Need adjustment for carbs on a 95 OMC 70 HP

[snowseeker]

Hello,<br />I just ordered a factory OMC service manual for this motor, but it won't be in for a week and I kinda need this info asap for our work boat.<br /><br />Can someone please tell me what the correct adjustment for the idle, and WOT needles on a 1995 evinrude 70 HP motor are.<br /><br /><br />Also at idle this motor use's way to much oil. The smoke is just unbearable at idle. Is there any way to turn down the oil consumption at idle?<br /><br />Thanks for any help!!

 

[G DANE]

Re: Need adjustment for carbs on a 95 OMC 70 HP

Hi snowseaker and welcome to this forum.<br /><br />The 1995 tripple looper has all fixed jets in carbs, making adjustment possibilyties next to none. If your carbs are dirty, your mixture will be wrong. If you have an airleak somewhere in your fuel lines og filters, or any restriction on fuel side, it will overoil, as this motor does oilpump strokes compared to gas pump strokes and rpm. Another option could be your ignition/throttle sync is off, making combustion inadequate, but you will need the manual to correct that.

 

[snowseeker]

Re: Need adjustment for carbs on a 95 OMC 70 HP

Thanks much for the quick info. I was just in the shop and noticed the build date on the power head says 10-2-96 I don't know if that would make it a 96 or a 97, is it still the same as the 95's?<br /><br />We put in all new fuel lines and a new VRO last year. It was dieing out at WOT and we took it in, they replaced the VRO with a new one. That didn't fix it, but thats when the motor started to smoke alot more at idle. Than after that we replaced the lines and found out that the middle carb was plugged and wasn't getting the fuel it should at WOT.<br /><br />With the old VRO the motor ran GREAT! with normal 2 stroke smoke. Now since the new VRO was installed it smokes bad at idle like I was talking about earllier with the carb adjusting stuff. And seems to load up a bit when putting around in backwaters for a few min's.<br /><br />sorry I didn't mention this earlier. When we had the motor in for the VRO the mech. was cranking on (what I thought was) the idle mixture screws and I didn't really like how this mech was. I figured he had the idle screws way to rich. The screws he was adjusting were all set around 3 1/4 turns out.

 

[Dhadley]

Re: Need adjustment for carbs on a 95 OMC 70 HP

What spark plugs are you using?

 

[snowseeker]

Re: Need adjustment for carbs on a 95 OMC 70 HP

there are champion QL78YC plugs in it.

 

[Dhadley]

Re: Need adjustment for carbs on a 95 OMC 70 HP

Excellent choice.

 

[ob]

Re: Need adjustment for carbs on a 95 OMC 70 HP

What is the engines top rpm at WOT as currently propped?Should turn up near 6000 with a light load. 3 1/4 turns open on each mix screw may be a bit rich idle mix.Mine are set at 2 3/4 turns open.Each setup will be a bit different depending on exhaust back pressure which is influenced by the height of the engine as mounted on transom which places the exhaust hub deeper or shallower in water.Three cylinder loopers don't liked being trolled at low rpms for extended periods and the idle mix setting is most challenged when doing so.Too lean will cause in gear stall outs and too rich will cause excessive load up or rich stall outs.

 

[G DANE]

Re: Need adjustment for carbs on a 95 OMC 70 HP

I stand corrected, it seems the low speed mixture needles are back on the tripples ?? Sorry.

 

[snowseeker]

Re: Need adjustment for carbs on a 95 OMC 70 HP

At WOT the motor can run up to 6000 rpm trimed up, but the prop has a shallow pitch because at times there is over 1600 pounds in this boat and we need the extra power out of the hole.<br /><br />it is a short shaft and the boat is a tunnel haul so even sitting still with the motor trimmed all the way down just the lower unit is under water.

 

[snowseeker]

Re: Need adjustment for carbs on a 95 OMC 70 HP

Adjusted the carbs to 2 3/4 turns last night. Took the boat out for work today and it has normal 2 cycle smoke again! But now it is idling at 1500 rpm. I looked for an idle adjustment and couldn't find any at work. I am going to look a little more now when it is home and in the shop.

 

[ob]

Re: Need adjustment for carbs on a 95 OMC 70 HP

No idle adjustment per say on your engine.Insure that when the controls are in the neutral position that the carb linkage is allowing the carb flaps to close completely.You'll need to remove the silencer intake cover to inspect.Two things can cause the linkage to be out of adjustment.The throttle cable trunion , and the linkage roller.When the controls are in the neutral position insure that the carb link roller is aligned exactly on center and "just touching" the scribe line on the fiber cam.There is lock screw that can be loosened and retightened to perform this adjustment.

 

[seahorse5]

Re: Need adjustment for carbs on a 95 OMC 70 HP

The idle speed adjustment on your 70hp is a small screw under the flywheel on the stb. side. It moves the "timer base" and changes rpm at idle only.<br /><br />Before setting the idle speed, make sure the "sync and link" described in the service manual is correct, as OB pointed out in the previous post.<br /><br />The engine has to be up to temp and in the water, not on a flusher.<br /><br />I don't have a manual handy but most engines are set to 650-750 rpm in fwd. gear.

 

[snowseeker]

Re: Need adjustment for carbs on a 95 OMC 70 HP

Ok, I did the sync n link and made sure all the throttle controls were working perfectly.<br /><br />I threw the boat in one of our ponds and tryed to set the idle with the timing screw. I have the screw backed all the way out and the timing is way past the -4 mark and the motor still idles at 1000 - 1100 in nutral and around 900 in gear. The idle mixture screws are set at 2 3/4. if I back them out to 3 1/4 like I found them the motor idles down to 800 - 900 at idle and around 700 in gear but the motor loads up a bit and smokes bad.<br /><br />I don't think there is any leaky carb gaskets because the mech replaced them when he cleaned out the carbs.<br /><br />All the carbs do close completely. And I have the roller linkage set just off the throttle cam. About a papers width off the cam.

 

[seahorse5]

Re: Need adjustment for carbs on a 95 OMC 70 HP

Are you using a "shop tach" or digital for accuracy, or are you looking at the dash mounted tach?<br /><br />Is the thermostat allowing the motor to idle about 140 degrees F ?<br /><br />Does the timing pointer line up with the TDC mark when #1 piston is at TDC?<br /><br />If so, and you cannot get it close to 4 ATDC, pull the flywheel and check the inner magnet for dislocation and/or looseness.

 

[seahorse5]

Re: Need adjustment for carbs on a 95 OMC 70 HP

Are you using a "shop tach" or digital for accuracy, or are you looking at the dash mounted tach? Is your dash tach set for 6 pole operation?<br /><br />Is the thermostat allowing the motor to idle about 140 degrees F ? The motor may be stuck in QUICKSTART which advances the timing about 10 degrees until the motor warms up.<br /><br />Does the timing pointer line up with the TDC mark when #1 piston is at TDC?<br /><br />If so, and you cannot get it close to 4 ATDC, pull the flywheel and check the inner magnet for dislocation and/or looseness.

 

[ob]

Re: Need adjustment for carbs on a 95 OMC 70 HP

For what its worth ,over the years I've found that the three cylinder loopers idle in water in gear best at around 900 rpm.1000 rpm out of gear in water is where my 96 70 hp runs now and is trouble free.I think you're pretty close now.<br /><br />Follow seahorses advice on the T/stat and insure the engine isn't stuck in quickstart.You should be able to detect a 100 - 150 rpm drop around 10 to 20 secs after starting engine cold if the quickstart feature is working.If its been more than 2 years since the T/stat assy was replaced it's due.They tend to get crudded up over time and don't actuate smoothly.

 

[snowseeker]

Re: Need adjustment for carbs on a 95 OMC 70 HP

it is a snap on digi timing light. The motor does come out of cold start and idle down like it should. It runs much much better now after doing the link n sync and it does seem to idle normal again. Just kinda bothers me that the timing screw has to be backed all the way out to get the right idle.<br /><br />I was thinking of rebuilding the carbs this winter after our work season is done. They were cleaned before by the egg head mech. but not rebuilt with all new seals and gaskets and we put about 800 - 1200 hours on the motor a year.<br /><br />I would like to say thank you to all that have help me so far with getting this motor running like it should! I am very glad to have found this forum!<br /><br />One last thing, what are some performance upgrades for these motors, without sacraficing much reliability? With the weight that we haul more power is always good.

 

[snowseeker]

Re: Need adjustment for carbs on a 95 OMC 70 HP

It has been awhile since I've been here. I just wanted to follow up on this deal with the 70. We still have the motor in service and it is running strong as ever! I ended up getting a carb rebuild kit for all the carbs. The plastic shaft collars were worn quite a bit letting air in causing the high idle when the idle mix screws were set to factory specs. With new collars, seals, float valves, the whole deal everything is working great!


Another exciting deal is I also just rebuilt a 92 60hp (the 70's parts motor we had laying around) over this last summer. The 60 ran hot and scored all the pistons and cylinders. I got in new .020 over pistons and had the block bored. I brought the block home from boring and honed it in myself the last .008". I found the over heat problem under the side exhaust cover. There were places in the casting where the water was to flow from the exhaust to the water jackets around the cylinders and then to the head and out but many of the holes from the exhaust to the cylinders were not poked out. There was a little very very thin layer of casting over many of the holes. I think out of the 6-8 possible holes 2 were actually free and able to flow. I also moved the fitting for the water line from the cold side of the exhaust to the hot side. This is the same location that is used on my Dads newer 70hp.

I've ran a few tanks of gas threw the motor already and it runs just great! I am very happy with the build and how the motor performs!