1999 royal star that wants to drop 2 cylinders when you throttle up

[yamahoppy]

I have a royal star venture that for some reason wants to drop two cylinders between 35 and 50 miles and if you work the throttle a little bit they kick out of it and runs like a top. I have had the carbs completely rebuilt, my mechanic is at a loss of what it might be, i have also installed a new ignition module  and ingnition switch with no change . Any thoughts?

[M61A1MECH]

So tell us what gear are you in when you roll on the throttle between 35 and 50? 

If you are in 4th or 5th (both are overdrive gears) this response is  completely normal. At 35 to 55 you should still be 3rd gear, roll on the throttle at those speeds in 3rd and she should take right off. No need to be in 4th or 5th below about 60.  This engine does not perform well at low RPMs.

[PreachJohn]

If it is not an improper gearing issue, can 2 ignition coils have weaker output?

[Stasher1]

4 hours ago, PreachJohn said:

If it is not an improper gearing issue, can 2 ignition coils have weaker output?

I would be looking at plug boots/caps before coils, but weak coils is a possibility. 

I've been experiencing a missing/stumbling under load, and I traced some of the problem back to bad factory plug caps. I replaced the ones in cylinders #1 & #2 with new NGK SD05F, and the situation improved drastically. Managed to replace #4 as well, but the factory plug wire on #3 is too short to do the swap. I had to order a bit of 7mm wire and a NGK J1 plug wire splicer. Hopefully I'll have a chance to install it this afternoon.

 

[Squidley]

11 hours ago, Stasher1 said:

I would be looking at plug boots/caps before coils, but weak coils is a possibility. 

I've been experiencing a missing/stumbling under load, and I traced some of the problem back to bad factory plug caps. I replaced the ones in cylinders #1 & #2 with new NGK SD05F, and the situation improved drastically. Managed to replace #4 as well, but the factory plug wire on #3 is too short to do the swap. I had to order a bit of 7mm wire and a NGK J1 plug wire splicer. Hopefully I'll have a chance to install it this afternoon.

 

Where did you purchase your caps from?

[Stasher1]

Amazon, same with the 7mm wire and the NGK splicer. 

[99silver]

Getting my 2000 RSV ready to go, was unable to ride last year so I drained the fuel and put in fresh gas with some Sea-foam however the front right and left rear cylinders don't seem to be getting fuel or spark as the pipes are not getting hot. I'll check for spark and put in some fresh plugs. What plugs are recommended?

 

[Marcarl]

Wow Gary, haven't seen you around for a while!! GOOD to hear from you again. Suggest OEM plugs.

And a hotshot cleaning of the carbs.

[99silver]

Carl, life has made a few turns in the road but the Good Lord has kept me on the road and I am slowing down and enjoying life!

I changed the plugs and while cleaning out the spark plug wells a Q-tip fell into the front left spark plug hole and disappeared, I about had a stroke. I stopped and prayed. Ok I turned on the ignition and just bumped the starter button and wow it was sticking out of the hole but would not come out, I clamped onto it and bumped the starter again and it freed up. WHEW!!!! thought I was in for some major work!!!

[Marcarl]

19 minutes ago, 99silver said:

Carl, life has made a few turns in the road but the Good Lord has kept me on the road and I am slowing down and enjoying life!

I changed the plugs and while cleaning out the spark plug wells a Q-tip fell into the front left spark plug hole and disappeared, I about had a stroke. I stopped and prayed. Ok I turned on the ignition and just bumped the starter button and wow it was sticking out of the hole but would not come out, I clamped onto it and bumped the starter again and it freed up. WHEW!!!! thought I was in for some major work!!!

Seeee, He even helps out in the little things. Good news for sure!!!! Next time, crack open the plug, shoot some air into the area and you should be good to go.