Tri z wrench report gone wrong

[6spdls1z28]

I recently sent the top end to the machine shop and the guy said he could add the port. I talked to him yesterday and he said that he broke out the side. He said he could weld it has anyone had to do this?

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[El Camexican]

Many people. The correct way to do the port is weld and then drill, but you’ll be fine. Better now than having it crack later.

[6spdls1z28]

Awesome I was scared there.
Many people. The correct way to do the port is weld and then drill, but you’ll be fine. Better now than having it crack later.

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[El Camexican]

Just try to get them to make it look like the opposite side does on the outside so you can still get a socket in there. I don’t know what Yamaha was trying to accomplish by leaving that small amount of aluminum off of the cylinders when they cast them, but it sure has caused people a lot of grief over the years when trying to add that boost port.

The other thing I would recommend is not to get too crazy on the width of either the original port, or the one that you’ve added. I would focus more on trying to elongate them slightly. Unless you’re planning to drive it WFO all the time the risk of hogging out those ports and wreaking that cylinder aren’t worth the gains in power it will net you.

[6spdls1z28]

I was trying to get the exact wrench report done I talked to him and told him to add material to that side.
Just try to get them to make it look like the opposite side does on the outside so you can still get a socket in there. I don’t know what Yamaha was trying to accomplish by leaving that small amount of aluminum off of the cylinders when they cast them, but it sure has caused people a lot of grief over the years when trying to add that boost port.

The other thing I would recommend is not to get too crazy on the width of either the original port, or the one that you’ve added. I would focus more on trying to elongate them slightly. Unless you’re planning to drive it WFO all the time the risk of hogging out those ports and wreaking that cylinder aren’t worth the gains in power it will net you.

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[christph]

When I did mine, I started with a small drill bit to start the port. Then I used progressively bigger and bigger bits. Then you take a file and oval it out. I didn't have to weld anything up and it has held up fine over the years.

[6spdls1z28]

I should of just done it myself but I was too scared to make the first hole.
When I did mine, I started with a small drill bit to start the port. Then I used progressively bigger and bigger bits. Then you take a file and oval it out. I didn't have to weld anything up and it has held up fine over the years.

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[El Camexican]

When I did mine, I started with a small drill bit to start the port. Then I used progressively bigger and bigger bits. Then you take a file and oval it out. I didn't have to weld anything up and it has held up fine over the years.

Sounds like mine, I don’t have any welding either and my static compression is over 185 psi at 1,200 ft., but from what I’ve heard and been told we’re the lucky ones.

I have a few theories on why some cylinders crack starting with improper shimming of the head stay as well as the mating serfaces of the cylinders and the case not being flat after years of heat cycles. The other thing I have noticed when comparing the cylinders that I have, is that the quality of the casting seems to vary between them. On the one I recently polished there are some large pores in the material where the cylinder nuts go, but on the one I have a boost port in there are no pours at all.

If you were to combine a poor casting with a stressed head stay and a warped cylinder base and then add that boost port I could see how it might become a catastrophic failure waiting to happen.

[6spdls1z28]

Do you guys happen to have any pics of your ports. Or some that have been welded

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[6spdls1z28]

I mean where they broke through the side

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[christph]

Here are before and after pictures of mine.253038253039

[this old rz]

Consider your self blessed, that you don't have my Tri-Z, could you imagine if whomever owned it before me tried to do the port work..OH GOD, would that have been a sight to see

[6spdls1z28]

Right ! Mine was just as bad when I got it too. surprised they didn't try to add the port they already did the exhaust side. The one thing that makes me mad about mine is having an 85 engine in an 86
Consider your self blessed, that you don't have my Tri-Z, could you imagine if whomever owned it before me tried to do the port work..OH GOD, would that have been a sight to see

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