Poor acceleration on my S2R 800

[taun]

I need help trying to diagnose an acceleration problem with my S2R 800. I noticed that during my morning commute, everything seems to run fine, but during the commute back, the problem arises.  When I accelerate, the RPMs go up, the engine revs, but the bike doesn't accelerate at all.  It just makes loud sounds. 

Initially, I thought my clutch was slipping, but the problem is occurring in all gears, including 1st.  The problem only gets slightly better if I gradually twist the throttle, versus just cranking it.  For whatever reason, this seems to happen only in the afternoon and I'm wondering if the heat has any effect because it's cooler in the morning compared to the bike sitting in 90 degree weather all day while i'm at work.  My oil temperature is typically between 200 - 235 F when commuting home, still below the 338 F (HI) threshold.  So again, I'm not sure if temp has affect, but it's the only reason I can explain the difference between my morning and afternoon commutes.

About the bike, it's a 2005 S2R 800 with about 4500 miles on the clock.  Mods that would affect performance include an open airbox and full Arrow Ti system.  Still on the original ECU with no power commander.  I've also removed the charcoal canister and plugged the 2 holes to the intakes with m5 bolts and red loctite.  My spark plugs were changed back at the 3k mi mark and cables are attached.  Both cylinders  seem to be firing, at least from what I can tell (I'm no expert by any means).  Fuel lines also look ok with no kinks in bleeders or other lines. 

So do you guys think the problem is my fuel filter or clutch?  Is there a way to pinpoint without buying a new fuel filter?  How often are the fuel filters supposed to be changed anyways?

[stopintime]

Another non-expert here.....

From my experience with other vehicles and your explanations - it must be the clutch?
Just an idea: if you test the clutch the other way, by going from 4th to 2nd or 3rd to 1st fast-releasing the clutch - does it slip (more than usual) then too?
Could it be that your clutch is worn out by use or not fully engaging?

Sorry for the added question marks. I hope you get better help by others and that it works out.

[clubhousemotorsports]

+1 clutch
sounds like the bleed down at the lever is incorrect and as the bike heats up the clutch is staying disengaged.

RED LOCTITE! you must really hate your mechanic or never plan on synchronising your throttle bodies again.

[PizzaMonster]

From what you are describing your clutch is slipping (and probably quite badly).  Get a mechanic to look at it...(quick!!)...or you will be replacing it. 

When I accelerate, the RPMs go up, the engine revs, but the bike doesn't accelerate at all.  It just makes loud sounds. 

Initially, I thought my clutch was slipping, but the problem is occurring in all gears, including 1st.  The problem only gets slightly better if I gradually twist the throttle, versus just cranking it. 

If the engine revs higher without going any faster you have a slipping clutch.  If the engine is sputtering or dying out then a fuel filter is one of many possibilities.  This doesn't sound like what you are describing.

I'd also be curious as to what kind of "loud sounds" you mean?  Is it the normal exhaust noise or is it an unusual mechanical grinding/squealing type noise? 

[taun]

Thanks for the responses so far.  I'm beginning to suspect the clutch more now, especially considering it mainly happens when the bike is really warm (mid-afternoon).  As for the sounds, it's just the engine revving, no clunking or grinding. 

As for mitigating the issue, should a bleed and top off do the job?

[stopintime]

As for mitigating the issue, should a bleed and top off do the job?

Maybe, if you're lucky AND do it soon? Me, the non-expert, would have a mechanic checking it yesterday even if the bleed helps.

[taun]

Well, I stopped riding as soon as it happened, so it's been sitting in the garage since Monday evening.  I can't get around to bleeding the clutch until the weekend, but I'll post up to see if that helps alleviate the issue.

[tangueroHondo]

I've got the identical bike, except no airbox or exaust mods.  My charcoal canister is long gone too (sorry Greenpeace).  I don't understand some stuff here;

1.  How can a clutch be bad on an 05 with 4k?  Mine has about 4.5k on the clock. It's basically like new.

2.  When my clutch needed a bleed it was b/c it wasn't fully DISENGAGED with the lever pulled to the grip.  Air in the lines didn't allow the slave to fully depress the push rod through its' required travel.  You have the opposite prob - not fully ENGAGEDi.  I can't see this being a bleeding prob.

What oil are you running?  My transmission behaved like a bear when I switched to 10W40 dino oil.  Clunked and whined like hell.  I didn't even have 200mi on that oil and changed it back to Motul 300V 15W50.  Can't say that I recall the clutch slipping though.  Had other horrific things going on during that time.

[Howie]

Your slipping clutch can be caused by a lack of free play at the clutch lever or wrong oil.  Energy conserving car oil can cause slippage.  Another possibility (slim) is a sticking push rod.  If the clutch has been slipping for a while you may need to replace the plates.

[taun]

Yeah, I've been reading around the old board and am beginning to think it could also be my oil.  Some people with wet clutches said they had problems with the synthetic stuff.  I bought this bike used and did an oil change around the 3k mile mark to Mobil 1 V Twin synthetic (10w-40 i think, i'll check when i get back home).  That was towards the end of last summer and i've only put a bit over 1500 miles on it since then, bringing it now to about 4500 miles.  So this weekend i'll probably end up changing out the oil to something like 20w-50 dino or half-synth and bleeding the clutch. 

[Howie]

The Mobil 10w-40 you used is fine for your wet clutch.

[johnster]

The "homemeade slipper clutch" probably isn't the greatest thing to continue running on your bike  , so I say start w/bleeding the line to see if that takes care of it,  just like everyone else would tell ya...

-I'm currently having the opposite problem... Ever since putting a new pressure plate on my clutch, the gearbox "clunks" much more violently now than it used to when shifting, which is indicative of air in the line.... I just hope I'm not doing tranny damage in the mean time until I get a chance to bleed it...