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Cr250 fixing warped head

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I have a 2001 cr250r that I got in a trade bike started but was spitting out coolant from the head, iv taken the head off which had a gasket and red rtv as well. Should I send the head off and have it milled? If so would that effect the piston to head squish? Thanks

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Depends on how much you get milled but if you simply get the head surfaced to make it glat, you will be absolutely fine.

You could possibly fix it by sanding it on a flat surface with some 220 grit sandpaper.

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I was thinking of doing that iv seen a video on lapping. I'll try that out tonight and see if it will work would the cylinder need it too or are the heads mainly at fault for coolant leaking and blown gaskets

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The cylinder could be warped but it takes a bit more heat for that to happen. The head & gasket will almost always fail before the cylinder gives up.

Be sure to work even & smooth. As soon as the entire gasket area is making contact, you're done.

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kirk-meme.pngI personally never put rtv on cyl gaskets head or base! You could spray gasket sealer but that would invite leaks also, Straight gasket to surface no worries! You could lap the head mating surface, bet bet is to get a perfectly square straight edge or ruler and measure with a feeler gauge in criss cross patterns to check surface warpage, as the gents stated above you could lap it with sand paper on a perfectly flat surface, but be careful and re-measure it!

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I'm gonna try with some sandpaper today, the only worry I have is that the head is beyond fixable and I'll have to buy a new one. From what I seen the head nuts are to be torqued at 21 foot pounds but the nuts where so tight I damn near needed a breaker bar to get them off.

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They were most likely intentionally over-tightening them to try to get the head to stop leaking. I agree with you that you should get the sealing surface on the head milled to make it perfectly flat, then try a new gasket. If that does not seal it up, then you will be pulling the cylinder and having it milled. It might be cheaper to just buy a used head off Flea-bay than to have your old one milled though. Check prices local to you on used heads. If you were close I'd tell you to come by the shop and we could fly cut it on my milling machine (taking off maybe .005") and that should be all it needs to clean it up and make it perfectly flat unless it's really out of whack. If it's really far out, you would be buying a new or used head anyway.

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After using some steel blue I realized the head isn't warped tried to do the same with the cylinder but I had one stud that would not budge. The cylinder has a couple small marks but nothing major should I use that copper gasket spray on the head gasket and try that 1st or just use the steel gasket alone. Also does the gasket go round side up or down? Snapchat-3189234032308694720.jpg Snapchat-6050404617775398299.jpg

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Is the stud that cannot be removed on the side where the coolant was leaking from? There should be a small tab on the metal gaskets and one side will have "up" marked in white if I remember right. Replace with new oem gasket either way in this case. Copper spray the new one. Take a straight edge across the top of cylinder and see if light comes through anywhere. If head and gasket look fine I'd take a good look at the stud(s).

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I have used copper seal spray on several head gaskets. From trx250r to cr's. Never a fail, using it.  I even reused a gasket after spraying it....No problems.  I usually give each side about 3 coats.

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Well I lapped the head and it was perfectly straight, I checked the cylinder and it wasnt out of spec I installed a new gasket from tusk sprayed it a couple times on each side with copper gasket spray and I still have coolant leaking from the head. It also sprays coolant out of the overflow. I put the gasket with the tab in the back and the holes facing upward. Should I take it back off clean it again and maybe spray more gasket spray then torque everything back down?

Edited by Jumpman746

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220px-UnknownComic.jpgMan o man, decarbonize that cyl head, sheeze!, the head gasket indentions face down to the barrel, tab in the back. you may need to shim the sides of the head stay, your frame may be tweeked! just use 2 washers to take some of the load off of the head, eric gorr explains this in his how to manual. as for fluid coming out of your overflow, you need to flush out your whole coolant system. also check with your rad cap off and engine running to see if your water pump is working! the cooling system in any water-pumper cr's is pretty simple, you shouldn't have any trouble keeping it leak free!

Edited by cr-dude3

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I just picked up a oem gasket from Gonda the tab says up and the edges for the coolant are facing upward. Should I even use that copper spray if both cylinder and head are both clean ?

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You shouldn't need it but it doesn't hurt to use it. Just enough to coat the gasket. Any more than that & it will just ooze out in the water passages, combustion chamber, & out around the head.

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It sounds like you have a pretty sizeable leak. It might be prudent to do a cooling system pressure test. Your local auto parts house can loan you the tool. With this tool, it plugs on the radiator at the rad. cap location and you have a hand pump that you use to pressurize the system. In this manner, you can see where the leak is without running the engine. I would pull the seat, gas tank, spark plug, and then pressurize the system. Using a flash light, and a mirror if necessary, look into the cylinder and see if coolant is also leaking into the cylinder. My guess is that it will be. If that is the case, and you have already tried a new gasket, you may have a hairline crack in either the cylinder, or the head.

 

Do the pressure test first though and let us know where the leak actually is, and if it is leaking bother internally into the cylinder, and externally. Here is what the tool looks like: http://www.toolpan.com/ATD-Tools-3305--10-Piece-Radiator-Pressure-Tester-Update-Kit-_p_2439.html?gdftrk=gdfV27228_a_7c824_a_7c2023_a_7cATD3305   Your local auto parts house should have one for loan.

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In aviation, for the recip's they taught us to magna-flux the cylinders, on the lycomings, then shine a ultra-violet light to find said cracks, You may have hit a grand slam Kawbuggy with the crack issue! Once you get a hairline you will always leak.

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I appreciate all the info. I put a new head gasket on it, used a little copper spray, new coolant and oil. Put it back togethor it doesn't leak but now burns coolant. I gave up on it so I traded it for a 2002 400ex I'm pretty happy but again thanks for the advice

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I appreciate all the info. I put a new head gasket on it, used a little copper spray, new coolant and oil. Put it back togethor it doesn't leak but now burns coolant. I gave up on it so I traded it for a 2002 400ex I'm pretty happy but again thanks for the advice

Have you inspected the cylinder studs? Sounds like one might have backed out enough to keep the head from sitting flush.

Are there any cracks? On anything?

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Have you inspected the cylinder studs? Sounds like one might have backed out enough to keep the head from sitting flush.

Are there any cracks? On anything?

Too late man! He traded it in for a chesterfield!

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