How many spark plugs are there to change on my 2005 Honda VTX shadow ?

As for a direct answer to your question, several of us run the Champions ( 810's RA8HC). Much less $$ than the Densos or NGKs. Can get them at almost any Auto Parts Store.

+2 on champions.get at any auto parts store around $1.69 ea. here's a list of plugs that will fit.
H-D Standard 6R12
H-D Gold 6R12G
H-D Platinum 6R12PP
Champion RA8HC
Autolite 4164
Autolite Platinum AP4164DP2
ACCEL 2418
Y2418P
Splitfire SF416D
Screamin Eagle EX12S
EX12P
ACDelco
NGK DCPR7E
Bosch
Denso Iridium IXU22

https://www.google.com/search?safe=off&rlz=1C1QJDB_enCA643CA644&sxsrf=ALeKk02yh9BeBTYNAMgC4RBMaC8q_wRetA%3A1615312662320&ei=FrdHYO_2EoSx5NoPyb2BgAo&q=honda+vtx+1300+spark+plug

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I reckon when you remove them to check the gaps and they are either badly worn, thin electrodes or have failed. The manufacturers will say every 2000 miles, because they will sell more plugs!
If it gets a problem to start or misfires, check the plugs and adjust the gaps as required or replace them if they are badly worn or damaged.

1st thing you need to do is see if the spark plugs have spark.Remove a spark plug,put the plug wire back on the plug, ground the spark plug to the engine ( lay on a bolt) turn bike on push start button check plug for spark.If it has spark then you have a fuel problem.Hope this help let me know what you find
D.

Maybe you must change with Premium Spark Plug Wire Set below, you can select your vehicle model.We replaced our old spark plug wires with these when kept shutting off. They worked great and helped to solve our problem. Amazon com NGK 9160 ZE21 Premium Spark Plug Wire Set Automotive

VT1100 has two spark plugs per cylinder, the sparkplug caps are snap-ons so they're fairly easy to remove. You need a spark plug socket wrench to remove and replace the spark plugs.

Check the Gap according to manufacturers specifications :)

it sounds like a fuse or a relay