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Need Spark Plug Advice! Champion QL78YC VS. L78C

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BayLiner160

New member
I'm new here and so let me say right up front I appreciate any help you guys can offer this newcomer to the forum!
I recently bought a small Bayliner, a 2001 Capri 160 with its original 50HP ELPTO Outboard.

I am spending the first couple days cleaning the boat up, and during this process I took the cover off the powerhead and discovered the two screws that hold the 2 stroke oil tank up top had come loosened, one completely out (thankfully I found it in the bottom of the powerhead casing) and the other hanging in there on two threads.

After a consider amount of time was spent "cleaning up" in there, I decided to check the condition of the plugs.

They were so loose they literally were turning as I pulled off the plug wires.

They looked really black and oily, which I understand is a component of a 2 stroke older engine (I guess?) but I decided fresh plugs can't hurt.

Here is where I finally ask my question!

The plugs in the motor are Champs QL78YC.

In my parts box I own a dozen brand new in the box Champion L78C plugs. Bought them years ago for some long forgotten reason and they have been sitting there ever since.

Can I safely use these instead of the same plugs previously used in this outboard?

I know the plugs are relatively cheap, it's not the cost. I would just appreciate the opportunity to use plugs I already own if no hard will come of it.
If it's not safe to sue them I'll take the ride to town and buy the same exact plugs that were in there, but if I do in fact have to take the ride, I'd appreciate any advice as to the "best" plugs to buy if there is an even better choice.

So I guess I have two questions after all!

Can I use the L78C plugs I already own?
If not, do I buy the QL78YC plugs or an alternative that is better?

Thanks in advance!!
 
Champion racing series spark plugs have a nickel shell, copper core and a protected tip to help dissipate the heat even at high RPM's. The QL78YC helps reduce the timing and gives you better throttle response.
 
To answer your question........Champions are not Mercury OEM plugs and the QL series is not a racing plug. If its a 50 ELPTO it should use surface gap NGK BU8H... the QL78YC is a long reach gap plug and will likely hit the top of piston.
 
faztbullet said:
To answer your question........Champions are not Mercury OEM plugs and the QL series is not a racing plug. If its a 50 ELPTO it should use surface gap NGK BU8H... the QL78YC is a long reach gap plug and will likely hit the top of piston.
Click to expand...
I appreciate the response, but take a look at this....I found the original owner's manual for the motor on my boat. Please note the recommended spark plug is NGK BPZ8H-N-10. Also please note that NGK notes the Champion alternative is QL78YC. So I am thinking the reason the motor had the Champion QL78YC plugs installed is because someone at some point found the same information I did about their compatibility. So....my question is now a two-parter. First, is the cross-reference chart wrong in this case? And second, please refer to my original question. Thanks again for any help and/or advice/tips!
 

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faztbullet said:
To answer your question........Champions are not Mercury OEM plugs and the QL series is not a racing plug. If its a 50 ELPTO it should use surface gap NGK BU8H... the QL78YC is a long reach gap plug and will likely hit the top of piston.
Click to expand...
Also, just to confirm my model number.....take a look....
 
The QL is a resister plug designed to reduce ignition noises and Th NGK BP is also as resistor plug..The MFG wants a resister plug for a reason and the L78 is not.
 
If you're still not sure or feel the question has not been answered, call Mecury. My gut says they'll steer you the book as what bullet noted above. I always try to stick w/OEM. Knowing the ramifications in being stuck on the water, I prefer to be risk averse and use parts in the service manual.
 
jduda22 said:
I found a NGK guide to what the letting and numbers mean.
Click to expand...

VERY helpful, and thank you!!

I do have to say though, according to this breakdown, the plug recommended to me here in this thread, the NGK BU8H, does not seem to be supported by the manual for the motor (See the pic I posted from my manual) nor does it seem to be compatible with the alternative Champion plug to the NGK that the manual recommends, which I was told could cause damage but as a listed alternative to the factory recommended NGK as well as the plugs the motor has been running on for the last few years (at least, from the look of them), seems to be no problem at all.

Of course, my initial question, regarding whether I could safely use the L78C instead of the QL78YC plugs currently installed, was only asked because I happen to have a dozen brand new ones in my parts box! Trying to save a few bucks plus the convenience of already owning them rather than having to order them was tempting! If at the end of the day I have to order plugs, I'll just order the factory recommended NGK BPZ8H-N-10. Still curious though about my original question as well as why the QL78YC plugs would have been thought to be potentially damaging, but maybe I am just putting way too much thought into this! Haha!


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