89 Johnson 70HP 2 STROKE bogging issues

[Aurobinson]

I recently purchased a pontoon with a 70HP Johnson on it. I took it out today for a test run, when going out it seemed okay. However, when returning I tried to accelerate and it would not go more than 20% throttle. As I was heading back if I hit the choke the boats RPM went up and took off for a few seconds & then went back to bogging. I’m new to this, not very familiar, just trying to see someone’s opinion who may have more knowledge with these 2 strokes. Thanks in advance!

 

[flyingscott]

What happens if you pump the primer ball when that is happening? What is your compression?

 

[Aurobinson]

What happens if you pump the primer ball when that is happening? What is your compression?

Unknown on both of those, will have to give it a try and let you know the compression. Thank you for some starting points!

 

[racerone]

Clean the carburetors.----And does the fitting for the tell tale come off the side of the exhaust manifold ?---Or off the top of the block ?