the block, should line up with either the single slash or groove in the flywheel or the number "0" mark on the flywheel. If it does not line up, it's not the correct flywheel.

5) both flywheel and shaft are clean and key fits great.

This is good IF it's the right flywheel.

6) after putting everything how it belongs or as close to it I adjusted the shift rod and shift cable and the throttle cable so now everything is back to its original form or best possible and the gears are set properly cuz they were not and the only thing that is not touching is the cam on the throttle roller.

The shaft that the cam pivots on is on an eccentric. If you loosen the nut that holds the shaft, and turn the shaft, it will move the cam closer or farther away from the roller. Once you get it set the way you want it, tighten the nut and don't allow the shaft to turn.

7) the manual's specs says this motor needs to be set at 30 at cracking for it to be at 32 when running.

You normally set the timing at cranking speed. This is referred to as "static timing". Pretty hard to set the timing at WOT out on the water. This is referred to as Dynamic timing.

8) my boat does not have a tachometer.

A lot of folks just use a "Tiny Tack". You can google it. Make sure it's for a 2cylinder two stroke motor. There are several models for different motors.

 

[pnwboat]

Re: How to adjust and prepare for 1st start after power head swap

I double checked....both 1989 and 1991 flywheels are the same. Not sure why when you bring #1 piston to top dead center it doesn't line up with the zero degree mark on the flywheel?

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

Sorry about the delay with the pictures but my computer smoked and never turned back on. Now I got another project. LOL!
Ok these are the pictures of everything back without any adjustments. Frank - I will adjust the shift and throttle cable at the controls and at the motor like you said. PNW - thank you for checking on that flywheel's comparability, you had me so worried. Thank you Jiggz I shall do as you say. Thanks Nordin.

Note: motor started just fine, I made sure fuel reached all the way to the carb, bulb got hard, changed the main needle jet and the gaskets, I used the choke several times before I started it. I used freshly mixed fuel at a 50:1 ratio, and also put some mixed fuel into both cylinders,
I made sure shift rod was properly adjusted gears were adjusted and not half way out, made a mark on flywheel for TDC.
Question
1) which of all the adjustments should I do first? Is the first one throttle pickup point and wot? Or cables at control box and engine? Second timing? Third? Or where do I start and what follows?
2) is it ok to put it into gear to test? For sure with no throttle only at idle speed.
3) I purchased a new $100.00 digital timing light that works with 2/4 strokes and also shows me RPMs, is this good enough to set idle speeds or do I need a permanent tachometer ???
4) how hot is the head supposed to feel at idle? I saw good amount of water and I installed a brand new thermostat and was using the appropriate ear muffs for this engine and did not increase the idle at the carbie since it was only a quick start test and was on only for a few minutes due to the late time of the night. Should I get a temperature sensor? I will test the thermo switch and the buzzer.

Please let me know! I will record and post another video tomorrow. Ok Thanks Gus!!!
View attachment 231757View attachment 231758View attachment 231759

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

 

[pnwboat]

Re: How to adjust and prepare for 1st start after power head swap

It's alive!

The timing mark is off by about 4 degrees from what I can see. Are you sure #1 piston is at TDC? When you bring #1 piston to TDC, you can turn the flywheel a degree or two and still have the piston at TDC. Bring the piston to what you think is TDC. Turn the flywheel clockwise until you just start to see the piston move down. Mark the flywheel using the TDC mark on the timing gauge as a reference. Now turn the flywheel counter-clockwise until the piston moves back up, and then just starts to move down. Mark the flywheel using the TDC mark on the timing gauge as a reference. Halfway between those two marks is TDC.

Before you take the boat out, you definitely need to set the timing if yo haven't already done so.

Anyways it looks like you're making some headway. The real test will be out on the water. Keeping my fingers crossed!

 

[Jiggz]

Re: How to adjust and prepare for 1st start after power head swap

The cam not touching can be caused by two things, the swapped carbs mounting flange is thicker or of different thickness than the replaced one thus placing the roller farther from the cam or the rod linkage from the tower to the cam is shorter than the one the new carb came with originally.

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

1) which of all the adjustments should I do first? Is the first one throttle pickup point and wot? Or cables at control box and engine? Second timing? Third? Or where do I start and what follows?
2) is it ok to put it into gear to test? For sure with no throttle only at idle speed.
3) I purchased a new $100.00 digital timing light that works with 2/4 strokes and also shows me RPMs, is this good enough to set idle speeds or do I need a permanent tachometer ???
4) how hot is the head supposed to feel at idle? I saw good amount of water and I installed a brand new thermostat and was using the appropriate ear muffs for this engine and did not increase the idle at the carbie since it was only a quick start test and was on only for a few minutes due to the late time of the night. Should I get a temperature sensor? I will test the thermo switch and the buzzer.

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

Jiggz, I checked the part number for the throttle link and the cam and they are different for the 89 and the 91. i measured the gap and its a little over 1/4 of an inch and im thinking i can adjust things to close that gap, question is should adjust the link, the cables, camor evrything possible to make it touch?
PNW - I checked TDC once again. The "0" degree mark is the perfect TDC but it wont stay on the mark, is that a problem??? There is a bump and then it rests on the white mark i made as the first TDC. question is does it matter once its cranking? can i just make my new white mark right at "0" degrees and adjust from there??
Frank -I copy you've only worked on a 50 HP once and will follow your advice and I got my notes all ready for cable adjustment, and the rest of the adjustments the question is which one do i begin with so everything ends up in harmony??


View attachment 231811

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

 

[pnwboat]

Re: How to adjust and prepare for 1st start after power head swap

Try adjusting the link and make it longer. Make sure that there is enough thread engaged in the two plastic pieces so that they don't suddenly fall off. You can also go to the hardware store and get some all thread rod and cut a piece slightly longer than what you have if needed.

Very strange with the timing mark. The only thing I can think of is that the magnet in the flywheel are interacting with the coils on the stator and moving the flywheel slightly? I don't know.

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

pnw - that is an awesome idea to go to the hardware store because i am concerned as to how little thread i got left i will go tomorrow morning.
My only theory on why the wheel wont stay right on the mark is the magnets inside right where they split in half or where they meet the stator.

I made some adjustments today and will, for the first time try to set my timing. I used a 32 gallon trash can to turn it on cuz i dont want to worry about not getting enough water, i moticed it gets warm cuz its idling and when i give it some gas it cools down.
Motor sounds good to my ears and runs good but i hear an occasional knocking - please tell me that has to do with the timing??????
Is it safe to add some simple green to the water in the tank to wash / flush the water pasages?? will it dry things? damage the impeller?
I say that cuz i found some sand in the tank after i was done, not a lot.
should i use some seafoam???

 

[pnwboat]

Re: How to adjust and prepare for 1st start after power head swap

When you set the timing, use the factory timing marks on the flywheel.

I used a 32 gallon trash can to turn it on cuz i dont want to worry about not getting enough water, i noticed it gets warm cuz its idling and when i give it some gas it cools down.

This is normal, giving it some gas increases the water flow.

Motor sounds good to my ears and runs good but i hear an occasional knocking - please tell me that has to do with the timing??????

I wouldn't worry too much about that just yet. If you hear a loud knocking with the boat in the water under a load, now that would be a concern.

Is it safe to add some simple green to the water in the tank to wash / flush the water pasages?? will it dry things? damage the impeller?
I say that cuz i found some sand in the tank after i was done, not a lot.

A little sand in the bottom of the container is not going to hurt anything unless you see some signs of blockage (overheating). Simple Green won't do much as far as cleaning out the water passages. I wouldn't bother with it, unless you want to make a big bubble bath.

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

Ok guys my boat (our project) is more alive than ever, only thanks to you guys' advice, recommendations and patience. here is the latest update and my request for help


I have just finished setting the timing. I think it was done right and i say that because i have a brand new timing light that is digital and not only does it time but also works as a tachometer but i was not able to use it to its fullest. i adjusted the timing link and it was lined up and timing was set.
I also did adjust the carb at wot and after made the proper adjustments to the throttle link. I needed a longer rod so i bought a rod almost 5 feet long and cut it to my desired length. Throttle pickup point was not perfect, perhaps the original cam was bigger but i did the best i could. adjusted the throttle roller too. Adjusted the cables too.

I need to set the idle speed and screw and i know it has to be done with controls on first gear and i did that in my tank and know that i need to have a load on the boat or be in the water to do it properly.
Have not messed with the idle mixture screw on the carb and i almost dont wat to mess with it.
I can not tell the RPMs by hearing the engine and i cant figure out my lights ability to do rpms.
I would liketo learn and do a leak down test. I am very concerned with 2 things - 1) the compression test before warm up was 93 just like my original 89 i swapped from. 2) there is a knocking sound on this motor sort of coughs slows down and kicks back in.
what do you think?
What do you suggest?

 

[Jiggz]

Re: How to adjust and prepare for 1st start after power head swap

First set the carbs idle mixture screw, you can do this as an initial setting even without a tach to 1 ~1 1/8 turn out from lightly seated. Even with the engine off you can do this. It is very critical setting and usually the initial setting is all you need. Turn the screw clockwise until you start to fill hitting bottom on the screw and then back out one full turn up to 1 1/8 full turn out. Test motor again. As for the compression, it is most likely a gauge thing. Might want to try another gauge and see if it makes a difference.

 

[Eddie Rivera]

Re: How to adjust and prepare for 1st start after power head swap

Ok guys i just adjusted the idle mixture screw to slightly passed a full turn and sounds good to me. I also put it in forward gear and adjusted the idle screw a bit cuz it sounded kinda low then when i put it back to neutral it sounded faster or higher RPMs. I know I will need to properly adjust it when I'm in the water and on forward gear at idle speed.

There is a plastic screw that covers a jet on top of the carbie i removed the plastic holding screw and put some carb body cleaner there.