Board index Flathead Power-Technical Questions, Answers, and Suggestions 45 Flatties stroker pistons

stroker pistons

Post Mon Feb 27, 2012 3:28 am

Posts: 2
I hear that the stroker pistons for sale are neither cam ground nor tapered. So, would it not be better to use std HD pistons and saw the bottom skirts down to clear the crankcase mouths ? Obviously you would have do a tidy job and make sure the pistons after shortening are both the same weight. Also, why is it necessary to provide an oil spray to the front thrust side of the front piston if the baffle has been cut out ? Surely a shallow routed cut in the piston face to retain oil would be ok - I believe +80 genuine HD pistons had such grooves as standard ? Would appreciate your comments on this. Thanks.

Post Mon Feb 27, 2012 10:30 am

Posts: 391
The advantage in stroker pistons is not in their skirt clearance (easy to change on stock pistons) but in their ability to use standard length cylinders without stroker plates. When using plates a whole new set of problems arises, from valve cover length, width of manifold, etc. And I believe that the newest T&O pistons are different than the originals and are now correctly made.

Post Tue Feb 28, 2012 3:48 pm

Posts: 2
many thanks. I understand the problems about valve cover length etc., so these stroker pistons are the best way to go. Pity because I planned the extra height given by the stroker plates would mean the inlet ports would be further apart thus making it easier to fit twin carbs. Never mind there must still be enough space to shoe horn 2 inlet ports in there if careful. What do you think about carefully using a mini router to provide a shallow groove on the skirt to retain oil and prevent any scraping of the thrust face of the piston skirt ? This would mean no necessity to provide an actual jet of oil.

Post Sun Mar 04, 2012 5:39 pm

Posts: 369
Location: Bergen, Norway
Not sure if stroker plates will move the cylinders apart enough to make it more convenient for dual carb intake, it will still be tight. But for sure will make all out of alignment as stated by RUBONE. Do a search on the board, are quite some examples of dual intakes. Frenchowl, Enigmas, Frankenstein and other members have over the years shown pictures of creative dual carb intakes.

I bought 45” stroker piston from T&O when they first released them some years back. I have no idea if they have changed the design later. Here is what I learned:
I set them up with 0.0021-0.0024inch clearance. Rear seized! Not dramatic, could restart bike immediately after, but enough for me to tear apart.
I talked to T&O and they informed they had learned the same and they experienced the piston grew more in size when hot compared to what they had expected/normal for this type of pistons. They now recommended a clearance of 0.0035 to 0.004 inch.
I re-honed the cylinders and set them up with 0.0035 Inch clearance. As a note, I have sleeved cylinders, skirt oilers and have had no problem since, but still not pushed the engine to its maximum as am still in brake in mode.
To the cam-ground pistons or lack of such, I looked through my notes, but could not find what I measured the T&O pistons to, but for sure I remember them having a slight cam. Remember they are much shorter and by that they will have less cam as the longer standard pistons.
To your question of an oil groove.
Not sure if you want to have the piston protrude below the cylinder skirt all the way down with minimum clearance to the flywheel, and by that collecting oil in a groove in the piston?
Not sure if it is a good idea to let the piston drop below the cylinder skirt. May have it wearing on the edge and introducing additional wear on the edge of the cylinder skirt.
Maybe I did not understand your question, a sketch would help.
Adding piston skirt oiler inside the cylinder was not such a big deal, all can be done by yourself if you have the time and patience. Descriptive instructions in Panics booklets.

Post Wed Mar 14, 2012 7:05 pm

Posts: 202
Location: Middle England UK
It's not just the skirt that's shorter on stroker pistons,the distance from wrist pin to crown is also less.
Using T&O flywheels,for the first two increases in stroke,I'm sure you don't need to remove the baffle.

Post Thu Mar 15, 2012 4:50 pm

Posts: 72
Location: South Australia
I'm building a stroker motor myself, I have 4 -7/16" stroke flywheels with T&O stroker pistons fitted , these pistons clear the baffle fine, and sat .055" below the deck height, i contacted T&O in regards to clearance between the piston and cylinder wall, as some folk were having seizing troubles , their recomendation was between .004 and .006"
" The more I learn the less I know"

Post Sun Mar 25, 2012 11:13 pm

Posts: 42
Location: seattle, washington
On the stroker pistons, are there different types made, i see these pitons advertized by victory and flatland are these the T&O pistons we are talking about or something else. What brand stroker piston would be best to use for a stroker engine ??

Post Mon Mar 26, 2012 6:13 am

Posts: 426
Location: Tucson Arizona

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