wrx:hesitation/stutter on acceleration

I first noticed a 'stutter' when accelerating after leaving work on monday. It happened once, then nothing so i didn't worry about it. Then yesterday i took it out & it started hesitating when under load.. not just at the start of the throttle twist, but all during the acceleration. I had just changed the oil & filter (660 miles now), but no other changes. I had ridden it in the mud on the friday before, & hosed it off that night. Coming home last night (tuesday) it was doing it all the time. Even at steady throttle you could hear & feel the 'bumps' from the hesitation. If i open it up & run at high rpm's, it seems to subside a little.

No major mods.. screwed down the flapper & removed the vacuum & cannister stuff. Took off clutch & kick switch. Everything else stock.

I had filled up with gas on the friday after the mud ride, & ridden ~ 50 miles with no problems. I can hear the fuel pump go on normally. I checked the spark plug..it was tight & looked fine. It's under warranty, so i can take it to the dealer if necessary, but i thought if it's something simple i can fix it. I've searched here, but not found any similar symptoms. Here are some of my theories:

1. water got in gas somehow when washing bike off.

2. loose connection.. but it does it even when not vibrating much.. on smooth road, no load.

3. fuel pump. Others have had this problem.. mine is not same symptom.. does it right away, not waiting until warm. It idles fine.

Today maybe i'll take it out & open it up on the highway for a bit.. get some full throttle going.. & maybe fill with new gas.

Anyway, if someone has had a similar issue, let me know & i'll check your solution. Otherwise, i'll run up to the dealer.



Without sounding too elementary, is your chain too loose or any teeth broken on the sprockets?

At first i thought it was the chain.. but the tension is ok, & i took off the cs cover & the sprockets all looked good, too.

thanks for the thought.. i had just put on the yamalink on saturday, too! Maybe that's the culprit! :busted:

Well, it was the chain. I had the changed out tires last week, & a few hundred more miles on the bike must have stretched the chain out enough to slip. I'm a little surprised.. i tend to leave the chains a little on the loose side, rather than too tight. But i guess with the smaller front sprocket (13t stock) it needs to be watched more carefully.

Yamalink & jjm525 were right on target. Jjm525 pm'd me. Thanks for the suggestions!!:banana: :banana:

I went out & barely tightened the chain adjusters & the slipping went away! I went on a ride we had scheduled, since the bike was working.:busted::thumbsup: But of course, i rode off & forgot to tighten the axle nut.:banghead:

..good thing i remembered.. i stopped & got my axle wrench & tightened it before i got too far along.

Thanks again, jjm525 & yamalink!!! :banana: :banana: These guys are good!!:banana::D


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