1984 Cr 250 resto/ rebuild

[Teador Beeman]

So I was given a 84 Cr 250. The guy I got it from thought it needed new reeds due to what he thought was fuel getting into the pipe. He in stalled new carbon fiber reeds and no fix. So I get it and I believe that the liquid getting into the pipe is coolant /water . Would this be from a bad head gasket? The bike needs rebuilt regardless it sitting at about 40 psi. 

[EmpireofDerp]

Yup, teardown time.

[Teador Beeman]

Ya I have it torn down atm. I just don’t wanna miss something and get it together with the same issue 

[drumiv]

I had one. It's a "orphan year" bike, so hard to get some parts. Take a look at your water pump while you're at it. Notorious for corroding the case. Good luck. 

[Teador Beeman]

I’ve checked the water pump not much corrosion just alot gunk looked like mold. I believe it is in working order. I’m just curious if coolant can get into the exhaust any other way than a leaking head gasket

[2 Stroke Boogie]

Pics???

[87' CR 5003]

42 minutes ago, Teador Beeman said:

I’ve checked the water pump not much corrosion just alot gunk looked like mold. I believe it is in working order. I’m just curious if coolant can get into the exhaust any other way than a leaking head gasket

If the case cover seal leaks AND the main seal you could get coolant and gear oil in the lower end.

[Teador Beeman]

The oil I drained looked fine. Little clutch color. I saved the oil in an old 2 liter and no separation 

[Teador Beeman]

[Pittbull]

Just went through all this with my 86 CR500. Bought new right side cover from a company in Australia due to the massive amount of corrosion in my water pump. Good luck with your build.

[Teador Beeman]

Did u have to split the case ? I’m planning on re doing the seals to keep anything from happening don’t wanna put in a new top end and fry it ? . Can any 1 tell me if coolant could get into the exhaust any other way than a bad head gasket putting coolant in the cylinder and being pushed out by piston 

Edited February 9, 2019 by Teador Beeman

[Pittbull]

3 minutes ago, Teador Beeman said:

Did u have to split the case ? I’m planning on re doing the seals to keep anything from happening don’t wanna put in a new top end and fry it ?

No, everything else was good. The last owner of the bike had just done a fresh rebuild but due to the difficulty of finding the clutch side / water pump case, he did a farmer fix with a plug, some silicone and black paint. I didn't see it until I noticed an external leak. Nothing but clean oil in the case so I was lucky.

[Teador Beeman]

Sweet I didn’t wanna have to split since I never have but I did get the bike for free!! So I would have ? I don’t think the seal is bad the oil looks fine. Minimal corrosion on the impeller cover but like I said it was covered in some kind of mold or something

[Pittbull]

I had to stop the rebuild due to financial restraints but hopefully I can get back onto it sometime soon. I need to either rebuild my wheels or buy new ones and get a new front brake line. Everything else is pretty much ready to go. 

[Singletrack_rider]

It's not mold but the byproduct of the coolant eroding the magnesium. From the pics you showed it doesn't look good.  I've gone through this myself a couple times. I would imagine the damage under the impeller is fairly bad.  The problem will be when you try to clean it. Material will just keep coming off. Think of rotted wood. The seals are probably clogged up with gunk that's keeping it from leaking coolant into the cases. If you get it back together and running use this for coolant.

[Teador Beeman]

3 minutes ago, GreenMT_Rider said:

It's not mold but the byproduct of the coolant eroding the magnesium. From the pics you showed it doesn't look good.  I've gone through this myself a couple times. I would imagine the damage under the impeller is fairly bad.  The problem will be when you try to clean it. Material will just keep coming off. Think of rotted wood. The seals are probably clogged up with gunk that's keeping it from leaking coolant into the cases. If you get it back together and running use this for coolant.

Is there a trick to pulling the impeller I was trying last night but couldn’t think of a good way to keep it from spinning.my plan is i don’t wanna complete restore it just want it to run for now maybe when it’s old enough for armah  it’ll get a resto. Thanks for the heads on the coolant wasn’t aware of it 

[Pittbull]

1 minute ago, Teador Beeman said:

Is there a trick to pulling the impeller I was trying last night but couldn’t think of a good way to keep it from spinning.my plan is i don’t wanna complete restore it just want it to run for now maybe when it’s old enough for armah  it’ll get a resto. Thanks for the heads on the coolant wasn’t aware of it 

The impeller threads off if memory serves me right. But the corrosion is a real issue. Some have cleaned it all out and used things like JB Weld to reshape and rebuild it temporarily. Be careful though as coolant is not JB Weld friendly and will quickly fall apart. There is a tiny weep hole that allows oil from the crankcase to lubricate the impeller shaft. That weep hole is quick to corrode and will let water back into the crankcase in no time. You're going to have to get a new case cover IMO.

[Pittbull]

The dreaded weep hole.

 

[Teador Beeman]

29 minutes ago, Pittbull said:

The impeller threads off if memory serves me right. But the corrosion is a real issue. Some have cleaned it all out and used things like JB Weld to reshape and rebuild it temporarily. Be careful though as coolant is not JB Weld friendly and will quickly fall apart. There is a tiny weep hole that allows oil from the crankcase to lubricate the impeller shaft. That weep hole is quick to corrode and will let water back into the crankcase in no time. You're going to have to get a new case cover IMO.

I’m gunna pull the cover today and check it out u r probly right I’m hoping it won’t be to bad ? I’ll be buying a new impeller they aren’t too expensive. But the cover on the other hand ? Hopefuly I can save it.. 

Thanks for all the info really appreciate it you guys have bin at my wits end till I find this site ! 

[Dirtbug26]

3 hours ago, GreenMT_Rider said:

It's not mold but the byproduct of the coolant eroding the magnesium. From the pics you showed it doesn't look good.  I've gone through this myself a couple times. I would imagine the damage under the impeller is fairly bad.  The problem will be when you try to clean it. Material will just keep coming off. Think of rotted wood. The seals are probably clogged up with gunk that's keeping it from leaking coolant into the cases. If you get it back together and running use this for coolant.

I wish that stuff was available in 1986, it would have saved me a lot of heartache with a KTM 500, as water ate through the case. Sounds like motorcycle engineers must have slept during chemistry class in the mid 80’s, as water steam reacts and disolves magnesium. ?

 

Edited February 9, 2019 by Dirtbug26