wot timing

[elwilliams13]

Got a 1991 evinrude 225 and can only get to 4000 rpm with my boat 1979 mako 235. I was wondering if a decrease in wot timing can limit my rpms this much. It worked fine when I got it. Did the 4 degrees timing method set at 14 because spec is 18 BTDC. Now I am lost. Need some more info. All cylinders spark and compression is even at 85 psi which I was told is normal for my motor. Any help would be appreciated.

 

[walleyehed]

Re: wot timing

The OIS system can only be set with the proper electronic equipment.<br />I don't believe the 4 deg retard method will work on OIS systems.

 

[elwilliams13]

Re: wot timing

Can you go over the OIS system never heard of it.

 

[elwilliams13]

Re: wot timing

Does anyone have more advice on any procedure other than the 4 degree method to get me in the ballpark so I can fine tune in the water.

 

[elwilliams13]

Re: wot timing

^

 

[elwilliams13]

Re: wot timing

^

 

[Seasport]

Re: wot timing

Are you sure you actually have the OIS 2000 system on that motor? Is there a big OIS 2000 label there?<br /><br />Rather than using a timer base which is triggered from magnets in the flywheel, the OIS system uses an optical "magic eye" sensor looking through a slotted rotating plate mounted on top of the crankshaft. The slots in the rotating plate cause a signal to the powerpack which initiates the spark.<br /><br />I think the 4 degree method works on conventional ignition systems due to the slower than normal rise and fall of the trigger pulses as the motor rotates at cranking speed. The OIS triggers will always be sharp.<br /><br />On the OIS systems, the powerpack has electronic smarts which activates the 10 degree Quikstart timing advance when the motor is cold and first starts. So if you set the timing with a timing light, you need to make sure that Quikstart is not activated. You can ground the tan temperature sensor wire to the powerpack to fool the powerpack into thinking that the motor is up to temp. This should allow you to check timing using a timing light.<br /><br />There's a good description of the OIS ignition system which can be downloaded from www.rapair.com (Troubleshooting guide).<br /><br />However, the best way to set timing is to use an electronic analyzer. These are expensive ($300+) but I have designed a fairly simple DIY version which a number of people are building at the moment. Email me at Seasport1@hotmail.com if you want to have a go at this.

 

[elwilliams13]

Re: wot timing

Seasport thanks for the offer on the analyzer. My motor uses the timer base and has magnets under the flywheel but it does have a quickstart. My manual says nothing of a OIS 2000.

 

[Seasport]

Re: wot timing

Thought so. I'm not so familiar with your system but I think you should be able to disable the Quikstart by grounding the temp sensor wire to the powerpack (tan). Then the Joe Reeves technique should work. Maybe someone else can verify this.<br /><br />In any event, why not check the timing with the boat in the water? You can either do this by hanging off the back of the boat at speed or with the boat on the trailer (in gear) with the motor just far enough into the water to be sucking cooling water.

 

[elwilliams13]

Re: wot timing

Thanks a million seasport. Great help.

 

[walleyehed]

Re: wot timing

Didn't mean to leave ya hanging...I thought I seen something in your post about OIS....I'm getting old I guess...sorry for that..???>>><br />And yes, the quick-start must be disabled....(I believe)

 

[rodbolt]

Re: wot timing

on the 91 225 to disable quick start grond the white/blk wire at the port head. however the system is designed to disable itself after 100 RPM regardless. even once you get the static timing correct it must be verified at or near WOT under full load. means a test wheel trip, dyno session or the old fashoined lake trip. if you do the lake trip be aware of the flywheel. they can bite. I still have the scars to prove it. use a trusted helmsman, preferably one not on your life insurance policy . and be very careful setting the timing stop screws.I reccomend shutting it down to reset them. one turn of the screw will give about 1/2-1 degree of change.

 

[elwilliams13]

Re: wot timing

Thanks alot fellas will get back after the weekend.

 

[elwilliams13]

Re: wot timing

Well found the trouble it was set with the quickstart on so it was actually at 24 btdc. Checked compression and looked at pistons through sparkplug holes no visible damage. Comp was equal accross all cylinders. Will take it out and do the fine tuning tomorrow. Any other advice.

 

[clanton]

Re: wot timing

If you set the timing at cranking rpm, the timing will be retared 6 degrees, because the quickstart will advance the timing 6 degrees for starting. After engine is up to operating temp or about 10 seconds on warm engine the quick start will retard the timing 6 degrees for normal running.

 

[elwilliams13]

Re: wot timing

Would that apply if I ground the black and white wire on the port temp sensor? Disabling the quickstart.

 

[clanton]

Re: wot timing

The Quick Start is disabled by disconnecting the white/black wire. This will NOt give you correct WOT timing at cranking rpms. The final maximun timing must be check at 4500/5000 rpms full throttle. Idle timing is done with a link/sync. Rodbolt said about the same as I. The easy way put the boat in the water, engine running at operating temp, in gear, throttle position at idle, idle timing should be close to 6 degrees ATDC. Full throttle in farward gear 4500/5000 rpms, timing should be 18 degrees BTDC.

 

[elwilliams13]

Re: wot timing

Alright going to do this today.

 

[elwilliams13]

Re: wot timing

Just checked in the water and after a few adjustments is right on thanks to all for your help.