1990 Johnson 90 hp V4 timing issue

[cwebb1624]

I recently purchased a lake home that came with a 1990 24 ft. Suncruiser pontoon with a Johnson 90 hp V4. The boat was hard to start from sitting a couple of years but once it got going it would run pretty good. Idle was low and would stall going into gear. A little backstory on me. I used to be a certified watercraft mechanic until I got out of the business in 2000. I am very familiar with 2 stroke engines and how the operate. I have some outboard experience but my specialty was watercraft. I cleaned and rebuilt the carbs and the VRO pump, installed new impeller, new gear oil, new plugs and new fuel line with primer bulb from tank to engine. Compression was 110 psi on all 4 cylinders. 135 psi with a little squirt of oil. The engine started up fine after rebuild, but still idled low, around 550 rpm in gear. I checked all the linkages and did a lync n sync but still idles low. I verified TDC and with a timing light I get 4* BTDC with the engine idling out of gear. To get the engine to stay running in gear I have to turn the idle up screw in till the timing is at 10* BTDC. It then idles fine, around 700 rpm in gear and will go into forward and reverse smoothly with out stalling. The timing at WOT is 27*-28* BTDC. 28* at WOT is what this engine calls for.
My question is why does this engine require so much timing at idle to stay running when put into gear ???? I don't see it hurting anything because the total timing at WOT is right where it is supposed to be.
Any help is greatly appreciated

 

[racerone]

Do a compression test.

 

[jakedaawg]

That's good advice.^^^

Did you find all the orifices in the carb bowls? 2 vertical and two horizontal high and low speed. I believe there are four in each bowl but I did not take the time to look your specific model up.

 

[cwebb1624]

Sorry, I edit the post to include that, Compression is 110 psi on all 4 cylinders, 135 psi with a little squirt of oil.

 

[Bosunsmate]

Do a drop test on each cylinder.
You could also remove the bypass covers and check the rings

 

[rothfm]

I dont see an issue, providing good compression, consistent spark...I've had motors where i have to in/out that screw more than others. If it idles consistant in-gear and shifts well--all is good.

 

[cwebb1624]

Thanks for the info rothfm. Boat goes into gear smoothly and will purr like a kitten with 10* initial timing. Runs smooth as silk on the top end as well. I was just concerned about so much initial timing when I've read that it should have around 4* initial timing.

​I have not considered doing a drop test because the engine runs so smooth. Smooth at idle and all the way through to WOT.

 

[jakedaawg]

Sorry, I edit the post to include that, Compression is 110 psi on all 4 cylinders, 135 psi with a little squirt of oil.

For a few dollars you can remove the covers and inspect for scoring. at 110 dry to 135 wet I expect to see ring damage which explains your issue.