Rattle at speed under load (not KIPS?)

Got questions? We got answers....
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Rattle at speed under load (not KIPS?)

Post by emmett »

This is my first real post here after reading a lot. I have a fairly new to me 1993 kdx200 that I have been going through. It is clear the maintenance has been neglected, so Ive flushed coolant, changed trans oil, semi-straightened brake rotors, replaced bars/adaptors/grips, muffler packing, countershaft seal, front sprocket, and a couple other small things here and there.

I am fairly competent fixing bikes and I'm mechanically inclined. It starts right up first kick and runs great.

It sounds healthy at idle (rattly at idle as they usually are) but when I get up into 5th and 6th gear under load, theres a knocking sound that it makes. I cant tell if its top end or bottom end (as i was going 40-50mph on the road at night and didn't want to take my eyes off the road).

Im not sure of when the top end was last done, if ever. It doesnt seem to have a TON of hours on it, given I can tell its definitely been ridden by the wear on the frame. The odometer was broken at 59mi, so ill never know.

Could this knocking be carbon deposits on the piston? Or would this knocking be the common kips rattle and I just didn't realize it would sound like this?

I havent pulled the kips cover off. is there any fluid in there or is it dry? im not yet sure how the kips system works.

Thanks for any help, it is greatly appreciated. If i can figure out how, Ill attach some photos so you can see the patient.
2C8B3F62-0032-4829-99A5-7D0397CC3A22.jpeg
2C8B3F62-0032-4829-99A5-7D0397CC3A22.jpeg (3.43 MiB) Viewed 2603 times
41F69A40-5B0B-4717-8CCE-D2BDA66347AF.jpeg
41F69A40-5B0B-4717-8CCE-D2BDA66347AF.jpeg (2.91 MiB) Viewed 2603 times
55AA71B3-BC85-47F3-B5BF-A7F357F4D730.jpeg
55AA71B3-BC85-47F3-B5BF-A7F357F4D730.jpeg (3.62 MiB) Viewed 2603 times
User avatar
Slick_Nick
Supporting Member
Posts: 1675
Joined: 10:06 pm Oct 22 2009
Country: Canada
Location: Calgary, Alberta
Contact:

Re: Rattle at speed under load (not KIPS?)

Post by Slick_Nick »

The KIPS can be pretty noisy. Are you sure it's got some nice high octane fuel in it? If you're hearing genuine pinging from detonation then you'll want to avoid riding it until you get it figured out so you don't damage anything.
'00 KDX 220R
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

Slick_Nick wrote: 09:24 am May 30 2021 The KIPS can be pretty noisy. Are you sure it's got some nice high octane fuel in it? If you're hearing genuine pinging from detonation then you'll want to avoid riding it until you get it figured out so you don't damage anything.
I am running MO gas from the airport. Not sure of octane. I can try running avgas (100 low lead) if you think that would be better? Whats the standard octane for these bikes?

the sound seems to really come on when i load the bike at a higher speed and the rpm are coming up slower (because of being in a higher gear) which coincides with engine pinging, no?
Last edited by emmett on 09:50 am May 30 2021, edited 1 time in total.
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

just looked, the mogas at my airport is 91 octane.
Goofaroo
Gold Member
Gold Member
Posts: 531
Joined: 12:42 pm Sep 09 2012
Country:
Location: Edmond, Oklahoma

Re: Rattle at speed under load (not KIPS?)

Post by Goofaroo »

If you’re sure the rattle is coming from the engine it sounds to me like you have an air leak. Is it hard to start? Does it snap back to idle or hunt it’s way down to idle?

Is the flywheel key sheared?

Otherwise, are you sure your chain isn’t completely shot and making noise?
John_S
Gold Member
Gold Member
Posts: 875
Joined: 06:59 am Jan 27 2017
Country: US
Location: Florida

Re: Rattle at speed under load (not KIPS?)

Post by John_S »

I would say since it’s new to you and other maintenance was neglected I would pull the top end and at very least take apart, clean and check the KIPS. It’s never a bad thing to put a fresh piston and rings. That way you know what you’re dealing with. I thought mine had a rattling KIPS sound and it turned out to be the piston slapping around in there. A quick top end job and there is no rattle.
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

Goofaroo wrote: 10:41 am May 30 2021 If you’re sure the rattle is coming from the engine it sounds to me like you have an air leak. Is it hard to start? Does it snap back to idle or hunt it’s way down to idle?

Is the flywheel key sheared?

Otherwise, are you sure your chain isn’t completely shot and making noise?
Runs awesome, and does not have any issue returning to idle. What makes you think air leak?

Not sure if it could be a flywheel key, but im replacing the stator soon so ill check.

I think chain would be most likely out of these options now that you mention it....
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

John_S wrote: 10:43 am May 30 2021 I would say since it’s new to you and other maintenance was neglected I would pull the top end and at very least take apart, clean and check the KIPS. It’s never a bad thing to put a fresh piston and rings. That way you know what you’re dealing with. I thought mine had a rattling KIPS sound and it turned out to be the piston slapping around in there. A quick top end job and there is no rattle.
Leaving for college this fall, and would like to be able to ride in the little free time I have, not spend all of it working on it! I don't think thats a bad idea, but working on a budget, alongside very limited time.
User avatar
KDXGarage
KDXRider.net
KDXRider.net
Posts: 14047
Joined: 06:45 am Nov 01 2004
Country: United States of America
Location: AL, USA
Contact:

Re: Rattle at speed under load (not KIPS?)

Post by KDXGarage »

run it till it pops then :-)
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

KDXGarage wrote: 11:32 am May 30 2021 run it till it pops then :-)
would i do any bottom end damage or any other detrimental damage besides a top end?

Sorry for the ignorance!
pumpguy
Gold Member
Gold Member
Posts: 821
Joined: 10:00 am May 29 2012
Country:
Location: Spring Grove, Illinois

Re: Rattle at speed under load (not KIPS?)

Post by pumpguy »

First thing I would recommend is you get a proper SERVICE MANUAL. This will answer many of your questions and is your best investment if you own a KDX. From the looks of your bike, I think you have an E series, not the later and final H series.

That noise you hear could be detonation or pinging. If it is, you could end up with a hole in your piston crown. Been there & done that. Check your ignition timing and don't go too far advanced. Your SERVICE MANUAL will tell you how to set the timing.

Also useful is an OWNER'S MANUAL. I understand these are available as a free download.

Good luck with your KDX.
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

pumpguy wrote: 11:44 am May 30 2021 First thing I would recommend is you get a proper SERVICE MANUAL. This will answer many of your questions and is your best investment if you own a KDX. From the looks of your bike, I think you have an E series, not the later and final H series.

That noise you hear could be detonation or pinging. If it is, you could end up with a hole in your piston crown. Been there & done that. Check your ignition timing and don't go too far advanced. Your SERVICE MANUAL will tell you how to set the timing.

Also useful is an OWNER'S MANUAL. I understand these are available as a free download.

Good luck with your KDX.
yup its an e series. Ive got an owners manual already, and ive been looking around for a service manual. I have not adjusted ignition timing before, but i will look into that. Thanks
User avatar
KDXGarage
KDXRider.net
KDXRider.net
Posts: 14047
Joined: 06:45 am Nov 01 2004
Country: United States of America
Location: AL, USA
Contact:

Re: Rattle at speed under load (not KIPS?)

Post by KDXGarage »

emmett wrote: 11:35 am May 30 2021
KDXGarage wrote: 11:32 am May 30 2021 run it till it pops then :-)
would i do any bottom end damage or any other detrimental damage besides a top end?

Sorry for the ignorance!
yep, could damage the cylinder, head, crankcases and/or crankshaft

If you don't want to work on a dirt bike, then don't. Ride it until it tears up, then sell it for what you can and go get another one. It is not the cheapest way to go, but if your focus is riding, then skip learning and maintaining, just ride it.

You're not spending my money, and it won't be me getting a scratch if it causes you to wreck. :hmm:
Thank you for participating on kdxrider.net. :bravo:
To post pictures from a device: viewtopic.php?f=88&t=24128
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

KDXGarage wrote: 12:23 pm May 30 2021
emmett wrote: 11:35 am May 30 2021
KDXGarage wrote: 11:32 am May 30 2021 run it till it pops then :-)
would i do any bottom end damage or any other detrimental damage besides a top end?

Sorry for the ignorance!
yep, could damage the cylinder, head, crankcases and/or crankshaft

If you don't want to work on a dirt bike, then don't. Ride it until it tears up, then sell it for what you can and go get another one. It is not the cheapest way to go, but if your focus is riding, then skip learning and maintaining, just ride it.

You're not spending my money, and it won't be me getting a scratch if it causes you to wreck. :hmm:
I do enjoy working on and taking care of my machines, that is why I came here for advice. The previous owner seems to be someone who rode it until he sold it, whereas I would like to bring it back to life. It seems to have some issues that may point to just doing a rebuild, but trying to gauge where to draw a line.

two main ones are:

I have noticed the airbox drips oil after riding (trans oil?). Not sure what would cause that.

Theres the tick/knock, which is why I created this thread.

Ive got lots of projects going on and Im not sure Id have the time to do a bottom-up rebuild. I feel that would probably be the best bet rather than do a top end and then realize it then needs a full rebuild.

Whats the rough price to have the motor completely rebuilt at a shop? $750? $1500? $2000?

Or maybe I should just run it...

:hmm:
Goofaroo
Gold Member
Gold Member
Posts: 531
Joined: 12:42 pm Sep 09 2012
Country:
Location: Edmond, Oklahoma

Re: Rattle at speed under load (not KIPS?)

Post by Goofaroo »

emmett wrote: 10:45 am May 30 2021
Goofaroo wrote: 10:41 am May 30 2021 If you’re sure the rattle is coming from the engine it sounds to me like you have an air leak. Is it hard to start? Does it snap back to idle or hunt it’s way down to idle?

Is the flywheel key sheared?

Otherwise, are you sure your chain isn’t completely shot and making noise?
Runs awesome, and does not have any issue returning to idle. What makes you think air leak?

Not sure if it could be a flywheel key, but im replacing the stator soon so ill check.

I think chain would be most likely out of these options now that you mention it....
An air leak will make it run hot and can definitely make it ping. A sheared flywheel key can advance the timing and make it ping. If the flywheel is loose that could certainly explain the knock you’re experiencing.

A compression test might reveal some clues. Aviation fuel is designed to burn cooler and run at steady throttle. If your compression test shows unusually high compression it could very well be severe carbon deposits from burning aviation fuel. Pull the plug and look at the top of the piston or pull the pipe away from the exhaust port and see how it looks. What does the plug look like?

You said the chain seems most likely of my suggestions. Is it shot? Can you only hear this noise when riding or is it there with the engine running in neutral? Chains can make all kinds of noise if they’re worn, damaged, and neglected. What about your chain rollers and sliders?
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

Goofaroo wrote: 01:25 pm May 30 2021
emmett wrote: 10:45 am May 30 2021
Goofaroo wrote: 10:41 am May 30 2021 If you’re sure the rattle is coming from the engine it sounds to me like you have an air leak. Is it hard to start? Does it snap back to idle or hunt it’s way down to idle?

Is the flywheel key sheared?

Otherwise, are you sure your chain isn’t completely shot and making noise?
Runs awesome, and does not have any issue returning to idle. What makes you think air leak?

Not sure if it could be a flywheel key, but im replacing the stator soon so ill check.

I think chain would be most likely out of these options now that you mention it....
An air leak will make it run hot and can definitely make it ping. A sheared flywheel key can advance the timing and make it ping. If the flywheel is loose that could certainly explain the knock you’re experiencing.

A compression test might reveal some clues. Aviation fuel is designed to burn cooler and run at steady throttle. If your compression test shows unusually high compression it could very well be severe carbon deposits from burning aviation fuel. Pull the plug and look at the top of the piston or pull the pipe away from the exhaust port and see how it looks. What does the plug look like?

You said the chain seems most likely of my suggestions. Is it shot? Can you only hear this noise when riding or is it there with the engine running in neutral? Chains can make all kinds of noise if they’re worn, damaged, and neglected. What about your chain rollers and sliders?
if running hot is one way it will ping, i should mention that one of my radiators is bent. It does not leak, but maybe that is causing the bike to get warmer than usual? I only took it for a ride around the block (maybe 10 minutes of riding, if that). ill attach a photo below to show the left rad.

I have not run avgas, only mo gas. and im fairly confident the previous owner just ran pump gas.

I havent seen the plug yet, because no wrench that i have will fit in there... ordered a low profile tusk plug wrench but it hasnt come in yet. I will run a compression test as soon as i can, and i will check the plug to see if its white.

Im not sure if the chain is shot. I did clean it up as much as i could, but couldnt get the master link pin out to remove and fully soak/scrub. Ive only noticed the noise under load, at speed. No unusual sounds when in neutral revving or riding around the yard. Just seems to be up in 6th, 5th, and maybe as low as 4th gear as i accelerate.

Ill try and get an audio clip of it whenever this rain stops. Just tricky riding it down the road I live on, as its busy and this bike is not street legal yet. I'm in the process of setting it up to be plated (small battery, reg/recitifer, stator, horn, hi/lo beam, brake light sw, speedo, etc).

It would be wonderful if this is only a chain issue :roll:

Radiator:
FA31D068-DCC8-4D2D-8701-A65D967C0041.jpeg
FA31D068-DCC8-4D2D-8701-A65D967C0041.jpeg (2.99 MiB) Viewed 2557 times
90CA7920-8DDA-42B4-9C0C-1DA7E9EE845E.jpeg
90CA7920-8DDA-42B4-9C0C-1DA7E9EE845E.jpeg (2.91 MiB) Viewed 2557 times
Goofaroo
Gold Member
Gold Member
Posts: 531
Joined: 12:42 pm Sep 09 2012
Country:
Location: Edmond, Oklahoma

Re: Rattle at speed under load (not KIPS?)

Post by Goofaroo »

You definitely need a radiator. Are you sure you aren’t just hearing the radiator banging against the frame while you’re riding? Stick a piece of rubber between the radiator and the frame and see if the noise stops. Is the radiator mounting tab broken off the frame?
Goofaroo
Gold Member
Gold Member
Posts: 531
Joined: 12:42 pm Sep 09 2012
Country:
Location: Edmond, Oklahoma

Re: Rattle at speed under load (not KIPS?)

Post by Goofaroo »

A bigger problem is the crack in your triple clamp. This bike took a very awkward hit.
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

Goofaroo wrote: 02:00 pm May 30 2021 You definitely need a radiator. Are you sure you aren’t just hearing the radiator banging against the frame while you’re riding? Stick a piece of rubber between the radiator and the frame and see if the noise stops. Is the radiator mounting tab broken off the frame?
rad is solid and does not move or rattle. I do plan on replacing it, but i am 100% sure that is not the noise. mounting tab is not broken either. and theres at least 1/4" between rad and frame and i cant make it touch the frame or even wiggle by pushing on it.
0101B2F0-CF84-48CE-ACE9-8073C3B735A5.jpeg
0101B2F0-CF84-48CE-ACE9-8073C3B735A5.jpeg (2.71 MiB) Viewed 2548 times
emmett
Member
Posts: 63
Joined: 07:06 pm Oct 30 2017
Country: USA

Re: Rattle at speed under load (not KIPS?)

Post by emmett »

Goofaroo wrote: 02:11 pm May 30 2021 A bigger problem is the crack in your triple clamp. This bike took a very awkward hit.
haha you had me worried for a second because that photo makes it look like a crack. but nope, thats just the clamp. My theory is the bike fell over onto a rock/sharp edge at a stop, and the rider weight added to the impact.

heres the clamp so you can see it.
00CB3B02-8A65-4B0F-97D1-825794453CF4.jpeg
00CB3B02-8A65-4B0F-97D1-825794453CF4.jpeg (726.23 KiB) Viewed 2544 times
Post Reply