Losing Power on First and Second Gear

hi! Folks. Just got 2001 VFR 800 several months ago and quite obsess with it. I need your expertise here. The bike ran awesome at the beginning but now I seem to lose power on 1st and 2nd gear, strange but true. I don't get the same torch as I used to. Accelerating on first gear is like starting on third gear. I have to use the clutch to get the bike up to speed. My D&D pipe used to sound awesome but now it sounds a little flat (drawing too much air in somehow). Once in awhile, it would stall when i slow down. The bike has only 7K miles. Please help!

 

Im not an expert by any means but I would start by checking your spark plugs perhaps one has fouled? Just a guess. Wish I could help more.

 

I wish I could edit my post...

If your plugs are ok, It defiantly sounds like something to do with your fuel/air mixture and maybe its flooding itsself out. Once you get into higher RPM's the engine can keep up with the mount of fuel being poured into it. So I guess another place to check would be to make sure your air filter is clean and nothing is blocking the flow. Your oxegen sensors could be a factor possibly to.

 

Just found out the problem the other day. My exhaust has a crack. Saving $$ for a new exhaust. Thanks...........

 

ah, never would have thought of that. Kind of an expensive fix though, good luck, I hope everything turns out well!:smile:

 

If it is just the pipe part, you can borrow my stock one till you save enough funds...

 

How could an exhaust crack cause a significant loss in power? I'm not buying it...

 

I would give a detailed "engineer's" description on how that works, but I'll just suffice it to say that exhaust leaks disrupts air flow.

 

I'm still not sure I agree that an exhaust leak can cause a serious drop in engine performance, but hey, what do I know? Just goes against common sense for me...(^_^)

So answer this one for me...

I've been troubleshooting a surging/hesitation problem on my 05 VFR for a few months now. It's definitely a warmed up running problem, and when I'm cruising in 1st or 2nd gear at 4-6K rpm, there are times...not always...where the engine begins to surge/hesitate as though it's been starved of fuel. I think the engine has this problem in higher gears, but it's hard to "feel" it at higher speeds. Anyway, I've checked just about everything I can think of, and nothing I've checked or done has solved the problem. Given the fact that maybe an exhaust leak could cause a problem, then perhaps this surging/hesitation issue could be caused from the known leak I know I have where my Staintunes fit onto the collector pipe? Hardly seems likely if you ask me...

 

Exhaust is not under pressure at all times. It is highly pulsed. A leak near an O2 sensor (do these bikes have O2 sensors?) and there could cause a false lean signal to the computer, which will make it run rich to try to compensate for the phantom lean.

Could also be a bad sparkplug or injector, or even just some bad fuel making the ECU retard the ignition timing.

 

Not sure about the older models, but the 6th Gen models have two O2 sensors in the catalytic converter. My O2 sensors are disabled with Dynojet O2 Eliminators...tried running with them in/out and no change in symptoms. Not fuel as I have run 10-15 tanks since the problem started. Could be a bad plug or injector...haven't checked those yet.

 

Check and post back in this thread.... I'm curious now what the problem might be.

 

Thank you so much R.W for the offer. I fixed it temporarily using a high heat resistance fireplace mortar found in my garage. Runs great now. Should have new one in about a month.

 

I don't know how it works either. But I have seen 125 & 250cc two strokes lose most of their power with a cracked exhaust.