Spark plugs...to project or not.

brianwheelies · Post by **brianwheelies** » Sat Dec 10, 2011 4:28 am

After some reading of my manual I found that the recommended spark plug for my Rattler 50 is a NGK BP7HS.

When I got my bike back from it's first service I noticed the spark plug they installed was the B8HS.

The bike never ran as good after getting it back from them and I am not sure why. I have since installed a B7HS which runs a little crisper than the B8HS from the dealer.

Should I be using the projected tip plug recommended by the manual and will it make a difference?

Lokky · Post by **Lokky** » Sat Dec 10, 2011 5:13 am

Mind you this is for my stella but the same should apply to you.
I had swapped to a colder spark plug for the summer, when it got colder I went to pick up another BP7ES. I installed it and the scooter had a noticeable loss of power. Took it out, checked it, and sure enough I had been given a BR7ES by mistake which is shorter and the electrode doesn't stick out of the threads. The dealer swapped it for the proper plug and the bike went back to riding well.

brianwheelies · Post by **brianwheelies** » Sat Dec 10, 2011 5:40 am

That is great news for me! I will have my hp back!

brianwheelies · Post by **brianwheelies** » Sun Dec 11, 2011 4:04 am

I finally got the spark plug after searching around town a bit today. It definitely made the mid-range crisper which is where it was lagging before. After running it for a while today I think I may grab the next cooler 8. It seems to be a bit white compared to the nice creamed coffee colored one of the non-projected tip that I replaced.

viney266 · Post by **viney266** » Sun Dec 11, 2011 5:41 am

Yeah, I have an older Yamaha single. It REALLY doesn't like the standard tip plug. I put a non-projected tip plug in once when it was all I had. Switched it to projected a few days later. Could believe the difference it had made

jmkjr72 · Post by **jmkjr72** » Sun Jan 08, 2012 4:50 pm

if you are still running an oem non squish band head (the hump head you need the bp7hs to get the spark down where it needs to be other wise you dont get proper combustion

but if you have an aftermarket bore kit or just an after market squish band head (this will bump compresion up and increase your perfromance) you do not want a p plug as it moves the tip of the plug too close to the piston you might hit the piston or you could burn a hole in the piston