Holy Cylinder Block!

[Drewski]

Where the rot is, there was some hardened on lumps of oily coke. Strange, as the rest of the block seemed really clean.
It definitely looks like it's from before the 1975 port modification. When Suzuki did this, I presume they just lowered the floor on the ports........... or did they move them and keep them the same length/height?

[Drewski]

I wonder if I could clean up the exhaust with this stuff:-

http://www.jb-weld.co.uk/j-b-weld-epoxy ... poxy-putty" onclick="window.open(this.href);return false;

I've never used anything like it...apart from Gun Gum and High Temp RTV.

[tz375]

On the exhaust they raised the roof - like you probably used o do back in the day. On the intake they dropped the floor.

That way both ports increased in area as well as changed port timing. Raising the exhaust won't hurt, but dropping the intake floor hurts low speed more than it helps at high revs, so try not to do that unless you are making a more sporty type bike.

So that makes it a 74 block.

On the epoxy front, that high temp epoxy might work for a while, but I have no idea how long it would last in an exhaust port. I suspect that it would erode slowly. the spec is intermittent exposure to 500 degrees F and exhaust gas is way above that.

I would just slip in a new gasket into the port and see how much of a step exists. If it's bad, try some JB weld and if not say the 10 quid. Thinking about it, on my race bike the port is larger than the exhaust O ring shaped gasket and it hasn't burned out yet. You should be fine.

[Drewski]

So I took the block to my local reborers yesterday to see about honing the cylinders and skimming the top and bottom. He wants me to get the hole built up first. He says that he works on a lot of Triumph Stag alloy heads and pitting like this can cause problems.
I've found a local welder that comes to you and going by what he said it's going to cost about £220 GBP, $300 US, so I'm going to see if it's something a mate of mine at a nearby bike workshop can do, he can weld wood to glass.

Offending hole:-

[Suzukidave]

For my .02 opinion that fault is all in the water jacket area and would not cause a problem . As long as there is clear metal around the cylinder bore , the outside edge of the block and around the stud and bolt openings you would be good for a skim . I bet a product like JB weld would fill those faults well enough without the need for welding .

[Alan H]

a mate of mine at a nearby bike workshop can do, he can weld wood to glass.

I guess those new dissimilar rods would be OK for that?

[Drewski]

For my .02 opinion that fault is all in the water jacket area and would not cause a problem .

I was looking at it that way myself but it would probably blow eventualy, and I'd only end up having to sort it then. Head gaskets aren't cheap either

As there's a surprising amount of meat on the barrels, and the sleeves all look nice and central, it's worth sticking with this block.

[Suzukidave]

Just for the test .. did you happen to put on the head with this new block just to see how well they line up

[old racer]

I have used the above on a honda 400 race engine,It worked for me.
On stripping the engine i saw deep gouging where i take it someone had been scraping the old gasket off.
If it were me i would skim the top first, then fill whats left and flat back with wet or dry paper.

[Drewski]

Before:-


After:-


I'll see what the bores line up with the head like Dave but I don't expect much problams as the sleeves seem quite central on this one.

[Drewski]

Talking about JB weld reminded me of the repair on the original block:-