testing solenoid and where to get replacement

[jdamron]

Re: testing solenoid and where to get replacement - pictures of pistons

Re: testing solenoid and where to get replacement - pictures of pistons

I finally got the head free. Yeah. I was able to turn the crankshaft enough to get enough clearance to rotate the head and then it came right out. Amazingly the bolt is still stuck in the head. It seems when I put this back together I may need to tap the bolt hole. But I do not think it is too bad because it seems I have room to possibly just add a nut behind a longer bolt to get it down tight. There are a few scuff marks on the top of the pistons from my rocking the head back and forth but I do not think that will hurt.

Please see pictures below of the pistons. My initial observation is that the number one piston has a lot of carbon build up - the tops of the other three pistons seem relatively smooth in comparison. Remember cylinder one is the one with low compression. Also, I did run my fingers around all the cylinder walls and checked for grooves. I really can't feel much difference in cylinder number one compared to the others. There are for sure some little grooves that catch in my finger nails but I don't see anything significantly deeper in cylinder number one compared to the other three, which have good compression. I tried to get pictures of the grooves but I am not sure how much you can see. Anyway, I do not see any obvious problem other than the carbon build on on piston number one. Do you think the problem could be a bad valve? Should I open up the intake access for cylinder one or take off the exhaust cover? Thanks in advance for the advice.

Head finally removed and still has stuck bolt:

Note carbon build up on top of piston one (cylinder with low compression) compared to the others:

Walls of cylinder one:

 

[jerryjerry05]

Re: testing solenoid and where to get replacement - pictures of pistons

Re: testing solenoid and where to get replacement - pictures of pistons

Looks like the walls are a bit scuffed??
Need a better pic of all.
The bottom piston looks like it's already been replaced?
Top looks like it's got pre-detonation?
Maybe sucking air?
What were the air screws set at?

 

[Jiggz]

Re: testing solenoid and where to get replacement

The black buildup on #1 piston, is that like tar substance that is sticky and wet? From the look of it I'll diagnose it as tar resulting from non-combustion and at the same time some moisture or water leakage. From the pic I cannot tell for sure if it is water leakage but if there is trace of rust in the piston crown, then definitely there is water leakage. The exhaust ports are clean without any carbon thus confirming the non-combustion in #1 cylinder. But the presence of the carbon buildup on the piston crown tells me it used to be firing with carbon build up on it and then when it started leaking or started losing compression, the carbon turned into tar. That is if the build up is more like tar rather than carbon. There is a little "nick" on the left side of the piston crown, and usually this only happens when one of the rings get caught with the ports.. Having gone this far, the next step is to remove #1 piston to further diagnose the rings. This can be easily done through the intake manifold. Of course, this is all my diagnosis based on the pics.

 

[jdamron]

Re: testing solenoid and where to get replacement - pictures of pistons

Re: testing solenoid and where to get replacement - pictures of pistons

Looks like the walls are a bit scuffed??
Need a better pic of all.
The bottom piston looks like it's already been replaced?
Top looks like it's got pre-detonation?
Maybe sucking air?
What were the air screws set at?

Thanks for the reply. Here are my answers to your above questions:

- The walls of all cylinders are a little scuffed. But I do not see any deep scratches, and I do not think cylinder one (the one with low compression) has any more scuffs than the other ones.

Let me try to take better pictures tonight or tomorrow morning. I may even try video to see is that would work better. It is hard to get still shots of all the cylinder walls.

I really do not know if the bottom piston has been replaced or not - unfortunately I do not know the service history. To me the bottom piston looks about the same as number two and three.

I have not modified the air/fuel screws or anything on the carburetor. I would not be surprise at all if it needed adjustment but I have not really looked at that recently as I was tying to find out why it would not start and why the low compression in cylinder number one. I can take pics of the carburetor adjustment screws if that would help.

Thanks.

 

[jdamron]

Re: testing solenoid and where to get replacement

The black buildup on #1 piston, is that like tar substance that is sticky and wet? From the look of it I'll diagnose it as tar resulting from non-combustion and at the same time some moisture or water leakage. From the pic I cannot tell for sure if it is water leakage but if there is trace of rust in the piston crown, then definitely there is water leakage. The exhaust ports are clean without any carbon thus confirming the non-combustion in #1 cylinder. But the presence of the carbon buildup on the piston crown tells me it used to be firing with carbon build up on it and then when it started leaking or started losing compression, the carbon turned into tar. That is if the build up is more like tar rather than carbon. There is a little "nick" on the left side of the piston crown, and usually this only happens when one of the rings get caught with the ports.. Having gone this far, the next step is to remove #1 piston to further diagnose the rings. This can be easily done through the intake manifold. Of course, this is all my diagnosis based on the pics.

Thank you for the reply.

It is funny because from the pics the build up on #1 does look like it would be sticky, but it is actually hard as a rock. It does not budge with a rag. Also I do not see any trace of rust.

"Having gone this far, the next step is to remove #1 piston to further diagnose the rings. This can be easily done through the intake manifold." - Can you please provide more information on this step? I do not really see an intake manifold. I see the little transfer port covers for each cylinder, which I think are on the intake side. And I see the large exhaust plate. But I thought to remove a piston you had to completely split open the cylinder block, which you could only do after removing the power head from the boat. Of course I have never done this before so I am only basing this on diagrams I have seen, but if it is possible to remove a piston without doing all that it would be great.

Thanks.

 

[jerryjerry05]

Re: testing solenoid and where to get replacement

You can remove the piston through the carb side.
Gotta take the reeds and intake apart.
I don't like doing it that way.
I feel doing a rebuild it needs to be done the right way.
Some like it,I don't.
It leaves the other cylinders in questionable condition??
#4 pistons crown looks like it has #s on it.
Usually they denote an oversized piston.
Pic wasn't clear enough to read the #s.
The black HARD stuff is carbon.
Someplace/somewhere along the way it was running rich and got gooped up and then it started running right? and the carbon goop got hard from the heat?.

 

[Jiggz]

Re: testing solenoid and where to get replacement

Thank you for the reply.

It is funny because from the pics the build up on #1 does look like it would be sticky, but it is actually hard as a rock. It does not budge with a rag. Also I do not see any trace of rust.

"Having gone this far, the next step is to remove #1 piston to further diagnose the rings. This can be easily done through the intake manifold." - Can you please provide more information on this step? I do not really see an intake manifold. I see the little transfer port covers for each cylinder, which I think are on the intake side. And I see the large exhaust plate. But I thought to remove a piston you had to completely split open the cylinder block, which you could only do after removing the power head from the boat. Of course I have never done this before so I am only basing this on diagrams I have seen, but if it is possible to remove a piston without doing all that it would be great.

Thanks.

Since this is a dual carb unit, it means both #1 & #2 cylinders share the same carb thus, it will be inappropriate to assume the cause of #1 cylinder carbon buildup is due to misadjusted carb. I'm not really sure what model engine we are talking about but for sure Force with 4 cylinders mostly have dual carbs. Personally, I would go a step further to finally get a good diagnosis and it is to remove the #1 piston off the cylinder from the intake side. Remove all fuel connections from the upper carb, dismount the carb and choke, dismount the intake and adapter, remove the reed V-block and you will have access to the piston rod caps. You will need a 12-point 1/4 socket to remove the two cap bolts and make sure you count and keep all roller bearings. From here you can just push the piston out. Before doing this, search the forum and you will see a lot of pictures on how to do it. Make sure you take a good number of pictures to have a reference when putting it back. You might also want to look at a breakdown picture which you can get at boats dot net with the reed and intake adapter.

 

[jerryjerry05]

Re: testing solenoid and where to get replacement

Same carb,different reeds??
Sometime you won't find the reason it took a dump?
I rebuilt 125 and found the foam from inside the cowl had crumbled and found it's way into the upper reeds and kept them open sucking air/fuel/oil into the combustion chamber.
Another time I found the water passage blocker had moved and it made the one cylinder hotter.
Lots of reasons??

 

[Jiggz]

Re: testing solenoid and where to get replacement

Same carb,different reeds??
Sometime you won't find the reason it took a dump?
I rebuilt 125 and found the foam from inside the cowl had crumbled and found it's way into the upper reeds and kept them open sucking air/fuel/oil into the combustion chamber.
Another time I found the water passage blocker had moved and it made the one cylinder hotter.
Lots of reasons??

That is correct, a faulty reed is a possible cause of the problem on #1 cylinder, which could also explain the slightly (but not wackily out of parameter) lower compression. In fact, after you dismount the upper carb and the individual reeds and come to find out the reeds on #1 were messed up or stuck opened, YOU DO NOT HAVE TO REMOVE THE PISTON. Instead assume the reed to be the problem, correct it and then put it back together and do a compression test again. If compression is good continue to do a op-test.

 

[jdamron]

Re: testing solenoid and where to get replacement

Thank you so much for the advice and ideas provided in this thread. I had to work a ton this past week so I was not able to work on this problem the whole week. However, I have now taken video and placed in a new thread as requested. It would be great I think if I found the problem to be faulty reeds and I could fix that without having to take the whole engine apart. When I get some time to work on it I think I will try to start taking off the top carb. Here is a link to the new thread I started since the subject of this thread does not really match the issue any longer.

Force 120 with low compression seeking advice

Thanks.