Piston skirt lubrication experiment

Fast Eddie · Mar 27, 2015

jseng1 said:
cjandme said:

Jim, is that weight reduction of 170 down from a 750 piston that started out at 185 grams? I looked back over the thread but it wasn't mentioned, I mean another 15 grams, it's quite amazing to me, great work there, that's for sure.

Click to expand...

The pistons in the photo are the first JE lightweight pistons for Nortons and started out at 190 grams. They had a little extra metal on the sides below the pin that you can see in the photo. After awhile I tore it down to check up on things. I milled off the sides and most importantly I undermilled the head and contoured around the valve pockets so the crown was a consistent thickness throughout and thats where I lost the most weight. I also taper-bored the pins and lost about 3-4 grams each there. The bike ran so incredibly smooth that I decided to market this stuff and the rest is history. There are hundreds of bikes on the street with these pistons now and I'm getting a lot of good feedback from them.

The pistons below are the very first lightweight Norton pistons - made from Wisco blanks from a GSXR suzuki over bore kit in the late 1980s. They went into an 850 and weighed less than 750 pistons.

Prior to going to the lightweight pistons I was breaking cranks and cases. All that stopped. I raced the monoshock Norton below against monoshock ducati's and did well - When I passed them in the turns they would re-pass me on the straights etc. I raced those pistons for a season, never tore it down and the bike always ran great.

Now I have a question for you CJ - do you have any personal experience with these pistons?

Jim, being the happy owner of a pair of your lightweight pistons, I have to ask this: if the holes are so beneficial, why don't they come that way as stock? Or at least why don't your offer it clearly as an option? I'm now feeling like I have inferior pistons !!

jseng1 · Mar 27, 2015

Fast Eddie said:
jseng1 said:

cjandme said:

Jim, is that weight reduction of 170 down from a 750 piston that started out at 185 grams? I looked back over the thread but it wasn't mentioned, I mean another 15 grams, it's quite amazing to me, great work there, that's for sure.

Click to expand...

The pistons in the photo are the first JE lightweight pistons for Nortons and started out at 190 grams. They had a little extra metal on the sides below the pin that you can see in the photo. After awhile I tore it down to check up on things. I milled off the sides and most importantly I undermilled the head and contoured around the valve pockets so the crown was a consistent thickness throughout and thats where I lost the most weight. I also taper-bored the pins and lost about 3-4 grams each there. The bike ran so incredibly smooth that I decided to market this stuff and the rest is history. There are hundreds of bikes on the street with these pistons now and I'm getting a lot of good feedback from them.

The pistons below are the very first lightweight Norton pistons - made from Wisco blanks from a GSXR suzuki over bore kit in the late 1980s. They went into an 850 and weighed less than 750 pistons.

Prior to going to the lightweight pistons I was breaking cranks and cases. All that stopped. I raced the monoshock Norton below against monoshock ducati's and did well - When I passed them in the turns they would re-pass me on the straights etc. I raced those pistons for a season, never tore it down and the bike always ran great.

Now I have a question for you CJ - do you have any personal experience with these pistons?

Click to expand...

Jim, being the happy owner of a pair of your lightweight pistons, I have to ask this: if the holes are so beneficial, why don't they come that way as stock? Or at least why don't your offer it clearly as an option? I'm now feeling like I have inferior pistons !!

As the header says. Its "experimental". I don't have any independent confirmation other than the cycle worldarticle at:
https://books.google.com/books?id=i...SK6ICgBQ&ved=0CB0Q6AEwADgK#v=onepage&q&f=true

I have only had one customer ask for drilled skirts. And simple as it seems it takes some time and layout and chamfering to do it right and that means adding some labor cost. I think its worth it and if for nothing else then at least for the lightening. But the truth is that many are put off by it - even if its beneficial.

Just as interesting and important (if it actually works) is the Federal Mogul 'hydroscopic" skirt modification mentioned by Hobot at:

http://www.federalmogul.com/en-US/Media/Documents/HighqualitySAEpaper200909PFL1163manuscript2.pdf

Look for AV 304 in the article.

If this reduces friction and wear then why hasn't anyone adapted it? The recess is shallow and supposedly helps to cause a hydroplane oil effect. An easy way to form the recess instead of machining would be to coat the pistons with a durable coating such as Calico coating or "hard tuff" from tiodize in the shape and depth on the skirt suggested by Federal Mogul.

If these things work then they are definitely worth doing and the industry seems to be missing it.

Fast Eddie · Mar 27, 2015

Jim, I wasn't talking about the global piston industry! I meant simply, why don't you offer it as a 'standard' option on your pistons on your otherwise good and clear web site. No holes = $X. With holes =$Y.

jseng1 · Mar 27, 2015

Fast Eddie said:
Jim, I wasn't talking about the global piston industry! I meant simply, why don't you offer it as a 'standard' option on your pistons on your otherwise good and clear web site. No holes = $X. With holes =$Y.

For about a year I offered ultralight pistons with these options - excess material removed including the skirt drilling. I only got one customer. After awhile you just decide to take it off the sight which is what I did.

Fast Eddie · Mar 27, 2015

jseng1 said:
Fast Eddie said:

Jim, I wasn't talking about the global piston industry! I meant simply, why don't you offer it as a 'standard' option on your pistons on your otherwise good and clear web site. No holes = $X. With holes =$Y.

Click to expand...

For about a year I offered ultralight pistons with these options - excess material removed including the skirt drilling. I only got one customer. After awhile you just decide to take it off the sight which is what I did.

Hmmm, I'm no marketing guru, but:

If you do publicise your wears... You MAY still not sell them.

If you do not publicise your wears... You will DEFINITELY not sell them!

Hobot · Mar 27, 2015

My take on the 304 pattern is no extra thickness coating needed unless already too loose a fit- then shallow feathered wide recesses that follow the radius of piston-bore so only a hand file needed to create oil holding-spreading texture. The article details the reasoning for 304's benefit over the other patterns and has everything to do with spreading oil not draining it off by allowing escape routes of grooves or holes from the oil pressured rub areas. If ya bored search up piston knurling or skirt texture for oil and friction and clearance control. Generally knurls avoided on load bearing sides as wears off fast but those remaining retain oil to spread. Can find reports of knurls wearing right out and hot rods getting 100,000 miles just fine. Only one way to know in Nortons and that takes risk takers to find out. Thank goodness our excessive risk taking Jimmy has stopped racing or would not of heard of any his hard wond secrets.

Piston skirt lubrication experiment

Fast Eddie

jseng1

Fast Eddie

jseng1

Fast Eddie

Hobot

Similar threads