Wiseco Piston Pics and Comments

[Terry Syd]

Pop-up

I'd expect that a lot of people would discount the wristpin gap issue if the piston came with a pop-up. With the pop-up, they would probably be willing to make some compromises (such as a longer bearing) in order to have a high compression piston.

Is there any feedback on why there isn't a pop-up/high compression piston?

 

[2000ssm6]

Is there any feedback on why there isn't a pop-up/high compression piston?

Not enough demand, we are a very small peice of the pie.

 

[parrisw]

Not enough demand, we are a very small peice of the pie.

Ya, plus I'm wondering, how it would work for every saw, since some can be slightly different. If your shooting for squish to within a couple of thou. I'm sure some saw can differ that much easy. Better off to make the popup yourself.

 

[2000ssm6]

They can call it acceptable to them (Wiseco), but it is unacceptable to me.

I expected a lot more from Wiseco than that, sad.

 

[2000ssm6]

Ya, plus I'm wondering, how it would work for every saw, since some can be slightly different. If your shooting for squish to within a couple of thou. I'm sure some saw can differ that much easy. Better off to make the popup yourself.

Yup, pop ups are "one of a kind" so to speak. The same one won't work in a different saw unless they(bases and squish band) are measured and machined accordingly.

 

[Bowtie]

Looking at the pic Brad posted, that is a lot of bearing floating to and fro. The side loads on the small rod end cant be good. If there was a way to keep the bearing in the center of the rod other than spacers, no big deal. But with the current piston configuration, that isnt possible.

 

[leeha]

There is no mention of the wrist pin bearing anywhere in that thread. No bearing pictured with the piston kit either.

You are correct Brad.
i forgot to put the bearing in the photo.
The bearing is not part of the Wiseco piston
kit. I had to buy them seperate from Wiseco
and supply them with every kit.

The width between the pin bosses is in there
machining process and can't make that dimension
as narrow as the stock piston. Not sure why.
I wasn't happy with that so they did the research
and found a bearing to make up the addition clearance.
The cage of the bearing actually a bit wider and not the
needles so the needles are still completely in the rod.


Lee

 

[blsnelling]

You are correct Brad.
i forgot to put the bearing in the photo.
The bearing is not part of the Wiseco piston
kit. I had to buy them seperate from Wiseco
and supply them with every kit.

The width between the pin bosses is in there
machining process and can't make that dimension
as narrow as the stock piston. Not sure why.
I wasn't happy with that so they did the research
and found a bearing to make up the addition clearance.
The cage of the bearing actually a bit wider and not the
needles so the needles are still completely in the rod.


Lee

Thanks Lee.

 

[2000ssm6]

Looking at the pic Brad posted, that is a lot of bearing floating to and fro. The side loads on the small rod end cant be good. If there was a way to keep the bearing in the center of the rod other than spacers, no big deal. But with the current piston configuration, that isnt possible.

Who would spend $130-140 on a piston then have to get spacers machined? Even with spacers, will these pistons go 1000-2000 hours with all that flop? Sounds retarded to me but I'll stick with Stihl and Mahle.

 

[wigglesworth]

Yup, pop ups are "one of a kind" so to speak. The same one won't work in a different saw unless they(bases and squish band) are measured and machined accordingly.

An 028 super piston has a factory pop-up that would be a good design to model for a universal fit. 028 Piston

 

[blsnelling]

Looking at the pic Brad posted, that is a lot of bearing floating to and fro. The side loads on the small rod end cant be good. If there was a way to keep the bearing in the center of the rod other than spacers, no big deal. But with the current piston configuration, that isnt possible.

First of all, I'm not real happy about this either. But the engineers say it's OK. I'm going to run it initially with the OEM bearing. I do intend to buy the wider B1015 bearing though. That'll give me a chance to go back in there after running it with the OEM bearing.

Do remeber that the rod will never be off to the side like I posted. It will be centered as in the pic below.

 

[wigglesworth]

First of all, I'm not real happy about this either. But the engineers say it's OK. I'm going to run it initially with the OEM bearing. I do intend to buy the wider B1015 bearing though. That'll give me a chance to go back in there after running it with the OEM bearing.

Do remeber that the rod will never be off to the side like I posted. It will be centered as in the pic below.

Isnt there side to side movement of the rod on the crank? Wont that allow the rod to float to the side?

 

[leeha]

Who would spend $130-140 on a piston then have to get spacers machined? Even with spacers, will these pistons go 1000-2000 hours with all that flop? Sounds retarded to me but I'll stick with Stihl and Mahle.

The Homelite Super 2100 uses spacers
from the factory and they had no problems.


Lee

 

[blsnelling]

Isnt there side to side movement of the rod on the crank? Wont that allow the rod to float to the side?

Very little. They all do a small amount, by design.

 

[blsnelling]

Who would spend $130-140 on a piston then have to get spacers machined? Even with spacers, will these pistons go 1000-2000 hours with all that flop? Sounds retarded to me but I'll stick with Stihl and Mahle.

What flop are you referring to?

 

[Jacob J.]

The Homelite Super 2100 uses spacers
from the factory and they had no problems.


Lee

Some of the Macs used a type of spacer as well, called "thrust washers"...

 

[2000ssm6]

What flop are you referring to?

Side to side. When that piston is on the rod ready to be installed, can you move the piston any along the wrist pin to the L or R?

 

[leeha]

Some of the Macs used a type of spacer as well, called "thrust washers"...

Exactly correct.

Lee

 

[blsnelling]

Side to side. When that piston is on the rod ready to be installed, can you move the piston any along the wrist pin to the L or R?

All pistons float on the wrist pin, just not normally this much. The crank centers the rod between the pin bosses.

 

[2000ssm6]

The Homelite Super 2100 uses spacers
from the factory and they had no problems.


Lee

Good point but Homelite nor Mac make saws worth a crap "anymore". I know they were great saws for their time era. Maybe it worked for them but why doesn't Stihl, Dolmar or husqvarna use these methods today? I just don't see any advantages.....