Hi guys, first post here, this is the situation I find myself in.

I purchased a 06 CBR 600 F4i from a friend of mine 6 months ago. The motorcycle had 800 miles on it, everything stock, no accidents or drops, buddy was in marines abroad so didn't ride it much.

About 3 months ago I started noticing a weird problem. Motorcycle seemed to hesitate 8 out of 10 times with acceleration/rpm. If I had to narrow it down it would be between 3-6K RPM once it would jump above that bike would run fine. This was in first gear.

1 month ago, the problem started getting much worse. The motorcycle would not want to go past 40-45 miles an hour. It would get past that speed, but at a snails pace, with throttle all the way back. This would occur in about the 5-8K RPM range, in 2nd or 3rd gear. Seemed to have a much easier time in 3rd getting past that.

I took it to a mechanic but they rode it for 5 mins, checked fluid levels and cycled through the gears, no problem showing.

2 weeks ago I'm going down the main street in town. I pull up at a stoplight next to another motorcycle, I think I can hear some strange noise but its hard to tell with the helmet on. Light turns green, I pull out, accelerate to 42 mph and hit that hesitation thing again. I pull the throttle all the way back in 2nd with the clutch all the way out, still nothing. I start releasing the throttle, and split second later, something, not 100% sure what happens.

All I know is I go straight down and hit the street. Bike goes straight down on its side and slides down the street hits the curb. All damage was on one side thank God. I was riding in a straight line. I've rode for 10 years and am reasonably experienced. I don't just fall off a motorcycle going in a straight line. It felt like the rear wheel locked up on me, simply because I didn't go over the handlebars just pitched to the side, the only problem is I didn't have time to fishtail, ANYTHING, just boom straight down in a split second. Or maybe a rock or something got jammed in there? The wheel was moving fine after the accident we pulled it on the tow truck no problem.

The owners of the motorcycle beside me, and fire department who were behind (lucky me lol) pulled up and they verified the same story. Riding in a straight line, bike just jerked and suddenly hit the ground.

I came out of it with some real bad road rash on elbows knees and thighs and a deep puncture wound on my elbow. Had no gear other than helmet I made the age old mistake of oh I'm just going around the corner to buy some cigarettes I don't need to put all that gear on. But at least I walked away.

Anyway, motorcycle was under Honda extended warranty. Took the bike straight to the dealer. Told them what happened. I have hit a stone wall here. I have a case with Honda, I've gone to second parties to ask for their opinion, but I'm at a loss. Honda CANNOT find a problem with the bike. The tech rode it around the block taking it up to 45. Nothing. They ran one of those magnets over the transmission and engine to check for anything loose or rattling around. NOTHING. The district service manager came out at my insistence they cycled through the gears and did a basic check. NOTHING. So now Honda is telling me they can't find a problem. They are more than willing to tear down the transmission and the engine to see if there's a problem. But I will be stuck with the bill if again they don't find anything. And we're talking 1K minimum just to pull the tranny apart.

I know I didn't imagine the problem. But what if it's something tiny and I will have to pay for all that labour. But if it is tiny how do I explain hitting the ground from nowhere while riding in a straight hand line. I know I can't take the bike back as is, it will kill me. I know I can't sell it, it will kill them. But if they take it apart and don't find a problem, I can't afford to pay that work at this moment in time.

The only option I can think of at the moment is my buddy has a dyno at a motorcycle mechanics nearby. Honda dosen't allow 2nd parties to perform warranty check up or repair, but he will run it for me for 30 mins to an hour on the dyno for $35. Would this be a good idea? The problem should be able to be duplicated if we run it pretty hard for awhile right?

Any suggestions or ideas would be so welcome right now and I appreciate your time reading this.

 

my busa it had a power commander hooked up im riding along and bike starts to cut out and lose power, no throttle response gauge cluster goes dead i pull in the clutch rev it up nothing try again and bike starts back up (all while im riding) bike rides fine in all gears, stop and go no issues at all untill it happens about 45min-hr later same thing but this time bike cuts out comes right back on but rear tire locks up and puts me down around 80mph in a straight line.

the power commander hooked directly into the ecm instead of into the fuel injectors like most hondas do. i found out from the previous owner of the bike that he took the power commander off cause it was causing problmes too, he neglected to tell me that when i bought it from him...

i rode the bike for like a 1-2 months with 0 problems including when the PC was installed untill that fateful day. i tell you this story cause it souds similar .mine was a problem caused by an external source maybe you have an issue with your fuel injection system and thats whats causing the hesitation

and yea youre lucky to have the FD right behind you, when i crashed i went down right in front of a ranger outpost where the entire squad was just coming back from a practice drill and they had full gear and saw the whole accident and by the time i finished sliding and took my lid off they were on top of me checking me out and supporting me (even heard them call for a helicopter for possible lifeflight which scared the **** outta me ! )

 

The other thing that could make sense is ignition issue... I've ridden a bike when one of the spark plugs was starting to go and I was a long ways from a shop to get spark plugs. It would run fine at some RPM and at others it would run on three cylinders and barely accelerate (this was a liter FZ1) So I would assume maybe a 600 on 3 cyliners may not be able to accelerate at all when the problem occurs... So I'd say check the plugs and ignition coils. Now, for the crash (here I may be going out on a limb) but perhaps as you were easing the throttle closed the 4th spark plug came to life and full throttle at a high rpm hit your rear tire and spun it up real fast... Just a theory, don't know what your tires are like or the condition/heat they were in, but it's possible.

And I've actually had a buddy fall of the bike from the rear wheel locking up, and that bike didn't run afterwards. The clutch basket exploded and locked up everything, he went down in a straight line in an instance and broke both wrists. At least you faired better than him...

Good luck

-Chad

 

I've been thinking something about the rear tire locking up. It's a very noticeable feeling. Something you can't mistake right? The accident felt more like I was just pitched straight onto the ground. Like I said no fishtailing nothing I just got thrown straight down. Your scenario could explain that. And the problem occuring at the time of the accident. Because that is exactly what it was doing. It would accelerate but by about 1 mph every second or two....very very slow.

But if this is the case, why is it running fine now? It's just maddening that I've experienced a problem on my motorcycle several weeks in a row, it finally almost kills me and I take it to get fixed and NOTHING!!

Thanks for the replies