Johnson 40 Rope Tiller, serial number only, unknown year model

[Island Pilot]

I have an unknown model Johnson 40. Can you help by using the serial number?

G4607066

thank you

 

[racerone]

Serial # is no help-----Post 5 / 6 pictures of the motor including the cowling if original

 

[Island Pilot]

[No message]

 

[racerone]

Based on the cowling you have a motor from 2003 or so.----Why is the head off ?

 

[Island Pilot]

The parts seem to match up with an 03 or 04. 93 psi top cylinder, 10 psi bottom cylinder. I am planing to take it apart and hone cylinders and install new rings. Already did 3 gallons of fuel with Seafoam and cleaned carbs. Bottom cylinder would fire on stand if I squirted thinned oil into carb throat to increase compression. Any help would be appreciated.

It it took about two hours to remove the head. 3 broken cap screws. Heat, penetrating oil and lots of hammering wedges. The head is 340100 which is the 50hp head. The 40 head is 339540.

 

[racerone]

Best bet is to bore the cylinders for oversize pistons / rings.-----Take it apart , post some pictures of both pistons.----Intake and exhaust sides.

 

[Island Pilot]

Reed valves.

Racerone, thanks for the proactive help.

 

[racerone]

Yes those are the reed valves.

 

[Island Pilot]

Well Racerone, how do they look?

 

[racerone]

Do you suspect that there is something wrong with them.----They look good to me in those pictures !

 

[Island Pilot]

I don’t suspect a problem with reeds. Just looking for an experienced eye to check the pic.

Here is exhaust manifold. Color differential looks bad. Light brown matches cylinder with 10psip compression.

I called BRP. Freeze plug number is the serial number. Engine is a ‘99 50 from a remote electric start model. The rest of the motor is most likely a 2004. I found a date stamped under steering bracket 4-29-2004. Color looks like 2004 part 771226 from EPC.BRP.com. EPA sticker says it complies with 2005 standards. 2005 white is a different part number.

 

[Island Pilot]

Pic of exhaust manifold was mislabeled. Light brown is fromcylinder with 95psi.

 

[Island Pilot]

Top cylinder and piston pics. 95psi

 

[Island Pilot]

Bottom cylinder and piston. 10 psi. This cylinder would fire if I squirted motor oil into it.

 

[F_R]

That lower piston and reed block have water stains on them. Water has been leaking into #2. If you don't find and fix the leak, it will just happen again. Pay particular attention for possible pin holes through the exhaust area.