Stihl 029 super to 039 conversion

[kkemp]

With that window into the transfers, I'm wondering if the jug may have been designed to use the 'slab sided' TS-400 piston.

What is the width of that transfer window, it looks like it may be wider than the exhaust port.

This may be a stupid question but how different are those pistons ? Is it gonna hurt to run this one if it ain't right ?

 

[Terry Syd]

Wouldn't that be a hoot, a close-port jug and a domed piston - 64cc of CHEAP homeowner power.

 

[Terry Syd]

No, you can run either piston. However, the slab-sided piston may give more transfer flow (it looks like that is why they put the window in).

Here's a link to a TS-400 jug and piston, notice that this piston even has windows for increased flow -

 

[kkemp]

Ok . I see that now .. so how big advantage would the slab side have ? As you all can tell I'm not an expert at this .

 

[Terry Syd]

It may not have any advantage. I would have to have the jug in front of me to do some measurements and see if there was a constriction in the tunnels.

It may be that the TS-400 piston and some clever port work could open up the flow even more, we just don't know at this point. This is new territory...

 

[Dub11]

My mind has been blow the last few days with these saws from a soon to be pop up kit to this were does it end.

 

[Terry Syd]

As far as the 'clever port work', when I've been confronted with a restriction in the transfers, I will thin the outside wall of the transfer tunnels. You have to be careful not to grind too far. What I do is drill a series of 1mm holes into the tunnels from between the fins. This allows me to assess how far I am getting to breaking through the wall. I stop when I can see I've got about 1mm to go. I then add GB Weld to the area outside the wall to help build it up a bit and to close off the holes.

 

[kkemp]

Who would know something about this cylinder? Curiosity is about to get the best of me Lol. I may try to give stens a call but I'm sure they won't know anything about it .

 

[Dub11]

Iam not sure maybe @Gentleman he rum s hl supply and sells highway stuff

 

[Dub11]

or maybe @Black Dog Chainsaw aka Nathan he is working on a pop up kit for these saws so he might know who to talk to. If @Terry Syd hasn't seen it maybe its a unicorn?

 

[Gentleman]

This may be a stupid question but how different are those pistons ? Is it gonna hurt to run this one if it ain't right ?

The pistons are exactly the same except for the opening on the bottom. I've had customers tell me that they have interchanged them and could not notice a difference.

 

[Gentleman]

View attachment 46902 View attachment 46903 View attachment 46904 View attachment 46905

That's a Hiway

 

[kkemp]

That's a Hiway

Ok. Is it a new design or what's up with it ?

 

[Gentleman]

With that window into the transfers, I'm wondering if the jug may have been designed to use the 'slab sided' TS-400 piston.

When I met with the factory owner he told me had an idea to make it closed port. He also did it to the HUS 340 cylinder and maybe a couple others. There was not really any engineering into it.

 

[kkemp]

Ok. I guess I'll see how it runs .. I've never used a 390 before so i won't really know If it's better . Thanks for the info .

 

[Gentleman]

They ain't scared over here. Post away.

We're cool here as long as @Mastermind approves.

 

[Gentleman]

Gentleman is getting a domed piston to have a look at and see if it can be copied.

It will be copied as soon as we get the sample.

 

[Gentleman]

Does anyone know a time line on those domed pistons ? I'd like to get the parts here in a couple of weeks but I would wait if there gonna be available in a couple of months or so ..

At least 3 months after we get the sample

 

[Dub11]

The closed port feature should be listened in the description if its not already. I might have gotten that ovee the cross

 

[Gentleman]

No, you can run either piston. However, the slab-sided piston may give more transfer flow (it looks like that is why they put the window in).

Here's a link to a TS-400 jug and piston, notice that this piston even has windows for increased flow -

That photo is not an actual TS400 piston. It looks like this.