Engine "stutter" at high throttle

[isuace]

2006, about 30k miles. Sometimes when I accelerate hard (usually when merging onto a highway or such) if I really whack it, the bike sounds like it misses and bucks. I can take it all the way up to redline without issue as long as I keep the throttle position midway or so.

Things I've tried looking at:

Ground spiders, all look pristine. I mean all of them. I haven't done the recall yet because they all look perfect.

Plugs look good.

Sent the injectors out to be cleaned and flow tested, they came back perfect. Guy said they're as good as they get.

I've run fuel system cleaner through it, but meh, the injectors weren't dirty at all.

I'm at a lost at what to look at next, any ideas?

 

[wheatonFJR]

I'd still change the plugs and see if it helps...cheap fix.

 

[mcatrophy]

Perhaps it's the rear wheel skipping a bit? Or, a lot worse, second gear dog slipping?

 

[gapiob]

are you check the air filter?

 

[LKLD]

Which gear does it happen, all, or just one? If it's just 2nd, then Mcatrophy is more than likely correct.

 

[NTXFJR]

If it's only at higher rpm's, might check fuel filter first, then pump, or could be an ignition coil or plug wires breaking down under high load?

 

[ionbeam]

2006, about 30k miles. Sometimes when I accelerate hard (usually when merging onto a highway or such) if I really whack it, the bike sounds like it misses and bucks. I can take it all the way up to redline without issue as long as I keep the throttle position midway or so.

Another vote for the gear dogs popping out. Typically it happens in 2nd gear but has also occurred in 4th and 5th. The symptoms are as you describe, and it only happens under hard acceleration. The fix -- take a deep breath, requires taking the engine out of the frame and tearing it down to access the transmission or an engine swap. In the search box at the top of the page, copy/paste +gear +dogs (needs the +) and scroll down the first couple of pages, you will get the idea of gear dogs slipping PDQ.

If it were a clutch issue the symptoms would be accompanied by rapid rpm rise on the tach without speed increase to go along with the tach rise.

But wait! There is another (very small) possibility and that is a bad TPS. A bad TPS will often be linked to a fully warmed up engine and then it causes misfire/bucking/popping in a fairly narrow rpm range and do it in every gear at that rpm range. The TPS is a wear-out issue and typically happens at lower rpm ranges unlike your situation.

Finally there is an exceedingly rare coil wire and/or coil breakdown at higher rpm but this would be noticed at both acceleration and cruising.

Typically fuel and air issues cause soft performance and soft failure modes unless the injectors are simply shutting off. Usually a hard, harsh failure is electrical or mechanical.

Edit: I see NTXFJR was posting similar diagnostics while I was typing.

 

[RossKean]

I am in agreement with the 2nd gear issue. I don't suppose that it is just a simple matter of hitting the rev limiter? Could be quite noticeable under heavy acceleration...

 

[eflyguy]

Sounds like 2nd gear to me too.. I "discovered" that I had this issue passing a dickhead truck driver. Now I know I have it, I don't go WOT in 2nd, and it hasn't happened since.

 

[rbentnail]

KISS. Check your air filter and housing. Do you have a PC installed making it run too rich?

 

[RaYzerman19]

I'd check the plugs depending on how old they were, and while in there, unscrew the plug caps, trim a little over 1/4" off to get fresh copper, then spread the wires evenly, screw plug caps back on. Just fixed an FJR with this (and an idling) issue. Could be something else, but KISS.

 

[isuace]

Wow, thanks for all the replies. I'll try the simple stuff and see if that helps. It's been a while since I've been able to ride it, but as soon as I get it back together I'll see if it happens in second gear at WOT (my memory says yes, but I don't trust it anymore).

Thanks for all the info.

 

[El Toro]

I don't suppose that it is just a simple matter of hitting the rev limiter?

Sure sounds like rev limiter to me.

I have to admit, I've never bounced off the rev limiter on an FJR, but if he's running it out to the red line before he shifts,

you've got to wonder.

 

[isuace]

I don't suppose that it is just a simple matter of hitting the rev limiter?

Sure sounds like rev limiter to me.

I have to admit, I've never bounced off the rev limiter on an FJR, but if he's running it out to the red line before he shifts,

you've got to wonder.

It's not getting to redline, that's one thing I am absolutely positive of.