Replacing KTM 640 Adventure head gasket ... guidance?

[D0dja]

I'm pretty sure the head gasket has gone on my 2002 640 Adventure -- coolant vanishes if I push it hard and get an insta-overheat; also bubbles rising in radiator with cap off.

Is there a way to check if it's head or base gasket?

I'm looking at doing the head gasket myself - there's very little info on this topic (unless I missed it in search?). Is it relatively straightforward (have a copy of factory manual) ... what's the chance of warped head? Should I leave this to a workshop?

I generally work on my bike myself, but not done something this major. I have also had LOTS of really miserable experiences with agents, workshops, etc, so would prefer to do it myself.

I recently replaced the seals on the water pump shaft and resealed tappet cover, which fixed the one coolant disappearing problem (and mayonnaise in oil) and a oozing oil leak.

[gunnerbuck]

Originally Posted by D0dja

I'm pretty sure the head gasket has gone on my 2002 640 Adventure -- coolant vanishes if I push it hard and get an insta-overheat; also bubbles rising in radiator with cap off.

Is there a way to check if it's head or base gasket?

I'm looking at doing the head gasket myself - there's very little info on this topic (unless I missed it in search?). Is it relatively straightforward (have a copy of factory manual) ... what's the chance of warped head? Should I leave this to a workshop?

I generally work on my bike myself, but not done something this major. I have also had LOTS of really miserable experiences with agents, workshops, etc, so would prefer to do it myself.



I recently replaced the seals on the water pump shaft and resealed tappet cover, which fixed the one coolant disappearing problem (and mayonnaise in oil) and a oozing oil leak.

If a gasket is leaking, it can only be the head gasket, as the base gasket does not seal the water jacket... You can pressure test the system before you remove the head by blocking off the lower rad to block tube and then make an air filler plug to bolt over the thermostat fitting above the spark plug... You can add 50lbs pressure into the block and see if it holds for a while... If it does hold then your leak is outside of the cylinder waterjacket, either at the waterpump, rad or hose fittings...

If the leak is found within the water jacket then it will either be a faulty gasket or a cracked cylinder/head...


This thread will give you an idea of how to pressure test: http://www.advrider.com/forums/showthread.php?t=405073

[D0dja]

Great, thanks for the feedback.

Will try talk a nearby bike shop into testing it for me (in exchange I'll buy more tyres and a new chain from them :) )

I recently relocated and now living in an apartment so don't have a workshop to fabricate things. Going to have to strip the engine in the garage at my girlfriend's place. Sigh.

The alternative is having the local bike shop do it - they have good rep, but I talked to the mech and he has not worked on the 640 much (they mostly do dirtbikes), And I'm a bit anal about how stuff is out together. Prob cost around $200 labour. Hrmmmm.

[D0dja]

I stripped the head and replaced the gasket. Problem not solved.

Pulled head off again.

There's a crack across exhaust ports right down to the valve stem seals. Unfixable,

I'm not a happy bunny.

[Kawidad]

Ouch!

[Droptarotter]

Originally Posted by D0dja

I stripped the head and replaced the gasket. Problem not solved.

Pulled head off again.

There's a crack across exhaust ports right down to the valve stem seals. Unfixable,

I'm not a happy bunny.

Are you sure it's not repariable??

Have you taken it to a good welder? Some of the welders are amazing what they can do.

Good luck.

[D0dja]

Originally Posted by Droptarotter

Are you sure it's not repariable??

Have you taken it to a good welder? Some of the welders are amazing what they can do.

Good luck.

I took it to a guy who's apparently very good, does all the repair work for one of the Kawasaki racing teams, has a good rep.

Recons it's cracked right to the valve stem seals, so can't even get in there.

Have a lead on a second hand head...