QL77V vs Ll77V

[red boat]

I have a 1990 Evinrude XP200 and use L77V-jc4 plugs and gap them at .35 what is the diffrence between L77V-jc4 and QL77V-jc4? Is ther anything wrong with running the L77V's? Also after my first outing this year I started having a problem- above 4000 rpm the motor will drop out just like a no fire condition for 1/2 sec then pick right back up. Example wide open 6000rpm for 2 secs then drop to 4700 for 1/2 sec then back to 6000 over and over. Under 3400 no dropping out at all. Stator and rectifier/regulator just replaced last summer. When I put it up for the winter it was running fine. All the carbs have been cleaned, soaked blown out with compressed air etc. tried putting new coils on all 6 cylinders- no diffrence.I am no expert but this seems like an electrical problem, almost like a "dead miss" Could this be my ignition switch in control box maybe shorting out? Some type of shift switch? Sorry about the long post but i'm running out of options!!

 

[chris in va]

Re: QL77V vs Ll77V

I'm having the same problem with my 77 9.9. Should be interesting to find out what each other's solution is.

 

[OBJ]

Re: QL77V vs Ll77V

Hey red boat....welcome to iboats!<br /><br />The plug you should be using is a QL77JC4. It's a suppressor plug. <br /><br />It sounds like your dropping a cylinder....meaning one cylinder quits firing. Would the plugs cause this? If they are new, I would not think so.....but it's possible.<br /><br />Have you looked at the plugs? Does any one plug look different than the others?

 

[red boat]

Re: QL77V vs Ll77V

OBJ, thanks for the welcome!! Plugs are new, I even tried gapping them at .030 like the manual says and no diffrence. By the way motor was rebuilt beginning of last summer, Bored .040 weisco pistons, boysen dual stage reeds, vro unhooked premix 50:1. The plugs all look the same a light tan color. I agree I am dropping a cylinder what could be a possible cause?

 

[McGR]

Re: QL77V vs Ll77V

As OBJ stated, the "Q"s are supressor plugs. Non-supression plugs can cause increased amounts of both radiated (radio) and conducted (electrical) noise. Such electro-magnetic interferance can raise hell on electronic ignition systems. This is why Qs were specified on your motor rather than the standard plugs. For the price of six Qs, I would change the plugs out then start troubleshooting from there.

 

[red boat]

Re: QL77V vs Ll77V

I will give that a try and I will post results. I wont be able to run the boat for a couple of weeks

 

[myrone]

Re: QL77V vs Ll77V

I've had some problems (fouling) here at altitude (Colorado) with the plugs your running, I've gone to an Autolite 2634 and like the difference. I'd check the plug wires as well.

 

[moderator1]

Re: QL77V vs Ll77V

myrone, you are asking for trouble running those plugs.<br />You are fouling plugs because you need to re-jet for the elevation.<br />Don't be surprised if new pistons are in your future...<br />If you'll post your engine model, I can tell you what you need to do there.<br />We've tested OMC engines in years past from eastern Co., up to Dillon and back. about 20 years worth. Post your info and we'll start from there before you ruin your rig...

 

[myrone]

Re: QL77V vs Ll77V

1990 90hp Johnson

 

[walleyehed]

Re: QL77V vs Ll77V

Myrone, you need to drop 2 sizes in main jets (.002) for anywhere in eastern colorado, or above 3000ft. If you run at 5000 or above, you'll need to drop atleast 3 sizes. <br />First thing to do is pull the bowl nuts and remove a jet and verify it has the sea-level jets installed now-most do. You'll have to visit a JohnRude Dealer to find this info out once you pull a jet and determine the size. What ever you find in there, unless it has had some serious performance upgrades, you want .002 smaller than the sea-level specs for 3000-5000ft.<br />This is a crossflow engine so it doesn't have the OIS ignition system, so we need to advance timing atleast 1 degree, maybe 2....I run about 4-1/2 degrees advanced from max at 5000ft, but I'm not going to tell you to do that because there are other variables involved..stay at 1-2 degrees over max. If you set the timing static, set it at 1-2 degrees retarded from max, which will put you at 1-2 advanced from max on the water. If you mechanic sets the timing, he "should" know how to do it but most don't for fear of the customer hauling his boat down to 1000ft elevation and burning one up, so keep that in mind, and explain to him what you want.