Low Throttle miss

harpo · Jul 8, 2011

This is a head scratcher.I was ridding the outher day when after several hours my 03 begain to have a miss when I was rolling along at a steady speed. After I stoped and let the bike cool a few, it did'nt miss for a while but started again after ridding fifty or sixty miles.

I found it takes ridding for a hunderd miles or so for it to start to miss,and only when not exccelerating.It idles fine and the miss doesnt affect the rpm. What could it be?

ionbeam · Jul 8, 2011

Your FJR is in the range of bikes that should have had the TPS replaced under recall. Call any Yamaha dealer and have the service desk look up your VIN, they should be able to tell you on the spot if your TPS has been changed.

If you are indeed experiencing a TPS failure (you have the classic symptoms) you will experience misfire with the throttle in exactly the same rotation position and it will be a very narrow range. The rotation position will be the same regardless of gear or RPM, though at steady cruising the misfire will occur at nearly the same RPM.

IMO, the TPS is the first thing you need to eliminate.

If the misfire is independent of any one specific throttle position then Forum member 03HiYoSilver has located a connector under the tank that is prone to corrosion and may be responsible. If you want to check this connector we can link you to the page with pixs.

03HiYoSilver · Jul 8, 2011

Here are the links to the Connector Cleaning:

https://www.fjrforum.com/forum//index.php?s=&showtopic=22734&view=findpost&p=268059

RAD's Symptoms- https://www.fjrforum.com/forum//index.php?s=&showtopic=105232

Queensland Ken · Jul 8, 2011

Hi,

A mate near where I lived had a spanking new FJR with 5K kms.

The local bike shop couldn't fix his problem, similar problem to yours. Wasn't a Yamaha dealer.

He brought the bike around and I had a looky, turned out to be the plugs.

The centre electrodes of the plugs were eroded away, 2 were quite bad with only a few thousand miles on the clock.

Good luck and let the froum know what you find.

Cheers

harpo · Jul 9, 2011

Thanks for the info,I will look into the TPS first. The plugs have been replaced in the spring and I have checked the connections under the tank so maybe we got it narrowed down to one last thing.