Spark Plug trouble shooting

[MotoKatana]

Hey guys,

Here's the story.

Part 1: The 1996 kat 600 has been having sudden loss of power issues during long high-speed rides. Oil level has stayed consistent, so no overheating. The dealer said to check the plugs. They are almost completely white(a few specs of brown) instead of light brown after 4k miles. From what the internet has told me this means they are running too hot and are possibly the source of the problem.

Part 2: I decided to go for the next heat range up in plugs. The Kat has cr9ek plugs and so i replaced them with cr8eks for 8 bucks a piece. I start it up and sounds horrible + dies.

Should I just buy new cr9ek plugs and try other things for the loss-o-power?

[MotoKatana]

I just put the old plugs in and it sounds just as bad. this is my first plug job so I probably did something wrong. Do you twists the spark plug caps till they stop or just a bit?

[Jman2343]

What do you mean plug caps? And also make sure you tighten the plugs to torque specs, you don't want to strip out the cylinder head.


White/brownish I'd say your running lean (which would make it run hot, lean is mean fat is happy). Fuel problem (fuel petcock flow) rusted tank and dirty carbs. Or you have a vac leak, check airbox tube, airbox boots (also need stock filter not a k&n).

[Rare83Kat]

Hey guys,

Here's the story.

Part 1: The 1996 kat 600 has been having sudden loss of power issues during long high-speed rides. Oil level has stayed consistent, so no overheating. The dealer said to check the plugs. They are almost completely white(a few specs of brown) instead of light brown after 4k miles. From what the internet has told me this means they are running too hot and are possibly the source of the problem.

Part 2: I decided to go for the next heat range up in plugs. The Kat has cr9ek plugs and so i replaced them with cr8eks for 8 bucks a piece. I start it up and sounds horrible + dies.

Should I just buy new cr9ek plugs and try other things for the loss-o-power?

jman2343 hit it on the head. too lean and possible fuel starvation !

Stalling or losing power during long high speed wot runs could easily be from inadequate fuel delivery to the float bowls. ie: fuel starvation
If it's happening only when your on wide open throttle after say a half mile blast, and the power returns to normal after you let off the throttle and slow down to reasonable speeds then that's what you're looking at. If so replacing the petcock with a nice "pingle" unit will cure your woes.

As for the white plugs, yes you're running quite lean and could use richer jetting. Why oh why though did you go to hotter spark plugs when you already know it's running hot? I would go back to the stock nines right now and if you ever have a notion to do anything regarding the heat range of your plugs you should look towards running "colder" plugs ie tens.

Rule of thumb... always run the coolest plug that won't end up fouling.

[hardlydangerous]

if its lean (white plugs) why in GAWDS name would you put a hotter plug in it.
you just asking for serious trouble (pre-ignition)

you want a colder plug I run Iridium 10's in mine !

your problem sounds more like a fuel starvation issue or just WAY too lean.
start by removing the petcock and cleaning it and the filter. Replace the fuel lines as well as the vacuum line for the auto petcock. Make sure the lines are the correct size and a snug fit.
pop the vacuum caps off and check the needles. if not adjustable go buy some #4 washers from radioshack and shim the needles up.
set the mixture screws at 2.5 to 2.75 turns out.

[rockat]

Do you twists the spark plug caps till they stop or just a bit?

Twist a quarter turn for new plugs.

Twist an eigth turn if putting old plugs back in.

So, you twist the plugs in using the spark plug tool that should have come with the bike or whatever tool you have. Once they don't turn easily with your hand, you follow the above twists

[kevin2502000]

I just put the old plugs in and it sounds just as bad. this is my first plug job so I probably did something wrong. Do you twists the spark plug caps till they stop or just a bit?

Put the wires on in the right order? L coil 1&4, R coil 2&3 as you sit on the bike.