Cracked Head!!!???

[Jet-ex]

I tore down my son's 400EX to freshen the top end and take care of an oil leak between the head and the jug. Its a 2003 that I bought new in Nov. 02. Always maintained (oil changes, valve lash etc) and has never been apart before. The oil was seeping from the back of the head on the cam chain side. I found that the head was cracked From the cam chain cavity corner (inside rear)to the nearest cam cover hole allowing oil to seep out. The crack actually runs up along the corner of the cam chain cavity for about an inch. Man this sucks, a new bare head is around $500.
Has anybody seen anything like this before?
I have the head out being checked to see if it can be welded. (which doesn't give a warm fuzzy feeling) I also need to check salvage yards. The new head from Honda will be the last resort.

Thanks

[44oEX]

never heard of anything like that. not on a still running motor anyway. I don't think welding will be good, it will whorp ( sp) the head and it will leak. I say try to find used one you sould be able to find one on here. post a wanted add for one.

[Summit79]

$315 at www.servicehonda.com will get you a new head. The pn is 12200-KCY-670. You also may try ebay to find a better deal on one. Also, a machine shop can weld it. They usually just bake the thing first to prevent warping. If it does warp they have to technology to deck the thing afterwards and true it up again. The cheapest route is to clean it really and get yourself some jb weld. It's only a 4-wheeler, it's not too critical of an aera, and it's only a few hours and a head gasket to do it over if that doesn't work.

[blue416ex]

jbweld melts under high heat :rolleyes:

[Summit79]

Originally posted by blue416ex
jbweld melts under high heat :rolleyes:

http://jbweld.net/faq.php#faq001

Q: How much heat can J-B Weld withstand?

A: J-B Weld (Part # 8265-S, 8265, and 8280) can withstand a constant temperature of 500 degrees F. The maximum temperature threshold is approximately 600 degrees F for a short term (10 minutes).

I'd really like to see an engine that runs at 500 degrees.

[blue416ex]

well i had it on my header about 3 inches from the motor (on my old 3wheeler in 2001)and it melted clean off and left a nasty ***** smell for about 2 days to clean up a small leak in the header cuz i didnt have a welder at the time tryed it and wouldnt ever use it again on a motor and hes talking about putting it directlt on the head id say no thankx:rolleyes:

[Summit79]

Originally posted by blue416ex
well i had it on my header about 3 inches from the motor (on my old 3wheeler in 2001)and it melted clean off and left a nasty ***** smell for about 2 days to clean up a small leak in the header cuz i didnt have a welder at the time tryed it and wouldnt ever use it again on a motor and hes talking about putting it directlt on the head id say no thankx:rolleyes:

The header, as in the exhaust header? The exhaust system will always be well over 500 degrees the closer to the engine it is. The head itself would not hold up to anything anywhere near 500 degrees for too long.

[blue416ex]

then y did u argue with me that it wouldnt melt when you just proved yourself wrong
The header, as in the exhaust header? The exhaust system will always be well over 500 degrees the closer to the engine it is. and yes the exhaust header there isnt anything else on a quad called th header:rolleyes: and what do you mean by this
The head itself would not hold up to anything anywhere near 500 degrees for too long. as you said before it should get tp 500 and i know that i use a cat temp sticker on my head and it read around 275 and i use a laser heat gun just to see how its cooling and such so what do you mean by that ???

[ryann mx68]

dont know about the head, but i had my case welded by a machine shop, it had a crack in it about 2" long. didnt affect motor reassembly or anything. didnt warp, didnt leak. side cases are pretty thin and this guy did a great job.

[Summit79]

I mean JB weld melts at over 500 degrees. So, yes the exhaust header will be hot enough to melt it. The exhaust pipe is able to withstand the heat because it's thin and made of steel. The head, where the crack is, is aluminum, has a cooling system, and will not be hot enough to melt jb weld. By that rational If the cylinder head was ever hot enough to melt jb weld it would have to be over 500 degrees. If an engine were to even make it over the temperature of 500 degrees it would most certinly grenade.

[blue416ex]

i know its not supposed to be at or even close to 500 but i still wouldnt use it its kina booger-rigging-it i would never do it on any of my bikes ever again the mess isnt worth it to me id rather get a new head for like 200 off here or Ebay o something

[Summit79]

I whole heartedly agree that it's "booger-rigging-it". I just included it in my origional post as a suggestion and stated clearly that it's an option depending on how much you care. I personally wouldn't do it either. I'd throw it in an oven and then bring it out to the garage and tig it. I'm not argueing either, I'm just standing by my suggestion in saying that it won't melt due to heat.