# Low compression



## Sheremeta

also where can I get a good torque wrench kit?


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## fsae99

Casa,
The old school field check for ring issues is to put an oz in that cyl and check compression. If compression goes up then most likely rings are bad, but could be rings not aligned properly, or cyl wall issue. All 3 require head removal.

I've had good luck at harbor freight with torque wrenches. I check mine against my brothers snap on's and they have been right on. It is Harbor freight so YMMV.


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## Sheremeta

Thanks, 

I am in the process of decarbonizing the engine with a shock treatment of ring free and have been seeing improvements in my idle range. I am also 99% sure the head gasket is bad and plan to replace it this week. When doing that I will check the rings and cylinder walls.


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## Creek Runner

Only way to tell whats going on is to pull the head, Sears would be my 1st choice for any tool if Snap on or Matco was out of the question.

If the head gasket is bad then that could be the reason for low compression.


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## Sheremeta

Compared to all the other gaskets the head gasket looks the worst. It has the tell tale signs of failure and is greenish brown in areas and the factory paint on the cylinder head where it touches the gasket has light surface corrosion. 

I am pretty impressed with the ring free. I have been starting the engine and letting it idle high for 5-10min then shut it off for 30 minutes to an hour and come back and restart. Lots of smoke. 

I can do this without a shop manual but I would like to have one for reference. Does anyone know where I can find one?


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## Sheremeta

Just sprayed deep creep into the carbs and stalled the engine to soak overnight. I made such a large cloud of smoke a neighbor called me.


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## Sheremeta

well I removed the head cover today and found my problem. I have a chip in the piston head and deep scoring in the cylinder walls. I am going to get a price to bore and install a larger piston but will probably repower. I am going to look at new hondas this weekend.


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## cutrunner

Sorry to hear that


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## Sheremeta

Thanks but its no big deal. I had plans to repower the boat anyways. The only upsetting thing is I cant go out and buy a new 2 stroke. How are honda outboards? I have never owned one.


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## cutrunner

Well everyone has their opinion...
But in my professional opinion, comparing their hardware, wiring, metal to others..
Theres cheaper ways to anchor your boat if you get my drift


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## Sheremeta

Do you know if my engine can be resleeved or does it have to be bored smooth. I don't want to install a larger cylinder.


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## cutrunner

Any pics of the gouges in the cylinder wall?


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## Sheremeta

It's pretty bad. Look at the marks on the head cover.









Even if I take the head to a machine shop to bore the cylinder and reassemble new parts it's not worth it. A new piston, rings and head cover plus gaskets im putting too much into it. Plus there is that missing piece of piston that I will have to verify that is still not in the block. The head gasket was also toast and looks like water made it past it.


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## dingdangdoo

Did you use yamaha ring free and stabil or anything of that nature? I hope what my yammie is good to go, hopefully you get everything back to tip top shape.


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## Creek Runner

I would take it to a good local yamaha dealer and have a complete overhaul done with a short block from Yamaha. Your looking at probably less than $3500 from the lower case to the carbs and everything in between. Cheaper than a new motor and will run for another 1000hrs.


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## Sheremeta

Ya but for 3k more I can get a new F50. 


Engine was broken down and everything else is in good shape. 

Crankshaft and bearings 









Reeds

















Bad piston

















No pieces of metal were found in the engine and everything was pretty clean. It appears the damage was a result of the cylinder running lean. 3 new pistons were ordered from wiseco and the block should be back by Friday.


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## cutrunner

Get some chris carson reeds too!!
And clean up the ports


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## Sheremeta

Going to pass on the plastic reeds. 

The crank case and everything else will be smoothed out by hand with emery cloth as well as washed to remove deposits.


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## Snookdaddy

> Going to pass on the plastic reeds.
> 
> The crank case and everything else will be smoothed out by hand with emery cloth as well as washed to remove deposits.


I feel you're doing the right thing. I had a rebuilt 90hp Johnson and a rebuilt Mercury 25hp awhile ago.. ran both for 4+ years and both ran like a top and had great compression when I sold them.. As clean as everything looks, I think you will be happy... 

As for the Yamaha 40-50hp outboards... They are supposed to be "bomb proof"... I have a 1997 40hp Yamaha on my Challenger and it has never let me down.. It only has about 350 hours, but it is a damn dependable motor that I have relied on for many trips to the Everglades.. I will be taking the same rig down this weekend and expect nothing less than butter-smooth performance..

IMHO, I think that simple 2 stroke motors sometimes have an edge on more advanced tech.. I'd be f*&ked if a mother board or comp chip went out while fishing 25 miles deep in the Glades...

What was your quote on the re-build? PM me if you do not want to disclose...

Thanks,

Bob


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## Snookdaddy

Forgot to ask... What caused the lean condition? Any ideas. I want to keep my 40ho Yammi in top condition and any info would be helpful to everyone.


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## Sheremeta

If the time is taken to do everything right then a rebuilt motor will last a long time. I can't wait to see how those forged wiseco pistons perform. I had a block rebuilt years ago and it ran fine for years and still is today, better than when new.  The rebuild is going to be around $1,500-$1,600. If anyone needs a great mechanic in the palm coast/St. Augustine/Jax area Pm me. 

It's believed that the hose on the crank case that feeds the bad cylinder came loose and was sucking air which made the oil/fuel ratio lean. 

I would say its a tough motor. It ran fine with one cylinder down. I rebuilt the lower unit myself and there was no oil in the case when I bought it so it had been ran with just sea water. I took apart the entire gear housing, drive shaft, etc and there was no wear. All it needed was prop and shaft oil seals.


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## cutrunner

I think your making the right decision on rebuilding this motor.
Those wiseco forged pistons are a nice upgrade


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## Sheremeta

Thank you, 

Those reeds look good but what life do you get out of them compared to metal reeds?


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## cutrunner

They usually last about as long ,
Everything can break tho.
Only thing with the fiberglass reeds is if you get one backfire or hiccup, new reeds..


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## Sheremeta

They say better performance. Do you think thats true? How long does it take them to ship? I may change my mind.


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## Creek Runner

Wiseco Pistons are some of the best on the market, Chris carson reeds are some of the best on the market, Your really not going to see any performance gains by running either of them though. Takes more than that to create more power out of a 2stroke. However you will probably see a performance gain just because your #2cyc is back in good shape and an overall fresh up on the engine. 1 of the biggest advantages of glass reeds if 1 does break it won't cause internal engine damage.

I personally will no longer rebuild outboard motors for customers, due to the current price of a short block. You could have bought a short block from Yamaha for $1800 with a 1 year warranty, and everything would have been brand new Piston, crank, block, head etc, etc. For the cost difference I just don't see the advantage to rebuilding it. It's only about a 3hour job to take your power head off, install your electronics and reinstall the new power head.


Who is your dealer/technician?


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## Sheremeta

Are you sure they are new power heads and not rebuilt cores? 

I use Trident Marine in St. Augustine.


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## Creek Runner

Yep new from the factory, there is no return core needed.


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## Sheremeta

I think I made the right choice. Still a few hundred less and I know its built right.


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## Creek Runner

Of I think you're doing the right thing by rebuilding the engine whether it be a rebuilt power head or new, it' the best way to go for sure, that's why I recommended it from the beginning.

On another note I don't think your engine failed due to a lean condition, I believe it failed due to a head gasket failure by the pictures of your piston and cause you said the head gasket was bad. Either way you're going to have a good motor when it's fixed. Make sure you do proper break in procedure when you get it back that will determine how long it last.


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## Sheremeta

The gasket did look bad but when I removed the head cover each area of the gasket immediately around the cylinders was dry and intact. The outer edges of the gasket were showing their age and it was failing. I could see in the cylinders were the pistons had sat in the same position for some time. When the crank case and carbs were removed the pipe joint to the bad cylinder was loose and fell out. The pipe joints on the good cylinders were harder to remove. It may have been sucking air at that pipe joint but thats just a wild guess. 

What do you recommend for a break in? 10hrs and higher oil ratio?


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## Creek Runner

> The gasket did look bad but when I removed the head cover each area of the gasket immediately around the cylinders was dry and intact. The outer edges of the gasket were showing their age and it was failing. I could see in the cylinders were the pistons had sat in the same position for some time. When the crank case and carbs were removed the pipe joint to the bad cylinder was loose and fell out. The pipe joints on the good cylinders were harder to remove. It may have been sucking air at that pipe joint but thats just a wild guess.
> 
> What do you recommend for a break in? 10hrs and higher oil ratio?


Yep 10hours of break in @ double oil ratio, 1st hour will be nothing more than a fast idle 1300Rpms give or take depending on the boat. For the 1st hour you will run it for 15min and then let it cool for 30min etc, etc for 1 hour. After the 1st hour you will be limited to cruising speeds only varying the RPM range from idle to cruising every 10min or so for the next 5 hours. I also recommend to let the engine cool every 30 min of run time. No prolonged running periods, after the 1st 6 hours you can give short burst of WOT not holding it for more than 1min, then back down to cruising range; again varying the RPM's and letting the engine cool, after 10 hours you will return to a 50:1 oil ratio, change the spark plugs and re-torque the head bolts.

When I rebuilt engines that was my break in procedure


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## Sheremeta

Thanks. I need to find a tach. What do you recommend? Can I use a tiny tach?


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## Sheremeta

Engine is done. Break in starts tomorrow.


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