ok so i am going through my bike to make sure everything is up to par its my first street bike so i want to make sure i have no problems and everything is safe as it can be anyway the story behind the bike a buddy of mine had it for his first bike he ended up getting a 929rr and sold me the f2 because he couldn't get it to start i got it for 500$ it ended up being the diaphragm in the petcock valve was bad lol good for me got it running and it is a champ dosent skip a beat so what it needs is fork seals brake pads oil change the previous owner did oil changes on a regular basis some plastic welding and painting new mirrors clutch lever and blinker bulbs the last thing to do the spark plugs but i took the old ones out and they are NGKr CR8EH9 the manual calls for NGK CR9EH9 what is the reason for the different plugs? the bike ran awesome with them the bike also has vance and heins aftermarket exhaust including headers k&n air filter also vance and heins power commander or ignition not sure what the box is but it says vance and heins on it srry for lack of knowledge but if a pic of it is needed i can take one and also jet kit im assuming or i figured it would run like crap with all that said whats the reason for the different plugs or is there one? my buddy (previous owner) said he never changed them and never had a problem guy before him might have put them in he is not sure thanks for all the help guys pics will be coming when im all done with going through the bike but if you need some of specific things to help answer question let me know

 

Someone put a plug that operates in a slightly different heat range. If the hotter plugs work in there, run the same ones. If you go back to stock, you probably won't notice any difference.

 

I asked a tech about this the other day, he said if you're gonna do a lot of local riding, you're better off with a hotter plug because you'll get better response. If you're gonna do a lot of highway and distance riding, go to a colder plug because it'll help with longevity in this case. If you're trying to find a balance, go with the recommended heat.

Now, this is usually the case with a stock setup, but as people like to tinker with jet sizes and air filters and exhausts and cams n' whatever else it may be to change the A/F mixture and delivery, some people change spark plugs to compensate. A lot of tuners who increase power like to go one step colder on their plugs, which is what the tuner of that bike seems to have done. Best thing to do is to read the plug, is it black, honey brown or white? If it's that honey brown color, leave it as is as it's running healthy.