What Spark plugs to install?

bosch or NGK mag wires are best.
plugs any you want , if car short miles car, every year go cheap plugs , if hard to reach go best plugs.
I like NGK the best, but there are other good brands.

I would definitely go with an iridium plug offered by NGK for the most complete combustion which increases engine efficiency, fuel efficiency, and power. The part number for an NGK iridium spark plug for a Yamaha dragstar is DPR7EIX-9. These are a bit more expensive at around $7 but are absolutely worth spending the extra money as they are proven to last significantly longer. If cost is a factor, a regular ngk spark plug is around $2 and would be part # DPR7EA-9. I hope I've answered your question satisfactorily and ask for you to take a moment to rate my answer. Thank you, Jim. NGK 7803 DPR7EIX 9 Iridium IX Spark Plug Pack of 1

NGK 5129 DPR7EA 9 Standard Spark Plug Pack of 1

I use NGK iridium plugs. The bike runs very smooth at a low idle and the throttle response is spot on. DPR7EIX-9 is the plug number. Remember to take off the spark plug caps before installing as the wires only connect to uncapped plugs. Good luck!

check Gap: .040

Bosch Spark Plug: Part Number: 18594-05120685

PLATINUM -- Original Equipment is Iridium. Gap is Preset

OE Fine Wire Platinum -- Do Not Gap, Gap is Preset

OE Fine Wire Iridium -- Do Not Gap, Gap is Preset

Description:
V-Power Plug, 14mm Thread Size, 26.5mm (1.04") Reach, 5/8" (16mm) Hex Size, Gasket Seat, Resistor, Projected Tip, Solid Terminal Nut, V-Power (V-Grooved Center Electrode), .043" (1.1mm) Gap, Heat Range 5

To purchase:
http://www.ngk.com/results_cross.asp?pid=LFR5A-11

or here...
http://autoparts.greencarreports.com/auto-part/ngk-6376--ngk-6376-lfr5a-11-v-power-spark-plug-pack-of-1

cross to a Denso;..
http://autoparts.greencarreports.com/auto-part/denso-5343--denso-5343-ikh16-iridium-spark-plug-pack-of-1
or
http://autoparts.greencarreports.com/auto-part/denso-3417--denso-3417-sk16hr11-iridium-long-life-spark-plug-pack-of-1
or just a standard NGK #...
http://autoparts.greencarreports.com/auto-part/ngk-5018--ngk-5018-spark-plug
And last but not least:...

Did you change the plugs with the correct OEM plugs? Also, you may a bad spark plug wire. Check that plugs are set at the correct gap.

I assume it was running before you changed the plugs and wires, verify you didnt disconnect accidently another wire such as a crank position sensor or an oxygen sensor on or near exhaust manifold
also check the wire firing order make sure that is correct...

Have a look at your spark plug wires. You may have one laying upon a hot surface which may have caused degradation to the wire's insulation which would allow the spark energy to short to ground instead of going to your spark plug. If you find a damaged wire, replace them all with NGK stock wires (very good quality), and find a way to prop up your wires so that they won't touch anything.

Also, you may have a defective spark plug. Change them all as well. I just installed NGK Iridium plugs and they perform excellently.

You should have coil packs. Each coil pack fires two plugs. You may have a defective coil pack.
They should be right up front on top of the engine. Engine coolant lines run underneath them, perhaps the defective unit is affected by the heat from the coolant hoses.

My 2004 Verona had factory installed "NGK BKUR6ETB" regular spark plugs which I replaced at 30,000 miles. The 2005 model year is supposed to have Iridium spark plugs. To replace the spark plugs: 1. Remove plastic top engine cover. 5 nuts 10mm socket. 2. Unplug connector from each ignition coil. qty 6. 3. remove 2 hold down bolts per ignition coil. 10mm socket. 4. remove ignition coil, lifting straight up. 5. Spark plug is now accessible, use deep well 5/8 spark plug socket to remove.