Looking for a 49mm piston with 12mm wrist pin

[Yotaismygame]

I need a 49mm piston with longer skirts for a shindaiwa 695 project. Overall height of the stock piston is 49mm. Center of wrist pin to top of crown is 21mm. Outside of wrist bin boss to boss is 47mm. crank measures 15mm. There's plenty of room above the piston so a larger pin to crown height would be ideal. Could do some machine work if needed.

Any ideas?

 

[huskihl]

Only one I know of. Not sure if they measure compression height from the top or center of the pin. D Dave has one in his eBay store. http://www.ebay.com/itm/222854409308

 

[Ronie]

Ereplacementparts says the can special order one.

 

[Yotaismygame]

I’m not looking for a stock replacement. I have a stock piston. Looking for a better than stock piston

 

[Yotaismygame]

Only one I know of. Not sure if they measure compression height from the top or center of the pin. D Dave has one in his eBay store. http://www.ebay.com/itm/222854409308


View attachment 724784

That seems close but it says overall height is only 38mm. So it’s shorter by quite a bit

Edit: am I reading that right? Or is length strictly the length of the skirt? So total length is 57mm??

 

[Yotaismygame]

How about the poulan 3750 piston? I don't see there specs on meteors website but it looks promising.

 

[Yotaismygame]

I measured a 266 piston I have here and the measurements meteor gives is center of wrist pin to top of crown and overall height. I also miss typed the overall height of the 695 piston. It’s 39mm not 49mm

 

[Yotaismygame]

I think a turned down 372 piston is my answer. Its 1.5mm taller pin to crown, and overall about 2.5mm taller. I put it on the saw and it clears the crank.

 

[Yotaismygame]

 

[huskihl]

That seems close but it says overall height is only 38mm. So it’s shorter by quite a bit

Edit: am I reading that right? Or is length strictly the length of the skirt? So total length is 57mm??

No that would be the total length I believe

 

[Yotaismygame]

If my machinest can make a 372 piston 49mm I think it will be perfect. It has more crown height and longer skirts. Which is everything I need.

 

[CausticUC]

If my machinest can make a 372 piston 49mm I think it will be perfect. It has more crown height and longer skirts. Which is everything I need.

However you would be going to a single ring based on your image, unless your machinist has a ring groove cutter.

 

[Yotaismygame]

One ring two rings heck even three rings... doesn’t make a difference. Probably end up using a OEM 372 piston I have laying around anyways, then I can use some 49mmx 1.2mm caber rings I already have

 

[CausticUC]

Affects compression and thermodynamics, however that may not make a difference in your application.

In most smaller engines it usually only seems to affect long term reliability. I have only ever broken rings on single ring pistons.

 

[Yotaismygame]

Won’t make a difference period. It’s a non issue. 372 pistons come in both single and dual rings. Most prefer the single.

 

[cus_deluxe]

Youll have to have your guy cut ring lands to no? If your reducing piston diameter, youll be reducing ring land thickness, which will have to be accounted for

 

[Yotaismygame]

Youll have to have your guy cut ring lands to no? If your reducing piston diameter, youll be reducing ring land thickness, which will have to be accounted for

Yessir.

I actually dropped it off about an hour ago. Owner said he thought they could do it.

 

[cus_deluxe]

Good times!

 

[wcorey]

The problem I've had altering ring grooves is getting the pin out.
Last one I did I just ground the pin flush to the top of the groove and put another in a different location after machining.
On another I cut a little groove underneath across the pin and pried it out with a screwdriver.
I don't always quite trust reinstalled pins though...