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Author Topic: 2003 1200S Spark Plug Reccomendation  (Read 1336 times)

Offline Rainrider

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2003 1200S Spark Plug Reccomendation
« on: August 20, 2015, 05:47:19 PM »
I recently purchased a 2003 GSF1200 S. It runs fine but I am going through all the maintenance procedures prior to a a 1700 mile ride from WA to AZ. When I pulled the plugs I found NGK DPR8EA-9 plugs installed. This is not a recommended plug according to the Haynes manual I bought.
It appears that the bike may have had some tuning work in the past as the pilot air/fuel screw caps have been drilled out and it has a Scorpion exhaust can installed.
I'm wondering if anyone else is running this plug and if I should change them back to stock? All the plugs seem to be burning correctly, (a light tan color).

This is my first post to the forum so please do not be shy about educating me on proper protocol etc.

Offline txbanditrydr

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Re: 2003 1200S Spark Plug Reccomendation
« Reply #1 on: August 27, 2015, 12:43:14 PM »
 :welcome: to the site....  Glad you found us.

If things are running right and the plugs look good (tan is good) then I wouldn't worry about it for your trip.  Once you get back if you'd like to try the recommended heat range then do so but I wouldn't change too much right before heading out.

 :beers:
'01 B600S ... sold
'05 B1200S ... Top 20 mods... #20 through #2 - All The Usual Ones, Yada, Yada  & #1... 150,000+ Miles and Counting!!!!

Offline Rainrider

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Re: 2003 1200S Spark Plug Reccomendation
« Reply #2 on: August 28, 2015, 09:37:23 PM »
Thanks for the advice. I actually went ahead and installed the standard plugs yesterday and took it out for a short ride. I bought a new set of the hotter plug as well and am planning to just carry those along with me in case it starts to load up.
Maybe it's better to run the risk of fouling a plug rather than risk overheating?

Guess I'll try to ride it around as much as possible before I leave and see if I can induce any bad behavior.


Offline ventYl

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Re: 2003 1200S Spark Plug Reccomendation
« Reply #3 on: August 30, 2015, 06:12:16 AM »
Well I feel a smell of misinterpretation.

What risk of overheating? Cold or warm spark plug is only related to the temperature of burning process inside cylinder (more precisely to the temperature at which spark plug operates in engine). The burning temperature is given by construction of engine and fuel mixture ratio. All these things are *not* affected by spark plugs on carburated engines because it has no way to give a feedback from exhaust back to carbs.

Spark plug is able to work reliably only in relatively narrow band of temperatures (let's say 150 deg. C). If spark plug is not warmed up to target temperature it is not able to clean itself of carbon deposits which naturally occurs in cylinder upon combustion. Warm enough surface of insulator disallows it to deposit and if (when engine cold started) it forms deposit it is able to get rid of it. Contrary if the spark plug heated being warmer than intended it tends to wear much faster. In extreme cases insulator can crack or electrode can melt itself and if piece melted down is large enough it can damage the piston. Yet these extreme cases count only for engines which had some part of fuel mixture preparation or engine construction (cams, compression, etc.) heavily modified.

One thing which is not very standardized among manufacturers of spark plugs is warmer - colder rating. With some of them higher number means *colder* while for other it means *warmer*.

Sometimes for some bikes there is one standard setup and recommendation for either warmer or colder environment if original spark plug does not work well.

So if your spark plugs are not cracked, fired to be with whitish layer nor covered in carbon deposit layer I don't think your bike is eligible for spark plug change.
Bandit 400 1991 - stock except of swap from GK75B to GK75A

Offline Rainrider

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Re: 2003 1200S Spark Plug Reccomendation
« Reply #4 on: September 01, 2015, 11:55:05 AM »
Thank you for the detailed explanation. I guess my concern was more with subjecting the bike to more high speed running on the ride to az. I suspect that the hotter plugs installed were in response to build up of carbon deposits from cold starts and in town low speed use.
You are probably correct with the "if it ain't broke, don't fix it" approach.

Offline ventYl

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Re: 2003 1200S Spark Plug Reccomendation
« Reply #5 on: September 01, 2015, 12:04:15 PM »
If that should be the case then colder plugs would be installed (because warmer wouldn't reach it's self cleaning temp band under such conditions). It is not uncommon that bikes come with different set of spark plugs for .... for no good reason.
Just for sake of completeness: the temperature of combustion varies with usage. Cruise and colder environment make combustion a little bit colder while full throttle in warm temperature make everything including combustion hotter. But the temperature band of spark plug is usually able to withstands such a variations when using in same climate. There shouldn't be need for e.g. warmer plugs for freeway riding and colder for commuting. Under most circumstances...
Bandit 400 1991 - stock except of swap from GK75B to GK75A

Offline Rainrider

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Re: 2003 1200S Spark Plug Reccomendation
« Reply #6 on: September 02, 2015, 12:15:15 AM »
OK I guess I'm still confused. On the NGK website it says carbon fouling can be caused by too cold a plug.
http://www.ngksparkplugs.com/tech_support/spark_plugs/p2.asp

Offline ventYl

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Re: 2003 1200S Spark Plug Reccomendation
« Reply #7 on: September 02, 2015, 04:14:30 AM »
Oh I am sorry. I wrote two statements about the same which both try to say direct opposite of each other.  :banghead:

You are right
Bandit 400 1991 - stock except of swap from GK75B to GK75A

Offline Rainrider

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Re: 2003 1200S Spark Plug Reccomendation
« Reply #8 on: September 02, 2015, 11:59:58 AM »
No problem.
Tanks again brother.

 

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