Another Loss of power while cruising in 6th...

I have a 2011 WR250R, I have read others threads concerning power loss and they didn't' fit my description and I didn't want to hijack their thread with my issues.

So the problem is last ride my bike could not go over a GPS indicated 60 mph in 6th gear. It used to pull to almost 80 indicated on GPS but now when shifting to 6th it slows down to settle at 60 mph. I ride with another 2011 WR250R (rider of similar weight) who pulled past me with no issues on the same ride. Both bikes are stock. I have ordered the power bomb, Q4, programmer from FMF and the AIS block off kit. I also removed the flapper last night and opened up the air box. I haven't ridden since the air box mods (and don't want to till I get the programmer), but I'm looking for any ideas of what might cause the bike to suddenly be so anemic in 6th gear. All other gears feel right, still lifts the front tire in 1st gear. Couldn't be gas because the trip used 3 different fill-ups from 3 different stations with no difference in power. I checked the air filter, and while I haven't serviced it yet (1500 miles) it appeared clean and oiled. Almost all miles are highway miles. Any input is greatly appreciated.

What happened when you shifted down into 5th gear?

Is it only a 6th gear thing, or might it be an rpm thing?

Can you run bike up to rev limiter in 1st through 5th?

Are you living in USofA, or some country where you have an oxygen sensor in the exhaust?

I have no clue why you would have such a problem. Just trying to get some more information.

Yup, here in Alaska. Situated right at sea level. In 5th gear the bike will climb to almost 70 on the GPS until I run out or RPM, then a shift to 6th just makes more bogging sounds and a loss of power. Last week this did not happen. 6th used to pull to the rev limiter, or close to it. The only thing I haven't checked was tire pressure. They aren't flat, and don't feel low but that is another thing for me to check tonight. I literally drove at WOT to keep the bike at 60 mph. I couldn't even do the speed limit of 65 in 6th gear.

My initial thoughts were
1 clogged air filter (checked and looked spotless but still should be cleaned)
2 Stuck flapper, but it was in the lower position and had spring tension. (removed anyway)
3 Low tire pressure, and I still need to check that. But it went from working fine for the first 30 miles of the trip to being gutless for the remaining 160 miles.
4 Bad gas, but after the 3rd fill up I really don't' think this is it.

There is no sputtering, backfiring or other indications of something amiss. I'm stumped.

I'd shit myself if tire pressure was the issue. Not from what you just posted.

5th gears pulls to limiter but 6th bogs???


Sounds like there's something wrong with the Yamaha fuel injection system and/or some sensor involved in all that.


There's no reason why 5th should pull hard to limiter and then have things choked off once you shift to 6th.

It's a 2011 right? brand new to you? Under warranty? I'd be taking it right to Yamaha dealer ASAP if that's the case.

Something is not right.

I'm debating that too. Since I gutted the air box I'm a little hesitant to bring it in unless I'm sure it isn't something I can fix. The bike is new and a 2011. It's like the torque isn't there when I shift to 6th gear. 5th pulls hard though. I'm just looking for something that is robbing power. It could be something with the fuel system too, not throwing any codes yet so if that is the case whatever is wrong isn't far enough out of spec to trip the ecu. I'll post back when I get the parts I ordered, and see if the problem persists with added upgrades. If it does then it's off to the shop.

Can you put the "gutted airbox" stuff back?

Can you basically return the bike to stock trim?

Any chance you have a vacuum leak somewhere?


When you say you gutted airbox, what do you mean?

When I say gutted I mean that I used a dremel tool to remove the plastic rivets on the intake portion of the air box, pulled that out and removed more plastic rivets from that to separate it into 2 halves. Thus being able to remove the flapper as well. I then used the "right stuff" to glue the intake portion of the air box back on top. I suppose I could remove again and glue it all back together, then reinstall the bits and pieces for the flapper. It can all be undone, I'd just rather not if I don't have to. Might have to order a new air box to get the unmolested parts off to put back in mine. Right now I'm playing the waiting game for all the bits and pieces I ordered before I fire it up again.

it sounds like a clogged exhaust to me... I wouldn't be concerned unless the new exhaust doesn't fix it.

I've had more than one car over the years display similar symptoms when the cat got clogged.

Arkmage wrote:

it sounds like a clogged exhaust to me... I wouldn't be concerned unless the new exhaust doesn't fix it.

I've had more than one car over the years display similar symptoms when the cat got clogged.

But wouldn't wide open in 5th gear be a problem then?

Wide open is wide open. It's only gearing that really changes the speed overall.
Not increased output from the engine.

If the OP can rev hard right up to the limiter in 1st through 5th gear but choke out in 6th gear I have trouble thinking it's a clog in exhaust.

It's also a 2011 with not too many miles on it.


Not saying you're wrong, but trying to think through the clues we've been given.

Am I making sense?

I suppose I could mention that I have 1600 miles on the bike.

As far as a clogged exhaust I suppose that is possible. But like others have mentioned it does rev in other gears. I literally shift from 5th to 6th on a level road and watch the speedo drop. But, I don't want to get too wrapped up in what-ifs quite yet. I'm going to be brave and take it for a little run with the modded air box. In 6th from half throttle to full the only indication that anything changed was a deeper tone from the intake. No pull, something is stealing my torque.

Update

It appears that tire pressure was a factor. I know they were good when I bought it 2 months ago, but now the rear was at 18 PSI and the front was 17 PSI. I'm sure that is the problem. Still waiting on parts, I did take it for a little spin but didn't get into 6th. Without the flapper and a slightly modified air box it sounds a little throatier and seemed more seat-of-the-pants powerful. Need to ride with another WR to compare again. Will update when I do.

Sorry, but I refuse to believe tire pressure has anything to do with it.

see this thread <-- clicky


Much more inclined to believe it's your FmF fuel programmer. Or something related to fuel management.


If you can pull hard through 2,3,4,& 5th gears, but lose power in 6th gear, that is NOT tire pressure.