Breisch little brother air cooled

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myrickman

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Working on freshening up a Breisch little brother air cooled for a friend who purchased it and here is what I found when I took the piston out. Since then I bought 3/4” rings and plan to remake the piston. The owner has the prints and says they do not have rings shown on the piston...weird... Did they really spec it out without rings?
 

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Just 3 oil grooves on the drawing with no rings.
 
Working on freshening up a Breisch little brother air cooled for a friend who purchased it and here is what I found when I took the piston out. Since then I bought 3/4” rings and plan to remake the piston. The owner has the prints and says they do not have rings shown on the piston...weird... Did they really spec it out without rings?

Hi from British Columbia Canada...
Would you be interested in contacting me to discuss my upcoming build of the Lil Brother air cooled?
Much appreciated...Carson
 
Don’t know how much I can tell you as I do not have the plans, just the completed engine. But it appears fairly straightforward. Lots of tiny parts though...but ask away.
 
I also have a Lil Brother air cooled. I can confirm that the Lil' Brother has three 1/16" wide grooves on it and no rings.

Jo
 
If you're going to use rings make sure the bore is exactly .750 or the compression won't be good at all.
 
Lodalodge, Huh!
 
I ran a Sunnen precision hone through the bore since it was tapered and egg-shaped and was able to true it up nicely. Plan is to re-make the piston per the print with revised diameter to assure fit and no rings.
 
Update: made a new piston with a half a mil clearance and the three grooves like the print and got it running straight away. Problem now is a bit of erratic running with low fuel in the tank so plan is to raise the fuel tank a bit and have a look at the check valve seating.
 
Update: made a new piston with a half a mil clearance and the three grooves like the print and got it running straight away. Problem now is a bit of erratic running with low fuel in the tank so plan is to raise the fuel tank a bit and have a look at the check valve seating.
Glad to hear you have it running, I have chosen to make the piston with .001 clearance and use two rings. My thinking being that has to provide better compression than oil grooves but I am no expert and have been wrong many times before. Am about 1/2 way through the build so time will tell. Anyway aluminum is cheap so if I need to make another piston with oil grooves, no biggie.
 
have both uprigh little brother and air cooled both partly machined by louis pilch I finished with o ring on piston also used spray bar they run great plenty of compresion
 
have both uprigh little brother and air cooled both partly machined by louis pilch I finished with o ring on piston also used spray bar they run great plenty of compresion
I have built both the horizontal and vertical Domestic engines which of course, use rings so I am cautiously optimistic.. Question....what is spray bar?
 
Raised the fuel tank a bit and it certainly helped it running for longer periods. Tank is set up so when fuel is at 2/3 capacity the level is even with the adjustment screw on the mixer. Funny thing...when I let my friend know I got it running he said he had the water-cooiled cooled version also and wanted me to check this one over. The water-cooled version needed a check valve in the fuel line in the tank which I made. the water-cooled also has the ringless piston and has great compression.
 

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