Exhaust Leak

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mobrown

Member

Jan 26, 2004

198

0

• Feb 7, 2004

• #1

I have a 1991 CR250 that runs really strong. I finally got to take it out today for a spin around the block a couple of times (lots of snow in Delaware!) and I am noticing an exhaust leak and I can't tell where it's coming from.

At first I thought it was from the pipe/exhaust port connection but it that wasn't it. Can exhaust be leaked from the cylinder and the bike still run strong? It seems like it may be coming from the bottom of the head/top of case interface but I just can't tell. I also thought the pipe may have had a leak (Fatty) but actually the residue seems to be hitting the pipe. Is this a gasket problem? If so can I simply take it apart and change it or is more involved? How hard is that? I am actually a rocket engineer by trade and education but never did more to a bike but change plugs and fix tires. Could it simply be the screws aren't torqued enough?

Appreciate any help you'll could give. Any repair manuals available for these things? Is the bike in danger of further damage?

Thanks for any advice in advance.

 

Y

yz125_894

Member

Nov 23, 2003

42

0

• Feb 7, 2004

• #2

It may be (as in the case of my Bike) that the seal that goes around the rod that opends and closes the power valve is leaking. is it comming down the left (kickstart) side. If so take the cover off to the shaft that leads to that rod and then see if oil is in there. if so just get a new seal. it doesnt hinder performance just hinders cleaning ability lol.

 

A

adbot

• Feb 7, 2004

• #3

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• Feb 7, 2004

• #4

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M

mobrown

Member

Jan 26, 2004

198

0

• Feb 7, 2004

• Thread starter
• #5

Left or right?

The kickstart on the bike is on the right side (facing forward and sitting on the bike). The leak is also on the right side. I can't figure out exacly where it is coming from. At times I think it's the cylinder head/case interface and at times it seems to be coming from around the waterpump.

Can exhaust come from anywhere within the cylinder, i.e. from an area below the piston? I can't figure it out.

yz125_894 said:

It may be (as in the case of my Bike) that the seal that goes around the rod that opends and closes the power valve is leaking. is it comming down the left (kickstart) side. If so take the cover off to the shaft that leads to that rod and then see if oil is in there. if so just get a new seal. it doesnt hinder performance just hinders cleaning ability lol.

Click to expand...

 

A

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• Feb 7, 2004

• #6

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Y

yz125_894

Member

Nov 23, 2003

42

0

• Feb 7, 2004

• #7

I meant on the right side (stupid me) sorry about that one I think your best bet is to check the powervalve that is were all the excess oil goes when the gas in burned in the cylinder. if you remove the plave covering the linkage to the rod on the RIGHT side there should be oil commin out of it if i am correct. if it is not that check the powervalve gasket to see if it is leaking. just keep checking the gaskets and your find it. Sorry for any confusion

 

A

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• Feb 7, 2004

• #8

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yz125_894

Member

Nov 23, 2003

42

0

• Feb 7, 2004

• #9

if it seems to be comming from the water pump that that is it. the plate is just above where the water pump is.

 

Y

yz125_894

Member

Nov 23, 2003

42

0

• Feb 7, 2004

• #10

It is the seal leaking that i mentioned not the water pump and the only way oil (not the 2 stroke mix) could leak below the piston is the cases and that does not seem to be the case check what i said and you should be set e-mail me for more q's or if you have some pics that would be great Yz125_54@hotmail.com :thumb:

 

M

mobrown

Member

Jan 26, 2004

198

0

• Feb 7, 2004

• Thread starter
• #11

Thanks alot.

I'll take a look at what you mentioned...

yz125_894 said:

It is the seal leaking that i mentioned not the water pump and the only way oil (not the 2 stroke mix) could leak below the piston is the cases and that does not seem to be the case check what i said and you should be set e-mail me for more q's or if you have some pics that would be great Yz125_54@hotmail.com :thumb:

Click to expand...

 

M

mobrown

Member

Jan 26, 2004

198

0

• Feb 8, 2004

• Thread starter
• #12

Schematic

Just looked at an online schemetic of the cylinder head and the exhaust valve thingy is on the left side so it must not be that. I suppose it may be the bottom head gasket or something...can't figure it out. Can exhaust come from waterpump area? I wouldn't think so if the bike was running well ( I suppose there's a seal in there separating oil and water).

Does anyone know the torque values for the bottom cylinder head bolts? Where can I get the values? I don't have a repair manual as of yet.

 

M

mobrown

Member

Jan 26, 2004

198

0

• Feb 8, 2004

• Thread starter
• #13

Can anyone else offer any insight

I was hoping someone with a similar bikecould offer a littel help on my exhaust leak problem (see first thread)

 

P

Peer Lovell

Member

Nov 25, 1999

600

0

• Feb 8, 2004

• #14

mobrown said:

I was hoping someone with a similar bikecould offer a littel help on my exhaust leak problem (see first thread)

Click to expand...

Skirt some baby powder all over the engine, then start it up.
Any leaks will show up as a black mark.
That will help define just where this is coming from.

 

M

mobrown

Member

Jan 26, 2004

198

0

• Feb 8, 2004

• Thread starter
• #15

Thank you..

I was thinking about using soemthing we use at my job called leak tec but baby powder will do the trick.

Thanks again