What the heck?

[goatman]

I thought I should change my spark plugs since I had not done that since acquiring this bike. First challenge was I could not get the 18mm socket over the plug. After 10 minutes I finally figured out that these were not
18mm plugs. My standard spark plug wrench did the job and I took out
some champion plugs that actually looked OK. I put in the new correct plugs thinking "this thing will really run great now with the right plugs".
Not!! It runs like crap. I got out the carbtune hoping that would do the trick, but no adjustment was needed. Under hard throttle it does OK, but
under part throttle it surges, backfires and generally sucks. The only other
thing I did was fill the tank right after I changed plugs, but I went to the same station as always and put in seafoam also. Any educated guesses as to what is going on here?:ummm:

 

[PATMAX]

Just a educated guess here. Pull the plug wires off again and make sure they are fully engaged or seated. I had this and could
not figure why it would run ok under accelleration and poorly down low. Maybe the spark was stronger under load? Just make sure they are fully engaged on the plug.

 

[goatman]

I did double check the boot fit, but checked again to be sure, and they are all the way on. It does seem like it could be somehow related to the wires, since that is about the
only thing that even moved when changing the plugs, it's the only thing I touched since
it started running bad.

 

[satariel666]

Actually i would say that IMO Champions plugs are better then NGK.

Thers a lot of fake ngk's those days. Also bought some absolutly original japan ngk's and they never fired up :confused2:

Never failed with champions, never unk:
Always marvelous quality and long life.


Remember that is no matter with manufacter you will go. Each spark manufacters have thier own heat rating but its always very close to other manufacters
Yama recomending NGK DPR 8 EA-9 and it means D: 12mm thread, P: projected insulatro type, R: resistor type,8: heat rating, EA: dunno but rather it means "special desing".

So theres no big diffrence witch manufacter you will go.

Only advise i will give that you should check the spark gap and check thos Champions heat rating.

Imo carbs are synced to specific plug so if you changing them you should reajust carbs wuth reajusting AF ratio.

 

[Dano1]

Also check that your plug caps are still screwed on. The first time I pulled my wires off I pulled the wire out of the cap on accident. Sometime the cap sticks on the plug pretty good.

 

[naughtyG]

I thought I should change my spark plugs since I had not done that since acquiring this bike. First challenge was I could not get the 18mm socket over the plug. After 10 minutes I finally figured out that these were not
18mm plugs. My standard spark plug wrench did the job and I took out
some champion plugs that actually looked OK. I put in the new correct plugs thinking "this thing will really run great now with the right plugs".
Not!! It runs like crap. I got out the carbtune hoping that would do the trick, but no adjustment was needed. Under hard throttle it does OK, but
under part throttle it surges, backfires and generally sucks. The only other
thing I did was fill the tank right after I changed plugs, but I went to the same station as always and put in seafoam also. Any educated guesses as to what is going on here?:ummm:

Question #1: did the bike run fine before you changed the plugs?

Question #2: did you keep the champions, and have you tried putting them back in?

 

[goatman]

Yes it did run fine before, and I'm afraid I wasn't smart enough to keep
the old plugs.

 

[gamorg02]

can u get to a place with an a/f meter and adjust ur pilots?

 

[richwrench]

Just curious - do you remember the part number of the Champion plugs ? I wonder if they were a different heat range. :ummm:
I found on my original plug wires the core of the wire was eroded back into the insulation on the end that fits into the coil. Could probably just cut an inch off & re-insert, but I just went ahead & replaced them. Plug wires can sometimes get pretty fragile as they age - more than once I've replaced spark plugs & then had wire failure soon after. The core breaks inside where you can't see it. You could measure the resistance of the wires with an ohmmeter , but by the time you get the front wires removed you might as well throw a new set in anyway - just my 2 cents...

 

[satariel666]

Just curious - do you remember the part number of the Champion plugs ? I wonder if they were a different heat range. :ummm:

And i second that. That is what i was trying to say.
After plugs changing its recommended to reajust AF.
Even if they are the same type.

 

[goatman]

I don't have access to an a/f meter, but I have tried the screws from 2 turns out up to 41/2 turns out in increments of 1/4 turn without the symptoms going away. Things seem to be best at about 3 1/4 turns out, but it still not ridable. The wires appear original with 36,xxx miles on the bike, the ends that go over the plug look like they've been baking too long. I will try replacing them first cause I'm sure they could use it anyway. By the way, thanks for all the responses.

 

[yukonerdave]

I think someone mentioned this, but check that the wires are firmly attached to the plug boots - when I changed mine one of the wires became separated and I just switched to COPs instead of replacing the wire.

 

[naughtyG]

Actually I think COPs may even be cheaper than wires, and then you can sell your coils!