Carb issue or just break in issue

[jwronkow]

I rebuilt my 1990 Evnirude 150 Powerhead. Had it bored, new pistons and I rebuilt the carbs. The person who did the machine shop work (only works on boat motors) recommended double oil for 10 hours for breakin. The engine starts fine with no choke idles great and top end works great. It is the mid-range that is having problems. During transition from ~1100 to 2000 it bogs sounds horrible and then after 2000 starts to clean up planes out and runs great. I am thinking that it is just the double oil messing with the proper air/fuel mixture. The carbs don't look like they are flooding and it doesn't sould like the engine is running lean. Should I take the carbs off and recalibrate the float or just live with it until break in is done and fuel mixture is back to 50:1? Am I wrong in thinking that the double oil mixture has anything to do with the air/fuel ratio? --Thanks in advance

 

[Walker]

Re: Carb issue or just break in issue

Double oil should not effect the running to any degree that you will notice.<br />Were the carbs thoroughly cleaned and rebuilt along with the engine?

 

[rickdb1boat]

Re: Carb issue or just break in issue

What was the reason for the rebuild and did you clean the carbs thouroughly and use rebuild kits?

 

[jwronkow]

Re: Carb issue or just break in issue

I had one power head that had low compression and bought a used block and rebuilt it as a spare. Finally got around to putting the spare on. The carbs were pulled apart and dunked, cleaned and blown out. Used full rebuild kits. Adj float with proper gauge and measurments.

 

[wilde1j]

Re: Carb issue or just break in issue

I assume you did a link & sync after the installation of the PH. Correct? If not, timing may be screwed up.

 

[Dhadley]

Re: Carb issue or just break in issue

And check to make sure you have Champion plugs.

 

[jwronkow]

Re: Carb issue or just break in issue

I am using UL77V champions and I did the link and sync. The pickup coil is at 8 degrees when the first mark and cam follower are lined up. It is a 1990 Evinrude 150 with 1985 Higher Compression heads. It was recommended that I use the UL77Vs.

 

[ob]

Re: Carb issue or just break in issue

My guess is that the low speed orifice in the carbs are either in need of size change due to the change in compression ratio or are partially restricted.Only way to really insure that they are clear is to remove them and run a fit size tip cleaner through them and visually inspect.The literature I refer to shows .029 low speed orifice for the 150 engine and .036 orifice for the 175.The idle air bleeds are also critically sized and may require inspection and or resizing.<br /><br />Otherwise,I'd install the QL77JC4 plug and restest.Just make sure any depth change in the heads won't cause an interference issue.The surface gap plug you have in there now is mainly recommended for continual high speed application.

 

[jwronkow]

Re: Carb issue or just break in issue

Thanks for the input. I decided to pull Carbs apart and check jets out. I don't have the tip cleaner so I ran a small brush to clean jets. All looked good except for the amount of Oil in the carb. I put them back together and reinstalled them last night. I need to take it to the water, warm it up, check timing and give it a try. If it still doesn't perform will change the plugs to the JC4s and test. Should know something by tomorrow.

 

[jwronkow]

Re: Carb issue or just break in issue

Ok, didn't see anything major with carbs. This is the first Evinrude 150 I have owned so I don't have a lot to go on regarding what is normal. It seems that the idle screw is so far out that it is almost touching the throttle cam. I checked the timing and it was between 2 and 4 degrees before TDC. I thought maybe something was up with the keyway in the flywheel. All looked good. I will take a pic of it and submit to see if the linkage looks normal. The Carbs performed a little better but still has hesitation in mid-range. I also checked the check valves in the mainifold to ensure the were working properly. Thanks

 

[jwronkow]

Re: Carb issue or just break in issue

Problem solved. Well, I brought my boat to a boat mechanic and he noticed that the boat was equiped with quick start. The sensor in the head wasn't working so the quick start was always engaged. I was adjusting the linkage/timing to slow the motor down not knowing anything about quick start. \He saw the extra pig tail on sensor, grounded it and the motor went to normal idle. After that, I was able to get linkage correct and he walked me through the link and sync and all is well now. Not sure if this will help anybody else out but wanted to pass along the info.