"Splitting" the power head *help*

[evil^^]

OKay so this is my ongoing project. I bought a boat and motor for cheap. I found that the 3rd piston was damaged. Bought a Clymer, read it, learned lots. Motor will be split tomorrow.

My out board motor is a Force 90hp
Model: 906X90C

Now for parts for a motor that the hours are unknown.
* 1 pistion with rings (I ask someone that fixes outboards if I should replace other 2 he said I shouldn't have to just re-ring, the compression was 120,125,25. what do you guys think?)
* 2 sets piston rings
* 1 Impeller kit
* 1 Gasket overhaul kit
* Gear grease
* Liqiud Gasket
* 1 Fuel Diaphragm kit

Please any suggestion before I order? Where is a good place to order parts?

Thanks for everyones input. This is the best boat forum I have found yet.

Tony

 

[Bigprairie1]

Re: "Splitting" the power head *help*

This is always a conundrum. Most people start with the intention of doing just the minimum (more or less) to the get the motor back up and running.
Once you've gotten this motor apart...that will be most of the tough part done somewhat. At that point, throwing a few more shekels at redoing all 3 cylinders won't take too much more time or money...and the peace of mind you'd get would pay back in spades.
How much more money (by percentage or whatever?) to do all three?
I'd do all three at that point...just for own peace of mind.
Go for it.

 

[Frank Acampora]

Re: "Splitting" the power head *help*

If you decide to just re-ring the other two cylinders, remember: The cylinders tend to "glaze" you need to lightly hone them to "break" the glaze so the new rings seat properly.
I prefer Wiseco pistons because they are much easier to install, but the rings will not fit your stock pistons. So: if you decide to re-ring the other two pistons, you will need to buy stock rings. In any case, you need a press to remove the wrist pins. If you buy stock pistons, you must use a special tool to re-install the wrist pin. Wiseco are loose fit and held in with circlips. The piston comes complete with matching rings, wristpin, and circlips. You must order a bearing kit for the wristpin. All oversize pistons are matched to factory weight so it is not necessary to replace all if they are in good condition. And the increase in cylinder displacement is so minor that the engine will never know that one piston is bigger.
And by the way: If all cylinders are in good conditio and do not need to be bored, you can replace the pistons without dis-assembling the engine--Take off the manifold and access the rod big ends through the reed ports. push out the pistons through the head end. Its just a little more difficult to install but it beats trying to get the powerhead off the leg. Of course, if it needs an overbore--very likely with a compression reading of 25 if its not the head gasket--then you must do a complete disassembly

 

[evil^^]

Re: "Splitting" the power head *help*

Can you please tell me what tool i need to remove the piston from the rod big ends, so i dont have yo split the head.

THANKS!

Tony

 

[Frank Acampora]

Re: "Splitting" the power head *help*

You use a 1/4 drive 1/4 inch 12 point socket to remove the rod big end bolts. They are on there tight though, and you need to grunt to get them off. You need a torque wrench to re install them to 185 inch pounds.

To remove and re-install the wrist pins from the piston, you need special tool T2990 and shim tool and pillow block. This spaces the needle bearings so they are not pressed tight against the wrist pin keeper. Not so critical when removing and not necessary if you use Wiseco pistons, but CRITICAL if you re-install stock pistons and wrist pins.

Shim tool end 295 is used to remove and 310 end used to install.

You must run a pencil point over the ground portion of the big end of the rods to ensure that the caps are properly aligned. Improper alignment will tear up the rod and bearings also ruining the crankpin. So: work slowly and accurately on this step.

 

[Kajun37]

Re: "Splitting" the power head *help*

if you don't have one... a manufacturers manual is worth its weight in gold when doing something as in depth as this...you can get them on ebay pretty cheap