stroker cylinders

[panfreak]

Good morning,
I am replacing the cylinders on a 4-3/4" stroke shovel and have come across something I haven't had to do before: plug or fill the drain hole into the cylinder. The old cylinders look like they've been plugged with brass, could've been brazed I don't know. The internet has very little info I could find on this, but one discussion said to machine a brass plug to press fit, insert and hone barrel to finish. I could do this, but my concern is what if during heat/expansion the plug worked it's way out and scored the piston? The pro to this method would be the ease in which I could still leave the drain into the case open, if I were to attempt brazing I'm pretty sure I'd fuck that up and have to drill... sounds sketchy to me.

Am I overthinking the brass plug, would a press fit stay in place?

Thank you for any advice, I've done a fair amount of engine work but have not built a stroker that required this plugging of the drain before.

[RUBONE]

The best way to do it is to push a thinwall aluminum or brass sleeve into the drain hole blocking off the cylinder drain. No need to put anything in the cylinder wall, the rings don't come down that far even on 4-3/4. Be sure to drill a new drain further down to allow the oil out.

[panfreak]

Thanks! I re-read the earlier thread that I had found and now see that the person who posted meant exactly what you're saying. This makes sense and is a really simple alternative to welding up the hole as I see has been done to the old cylinders.

Last question:
I see that the oil rings will JUST be passing over the hole at the bottom of the stroke. If its open (by using the method you've described) do you foresee any issue?

It's times like this I really value the forum, it's so helpful having the ability to discuss with others. Can you imagine bringing this up around the coffee table at work? All I'd hear is crickets.

[Mongrel505558]

Thanks! I re-read the earlier thread that I had found and now see that the person who posted meant exactly what you're saying. This makes sense and is a really simple alternative to welding up the hole as I see has been done to the old cylinders.

Last question:
I see that the oil rings will JUST be passing over the hole at the bottom of the stroke. If its open (by using the method you've described) do you foresee any issue?

It's times like this I really value the forum, it's so helpful having the ability to discuss with others. Can you imagine bringing this up around the coffee table at work? All I'd hear is crickets.

If you have the tube pressed in then the hole is not open. No new oil there. That's the whole reason for the tube.

I just had that done to a pair of cylinders. It's pretty common. I have two strokers and both have jugs set up that way. But you're right in that very few people outside of the old bike crowd would have any idea of what you're talking about.

[RooDog]

Most are surprised that Harleys had fully rollerized motors as far back as 1936, maybe longer, but that knowledge is beyond me....
....RooDog....

[kitabel]

I remember a stroker using a section cut from a pushrod to seal the drain, just push it up into the hole.

Full rollers: big twin OHV 1936, UL 1937, 45 1937
Before that, the drive side (sprocket shaft) was roller, but the timing side (pinion) was a bronze bushing.