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evo engine, head gasket leak

HDDon said:
I wasn't aware that the 1999 EVO had an O ring at the base. I don't doubt that if you're careful and the base gasket isn't leaking you might get away with just the top cyl. gasket but since you are already there and to be on the safe side why not go ahead and replace the base gasket too? JMHO
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Just an oversight on the type of base gasket; my bad. However, the same principle applies; if not leaking now and not disturbed (easily achieved IMHO) no reason it should leak post head gasket replacement, so why do more than necessary to address the OPs issue? I reply to forum posts based on what I would do in a specific situation and am not prone to advise anyone to incur more time and cost than may be necessary to address the issue at hand. The OP now has been presented with a couple of different approaches and suggestions and can make an informed decision on how he wants to proceed................;)
 
I'm with Don, if you're already there why not replace if not for any other reason, piece of mind.
I'd also be inclined to at least do a valve job as long as it's apart, but that's just me.
 
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My own personal bias is to do what you CAN based on how much needs to be disassembled to do what you MUST. I think that since the head has to come off to replace the head gasket, that I might as well pull the jug off too just to refresh the base gasket. With the head off, might as well get the valves done. With the jug off, might as well have it honed. Since the jug is off, might as well replace the rings. And I feel that both cylinders should be done so that they are in about the same condition. If it is a carb bike, that should be rebuilt too. Since the pipes are off, new gaskets and possibly a new exhaust system while it is all apart. The last thing is definitely a wish list item tho'!

Just my personal bias.

When I did the top end job back in '99 on the Dyna, I did NOT split the case or gut the tranny. I wish I had done a full rebuild then, because now I need to rebuild the tranny at least. Has sidelined the '91 for a long time waiting on me. Would have been just a little bit more back then. Now it is starting over!! Oh well. That is where my bias comes from!!!

Cheers,

TQ
 
TQuentin1 said:
My own personal bias is to do what you CAN based on how much needs to be disassembled to do what you MUST. I think that since the head has to come off to replace the head gasket, that I might as well pull the jug off too just to refresh the base gasket. With the head off, might as well get the valves done. With the jug off, might as well have it honed. Since the jug is off, might as well replace the rings. And I feel that both cylinders should be done so that they are in about the same condition. If it is a carb bike, that should be rebuilt too. Since the pipes are off, new gaskets and possibly a new exhaust system while it is all apart. The last thing is definitely a wish list item tho'!

Just my personal bias.

When I did the top end job back in '99 on the Dyna, I did NOT split the case or gut the tranny. I wish I had done a full rebuild then, because now I need to rebuild the tranny at least. Has sidelined the '91 for a long time waiting on me. Would have been just a little bit more back then. Now it is starting over!! Oh well. That is where my bias comes from!!!

Cheers,

TQ
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And for me as well as some others this all depends on if the piggy bank is half full or half empty. I do agree that when I have something apart I tend to do as much as I can. I think it comes from years of preventative maintenance.
 
Keep in mind when changing head and base gaskets there are different thickness gaskets chose the right ones so as not to change your compression ratio and stacked height, check that cylinders are aligned before torquing heads this makes a huge difference
Using a 30 degree triangle it must touch the intake ports in 2 spots if it does not slowly rotate until it does then torque
 
Summer can be a fairly short riding season this side of the pond although the op is at the southern end of the UK at this time of year it would be get the job done as quickly as possible to get the bike back on the road there is not the same aftermarket support here as there is in the US and HD prices have the same number here but in GBP then 20% Value added tax is put on the price so it can be very expensive to do more than is necessary
I would strip the affected cylinder replacing all the gaskets top to bottom and inspect everything else for possible winter project work
The last week of april we had our heaviest and most frequent snow of the winter last week was at times uncomfortably hot bike needs to be ready for the days the weather is suitable

Brian
 
headboltsequence.gif
Here is your torque sequence
 
Ive swapped heads (and gaskets) multiple times without base oring replacement. Luck? Maybe but if care is taken, its not an issue IMO.
 
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