Piston design - Aftermarket tweaks, why?

[_Iain_]

Rebuilding my CR engine over the weekend has got me questioning what the little differences are for!

Piston comparison - Old vs new Wiseco;

https://i.imgur.com/XszxlH3.jpg

https://i.imgur.com/fCHupyL.jpg

https://i.imgur.com/csBxgRb.jpg

https://i.imgur.com/edVK25E.jpg

Obviously Wiseco know what they're on about, but unsure what each bits actually there for, or what the benifits are?
____________________
Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340

[CaNsA]

One looks forged, the other looks milled.

Different material has different strengths, and with modern day computer wizardy it is easy to produce a more efficient and stronger piston.

[_Iain_]

Mhmm, but the new piston has two holes drilled in the back of it, a raised circle on the crown, and a single hole leading to the gudgeon pin rather than two either side of it - whats all this about?

I mean the actual shape of the crown should be the same across both I'd have thought?
____________________
Please be aware that the above post may be full of complete nonsense.
Riding: '07 KTM Duke II, Baotian BT49QT-20 Driving: '88 Volvo 340

[CaNsA]

maybe the raised bit increases compression slightly, enables the fuel to be dispersed equally and a more efficient process of how the exhaust gas escapes.

Email them innit bruv, it would be interesting to read that they say.

[The Artist]

[Hugh Farking Cant]

Research and development, Iain.
Advances in CNC tooling have supercededed many forging processes re. cost and accuracy.

The 2 gudgeon pin oilways may have proved to be unneccessary or a weak spot.

The rear drillings aid cooling and mixture dispersal.

The crown may have suffered from failure or poor flame dispersal in the previous model.

Ideas and proven modifications may have been introduced from more recent products to enhance the original.

[MarJay]

One is machined which costs a lot of money to do, the other is cast which can be done in massive batches. The aftermarket one is undoubtedly better quality.
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[MaybeGuy]

The two holes are to allow crank case fuel/oil to lubricate the exhaust port bridge to help stop the rings biting into it and seizing it. (note how they're right where the wear patch is on the old piston).

Also, one's cast, the other is forged. The raised bit is most likely a bit of extra material for combustion, as that's the part where a lean running engine will eat a hole in the top of the piston.

Also, CaNsA, change your avatar. I almost thought it was stinkwheel saying retarded "lol idunno" shit.
____________________
Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Ariel Badger]

Bang on Matt.
____________________
Bikers make great organ donors, get 115 on your licence today.

[_Iain_]

[sickpup]

[Fizzer Thou]

I have a Wiseco oversize piston for my XR400R waiting in my spares cupboard waiting for the right time to be installed.The quality of this forged piston is far superior to that of the standard Honda cast piston.From what I have been told by others who have fitted these pistons to XR400s in the past,they are slightly lighter than standard so as to put less stress on the standard con-rod

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Workshop/CIMG2949.jpg

As has been said.Make sure that the information is supplied to whoever is boring the cylinder and that it is honed to the correct clearance
____________________
Just talk bikes.What else is there?

Always have a 'Plan B'

[Ariel Badger]

[The Artist]

[Fizzer Thou]

They are both Wiseco pistons,but the one on the left is for my XR400R and the other is for a Honda XR250R.The picture was only used to show the comparison between Iain's 2 stroke and my 4 stroke pistons

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Workshop/CIMG2950.jpg

But you can see the differance between crown heights in the above pic,which I could not find earlier
____________________
Just talk bikes.What else is there?

Always have a 'Plan B'