I forgot something.....

R

Ramrod

New Member
Forgot to install the piston rubber 0-rings between the gasket and bottom of the cylinder.....around the cylinder sleeve. bike is a 71 CB350 twin.

how big of an issue is this...i assume there was a good reason to put those there. Will the gasket not keep the oil in the engine?

has anyone done this and not had issues later? What is the worst case scenario..that it leaks a little?

most of the engine is completely assembled and i really do not want to take it apart again, but am feeling like i will have to. CRAP.
 
I dont know what would happen but it was put there for a reason, if you're skeptical you should follow you're gut and bite the bullet
 
I've done a little Googling and found a few discussions around the interwebs from guys in similar situations and they haven't had problems. Some suggest the o-rings are there to compensate for less than perfect mating surfaces between the cylinders and engine cases, but somehow I doubt that is their purpose.

Some guys run without a base gasket at all, to increase compression in an easy and free way (cheaper to run without a gasket than it is to deck the head).

So.... for my money I'd keep building :D Nothing is gonna break. Worst case is you might get a little weeping, but if you used fresh gaskets and do things right, I'd bet you'll be fine.
 
thanks! i was kinda leaning toward running it and see if it leaks then tear down if i feel like it, i did use new gaskets and sealed them properly.
 
Ramrod said:
i know, just seems weird to have an o-ring to prevent oil from getting to a gasket...
Click to expand...

I was thinking about this too. The o-ring is a good seal, and will handle a little movement. So why the gasket?

I am guessing, but the gasket may be designed to keep dirt and liquids out of the o-ring groove. If the gasket isn't there, rain, water, dust, would accumulate in the area, eventually compromising the o-ring seal.
Another possibility is that the o-ring seals the cylinder sleeve, keeping oil and gases from getting between the steel cylinder sleeve and aluminum cylinder, while the gasket just seals the aluminum cylinder to the base.

You'll probably get away with not replacing it, but I would replace it if it was me....I think the o-ring is probably more important then the gasket...
 
There are plenty of bikes out there with aluminium cylinders and steel liners that only run a base gasket, I reckon you'll be fine, it was probably over engineered by Honda.
 
The 'O' rings prevent oil soaking up cylinder liner through capillary action.
Lots of Honda cylinders were not the best quality casting so oil could 'soak through' the alloy.
If your running stock bores it shouldn't be any problem at all.
I've done hundreds of 'big bore' motors with oversize liners, very few have had any oil weeping (Yamaha XS650 is a different matter as the base gasket isn't fully supported)
My 391cc CJ250 has very slight 'damp patch', but, you can see the liners in a couple of places.
It still doesn't actually leak or pool oil anywhere though (and I've given it some really sever beatings ;) )
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light

    • Spread the Love

    Back
    Top Bottom