2 Stroke 1988 CR250R Wont start / Wet Plug

[Stringer]

If you didn't see any coolant come out with the oil when the oil was drained, I would suspect head gasket, warped head, or cracked cylinder.

No I didn't see any coolant in the oil. But bike has not run since oil change. Oil was dirty though, especially for not actually being in a running engine!

I took the HPP system apart. Coolant appears to be coming from behind valve assembly. I take out assembly and I can see the piston behind it. HPP componants a bit soiled and a little sticky. Looks like I will wash these parts on solvent before assembly with new gasket. I also found the valve washer to be in the incorrect place, it was supposed to be sitting where the lower orange arrow is

 

[Stringer]

If you didn't see any coolant come out with the oil when the oil was drained, I would suspect head gasket, warped head, or cracked cylinder.

Well I got the head off and this is what I have found. Looks like a wet mess in there. This is what I have now. Do I need to continue to remove the rest of the cylinder or would you just throw a new gasket on it?

 

[2strokesteve89]

its clearly leaking past gasket.....you can see carbon (combustion leaking into water jacket and on gasket you can see where its blown also)....i would check to see if head is straight (use a straight edge and feeler gauges) but yeah, thats where the coolant leak is coming from.

edit. you may have, a worn piston also and now would be the time to do it, or you can cross your fingers and just replace the gasket. probably be better off knowing for sure though.

 

[Stringer]

its clearly leaking past gasket.....you can see carbon (combustion leaking into water jacket and on gasket you can see where its blown also)....i would check to see if head is straight (use a straight edge and feeler gauges) but yeah, thats where the coolant leak is coming from.

edit. you may have, a worn piston also and now would be the time to do it, or you can cross your fingers and just replace the gasket. probably be better off knowing for sure though.

Yep definitely was leaking from the head gasket. Well, I got the jug off and here is what ive found. It looks like part of the cylinder skirt has broken off previously, I guess it's an old battle scar? I found marks on the engine case where it was rattling around at some point before that was "fixed". It does look structually sound, but I really don't know if I should put this back in or not?? I looked in the manual as far as testing piston, rings, cylinder etc and I do not have the tools necessary for any of that. The cylinder walls and piston seem to be in decent shape as far as I can tell, again no tools to test anything.

I do have a digital caliper I guess it's called, and I measured side to side play on small end of connecting road and got 0.15mm. Up and down play was almost non-existant and too small to measure, maybe 128th of an inch or less not sure. I did not find any of these measurements in the clymer manual to compare. Crank seems to be soaked in gasoline, I turn the crank and it gets wet with gas. Not sure how to get that out?

 

[Mihylo33]

Oh damn!!!

 

[SRAD97750]

Oh jeez.

Just my 2 cents...
Um, yeah, that cylinder is toast. Even sleeved, I would not trust the cracking visible in the first picture. You could end up with alot more cylinder breaking off.

The cases have been cleaned up with a dremel. The cylinder head needs to be smoothed where all that debris damage could be causing hotspots.
How's the piston look?
-BIG DAN

 

[Stringer]

Oh damn!!!

I know, WTF!

Oh jeez.

Just my 2 cents...
Um, yeah, that cylinder is toast. Even sleeved, I would not trust the cracking visible in the first picture. You could end up with alot more cylinder breaking off.

The cases have been cleaned up with a dremel. The cylinder head needs to be smoothed where all that debris damage could be causing hotspots.
How's the piston look?
-BIG DAN

Yes I understand. That thing must be another ticking timebomb. Upon closer inspection the head has some deep gouges in it .... this doesn't look good I assume?


I don't know a lot about pistons but I guess it looks ok? Or maybe that black part is a hotspot? I have not cleaned either the head or the piston.


Im afraid all of this is getting rather expensive. What are my options? Also, it looks like I have the exact same gasket (K&S, though says D&K on many gaskets) as the one that just failed. :/

 

[SRAD97750]

Looks like the rings are about done. All that black on the side of the piston is 'blow-by' from worn rings or cylinder. Can't tell the condition of the piston without cleaning it up and inspecting closely.
Most of the time it's much easier to just buy a new piston kit, than find the right replacement rings for your piston.

You'll need to measure the cylinder with calipers to buy the correct piston kit. For example, this one is about $100 shipped.
http://www.ebay.com/itm/Honda-CR250...Parts_Accessories&hash=item5d4dc82a5b&vxp=mtr

I looked for a cylinder for you... VERY EXPENSIVE, even used. 225 for a good one on ebay. Yikes.

Your crank rod, is there ANY up and down play? (Side to side play is fine)
There should be none.

Good luck, should you decide this is something you are interested in putting money into, you will be rewarded with the bounty of experience you will gain by doing this work yourself.
-BIG DAN

 

[Stringer]

Looks like the rings are about done. All that black on the side of the piston is 'blow-by' from worn rings or cylinder. Can't tell the condition of the piston without cleaning it up and inspecting closely.
Most of the time it's much easier to just buy a new piston kit, than find the right replacement rings for your piston.

You'll need to measure the cylinder with calipers to buy the correct piston kit. For example, this one is about $100 shipped.
http://www.ebay.com/itm/Honda-CR250...Parts_Accessories&hash=item5d4dc82a5b&vxp=mtr

I looked for a cylinder for you... VERY EXPENSIVE, even used. 225 for a good one on ebay. Yikes.

Your crank rod, is there ANY up and down play? (Side to side play is fine)
There should be none.

Good luck, should you decide this is something you are interested in putting money into, you will be rewarded with the bounty of experience you will gain by doing this work yourself.
-BIG DAN

Oh that's from blow by then, good to know! As far as the crank, I have that 0.15" side to side action going on. As far as up and down there is the tinyest of movement it is literally a hair if I yank on it. 1/128th of an inch maybe or less? Very small, is this something to be concerned about? Most people probably would not notice it.

Yes the cylinder looks expensive as hell! geez! What about the head, is it toast too? Any other sources to try besides ebay?

A big thanks for all the help I am receiving!! Really appreciate it!!

 

[SRAD97750]

No, if you can't really feel any slop in the rod, you're good to go.
You don't have any tell tale crank seal issues either. Taking it apart is free, and really sheds light on what's going on.
If there had been oil behind the stator/flywheel, or a ton of trans fluid on the crank, I would say the seals are gone. You have neither.
Not to be too forward (as we don't know each other)... but, sounds like you have a good bottom end.

Ebay is my go to, and my local used parts provider lists all their inventory on ebay.
So, if it isn't there or OEM, I try junk yards, CL or the likes.

-BIG DAN

On a personal note, I REALLY appreciate your appreciation and willingness to listen to what everyone has to say. There are some who struggle with taking advice when asking for it...
We can all learn from each other, no matter what age or experience level.

 

[Stringer]

Well ive decided to go ahead and finish with the rebuild (since I've got alot of help if i need it

does this look like a good deal? It also comes with the head. Also how would I know what piston kit to buy for it? What should I ask the seller? Thanks again!

http://m.ebay.com/itm/301300507349?nav=SEARCH

 

[Stringer]

There is also this guy I just called. I send in my cylinder and get remanufactured one in return, he said I can choose to receive a replated or RE sleeved one. There would be a $45 up charge for rewelding mine, and 15 for shipping so I'm looking at 310 for that.and he said to send in my powervalve assemblies with it so they can check function. But no head on this deal. What do you think?

http://m.ebay.com/itm/141386861272?nav=SEARCH

 

[SRAD97750]

There is a possibility the used one will need work, so I would go with the second one and KNOW I have a brand new cylinder.
As it seems the 88 CR250's were steel liners, I would opt for the re-sleeve option. (Keep it stock)
When you send in your cylinder, you send in the new piston so they can bore and hone it to YOUR particular specs. So I would go with the stock piston kit. That way you can bore the cylinder and put an oversized piston in next go around with the top end. -BIG DAN

 

[Mihylo33]

eBay a used cylinder.

There is also this guy I just called. I send in my cylinder and get remanufactured one in return, he said I can choose to receive a replated or RE sleeved one. There would be a $45 up charge for rewelding mine, and 15 for shipping so I'm looking at 310 for that.and he said to send in my powervalve assemblies with it so they can check function. But no head on this deal. What do you think?

http://m.ebay.com/itm/141386861272?nav=SEARCH

I read the description and I don't think it meets the exchange criteria. You might want to call and double check on this.

 

[SRAD97750]

I read the description and I don't think it meets the exchange criteria. You might want to call and double check on this.

Mikey? Did you not read the post you quoted?

There is also this guy I just called. I send in my cylinder and get remanufactured one in return, he said I can choose to receive a replated or RE sleeved one. There would be a $45 up charge for rewelding mine, and 15 for shipping so I'm looking at 310 for that.and he said to send in my powervalve assemblies with it so they can check function. But no head on this deal. What do you think?

http://m.ebay.com/itm/141386861272?nav=SEARCH