Beggin for the Answer

[Daaj65]

I had an old thread (God-Awful KDX220 Rattle), and several responded and helped out. I have done everything suggested to try to isolate or stop the deep cat-purring rattle in the engine. I have replaced governer shaft and lower arm, installed new top-end (piston/rings/wristpin/writpin bearing), completely disassembled the entire power-valve (thanks to pictorial on Just KDX) and cleaned and lubed to factory new condition, pulled flywheel looking for broken woodruff key (still in place and looks factory new), disassembled carb and cleaned, new plug, new top end gasket kit. I felt like I've done all I know to do. Just cranked moments ago. Started on third kick (after being torn apart for 6-weeks) and revved up perfect, which is an improvement. Had good throttle response, but that awful rattle. Took off down the street. Still rattling. Then is started bogging and spitting with small backfires. Parked it. Screamed, kicked, and put in on the stand!!! Looking for that last hope recommendation from anyone out there. Next stop is the mechanic, unless.... :(

 

[Daaj65]

Not quite the answer I was looking for, but yet an answer. Might be a plan if money was no object!

 

[zeerx]

Bogging, spitting and backfire could be as simple as a bad plug. If the carb isn't tuned right you'll go through plugs like crazy. Try Champion N3C. I've had good luck with them. Cheers.

 

[Hoffies]

Is the rattle only there at idle(and just off idle)? If so you are sure it is a thorough bread KDX. You will find many threads on the KDX rattle. This said, as for the misfire and bogging and the fact that it only happens after a while tells me you might have a problematic coil or CDI(are any of them getting very hot when misfire occurs(I know CDI is difficult as resides under seat, but you will have to check!), or a fueling problem. Have you perhaps checked float level(needle and seat) tank, petcock, fuel pipe to carb etc as I suggested last time. An engine leaning out sometimes behaves eratically pinging, bogging, misfiring. If all these are OK definately look at the coil/CDI. There are basic measurements that can be done on both. Good luck

 

[BSWIFT]

When you checked your woodruff key, did you make sure to torque the flywheel back? Sounds as if you may have sheared the woodruff key and slipped time. I've done this myself after a flywheel weight change.
As for the rattle, does it dissapate slightly when you pull in the clutch? My KDX and KX rattled in gear and in neutral, pull in the clutch and it went away. Never found the actual cause, just rode the bikes and enjoyed them.

 

[danfree]

From what I've read, that purr is just part of the KDX charm. Have you tried putting in a full quart of oil in the gearbox? That's what every other die hard KDX rider does. Even endorsed by Jeff Fredette, the KDX guru.

 

[Rotorranch]

It's probably just the normal KDX rattle. A full quart helps, if that's what the noise is.

Rotor

 

[Daaj65]

I'll try the whole quart deal and investigate the coils, carb, etc. Oddly, I have never had any complaints nor had the "infamous KDX rattle" until it started all-of-a-sudden. And my son and I have ridden this '04 pretty agressively. To me it's more than a simple rattle. It sounds potentially catastrophic. The "purr" is more like a very pissed-off tiger, on steroids, with asthma!!!!

 

[THill]

Well this maybe a stupid question but here it goes..
Would you happen to be using the same gas now as when this rattle started ?
Just wondering if you have gotten gas at a different station than what you had before this started or maybe just some bad gas causing a " knock ping " noise..

 

[Hoffies]

Do you think the misfire/bogging and rattle are connected at all? I presume that you have already tried to determine the position of the rattle, as is usually quite difficult? You can however try to isolate whether it is engine noise or gearbox noise. Is the noise a rattle or knocking noise? Does it dissappear with clutch in, or when in gear, is it still there when bike rolling forward(riding in gear), when freeing downhill clutch pulled in and engine killed. So one can perhaps pinpoint it. In your case all this will be difficult if she does not want to run/rev properly either. Good luck.

 

[Kwakasaki]

Full quart is just a band-aid. KDX's sound like sewing machines, deal with it.

 

[hart125]

that backfire stuff sounds like plug or electric to me too. If you know someone who is familiar with the kdx rattle you could have them listen. If I was real concerned that it was power valve related I would remove the power valve and run it without it. the toung in the center is the one that makes all the noise. then at least you would know where the noise is coming from. my last thought is a bad rod would do most of the symptoms you are talking about.. sputtering/noisy rod bearings don't always go out completely. Good luck!