Cuyuna question

[smudvapor]

Is there a right and a left side head or are they both the same on a Cuyuna 440?

[jpswift1]

Is there a right and a left side head or are they both the same on a Cuyuna 440?

They're both the same.

[hydromike]

In some very rare instances (on late, late models...) Cuyuna used what they called a "flow through head", which had much larger gaps between the cooling fins on one head. This head is designed to be first in the air stream generated by the cooling fan, and provides less restriction for the airflow getting to the second head. Typically, the cooling fan runs in a normal mode and sucks in air from the mag side and blows across the head to the PTO. In this case, the flow-through head would be on the mag side cylinder. If the fan is a puller rather than a pusher, it'll suck air from the PTO side cylinder, across the mag side cylinder and out to the starboard side of the machine. In THIS case, the flow-through head would be on the PTO side cylinder.


There's the potential to overheat if you get them reversed with the particular fan direction. 99% of axial fans are set up to blow from mag to PTO, and probably 99% of heads are the same, but if you run into some weird ultralight engine stuff, it could be reversed. The first engine in my D/stock was set up with a flow through head and a reversed head....

[smudvapor]

In some very rare instances (on late, late models...) Cuyuna used what they called a "flow through head", which had much larger gaps between the cooling fins on one head. This head is designed to be first in the air stream generated by the cooling fan, and provides less restriction for the airflow getting to the second head. Typically, the cooling fan runs in a normal mode and sucks in air from the mag side and blows across the head to the PTO. In this case, the flow-through head would be on the mag side cylinder. If the fan is a puller rather than a pusher, it'll suck air from the PTO side cylinder, across the mag side cylinder and out to the starboard side of the machine. In THIS case, the flow-through head would be on the PTO side cylinder.


There's the potential to overheat if you get them reversed with the particular fan direction. 99% of axial fans are set up to blow from mag to PTO, and probably 99% of heads are the same, but if you run into some weird ultralight engine stuff, it could be reversed. The first engine in my D/stock was set up with a flow through head and a reversed head....

But if I bought a pair of heads that were the same they would work correct?

[hydromike]

Yes, that'll work. If you're getting a set off of ebay, make sure to take a good look at the insides of the chambers. It seems a lot of Cuyuna heads that I've seen on ebay in the past are sold after and engine fries a piston. Sometimes there's a bit of metal transfer onto the heads and if a ring let's go, it'll cause nasty damage that the sellers don't recognize or are willing to show. I've had about three sellers try to conceal damage in the past....

[smudvapor]

Yes, that'll work. If you're getting a set off of ebay, make sure to take a good look at the insides of the chambers. It seems a lot of Cuyuna heads that I've seen on ebay in the past are sold after and engine fries a piston. Sometimes there's a bit of metal transfer onto the heads and if a ring let's go, it'll cause nasty damage that the sellers don't recognize or are willing to show. I've had about three sellers try to conceal damage in the past....

I found a really cheap set on Ebay I thought I would give a try. I am going to try to clean them up and polish them, I figured that I would try on a cheap set so if I mess something up I won't lose a lot and if I get it right then I made out.

[hydromike]

I found a really cheap set on Ebay I thought I would give a try.

Did you get a set of "hemi" style heads, or the "wedge" style heads? The set with the vertical spark plug holes are move of a hemispherical combustion chamber. I ran a set of wedge style heads with a pretty tight quench area toward the exhaust port for a while. I was in the pits at Ashtabula one year (2012, I think...) and Mr. Gerber suggested that the other, vertical style plugged engines "seemed to run a lot better that way".


You know what? He's right....

[smudvapor]

Did you get a set of "hemi" style heads, or the "wedge" style heads? The set with the vertical spark plug holes are move of a hemispherical combustion chamber. I ran a set of wedge style heads with a pretty tight quench area toward the exhaust port for a while. I was in the pits at Ashtabula one year (2012, I think...) and Mr. Gerber suggested that the other, vertical style plugged engines "seemed to run a lot better that way".


You know what? He's right....

Hemi, I figure it works great on a car engine, it has to work great on a 2 stroke! I don't plan on winning (it would be nice) but I don't want to embarrass myself either.

[hydromike]

I don't plan on winning (it would be nice) but I don't want to embarrass myself either.

I never plan on winning. I plan on having fun. I've only been out front in a few races and I absolutely hate it. It's some stressful stuff! The most fun is being toward the front/middle of the pack and fighting off everybody else. You get a good running 440 Cuyuna and get your clutches dialed in right and you'll be right in the pack in the two stroke stock class. Be sure to post the build as you go along. There's a really big knowledge base on the JLO/Cuyuna engines. Lots of us have done a lot wrong for a long time and we might be able to help you get the most out of it. It's always better to have one more person on the track with a fast machine. "The Sweeper" can only get more fun with a couple more machines thrown in the mix.

[ARGOJIM]

I never plan on winning. I plan on having fun. I've only been out front in a few races and I absolutely hate it. It's some stressful stuff! The most fun is being toward the front/middle of the pack and fighting off everybody else. It's always better to have one more person on the track with a fast machine. "The Sweeper" can only get more fun with a couple more machines thrown in the mix.

You must have been pretty stressed with Duesel's (sorry Mike if it's spelled wrong) son behind you this year! That was a great race to watch and reminded me of Pauch and Horton around here, it's to bad you were looking at mostly track all race.

[hydromike]

You must have been pretty stressed with Duesel's (sorry Mike if it's spelled wrong) son behind you this year! .

Yeah, that's the most recent one, but it's happened often. Whipper's run me down, TechFX's run me down... everybody runs me down if they're not already out front. Like Joe H. says: "I'm gonna let you stay just in front of me and I'll pass you when your roll over..."

[smudvapor]

[QUOTE=hydromike;162385]I never plan on winning. I plan on having fun. I've only been out front in a few races and I absolutely hate it. It's some stressful stuff! The most fun is being toward the front/middle of the pack and fighting off everybody else. You get a good running 440 Cuyuna and get your clutches dialed in right and you'll be right in the pack in the two stroke stock class. Be sure to post the build as you go along. There's a really big knowledge base on the JLO/Cuyuna engines. Lots of us have done a lot wrong for a long time and we might be able to help you get the most out of it. It's always better to have one more person on the track with a fast machine. "The Sweeper" can only get more fun with a couple more machines thrown in the mix. [/QUOT

Having fun is a given. Winning just adds some icing on the cake. I will be sure to post pics. Thanks

[Joe H]

Yeah, that's the most recent one, but it's happened often. Whipper's run me down, TechFX's run me down... everybody runs me down if they're not already out front. Like Joe H. says: "I'm gonna let you stay just in front of me and I'll pass you when your roll over..."

I am going to rethink my strategy, it hasn't been working since you have quit the turtle on its back imitation. I think I am going to concentrate on running Don down and keeping Mike Gerber off my six.