Major bucking, 2nd gear strong accelleration

Recently I have installed the FMF fuel programer to my 08 X.
After bugging a member for info about "this & that" & getting more than my share of excellant data, I received #s & good advice.
I even called Dobeck. They actually manufacture the FMF unit.

Now the bike has some major set backs, not from any advice nor #s selected.
2nd gear needs to be slowly accelerated through or the bucking starts. It actually feels like someone has struck my rear axle w/ a 32 oz hammoer at times.
There is no back firing through the exhaust nor air box pops.
I can continue running & actually accellerate up & shift into 3rd, where the misbehaving stops.
However, now the whole thing begins again at 72-73 mph during a light increase in speed. I open the throttle wide open & it smooths out around 80-82 mph. This never occured before.

This bucking or jerking during acceleration started before I installed the FMF but ( never at high speeds) actually became much worst after the FMF. During the first few hundred miles I kept both rapid & high rpms down. I didn't get over concerned cause I figured it would be taken care of by the FMF FP.

The FMF has been removed & the same systems continue. Only 500 miles on bike & flapper glued down.
The smog air pump removed. Exhaust butterfly has be cut out. Stock muffler remains untouched. Air filter is K&N, clean. Have followed much of the changed posted here & each mod has shown slight improvement, until the FMF.
The bike is ridden at sea level, if that matters.

Numbers used in the FMF were 3-4-1-8-4-4.5 & later 3-5-1-8-5-5, nothing to extreme here. The actual programing is a real pain for me, so I let my experts do the needed deed.
Wife (mine) & a long time KLR riding bud that now wants our wr250r. For the record my KLR bud works in the computer business for AT&T....only saying this cause he is very comfortable punching bottons. He'll love this.

I don't want to take my bike to a dealer.

Any suggestions from our experts on solving my problem will earn major point from me & I'm think a from a few others that may run into this issue too.

Thanks,
Ponch

PonchoV wrote:

The FMF has been removed & the same systems continue. Only 500 miles on bike & flapper glued down.
The smog air pump removed. Exhaust butterfly has be cut out. Stock muffler remains untouched. Air filter is K&N, clean. Have followed much of the changed posted here & each mod has shown slight improvement, until the FMF.
The bike is ridden at sea level, if that matters.

I wish I could help. Could you please explain what you mean by "exhaust butterfly"? Is that the EXUP valve?

"Smog air pump"? Is that the AIS system?

Did you buy this WR250 brand new or was it used when you got it?

Can you think back to exactly what change you made to the bike right before you noticed some "bucking" and "jerking"?

You said that started mildly before the FmF programmer was installed. What had you changed from stock just before this started happening?

New bike from dealer about 2 mths back.
Yes the EXUP & the push pull cable device that goes up under the battery was removed. I also bought a little plug in unit to by pass something, about $50.
& yes the AIS which is up under the res for the radiator, removed & the bottom part of the air box was pluged.

Should know the correct terms but then wouldn't have any room in my head for the trails I keep forgeting.

Changes were more in my earlier riding style....I ran the bike more on the slow side, as so far as fast accelerating. Only started to run hard about two wks ago. Then is when the issues started.
CHANGES:
The first thing I changed was the little vaccums system which controlled the intake flapper thingy, 2nd I removed the EXUP & a wk later the AIS. Each step was done apart from the other by driving a hundred miles or so & time. No changes in bike's behavor, except it ran a little stronger after each removal of stuff.

The first time I noticed the jerking was just before I installed the FMF, again my riding style changed from gentle to LET'S GO. I have never hit the rev limiter.
Left the stock program on the FMF. During the test ride I noticed the bucking/jerking was greatly inhanced. Got some different #s & had them put in by my brainy wife (she really is smart). No change there, in the acceleration. Went over to my KLR bud, he attempted to put in the same #s & that did not change the behavor. Rode the bike around last night w/o the FMF (still runs bad) & now it sits waiting for some more input.
Note, I can get on the bike right now & ride it gently & there will be no issue.

I dont know why you'd remove the EXUP stuff but keep the stock exhaust????

I have no idea what is happening to your bike.

My guess is there's a connection to the EXUP removal and whatever thingy you purchased to by-pass the removal of that stuff.

BUT....that being said I don't know why you'd only experience issues in second gear.

I would try to back-track my modifications as best I could and return the bike to as close to stock as you can get it.

See if your problem goes away.

If not...I'd be returning to dealership you bought it from and ask them why a bike with 500 miles on it sputters in second gear.

Since you've modified a few things from stock you can't go back to dealer at this time.

Hopefully somebody else here can help you.

Kept the stock muffler cause I like the keep things quiet.

If replacing the entire muffler system w/ one of the aftermarket units is ok then why would just cutting out the little in pipe butterfly valve have any changes w/ the running of the bike? Not wanting to sound like an ungreatful here but there is no EXUP w/ the after market muffler.

The EXUP thing is designed by Yamaha to go with the exhaust system they also designed.

It's job is to regulate back-pressure to give the optimum power for the system based on throttle, speed, air-fuel mixture, and exhaust flow.

Theoretically you've decreased your power at a certain range by disconnecting that feature while still using the stock exhaust system.

The EXUP thing is a bit like a religous belief though. Some will say it robs power, and some will say it increases power.

I know a few guys here have actually welded the EXUP system into an aftermarket pipe.

I am not saying this is part of your problem though.

Just raising questions.

That is most interesting.
Back pressure is a need for an ever changing rpm motor which has demand for torque & hp at the same time.

I only ask, why do these torque/hp dyno test show jumps in torque/hp when more open flowing exhuast systems are installed? I only wish to limit the open exhaust, so to keep things quiet.

On this forum we have riders who replace both the header pipe & muffler only to show interesting gains. But don't make note about any lower rpm acceleration problems.

Is there anyone else who is experiencing these same systems?

clicky <-- a bit more on EXUP

You are the only person I've ever heard of who has removed the EXUP but kept the stock exhaust.

The stock "can" is highly restrictive.

Again....much of this is like religion where you might get 20 different opinons from 20 different people.

When you say riding gently versus riding like you stole it what are you talking about?

You say you've never hit rev limiter?

Where are you shifting? What speeds? How fast are you going when you shift and what is the throttle position?

Are you twisting throttle to the stop and holding it there? Twisting throttle really really fast?

You say you've got a K&N air filter and the Flapper glued down. So air intake is not an issue.

You obviously have spark.

So fuel must be the issue. Fresh fuel? High octane? 91 or so?

Are you sure you're not hitting rev limiter in second gear?

I'm just grabbing at straws here until somebody else chimes in and offers some help.....

Is your chain adjusted correctly?

motokid, grabbing at straw has opened up more answers than just keeping it to oneself.
Ohters may see something in your "grabbing at straws" & I am open to any straw right now.

First, I also ride a R12GS & know what it's like to hit the rev limiter, even my DL-650 use to tell me when enough was enough.

I rarely open & hold the throttle wide open. But when I do the rpm is no where near redline.

Use only the highest octane, not the regular plus & buy fuel from major high volume stations.
Around here that is Gate & the big company names. It is only a few dimes more for a full tank on the wr.

I'm going out right now to do another test ride inorder to better answer your question about at what speed do I shift & the break up begins.

Give me a few minutes, I'll be right back.

Yes, the chain is good, I thought about that earlier too.

Here's what keeps going through my mind.

8000 rpm is 8000 rpm. The motor does not care what speed you are going, or what gear you are in.

So why would something only happen in second gear, and not in third or forth as well?

A fuel delivery issue would effect all gears.
An air/fuel mixture issue would effect all gears.
An electrical issue would effect all gears.

Is it possible there's a vacuum leak somewhere that once the wind speed gets to a point the vacuum leak gets over-ridden by pressure?

I really wish somebody else would chime in and try to solve this.

Okay back from a little run about.
2nd gear bucking started at 26 mph w/ half to 2/3 throttle
3rd gear same behavior started at 40 mph & same throttle area.

Also it should be noted I did these runs three times each & this is a rough average.
The lowest speed in 2nd gear was 22 mph.

I like an average to compare so if anyone else is doing this, they would understand slight difference will show up.

Don't know if it matters but I now weight 140 lb....I know a real strain for the 250cc.

Also rode about at a lesser throttle & had a a very smooth response.

Hope this helps

I'm guessing the speed is irrelevant, it is simply the load on the engine that determines the stumbling. When you removed the AIS did you properly install all the vacuum caps? Did you remove the airbox flapper? If so, did you properly install the vacuum cap? This sounds like you are getting unmetered air into the engine. First off, remove the programmer just for simplicity. The EXUP motor removal did not do this (btw, for everyone looking to spend $60 on a servo sub, all you need is a 7.5K 1/4 watt resistor across the black/red white/red wires to avoid a Check Engine light). Next reinstall the AIS system and keep on going until it stops (but my $$ is on the improper removal of the AIS).

FYI, I found more power everywhere when I removed the EXUP motor. It's a good idea in theory, but the stock muffler with cat is already so plugged up the last thing the motor needs is more backpressure.

First.... why did you remove the EXUP and keep the stock exhaust? Might as well keep the EXUP in place then. What's the point of removing it? The systems were designed to work with each other. I don't get why you felt the need to remove the EXUP and keep the stock pipe. Put it back on.

Second.... if you still have the stock pipe, then you need to put the AIS back on too. It, along with the EXUP, are working in harmony with the stock exhaust system. The AIS is there to add fresh air to the exhaust for a cleaner burn, which will help the life of your catalytic convertor. Do you know more than the Yamaha engineers? Put it back on.

Take the FMF programmer off until you have fixed the jerking, and make sure you have the factory connectors tightly back in place.

When you removed the flapper junk under the seat, did you cap off the vacuum fitting going to the throttle body? If not, check it and make sure it is not leaking. It's OK to leave the flapper glued down if you want to, but you need to make sure there is no vacuum leaks in what you removed under the seat.

IMO, the K&N filter is a waste of money if you are keeping the stock exhaust. The stock air filter flows plenty good enough.

Other things I can think of are chain tension like mentioned before. But you said you checked that. Are you sure it's not the loose chain? Many guys have had the loose chain bitch after break-in. It will give symptoms like you are describing.

Another thought is possibly you have a bad spot in your TPS (throttle position sensor). If you say is stumbles at a certain throttle setting and is smooth in all other settings, you might have a dead spot in your TPS. It would be a very rare thing, but might be something worth checking into if all else fails. The TPS is on the throttle body. Did you happen to maybe pinch or nick a wire when you were under the tank installing the FMF programmer? Have you had the tank off before you installed the FMF? Maybe it happened then? Double check things under the tank. Things like pinched or nicked wiring, and maybe a pinched fuel line or other hose? There is a lot of shit under that tank and it doesn't always go back where it is suposed to when you reinstall the tank. I would make double sure everything is good under the tank.

Not really sure how you have been riding it. You say you were taking it easy for the first few 100 miles and now when you get on it you notice this problem. Maybe there is nothing wrong at all except you not knowing how this bike runs. Many have had the jerky complaint at low speeds. It's just the nature of the EFI system on this bike. It does take a bit of getting used to. Still doesn't make sense about you have this problem only in 2nd gear. That is just weird. Have you changed the oil since you bought it? Might be worth a try to change the oil and filter if you havent got the break in oil out of it yet. Maybe something is going on with the clutch from the dirty oil. Now I'm just stabbing in the wind. Don't know what else to tell you Poncho.

WOW!
I have to go to bed w/o dinner or at least til I fix my X.
I would rather spend the $ & get a loud muffler rather than put all that other crap back on the bike.
However going bak under the tank will be done...again.
Nothing like another check list to be sure.

Today it did the same problem in 2nd & 3rd gear, first time for 3rd gear.

About cutting out the butter fly valve & keeping the stock muffler.........I really enjoy a quiet bike. I ride a lot of off road back country areas out west & getting in to wild life areas quietly is important to me & those that I sometimes ride w/. Later I was going to go inside the muffler area & cut out the catalytic convertor. Tig it closed & keep the orginal looking outside can.

I did cap off the little brass nipple on the throttle body.
Not sure where or what the TPS is but will give it a look around.

The oil & filter was change at 100 miles & oil changed again at 300 miles.

I always appreciated ones passion & directness when trying to solve a problem.

I will reinstall the FMF & get my experts together for a joint programing session. This time I will leave the unit up by the handle bars.

So now I am in the hunt for a cheap used muffler, Q4.

Anyone want to sell their used aftermarket muffler?
I know this is the wrong place.

Working on this bike is not a difficult thing, so there is nothing wrong with a little experimentation.

All the people complaining about not changing things 'because they were designed to work together' have probably not tried these things for themselves (and if that is their attitude, why mod anything on the bike since it was all designed to work together). I noticed a large change simply by disconnecting the EXUP motor, as have others. I don't think you will gain any flow by removing the flapper completely and it is relatively irreversible at that point. The AIS system is not designed to prolong the life of the cat; adding fresh air to the exhaust will increase its operating temperature. When the exhaust is hot this is completely unnecessary; the system simply improves the cold-start emissions of the bike. I haven't seen a code breakdown for the ECU anywhere, but I'm willing to bet the AIS only does its thing when the coolant temp is low.

Once you have bypassed the programmer and checked for vacuum leaks I would be inclined to agree that it could be a bad TPS. Does the stumbling go away if you whack the throttle open? If not I really think this is a vacuum leak. Unfortunately most dealers aren't going to want to work on it unless it is stock and if you're hoping for the work to be under warranty you most certainly will have to put the EXUP and AIS system back.

Quote :

if you're hoping for the work to be under warranty you most certainly will have to put the EXUP and AIS system back.

It will be a bit difficult to restore the EXUP: EXUP removal

Shoulda' dug out the catalytic converter while it was all open!

I'll jump in with spaguru & say double check the chain.. it might just be a chain slippage. I had it when i put on the yamalink. I had the chain within spec, but on the loose side. Try loosening the axel, tighten the chain to the tighter side, then try it. I had all kinds of imaginings about what was going on with my bike, & it turned out to be this..

Thanks to yamalink & jjm on TT for this..

scotty

Seriously. Poncho. Check the chain.

Since it's doing it in 3rd, now, it is almost certainly the chain slipping.. it makes it 'buck' or stutter.

This is an easy, cheap fix. Your bike will run like new, you will be relieved, & we'll all be happy & sing kum-ba-ya together.

scotty

rydnseek wrote:

Seriously. Poncho. Check the chain.

Since it's doing it in 3rd, now, it is almost certainly the chain slipping.. it makes it 'buck' or stutter.

This is an easy, cheap fix. Your bike will run like new, you will be relieved, & we'll all be happy & sing kum-ba-ya together.

scotty

scotty, man that is my favorite song......I keep forgetting the words to the other ones.
Thanks for your interest here.

i think you have a bad tps.
what you are describing is the same symptoms i've found on cars/trucks that have had a bad tps.

I'm new all around, so forgive me if you've already covered or thought of this, but have you tried running your bike in diagnostic mode?

From 'scottmac' on ADV:

"try checking the Diagnostic Mode on your speedo/odo display

here are the steps to follow...

Enter Diag Mode =

with engine key and kill switch off

hold select 1 and reset buttons down while turning on key, keep holding until diag appears.

then hold down select 1 and reset again for about 2 more seconds until it changes to selection mode.

then in mode 61 will read out history codes

go to mode 62 and turn on kill switch = erases all history codes.

Codes =
12-Crank Pos Sensor
13-Intake Air Pressure Sensor open or short
14-Intake Air Pressure Sensor Pipe restriction
15-Throttle Pos Sensor open or short
16-Throttle Pos Sensor stuck
17-Exup servo motor open or short
18-Exup servo motor stuck
19-Sidestand switch open
21-Coolant Temp Sensor
22-Intake Air Temp Sensor
30-Lean Angle Sensor crash or laydown detected
33-Ignition Coil
41-Lean Angle Sensor Short
42-Speed Sensor, Neutral Switch
43-Fuel System voltage
44-Error in writing the amount of CO adjustment to EEPROM
46-Vehicle System Power Supply
50-ECU internal malfuntion
70-Long Idle detected 20min auto stop

Er-1-4=ECU internal Malfunction"

If there is a problem with the TPS you should get a code for that. I can't tell you what to do from there, but I hope this helps you out.

GO TIGHTEN THE CHAIN FIRST....