Page 1 of 1

2006 Yamaha Royal Star has poor throttle response

Posted: Fri Apr 10, 2009 5:43 pm
by jimmyblairnelson
:( this V-4 has a very complex Carburetor system and without understanding how each sub-system interacts with the whole, I am stumped. The engine starts and idles ok, but seems to have poor throttle response if lugged and if you are cruising and turn the throttle on, it will actually reduce power before accelerating. I have checked float levels (as best as one can), cleaned all four carbs, checked freedom of movement, checked TPS but could not adjust to limits (max resistance is 4680, ohms full throttle reads 1200 ohms and throttle closed is 4300 ohms) and ballanced the carbs. Fuel pump seams to work, choke seams to work. Any ideas??

Posted: Fri Apr 10, 2009 6:54 pm
by Wrider
Honestly it sounds like either 1. Your accelerator pump isn't working. or 2. Your carbs are running too rich and flooding the engine when you whack open the throttle.

Posted: Sat Apr 11, 2009 10:12 am
by jimmyblairnelson
That was a good call, but I do not believe my bike has accelerator pumps! Another thing is that keeping the throttle in one spot, and approaching a small hill, it will start running poorly without changing the throttle. should rule out a pump.

I will take the bike out and when it starts loosing power, I will pull the choke out a bit and see if it improves (running too lean) or makes is worse (running too rich). My carbs are Mikuni BDSR32 (four of them!)
appreciate your feedback!

Posted: Sat Apr 11, 2009 11:26 am
by Wrider
Alright, I wasn't sure, I didn't happen to deal with the V-4s at all. But yeah, check with your choke and see what's going on. Shouldn't be too hard to fix once you figure out what's up.

Posted: Sat Apr 11, 2009 1:10 pm
by jimmyblairnelson
Sure appreciate your response...will let you know. If you know anyone that has worked on a royalstar, let me know...this is a very complex bike! You can email me at

Motorcycle stumbled, pulled the choke out

Posted: Sat Apr 11, 2009 3:02 pm
by jimmyblairnelson
Wrider, just got back from riding it and when it was running poorly, I pulled the choke out and did not improve it except maybe under full choke! It started cold pretty easy and I am getting the feeling that the choke is not disengaging...will pull the carbs off and try to go through that system and see if I can see a problem. Jim

royalstar tour deluxe 2006

Posted: Wed Nov 25, 2009 11:35 am
by streaksf
I here you mine 2006 tour deluxe dont ride much, but issues with carbs i think. 1. must let warm up dont understand got 15 w heaters on each carb
2. had dealer replace plugs and they told me 1 carb was stuck and i should ride it more
3. i only use premiem gas
4. new fuel filter
5. still have issues not running smooth had to up the idle speed turning the screw to raise idle speed or it stalls even after riding for hours

Re: royalstar tour deluxe 2006

Posted: Wed Nov 25, 2009 12:09 pm
by Johnj
streaksf wrote:2. had dealer replace plugs and they told me 1 carb was stuck and i should ride it more

You might try riding it more. :wink:

Carb malfunction repaired!

Posted: Wed Nov 25, 2009 1:07 pm
by jimmyblairnelson
Just to let all interested know, I took those carbs off 3 times and totally went through them with no improvement! A mechanic that knows these engines told me that the brass caps that cover the idle jets (not mentioned the the repair manual because they are not to be 'screwed' with) were clogged with stale gas from the winter storage. $300 bucks later, he said he cleaned out the idle circuit and it runs fine now... He said if it happens again, I now know what to do. This close held secret is now out of the bag! Buy the way, this winter, I put stable in the fuel and ran the carbs dry and will run the engine once a month to keep seals working...