85 evinrude looper idle timing

[Kerpit]

I have a question regarding an 85 evinrude 140 looper e140tlco. I have an oem manual and i couldn't find any idle timing specs. I have the wot timing set at 22 degrees. But i was having a high idle and i found an intake manifold air leak. It was idling at 2000 rpm at 2 degrees btdc idle timing. If there is no idle timing spec and just an rpm idle spec, Does anyone know what the normal idle timing usually is? I just want to make sure i am not overly retarding the timing to achieve the correct idle and compensating for a problem i need to fix!

Thanks for your help!

​Brian

 

[jimmbo]

There is no idle timing spec. Retardation of the spark is what controls the idle speed. The only timing specs you have to worry about are, max advance, and the carb-spark advance pickup point.

 

[Kerpit]

I am chasing an idle issue with this engine. We have the oil side of the vro pump blocked and just pre mix 50:1. It will not idle fully trimmed down. The idle timing is at 4 degrees btdc which is with the idle screw on the timer base damn near full out. Yes i understand there is no idle timing spec, i'm just stating that it's fairly advanced and barely idles. It will barely idle at 800 in neutral and goes down to about 500 and dies in gear in the water. If you trim it up you can get it to barely idle in gear then it runs fine once on plane. At start up and low idle it smokes like hell! The idle screams on the muffs. This powerhead was rebuilt by a marina a few years ago. It has 127 psi of compression on all 4 cylinders. So far i have done the following things.

rebuilt carburetors
removed reed valves for inspection
removed welch plugs and cleaned calibration ports in the throttle body - epoxied over each welch plug after installing new
performed a link and synch
verified spark on all 4 cylinders with timing light while barely idling
rebuilt primer solenoid and removed the lines to verify the primer is not stuck open while idling
all new recirc valves and black plastic check valve - verified the recirc valves are working as well with press tester
removed vro pump and inspected diaphragms - also press tested each side of diaphragm - pulse hose bone dry.
the stator, timer base, and power pack were replaced a few years ago. oem stator/timing base, cdi power pack.
replaced thermostats and verified each cylinder head is around 140-150 degrees.
engaging the primer solenoid does not help
while barely idling there is no carb flooding over while looking down the throat of each carb
putting your hand over each carb causes fuel to puddle in the carb throat

Does anyone have any ideas?

Thank you for your time!

Brian

 

[racerone]

Note----Idle timing is the point where throttle plates start to open.----Thus it is a linkage adjustment in my opinion.----Not a timing adjustment !------Look into possible issues with crankcase compression too.

 

[Kerpit]

I thought the idle is set by synching all 4 carbs to be closed. Then adjusting so when the cam mark is in the center of the follower the carbs are just starting to open. This would be far off idle from the remote control. I'd say the first 1/4 movement of the throttle control is all timing. I'm referring to adjusting the idle screw which is the spark advance linkage part number 0396667. I'll check out the linkage between the spark adv link and the timer base...And the only reason i even mentioned the idle timing is i figured that at 4 degrees atdc it should be above 800 rpm neutral? As far as crankcase compression are you referring to the intake side under the piston? Possible sealing rings? Is there a way i can rig something up to test that? Is there any way to pressure test the crankcase under the piston with a leak down tester? On my snowmobiles i plug the exhaust and remove the reeds and install a setup i made.

Thanks for the reply!

Brian

 

[Kerpit]

oops, meant 4 degrees btdc not atdc. I read the timing synch procedure in the oem manual and i think it's not set correctly. After it's adjusted the correct way i believe the timer base will be much more advanced and i can probably turn the idle screw back in! Hopefully i'll test it out this weekend. Thanks for the help so far Racer!

 

[Blazinmonkey]

how are the plastic carbs? any air gaps? did you take the air-box off and put your hand over all four carbs?

 

[Kerpit]

Carb mounting surfaces were straight and i can spray carb cleaner or ether at each carb mounting surface with no change. I put my hand over each carb one at a time and not much change. It caused fuel to puddle in each bore i had my hand in. I stated that in the list of things i did above...

 

[Kerpit]

I adjusted the linkage per the oem manual and the engine ran much better yesterday. I understand these loopers idled like crap since new. Now fully trimmed down in gear it's about 650 rpm and chugs along smoking. Before it would just die immediately. It's around 1k rpm in neutral. I would imagine it would eventually die if just put in gear and ran for a lengthty time. But if i trim up a bit it's good to go. If everything else is performing correctly i was thinking of installing some boyesen power reeds. I have heard they can improve the idle on these loopers. Is that true and would you recommend installing them? Also, should i plan to change the idle and intermediate air bleed orifices to smaller diameters to richen the mixture to prevent any lean backfire? I really don't want to compromise any reliability of the engine.

Thank you for all the help on this engine!

 

[Bosunsmate]

You should check compression before spending any money.
Maybe post a video of it too, it might be quite normal and spending money might not change anything for the better, if it is smokey check the heads are warming up

 

[Kerpit]

My original post states the powerhead was recently rebuilt (50 hrs ago by a marina) and the compression a few days ago was 127 psi in all cylinders. This was with a mac tools compression gauge. I am a heavy equipment mechanic for a caterpillar dealer. The original post also states i replaced both thermostats and both cylinder heads are at 140-150 degrees f.

 

[Bosunsmate]

My original post states the powerhead was recently rebuilt (50 hrs ago by a marina) and the compression a few days ago was 127 psi in all cylinders. This was with a mac tools compression gauge. I am a heavy equipment mechanic for a caterpillar dealer. The original post also states i replaced both thermostats and both cylinder heads are at 140-150 degrees f.

Oh so it does in post 3, what a good lad.
If its not backfiring then i wouldnt mess with it.
Depends what oil mix ratio you are running at as to how smokey it will get but these two strokes are oily hence they are banned in many areas now due to the oil residue.
The idling actually i think sounds good on these, just takes a while to get use to and trust it, perhaps it wont stall out like you say it will, might need just a tad more turn on the idle stop

 

[Bosunsmate]

If you richen the mixture you will increase the smokeyness of course. 650rpm is a nice low idle speed, i think you might be trying too much to compare it to one of those catepillar four stroke engines performance

 

[jimmbo]

Loop charged engines are a little jumpy at idle speed. Just the nature of the porting and residual exhaust remaining in cylinder at low rpm

 

[Fed]

Keep an eye on your exhaust relief ports, submerging them can send the idle off and could be why trimming it up has helped.

 

[Kerpit]

Thank you to everyone who took the time to respond. Lots of good info! Bosunsmate - i was referring to richening the mixture if i installed boyesen reeds only. I think there instructions state to rejet due to the softer reeds allowing more air in. But they say if the motor is worn then to leave stock jetting...? I have read some reports that the reeds have helped the idle is all. I don't care about increasing any hp. This is actually my dad's boat, i own an 06 chaparral with a 350 mag mpi/bravo one. I am very particular and a perfectionist when it comes to engines. I want it perfect!!! But i used to boat with this 85 lund a lot when i was a youngster many years ago! It got me hooked on boating that's for sure. The boat has sat up at the lake house for a few years. So i just want to get it turn key so my dad can use it again, it's very close. This boat has always loaded up in long no wake areas and was a ***** loading on the trailer. Would die at idle. Starting it up at the ramp would send any spectators running...smoked like hell, mosquito killer! Fed - i never even thought of the exhaust relief ports. That would definitely cause excessive back pressure when trimmed fully down if they are restricted! I think i'll try to get a video of startup and some extended idling. Thanks again for all of the help! Could i drill the idle bleed orifice out basically one jet size larger at a time if everything else checks out ok or is that crazy? #41 idle bleed is .0410 which is #59 drill. I have tiny # drills and a pin vise. I've done it on snowmobiles...

Brian

 

[jimmbo]

There was a recall/modification on the early loopers. I recall the mechanics replacing and drilling jets and airbleeds. A change in the link and sync and several other items. It did have something to with back pressure and the idle relief. I saw the document about 15 yrs ago.

 

[Kerpit]

Very interesting! Now how could i possibly get a hold of this document?

 

[Kerpit]

Well i took it out and the engine did not die in gear at about 800 rpm. But to set it to where fully trimmed down it's 800 rpm it's about 1100 in neutral. And about 950 rpm if trimmed up a bit in gear. What i did notice is that the idle relief ports are fully submerged under water at full trim down. I was looking into the engine height a bit earlier last week. With the engine trimmed so the cavitation plate is parallel with the boat. The cavitation plate is about 3/4 of an inch below the keel. And i noticed the engine can trim down way past parallel. So i experimented with moving the trim pin to only allow it to go so far down. There definitely is a bit more bow rise when planing with it up one hole as expected but not too bad. But at that point the idle relief is just barely under the water. So how far down should the drive be able to go and do i absolutely need to raise the engine so the exhaust relief ports are above the water?

 

[jimmbo]

Put the trim pin back in the holes closest to the transom. There is no law saying the anti-ventilation plate is to be parallel to the hull bottom. In theory, the anti-vent plate and propeller shaft are supposed to be parallel to the direction of travel, which right there is not parallel to the bottom of the boat. Most boats go the fastest when the engine is trimmed further out than that. The exhaust relief does need to be out of the water. Perhaps you have too much weight in the stern of the boat? As for the engine height, 3/4 of an inch too deep will throw up more spray and have more drag. Your engine has several holes in the bracket to adjust the height. Even BPR AL props can handle being run 3/4" higher than the bottom of the hull.