Topic: Plating pistons to save a bore job.

[754]

There us a process I heard of on CycleDrag,  U.S. Coatings is the name of the place, they have 4 facilities in the USA. They claim good results on I think pro mod cars.
 They build up the piston up to several thousands with a good coating process, then you hone your bores and refit them. 36 bucks per piston.
 Anyone tried this. I wonder if they mask ring grooves and pins. They also do top coatings.
 Pretty interesting.

[754]

Sorry, I meant this for Hi Performance section..

[KayOne]

Hi Frank, I’ve had Piston skirts from my SBF coated to get more life out of the bore and piston. Works very well. A supposed benefit is less piston drag and wear on the bore. I’ve also thermal coated the top of the pistons but truly can’t say if there is any benefit. Yes they do mask off the lands somehow. There is a good coating shop in Calgary, couriered my pistons there and had them back the next week.

[gschuld]

Swaintech does a PC9 skirt coating.  They can go thicker if desired.  Mike Rieck has used them with success for the same purposes you are asking about.

George

[754]

Thanks for the info, nice to know we have one that close.  I probably have a few bigbires I can bring back for cheap.

[PeWe]

How much will the coating build up?
Total bore/ piston clearance.

[gtmdriver]

I wouldn't think that the process would be successful if there was any ovality in the bores though.

[PeWe]

Bores can be honed to correct shape which will need thicker pistons were a coating can do it right.
I guess this is rhe way this is done, right?

[754]

I am thinking they go a bit oversize,  then you hone and fit to piston.

[PeWe]

I have heard about pressing a forged piston over the wrist pin sides and let it swell so the skirts fill the bore better. A friend of mine heard that from an experienced mechanic as the last trick to get more life out from the pistons and their bores.

My friend had a cylinder where one of the forged pistons had sloppier fitment. Piston into a vice and press some. That helped!
He had a wristpin in just for sure to ensure how the piston change when deforming it.

[wwsummersjr]

What about ring gaps after honing cylinders to fit piston skirts?

[Steve_K]

When I was working in a bike shop, the shop owner knurled the pistons for a British twin.  The bike owner did not have the cash for a full rebuild, so the owner did that.  Back then, I think a rebuild cost $700 to $800 for that.   Remember, Brit bikes needed to be rebuilt after 10.000 miles.
I don't know how well I worked, but the shop owner was a very good tuner for BSA twins for dirt track.
Steve

[PeWe]

I have not heard that so I searched.  There are som pics of knurled pistons.

https://www.google.com/search?q=knurled+piston&client=ms-unknown&prmd=isvn&sxsrf=ACYBGNT1aYiBwtiTVo8ovWM-xJ3TSdfdLw:1578204562264&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjGy8OS5uvmAhXKo4sKHfpBCTsQ_AUoAXoECA0QAQ&biw=355&bih=620

[Terry in Australia]

I bought an antique piston knurler on Ebay many years ago, my cousin (vintage car and bike mechanic) told me all about it, it was a common procedure back in the Great Depression, when people had no money for rebuilds. I actually tried it on some CB750 836cc pistons to get rid of a "piston slap" issue using a standard knurling tool in my lathe, and it worked fine.

[PeWe]

More piston coating
https://www.line2linecoatings.com/slickCC.html
They have several products for pistons

It would be nice with a product that can be applied on pistons and baked in oven when wife is away
My oven can be set to max 300°C  (570°F ).

[MRieck]

I have not heard that so I searched.  There are som pics of knurled pistons.

https://www.google.com/search?q=knurled+piston&client=ms-unknown&prmd=isvn&sxsrf=ACYBGNT1aYiBwtiTVo8ovWM-xJ3TSdfdLw:1578204562264&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjGy8OS5uvmAhXKo4sKHfpBCTsQ_AUoAXoECA0QAQ&biw=355&bih=620

If the piston taper has been worn out I can't see how knurling would bring it back. I can see it expanding the OD a bit but not reestablishing taper.

[PeWe]

I have not heard that so I searched.  There are som pics of knurled pistons.

https://www.google.com/search?q=knurled+piston&client=ms-unknown&prmd=isvn&sxsrf=ACYBGNT1aYiBwtiTVo8ovWM-xJ3TSdfdLw:1578204562264&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjGy8OS5uvmAhXKo4sKHfpBCTsQ_AUoAXoECA0QAQ&biw=355&bih=620

If the piston taper has been worn out I can't see how knurling would bring it back. I can see it expanding the OD a bit but not reestablishing taper.

New for me,  seems to  have been done for years.
It might reduce rattling pistons due to skirt bore clearance.

[Terry in Australia]

Exactly, it wasn't a permanent fix, it was just done to get a few more miles out of a tired engine. Expanding pistons, on the other hand was a common fix for 2 strokes that would regularly "nip up" if the ridden mercilessly, or with poor quality 2 stroke oil.

[PeWe]

Another coating provider
https://techlinecoatings.com/tech-line-coatings/hi-performance-coatings/internal-engine-coatings/

This might be something for sloppy bores.

TLMB POLYPHEN BASE BUILD-UP COATING

High load durable thin film lubricant.

Primarily used to build up piston skirts.

Used in very high RPM engines or where very long rods are run.

Top coat with either TLML or PKSX.
Solvent based, cleanup with Acetone or similar.

Requires oven curing at 300°F for 1 hour.

Part #TLMB available in Quart & Gallon. For professional applicators only.

I have not verified "professional applicators".
Spray gear or workshop?

Would be perfect if available on rattle cans.

The juicy ribs will taste different  shortly after a piston job
Extra spicy rub needed....
Women in general do not like engine parts in oven.
New roller bearing in the freezer OK.

[johno]

Like your style and Love your humour PeWe