295 sleeve kit....head gasket and head q's 250R

[InPiEcEs]

I recently picked up a 295 sleeved cylinder for my 86 R, with the piston, and head, etc.
First thing I did was have the head and cylinder checked and decked, and ordered a new fiber gasket from Cometic.
Got it together, ran it a bit, retorqued the jug and head, and went through a tank or so for break-in.
I filled the tank a few days later. Got through half a tank, and blew a head gasket. Previous owner blew one once as well.
That's why I got it checked, and decked. Is there a solution to this? Also, I'm wondering if there is another option for a head besides a rechambered stock one. I cannot seem to find anything for 295/310 re-sleeves.

[max]

If you have had it decked the there must be some kind of hair line crack that you cant see. After the engine heats up it expands enough to leak.

On my 295 after a rebore. My sleeve sunk about .030. And it would start leaking. After i decked it she was fine. Make sure the top of your sleeve is perfectly flat with the cylinder and not sunk down a couple thousandths.

I would find another clean stock head. If it still leaked after replacement then its a problem with jug.

What are you torquing these too?
Are you tightening in a star sequence?

Good luck,
Max

[InPiEcEs]

Thanks Max......
Torquing them the same as a stock bore right from the Honda shop manual. 3 steps, and star, like lugnuts.
I think the problem may be in the head. The bore measures at basically 72 mm, and the head was brought out to nearly 76 mm to the decked surface.
I'm looking at a very small sealing surface. I don't suppose they made the dome/squish area too large when they rechambered?
I think I may need to find another head. I don't suppose they make any type of aftermarket head for the stock barrel big bores.
I also find that LRD does this kit with o-rings. I wonder if calling them would be a good call for the head, and o-ringing.

[tw05tr0k35]

Any aftermarket head manufacturer will be able to supply you with the right dome for your bore. These are usually not catalog listings, you'll have to custom order the dome. Fiber head gaskets will let you down every time in a high performance engine, I prefer multi layer steel (mls) or copper w/ steel o-rings and silicone (on watercoolers). I'm not sure that I've ever seen a copper head gasket for a R, I use vesrah mls but I'm only 1.5mm over and they don't offer a bigbore gasket set in the catalogs. I believe that lrd and pro-design heads use rubber o-rings like a yamaha. This is a great setup as long as your deck is finished properly. A crack in the barrel is not likely, although not out of the question either, most likely its the fiber gasket with its weak combustion sealing ring backed up with cardboard. Good luck,

[ceaserthethird]

Can we see pictures of this work ? ? ?, It would help when i do my own.

Also how much did it cost to total for this 295 big bore set up ?

Details would be great.

Thanks and keep us posted !

[InPiEcEs]

I'll get some pics a bit later for you. I payed $200 for the cylinder, piston , and head barely used.
If I don't like this once I get it running, I may look at a Pro-x power-valved cylinder later in the year.