1988 Johnson 90vro rpm question

[Cdkarem]

I recently finished my boat restoration and took it out for the first time. I had some overheating issues which I corrected. Now I'm moving on to figuring out a power issue. Should my engine be giving me more than 3k RPM at full throttle? I'm only getting about 23mph on a 17ft aluminum blu fin. It seems like the throttle is picking up late on the control. Can the throttle cable be adjusted?

 

[AEROCOOK]

Somethings not right. Assuming the boat isn't overloaded and cargo weight is properly distributed, that motor with a 17 pitch prop on a 17ft aluminum should rev well past 5000. When you get it sorted out, look for a target RPM of around 5800 with proper prop pitch selection.
For comparison purposes, my 1988 110 hp Johnson (with a bad cylinder) on my 17ft aluminum, revs to 5900 rpm and around 40 mph.
I think an engine sync and carb cleaning would be a good place to start. The sync procedure should reveal any issues with throttle cable adjustment.

 

[racerone]

The trouble shooting starts with a compression test.------No money spent and post results.

 

[Cdkarem]

I'll check the compression and see if the carbs are opening all the way and get back. I forgot to add that I removed the vro and installed a fuel pump for a evinrude 88.

 

[emdsapmgr]

Agree, post the compression.

 

[Cdkarem]

I picked up a harbor freight compression gauge and the motor is showing 74,75, 75, 75. Not sure on the accuracy of the gauge but it showed even on all cylinders. I tested it in my 1979 evinrude 25hp which runs very well for comparison and it showed 64 & 64.

 

[racerone]

Check for spark on all leads.

 

[AEROCOOK]

I picked up a harbor freight compression gauge and the motor is showing 74,75, 75, 75. Not sure on the accuracy of the gauge but it showed even on all cylinders. I tested it in my 1979 evinrude 25hp which runs very well for comparison and it showed 64 & 64.

I,d try a different gauge, 75 seems very low, my 110 shows 119, 119, 119, 101. Even compression is good but not if they're all low.

 

[Cdkarem]

No Title

Good spark on all. This is what I'm getting at WOT after alittle adjustment to the throttle cable.