Shudder and running rough at low RPMs

Yamaha FJR Motorcycle Forum

Help Support Yamaha FJR Motorcycle Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Gitbox

Well-known member
Joined
Jun 16, 2014
Messages
129
Reaction score
25
Location
Maryland
The problem is fixed but I thought I'd relate the story.

I had the bike apart a while back for a valve clearance check and decided to add a few things like stick coils, LED headlights, better horns, GEN I clutch slave, etc... After finishing and test riding, all was great until a week went by and it started running like garbage just off idle. It would jerk and snatch, sometimes stall, cough and sputter. Even idling was uneven and jumpy, but above three thousand RPM's it ran fine. Plenty of power and the mileage was normal. Thinking that I could have gotten bad gas, I went through the fuel system thoroughly. I pulled the tank, drained and flushed it with known good fuel. No improvement. I pulled the injectors and throttle bodies to clean them to like new condition. No improvement. Synced, checked plugs, wiring, sensors, ran diags - all good. It was a real pain but I decided at that point to go back to the stock ignition and that absolutely fixed it. The resistance readings for the stick coils all checked fine according to manufacturer specs so I could only guess that one or more of them was breaking down at running temperature. The upside is that now it runs smoother and better than it ever did. I suppose all the cleaning and syncing made an improvement. I never thought that ignition coils would cause symptoms like that.

 
As soon as I read "stick coils"....
Haha...That's what I said. Didn't someone just post up about installing these and it was the best thing ever? Was that you, Gitbox? I've only known of 3 guys that tried to use those, you make 4, and every one of them has had a problem.

 
Hot rod,

It might have been me. I did this mod on my old Concours with great results. I thought I would have the same with the FJR but I was wrong. I may have just scored a bad set of coils since I did get them off eBay.

Since it's running so well now, I'm not touching a thing.

 
The idea that got it started was to declutter the top of the engine. Removing the PAIR system and adding the stick coils would make it nice and tidy up there. Now my engine is back to TOTAL stock - PAIR and all. I even cleaned the reeds in the valve cover to shiny new.

The weird thing about the whole mess is the symptom. It started fine and ran smooth until warmed up and then the bad running began. Also, it ran crummy only from idle to about 3K. I still find it odd that a coil or coils can make the bike run that way.

Well, like Phil said, if it isn't broke...
smile.png


One more thing: I posted this story just in case someone else may benefit from it.

 
Last edited by a moderator:
Top