1997 Johnson 175 Fast Strike hard idle and get on plane when warm

[Ctconne]

J175GLEUC , G04323787 ; Motor runs and idles great in cool weather and when first starts in the morning. If it's hot weather and/or later in a day of fishing, it starts to want to cough and bog down, will sometimes cut off, difficult to get on plane with tournament load. My partner will have to sit on front deck to get on plane. Again, in cool weather and first blast off no problems. Only acts up later in tournament day and during hot/humid weather. This problem also makes it difficult to load on the trailer at the end of the day because it will bog down and not build power/sometimes shut off. I replaced the ignition system last year and I change the carb fuel bowls every year (they warp). This problem has been ongoing for a while and I have just dealt with it but with the warm weather and tournament season back I thought I may try to get some feedback on here. Potentially running too rich? Thanks.

[ChampioNman]

They warp from over torquing the pozidrive screws. Do a search here on heat soak, it has been discussed many times.

[Ctconne]

Been looking at all of this "heat soak" and trying to fix my problem. I did all the VST rebuild and still heat soak. I think my next step will be trying to adjust the carbs to 5-7 turns out. It also seems that changing the jets can help. Hoping someone on here could tell me what size jets I have on this motor and what size I should try to go to if the carb adjustment doesn't fix it.

[ChampioNman]

The Orifice size is on them on the mid has the number stamped on the end of the orifice It should be 39 the High speed is stamped on the side of it you'll have to remove it from the carb bowl to see the number it should be 73D. The changing of the orifices both mid and idle were done on the years prior to the idle adjust jets. You may also want to check the throttle roller adjustment in the stickies at the top of the page.

http://www.bbcboards.net/showthread.php?t=11790

[316jughead]

If the jets are stock you won't have to change them. Start with the carb idle adjustment screws at 5 turns out. Look at the roller that opens the carbs it should have a sleeve over the small black roller. What is your idle RPM in the water and in forward gear? If your idle timing is set at 6 degree's ATDC you should be able get the idle in gear at 750 to 800, with the carb adjustments. The book might say 650 but 750 to 800 will help with the hesitation. If you don't have the OMC service manual get one. They can be down loaded here, look at the sticky at the top of this page. Also could you have to big of a prop? The carbs and timing must open at the same time. If you search old Juggies post's, you will find many post's on this subject and how I set these motors up. Welcome to the forum.

[ChampioNman]

Ole Juggie is the king of the 60* motors.

[316jughead]

Ole Juggie is the king of the 60* motors.

Well, ChampioNman knows these motors. He won't steer you wrong.

[ChampioNman]

Well, ChampioNman knows these motors. He won't steer you wrong.

[316jughead]

That's what Bassmeister told me, but I didn't believe it.

[Bassmeister]

I TOLD YA SO!!!

[316jughead]

I TOLD YA SO!!!

[Ctconne]

Thanks guys. My idle in gear is ~700 RPM. I will try the adjustments and see if I can get that up a little bit. Thanks for the help.