Classic British SparesKlempf British PartsBaxter CycleBritBike Sponsor SteadfastCyclesSRM EngineeringLucas Classic MotorcycleHepolite PistonsIndustrial tec supply

Upgrade your membership to: Premium Membership | Gold Membership | Life Membership | Vendor Membership | Site Sponsor Membership
Welcome to BritBike Forum!
Britbike forum logo
Member Spotlight
Al Eckstadt
Al Eckstadt
Jordan, NY
Posts: 1,677
Joined: August 2001
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Previous Thread
Next Thread
Print Thread
#523263 01/16/14 11:34 am
Joined: Sep 2007
Posts: 179
Likes: 2
T
Britbike forum member
OP Offline
Britbike forum member
T
Joined: Sep 2007
Posts: 179
Likes: 2
Hi,
Is it an acceptable process to Anodize Piston Skirts to take up excessive clearance. The engine in question is an Iron Head 1947 Tiger 100. Using modern Harris Pistons I am just over 7.5 thou clearance and want to ideally be at around 5 or so. I have been quoted $125 for Anodizing the pair. Is this even worth it, I am worried about noise pistons on start up.
Thanks...

Last edited by tonupjonnie; 01/16/14 11:35 am.
Support Your #1 BritBike Forum!

Check out British motorcycles for sale: British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America
Joined: May 2013
Posts: 8,018
Likes: 148
A
Britbike forum member
Offline
Britbike forum member
A
Joined: May 2013
Posts: 8,018
Likes: 148
how much clearance are we talking? and how much is there now? If your talking 1-2 thou over then I wouldn't bother.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Joined: Jun 2007
Posts: 6,923
Likes: 17
H
Britbike forum member
Offline
Britbike forum member
H
Joined: Jun 2007
Posts: 6,923
Likes: 17
At 7.5 clearance, you're likely to have some piston slap when cold. It will likely go away when warmed up. I would consider teflon buttons before anodizing, myself. I've never used them, by the way, but on an expensive rebuild already and trying to save money while at the same time wanting a quiet civilized engine, that seems the best option.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Joined: Feb 2011
Posts: 3,592
Likes: 45
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2011
Posts: 3,592
Likes: 45
I've used teflon buttons in place of wrist pin keepers but not on the skirt surface. How would that work?


Bill B....


Boomer
Joined: Jun 2007
Posts: 6,923
Likes: 17
H
Britbike forum member
Offline
Britbike forum member
H
Joined: Jun 2007
Posts: 6,923
Likes: 17
Here's a discussion about it on a dragbike forum.
http://www.dragbike.com/forum/showthread.php?61043-Piston-skirt-buttons.
Generally, from what I gather, the buttons are used routinely at the wrist pin, and on the skirts to keep the rings perpendicular to the cylinder wall for better sealing. The additional benefit is that there is less piston slap which, admittedly, is superfluous in a drag bike.
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Joined: Jul 2010
Posts: 256
K
Britbike forum member
Offline
Britbike forum member
K
Joined: Jul 2010
Posts: 256
so where do you get these Teflon buttons and how do you fix them

Joined: Aug 2013
Posts: 492
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Aug 2013
Posts: 492
Superglue them to the skirt?

Joined: Sep 2007
Posts: 199
7
Britbike forum member
Offline
Britbike forum member
7
Joined: Sep 2007
Posts: 199
Anodizing is not exactly the right process for this application ( my opinion ). Take a look at this website : www.swaintech.com. They do all sorts of engine coatings. Cams, valves, pistons, lifter, gears , etc. They claim to be able to build-up a worn surface & the racers/companies they do work for is the who's who of racing. I've used them & like their work.

Joined: Sep 2013
Posts: 3,117
Likes: 101
Q
Britbike forum member
Offline
Britbike forum member
Q
Joined: Sep 2013
Posts: 3,117
Likes: 101


Why not over-bore and fit correct pistons ?
Are the cylinders already maxed out ?
Whats the rest of the story ?

Adding something as hard as anodized aluminum
And sliding it up against a 66 year old cast iron head
just to tighen clearances
May have unintended consequences

Would the anodizing stop short of the oil ring groove ?


Joined: Feb 2008
Posts: 5,630
Likes: 243
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2008
Posts: 5,630
Likes: 243
Not sure where you get them but they are used instead of gudgeon (wrist) pin circlips.
The button has a larger diameter on the outside which slides up and down the cylinder bore with the piston.
It also has a smaller diameter which sits in the wrist pin hole in the piston and stops the wrist pin from moving in either direction and touching the cylinder bore.
Was fitted as standard in some pistons in the 1970s--may still be for all I know. Particularly racing pistons.
The theory is that the buttons avoid circlips coming out and damaging the bore etc (they can't as there aren't any if you are using buttons) and also they are supposed to reduce friction by keeping the piston more upright, reducing ring and skirt friction.
At least that was the theory (proven in practice) when I started work in industry at the AE Group Development center in UK (AE Group included Hepworth and Grandage who made Hepolite pistons).
HTH

Last edited by Tridentman; 01/16/14 9:47 pm.
Joined: Jan 2004
Posts: 5,023
Likes: 84
D
Britbike forum member
Offline
Britbike forum member
D
Joined: Jan 2004
Posts: 5,023
Likes: 84
Let's see, 0.003" clearance over 2.5" piston height = 0.06875 degrees tilt in the bore. Probably not significant.
Anodized can be stopped out where it is not needed but first check to see if the alloy will work with anodizing, not all will.
Teflon wrist pin buttons will not change the fore/aft slop although shirt buttons will. Custom machining less than a bore and pistons?
Teflon buttons are also known to embed metal particles and act as a file on the cylinder bore.

Joined: Jul 2009
Posts: 232
E
Britbike forum member
Offline
Britbike forum member
E
Joined: Jul 2009
Posts: 232
In a similar situation (small car engine, though--not a bike), my machinist knurled the piston skirts and then machined them to the desired clearance.




For just a little more, you can do it yourself!
Joined: Feb 2011
Posts: 3,592
Likes: 45
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2011
Posts: 3,592
Likes: 45
This is what I used on my second rebuild of my first race engine for Vintage Racing in the 80's. It was wanting to push the piston pin circlip retainer out to the point of mushrooming the edge of the piston pin boss. The rod was centered in the bore and the crank was running true so this was the fix. Lasted 3 or 4 races until I built a new engine. Pretty late engine number.


[Linked Image]


Boomer
Joined: Sep 2013
Posts: 3,117
Likes: 101
Q
Britbike forum member
Offline
Britbike forum member
Q
Joined: Sep 2013
Posts: 3,117
Likes: 101
More on swaintech ,

http://swaintech.com/race-coatings/race-coating-descriptions/piston-skirts/

... PC-9™ has the same low friction properties ...PC-9™ is commonly used to salvage a motor that has excessive piston to wall clearance. Vintage motors and other applications with hard to find pistons can have up to .004” of PC-9™ added to the diameter of a piston to tighten piston to wall clearance.

.

Joined: Sep 2007
Posts: 179
Likes: 2
T
Britbike forum member
OP Offline
Britbike forum member
T
Joined: Sep 2007
Posts: 179
Likes: 2
Thanks for all the input on this topic. Think I am going to send them to Swaintech. These internal drain T100 Cylinders are not too common nowadays. .060 is as far as I want to go as far as reboring and the .060 Pistons I purchased are new from the UK. After the Cylinder walls were honed clean and straight the clearance was a bit on the large side. With this PC-9 process I can get it down to a more preferred .005 clearance.
Thanks all.

Last edited by tonupjonnie; 01/18/14 1:06 pm.
Joined: Sep 2011
Posts: 1,070
Likes: 3
Britbike forum member
Offline
Britbike forum member
Joined: Sep 2011
Posts: 1,070
Likes: 3
In a situation where you are getting the piston pin thrusting the circlip toward the cylinder wall it would be worth checking the bore is dead true perpendicular to the crank axis.
Morgo had a spate of barrels bored off-true when I building my vintage pre unit T120 racebike in the early 90's. Hopefully they've fixed that by now whistle

Boomer, I hope you kicked butt in some of them races.. mad

Joined: Oct 2012
Posts: 5,784
Likes: 130
knuckle head
Offline
knuckle head
Joined: Oct 2012
Posts: 5,784
Likes: 130
Coating the piston skirts is interesting....The coating might effect the rate of heat the piston skirt transfers to the cylinder wall ? Just being picky...


79 T140D, 96 900M Ducati ,61 A10 .On a bike you can out run the demons.."I don't know what the world may need
But a V8 engine is a good start for me
Think I'll drive to find a place, to be surly"
Joined: Nov 2006
Posts: 267
Likes: 4
R
Britbike forum member
Offline
Britbike forum member
R
Joined: Nov 2006
Posts: 267
Likes: 4
I had a 1958 matchless g-12 with knurled pistons, ran bike hard for 3 years without any problem. Used steen c oil and bike was very fast.

Joined: Apr 2002
Posts: 710
N
Britbike forum member
Offline
Britbike forum member
N
Joined: Apr 2002
Posts: 710
Knurling should be fine for a putt-putt like that —cheap and simple.


When people who should have known better cautioned me about the dangers of motorcycle racing, I always told them that a fear of death is nothing more than a fear of life in disguise.
Joined: Feb 2011
Posts: 3,592
Likes: 45
Britbike forum member
Offline
Britbike forum member
Joined: Feb 2011
Posts: 3,592
Likes: 45
Originally Posted by Excalibur
In a situation where you are getting the piston pin thrusting the circlip toward the cylinder wall it would be worth checking the bore is dead true perpendicular to the crank axis.
Morgo had a spate of barrels bored off-true when I building my vintage pre unit T120 racebike in the early 90's. Hopefully they've fixed that by now whistle

Boomer, I hope you kicked butt in some of them races.. mad



Check out my January entry in the Monthly Photo Contest to see a picture of myself and that engine in action. beerchug


Bill B....


Boomer
Joined: Dec 2010
Posts: 494
Britbike forum member
Offline
Britbike forum member
Joined: Dec 2010
Posts: 494
Isn't anodizing actually aluminum oxide? If so, that is an abrasive. Not sure it is the right thing to use as a coating.

Regards,
Rob


Moderated by  John Healy 

Link Copied to Clipboard
Job CycleBritish Cycle SupplyMorries PlaceKlempf British PartsPodtronicVintage MagazineBSA Unit SinglesBritBike SponsorBritish Tools & FastenersBritBike SponsorBritBike Sponsor






© 1996-2021 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5