Changing the pipe o-rings ?

[ian]

Can someone please help me with this? I need to change my o-rings that seal the pipe/engine. There are 2 black rubber rings and one copper. I have the shop manual but i don't want to make a mistake or get grease in my engine so any advice/tips would be great. It's an FMF pipe on a '90 kdx200 if it makes a difference.

Thanks :)
ian

 

[canyncarvr]

What's the question?

Not generally much need to change the O-rings unless they are damaged. You mention 'grease in the engine' concerns. You're wondering about greasing the O-rings then? That's not going to get grease in your engine.

Are you changing this stuff cuz your pipe is leaking? Exhaust or spooge?

If it's exhaust, there's a mating problem somewhere..something is likely bent (the pipe). If it's spooge, it's a jetting problem..and no O-ring/gasket is going to fix that.

I change my pipe several times a year (from kg30-kg35), usually put some grease on the O-rings each time mostly to protect them during install. I run two copper gaskets..don't do anything to them except make sure they're still there. With all this changing, my O-rings are still fine.

Do you have a specific worry about it?

 

[ian]

Just if there's anything that the shop book doesn't say that i should know about. This is my first time doing this and i don't want to do anything wrong. I assume they are just old/bad because it's leaking smoke and gradually got worse over the fall.

thanks

 

[David Trustrum]

Yeah they rattle about making grooves in the cylinder. Not much you can do about that, but new Orings & the gasket + new exhaust springs will help. Also a Hi temp silicone RTV is in order when they are leaking.

You can usually buy springs from many bike shops. Make a spring installer with an old spoke & 3” of broom handle as a handle (drill hole in handle & put nipple on to stop it slipping through). Sharpen the end to become a hook. Else use vice grips, but this way is much easier.

 

[Canadian Dave]

If you don't often have to remove your pipe I'd suggest sealing the pipe to the cylinder with high temp silicone as Dave mentioned. You'll want to use a rag and solvent to clean the end of the pipe and the cylinder up well. Install your new o-rings and insure the copper gasket is properly installed in the cylinder. Run a small bead of silicone around the o-rings and install the pipe. You should apply enough silicone that some squishes out from between the pipe and cylinder but not so mush that you're forcing it into the cylinder. You'll still be able to easily remove the pipe if required but if the exhaust port is worn where the pipe is inserted it will last much longer before leaking again.

While you have the pipe off the bike take the time to inspect the power valves as well. Its not uncommon for 89 to 94 KDX200s to strip or snap the top off the sub port valves if they are not regularly maintained/cleaned and become carbon seized. Look up into the exhaust port. Both sub-port valves should be closed. If you remove the gray plastic cover from the left side of the engine you should be able to operate the actuating shaft by hand. While rotating the shaft look up into the exhaust port. Both sub port vales should rotate open and the main valve should rotate to expose more of the main exhaust port.

David