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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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how do i adjust timing on a 2 stroke johnson outboard

Resolved Question:

<p>Im having back fire through the exhaust and wandering if its the timing? if it is how do i adjust it</p><p> </p>
Submitted: 3 years ago.
Category: Boat
Expert:  Dominick replied 3 years ago.
Chat Conversation Started
Dominick :

Are you there?

Customer :

yup im here

Dominick :

Is this a two or four stroke engine,....I am guessing two....?

Customer :

yes two stroke.

Dominick :

Have you made any changes that would change the ignition timing or linkage adjustments to the engine?

Customer :

i recently changed the cables. my engine is a 30 hp two stroke with the cables mounted on the outside of the motor

Dominick :

OK, there is no camshaft, valves or timing belt on this model engine....I am familuar with this engine and it's design,...When was the last time the engine ran correctlt? Has the engine been in storage for a period of time?

Dominick :

Hello, Are you there?

Customer :

just last tuesday. when i took the boat out of the water and flushed the motor i reved up the rpms and noticed it started backfiring through the exhaust. I usually run the motor on the hose at least twice a week for at least 15-20 minutes. I just ran the motor on the hose again and noticed it still did the same thing

Dominick :

All and all this is not a real good test for the engine...The should be put into the water and tested fully while pushing a boat...This will tell the true tale of how our engine is doing....

Dominick :

Poping through the exhaust while on an engine stand is not really that uncommon, but lets take a close look (More)

Dominick :

Ignition timing , being out of adjustment is nearly impossible on this engine without moving the linkages by a technician....

Dominick :

It is possible that there is a fuel issue or possibly a cylinder issue. We should start with a compression test of the engine. This will show the integrity of the engine cylinders and put us on track with the fuel system.

Customer :

i pulled the plugs and they looked good. dry, pretty clean. the fuel is a 50:1 ratio and i also added a fuel stabilizer for water build up

Customer :

but any how, how do i adjust the timing?

Dominick :

If the engine passed a compression test (Suspect it will) we would really need to take the motor to the water and run it on a boat to determine if it indeed does have an issue. Thing is, the engine really has an easy time turning the crankshaft alone and not having to produce the power necissary to push a vessel, and the poping through the exhaust could be caused by, running lean or rich with a fuel carburetor issue. (just got your last post) do you think the fuel is old in the tank, and when was the last time we pushed a boat with this motor?

Dominick :

To adjust the timing on this engine. (More)

Customer :

the motor is on a boat and i just ran the boat this past tuesday

Dominick :

We will need a timing light, same one used on a car is fine, attached to the top sparkplug. When we look at the timing plate under the flywheel while moving the throttle we will see it moving. The timing wheel will hit a adjustment screw or stop screw that prevents it from going higher. This is the adjustment screw for high timing. My suggestion would be not to adjust the screw, it cannot be out of timing. Anyway , the timing light is attached to the top screw and the timing is read while the engine is under full load in a test tank, at wide open throttle, and read off the flywheel at the pointer mounted on the block.

Dominick :

How did the engine run last Tuesday?

Customer :

the engine ran good in the water never had a problem

Dominick :

Most likely we don't have an issue, but a compression test is our first order of business....This will tell us a lot...The poping in the exhaust, does it occur when idleing? when throttling up, and down?

Dominick :

If the engine is not "backfiring" back out the carburetor, and the engine runs just fine in the water,....We don't have a problem....

Customer :

not when idleing, it happens when i throttle up and holding

Customer :

ok cool. thank you for your time.

Dominick :

Throttling up and holding with no load on the propeller will cause damage to the pistons in time....Lets not do that and lets do the compression test to determine that there is or isn't any issues with the motor....

Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience: 25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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