Loosing cylinders on first cruise of season

Well I took the bike out for a spin and everything was great so I thought...
When running around town I have mybe one or two cylinders droping out(stops firing or no fuel) I have not looked at it yet, but would like some ideas that you guys might have.
Before I rode I Cleaned out the petcock, reused old fuel filter seamed to flow well when I turned fuel on. Changed oil, put 20w50 Amsoil Synthetic. The bike has been sitting for 8 months. I put new fuel filter on and rode once are twice before it sat. Plugs are tan in color.
Also on the highway it dose not drop any cylinders.
Also it started doing this before it sat, now it is more aparent.

Info on bike:
KZ650B1 1977
Ignition is dyna green coils with supression wires, electronic ignition off a 1981 550A.
Gaps .035
New main jets 2 over in size
New pilots 15
Compression 165 in all four No carbon buildup
NGK plugs from last year
12.6 volts at coils after cruise, KOEO, 13.4 KOER

I'd start with checking all wire connections from the Ignition to the spark plugs, taking them apart, cleaning them with an electrical contact cleaner spray, add a dab of dielectric grease, and make sure the connectors are not loose.

How is it possible for you to use synthetic oil? My real question to you is have you been using synthetic oil before this oil change?

I have been using synthetic for about 6 years on the bike.

If the plugs are brown not black,and it runs
good at higher speeds only,it probably has
plugged pilot jets.

Silly question but is your fuel 8 months old? Had a similar problem drained off old fuel filled with new all ok now

The fuel is new, I am running 89 oct.

tjettim: I thought that pilots were for idle only???

To add some more info, it only happens at cruise on streets. I can be at idle to 4000 rpm it will cut out cylinders. Do the pilots still work at these engine speeds. Like I said at cruise or idle so I'm only giving it a little trottle when it happens, maybe 10-15% throttle. When I hit the gas it bogs for a couple of seconds then takes off.

The wife has me digging fence post holes so I proboble wont get to it till the weekend.

synthetic oil?? How much oil does your engine consume??

The wife has me digging fence post holes so I proboble wont get to it till the weekend.

Being punished for being bad?? :woohoo:

The pilots are effective up to around 1/4 throttle.

martijn wrote:

synthetic oil?? How much oil does your engine consume??

That offends me:P
Just kidding, No conumtion of oil.


HMMMM pilots work till 1/4 throttle, looks like I'll be taking the carbs off again before riding this season.
I'm going to just take the carbs off when I put it up for winter storage :silly: