I found oversize rings for Johnson 9.5!!

[wolfgang123]

So I've had a 1971 Johnson 9.5hp for a while now, sits in the garage because of low compression. Research online (even here on iboats) led me to believe oversize rings and pistons couldn't be found. Well before I order them I want to make sure this is right. But I think this is what we have all been looking for!

http://www.evinrudeonlineparts.com/..._1968/POWERHEAD_AND_STARTER_GROUP/33951/41432

 

[racerone]

Have you taken the cylinder head of to inspect cylinder walls ??

 

[wolfgang123]

yes they look good

 

[racerone]

Then likely you do not need new o/s pistons and rings.----What are your compression values ?-----Have you removed the flywheel to inspect the coils ?---Likely it has 2 new coils or it needs 2 new ones.

 

[wolfgang123]

every single part is new under the flywheel.. new head gasket ..fuel pump ..cleaned rebuild carb ..new impeller ..gear oil ..etc... i have 40psi of compression on each cylinder, now this is with the pull start, i think you can get the motor to turn over faster by winding a rope around the flywheel and doing the test that way? either way it has a hard time idling and is VERY under powered.. i have also tried all the de-carbing methods with no success.

 

[racerone]

See if it running on both cylinders.

 

[wolfgang123]

what is the best way to go about testing that? both cylinders are getting spark, i have tried pulling plug wires while running and motor dies no matter which plug wire i pull telling me its running on both cylinders right?

here is a video of it running, that metal clacking noise i am still trying to figure out
https://www.facebook.com/video.php?v=1029480093734493&l=5659743356689039838

 

[racerone]

That motor should keep running on one cylinder when you pull off a plug wire.-----Just so you know I have rebuilt more than one of those motors and currently own about 10 for parts / repair.

 

[wolfgang123]

I assumed it would die because the compression was so low, so what does my condition indicate about the motor? At this point I am surprised its running in the first place with 40psi...and I do appreciate all the help, what do you think it could be? any idea what that metal clanking noise is in the video?

 

[racerone]

Are the coils adjusted properly on the magplate ?----Rubbing on the flywheel perhaps.-------That is a " lean sneeze " and you may have open the low speed needle.--------Is the throttle opening at the correct time ? ---Have you looked into that adjustment?----------It sure sounds like a 9.5 , but not a very good example of one !

 

[wolfgang123]

I will remove the flywheel and check everything one more time this weekend. I will also play with the low speed adjustment and see where i can get from there. Still though what about this compression thing? can i just buy standard piston rings, hone the cylinder and be done? or do I need to get the larger piston/ring set and bore out the cylinder?

 

[boobie]

First you should probably check the cylinder bores with a micrometer and see if they're out of spec.

 

[wolfgang123]

So tomorrow im going to tear into this thing and figure out whats wrong. Ill start by taking off the flywheel and will recheck the coils and the points to make sure they are in spec. Ill give it one more test run and see if anything changes (doubt it will) before i pull the head off to inspect and measure cylinder walls. I have already replaced the head gasket once so i want to wait on pulling off the head until i have exhausted all other options.. Is there anything else i should check for or adjust before I pull the head off?

 

[wolfgang123]

okay so i started to tear it down today and found some interesting stuff.. So this video is of the cylinder walls, to my un-experianced eye they seem okay, the flash on the camera gives them a shine so i think they are in slightly better condition than the video makes them look. Running my fingers around the walls i cant feel any kind of scoring:
https://www.facebook.com/video.php?v=1032916970057472&l=2651026342085203656

In this video i can get the pistons to move around a little bit, i assume this is bad??
https://www.facebook.com/video.php?v=1032919576723878&l=3175461820774789386

I also removed the flywheel and recheck the point gap...everything else under there is brand new so all that checks out...I also laid the motor flat and let some seafoam sit to maybe de-carb the rings, i have tried this before with no change in performance or compression.....Im going to re install the head (or not depending on what you guys tell me) and re-check the compression and see were i'm at.

So what do you guys think? rebuild?

 

[Big Fish Billy]

Once you get it apart, and the pistons out, put the rings back in and check the end gap, not sure what it should be for your engine, but someone will chime in. Take multiple readings along the length of it's travel in the bore. If it's out of spec, you could try new standard rings if you can get them, or bore it out as you had planned. My guess is it will be out of spec causing low compression.

 

[wolfgang123]

So a rebuild is in order..I'll order OD pistons and rings wrist pins and clips, gaskets, anything else?

 

[wolfgang123]

* this is assume I find everything else in good condition

 

[wolfgang123]

okay hopefully yall are still interested enough to follow as i have made more progress!

I got the power head out and torn everything down and found this!!!!!:

Which unfortunately did this:

After more tear down i ended the day here:

I have all my parts nicely labeled and i don't think ill have any problems putting her back together.
So my question is what now? I have plenty of mechanic experience to tackle this job, but this is my first full on engine rebuild.
I am hoping I can use a bore dial gauge (any idea where to get one that wont break the bank?) measure the cylinder walls and if everything is withing the correct tolerances hone each one out and install new standard piston rings on the OE pistons right?

Obviously i will have more questions but I want to get that figured out first, one step at a time.

 

[joetheis]

On all the 2 smoke bike motors I rebuilt (as well as 4 wheel engines), before I rip it apart, I run a compression test, (warm WOT, S/plugs grounded), take a reading as it pumps up.
THEN I squirt oil into the cylinder and see if it changes. The oil will seal the ring for a test. If it's jumps up, you got it!
Worn rings will make it 1). run hotter (rings transfer heat away from piston), 2), compression.
The old buck who guided me @ engines used to tell me, if you need rings order O/S annd file them to the EXACT end gap.
Sometimes you get a end gap close to max, this way it's perfect.
Check cylinder wear top, middle and bottom of stroke, (I use a piston and magic marker marks on it so I know where I'm at).
Mike piston, (skirts collapse and will cause a "piston slap" or break off)!
I like "bustin' the glaze off a cylinder with the hone that has balls on the wire ends, instead of flex hone.
Check piston pin wear too, as well as rod small end.
Joe
As always take any advice I give with a can of beer er 2!

 

[racerone]

To do a compression test on a 2 stroke you simply do not need to open the throttle !!!---On this motor where the lockplates missing on the top cylinder ??