Black Plugs / what now ?

wildtalk · #1 09-21-2010, 06:27 PM

These plugs ( attached picture ) have less then 10 hours run time in a johnson 150 hp 1987. I had motor service just a month ago . I replaced them with spare set I had on standby. question is what do I need adjust ? Plug gap ? oil ? Oil Mix ( its an auto mix injection ) or change plugs type . They are Champion QL77JC4. Any and all help will be welcomed

Macrenovations · #2 09-21-2010, 07:35 PM

Had the same problem, The motor was getting way to much fuel adjust your carbs and make sure they are setup the same way. At least you know your getting oil and that's a great thing.

Here's the basic read on spark plugs that I found and a chart on which plugs to use and gap settings.Hope this helps. I set my plugs a 28 gap instead of the 30 seems run a little better and not foul out the plugs as quick.
For a two-stroke engine, having a fresh spark plug is incredibly important. So you should check your plug often.
By "reading" the color of the plug you can tell a lot of things about how the engine is running. The top of a new spark plug is covered in white ceramic insulation. If your engine is running perfectly, then this part of the plug would soon become a tan color. If your plug is grey or white, than you know that your engine is running too lean and you need to take steps to prevent engine damage. First, clean your fuel system, looking for any blockage. Dirt in your carb can cause the bike to run lean. Check your fuel mixture to see if you are mixing the oil and fuel in the correct proportions (50 parts fuel to 1 part oil). There are many factors that can cause an oil and fuel mixture that worked great to become less than ideal. The brand of the gas and the oil as well as air density can affect how well the mixture works.
The lean condition can also be caused by fresh air entering the engine somewhere it shouldn't. So you should look for loose intake manifold bolts, leaks in the carburetor mounting, faulty gaskets and leaks in the crank seals. You may also need to change to a larger carburetor jet.
If your spark plug is black or oily than that means the engine is running too rich and is not properly combusting fuel. This problem can be caused by too much oil in the fuel and oil mixture and/or having a faulty spark plug that is misfiring. First, you should figure out if the spark plug is the problem. To do so, touch the electrode end of the plug to the engine while pulling the starter. If the sparks that result are blue, then you know you have a fully functioning plug. Install the plug and run the bike for a few minutes. Then stop the bike, remove the spark plug and look at it. If the plug is dark and oily, then you know that the problem is not your plug. You should check your oil and fuel mixture. If the bike's engine stumbles, sounds clogged up or doesn't run clear than you might want to get a smaller carburetor jet.
While you should regularly inspect your spark plug, it is essential to check your plug after any type of engine modification to make sure the engine isn't running too lean. For standard use, the NGK B7HS short thread plugs and B9ES long thread plugs are recommended. For use in competition, the NGK B7HS-10 short thread plugs and the NGK BR9EIX long thread plugs are recommended.
First check your coil for a healthy spark. Use a fresh plug and ground the electrode to the engine while pulling the starter - the spark should be a healthy blue. If so, install the fresh plug, and operate the bike normally for a few minutes, remove the new plug and "read" it. If it still appears blackened or oily, the problem lies elsewhere. A hotter plug in not recommended - make sure your fuel mix is correct, and consider a smaller jet only if the bike stumbles or sounds "full of snot" and doesn't run crisp. Operating your bike a little too rich won't hurt it - but too lean is never good. A little dirt in your carb could cause it to run lean, and you wouldn't even know why your bike was running so nice and crisp until it seized

Hope some of this helps

150, 155 (90º crossflow V6) 1978 - 1987 UL77V or L16V Surface Gap
http://www.boatsetup.com/SparkPlugChart.pdf

THEFERMANATOR · #3 09-21-2010, 11:10 PM

Does it smoke blue at idle? If so you may have an air leak going to your VRO pump which will make it dump oil in. I persoanally pre-mix all of mine just so I don't have to worry about problems with the VRO and dealwith some smoke at idle. Also have the link and sync checked and make sure its right, and that all of the air bleeds in the carbs are cleaned and in the right places.

wildtalk · #4 09-21-2010, 11:27 PM

Yes its a smoker at idle. thanks for the info

wildtalk · #5 09-23-2010, 12:54 PM

After comments and some more research .. I came some research that states synthetic oil would help and burn better. Any Commenst on whats the best oil for use with my johnson 150 fast strike 1987 ? Also read thet spark plug gap set to 25 or 27,, is betther then recomended setting of 30 ? Looking forward to more comments. Im almost considering just mixing gas myslef if I cant find a solution . Last it was serviced was less then a moth ago VRO was click every 6 - 7 seconds. Is there a way to set the VRO ? or is it preset and un-adjustable ?

THEFERMANATOR · #6 09-23-2010, 09:08 PM

The VRO is not adjusteable on these engines. I reccomend the PENNSOIL synthetic blend for any of the old school carbed 2 strokes. Its priced right, available in many places, and burns relatively clean. As for how much oil it is injecting, have you checked how much oil to how much fuel you are using? If the VRO is working, it shouldn't smoke much at all at idle. Sounds like you have an air leak in the fuel line going to the engine from your description of the smoking. Remember that ifyou are running it hard, it should use roughly one gallon of oil to 50 gallons of fuel. And if you are running it at idle to slow trolling it should be closer to one gallon of oil to 90-100 gallons of gas.

wildtalk · #7 09-24-2010, 01:50 PM

Thanks for the info Thefermanator . I did a complete check of the gas lines yesterday .. and MAY have found a slight leak. To be safe I replaced that area of line. I was also told I could switch to a L78V { chanpion } spark plug . Its the kind that just has a dot in the middle no gap setting on this type. Anyone ever use this type plug ?

THEFERMANATOR · #8 09-24-2010, 01:56 PM

Quote:

Originally Posted by wildtalk

Thanks for the info Thefermanator . I did a complete check of the gas lines yesterday .. and MAY have found a slight leak. To be safe I replaced that area of line. I was also told I could switch to a L78V { chanpion } spark plug . Its the kind that just has a dot in the middle no gap setting on this type. Anyone ever use this type plug ?

Stay with the QL77JC4 plugs, TRUST ME. The QL78V plugs use a longer reach electrode for prolonged high RPM useage and will foul even easier at idle.

KEEPINGITREEL · #9 09-24-2010, 07:43 PM

Hey Wildtalk, F a Champion plug. ASE certified tech(come on guys you know you should spout it)with minimal ex with O/B. F a champion! Everytime I put one in, not so much. Still have to kneel to the pros! I may know stuff elsewhere, but this is where to find the right info.

THEFERMANATOR · #10 09-24-2010, 08:27 PM

Quote:

Originally Posted by KEEPINGITREEL

Hey Wildtalk, F a Champion plug. ASE certified tech(come on guys you know you should spout it)with minimal ex with O/B. F a champion! Everytime I put one in, not so much. Still have to kneel to the pros! I may know stuff elsewhere, but this is where to find the right info.

Are you trying to say CHAMPIONS are crap or something? If so you obviuously have never dealt with OMC outboards as they are the only plug that will run in one. Yes, I used to be ASE certified but let em expire as working for myself I have no need for them with my clientel. I have experience working on just about everything out there from cars to boats and classic cars. And most of the ASE guys I worked with I wouldn't trust to fix a go-cart.