HeadSmess
Well-Known Member
- Local time
- 10:20 PM
- Joined
- May 17, 2010
- Messages
- 3,048
it finally happened, a year of abuse, and the last week has been a rather strange rattling noise. she finally seized on me!
was it my 50:1 oil ratio?
no.
was it revving the poor lil thing to 8000+?
mmm, possibly. though no sign of ring flutter or any other type of damage everyone will tell you will happen if you do such things.
just the same old same old for me ...the stupid ring locating pin let go! i seriously hate it when they do that! i dare say it happened a week ago, due to the sudden loss of power and subsequent rattling noises, but the final straw must have been the circlip for the gudgeon pin snapping off today. bores a mess! pistons even worse! and i didnt even port this one this time! never even opened it! phooey!
everything else? perfect no shattered big end bearings, no play in anything other than whats normally there.
i blame it on my exhaust pipe :smug2:
was my bore, other than the dirty big gouges in it, worn at all?
no. surprising. someone on this site is adamant that running anything less than 25:1 causes excessive bore wear. ill stick with my preferred ratio, thankyou very much
i can now say a stock standard 48cc will take over a year of (almost) daily abuse at 50:1, revving its head off, only failing due to an inherent weakness... offset ring locating pins.
from jennings two stroke tuning guide...
"the “offset” ring-locating pin may prove prone to precisely the sort of loosening
and subsequent failure described in the preceding paragraph, which will lead you into a
piston modification that can be very tricky: installing a new locating pin in the back of
the ring groove. This gets tricky because in many cases the pin will be half-in, half
above, the ring groove and it is impossible to drill the hole for a new location after the
groove is machined. Impossible, unless you cut a small piece of aluminum to exactly fit
the ring groove, filling it flush, in which case you drill your hole half in the piston and
half in the filler piece. Then you remove the filler and your hole is ready for the pin -
which introduces yet another problem: what to use for a pin? Steel wire is a good choice
on grounds of strength, but is likely to work loose simply because the aluminum in which
it is pressed grows and contracts so much with changes in temperature. A small-diameter
“split pin” (which is like a rolled tube) is a better choice, but if suitable sizes are not
available, then a pin made of hard brass is at least as good."
i think im going to have to have a go at this, not relocate the pin itself, but simply replace the pin with something else... i call them "roll pins", also known as "spring pins"...a split pin, as ive always been aware, is the lil doodad you poke through a castellated nut, such as on the wheel bearings of cars. "roll pin" is far more apt, as the things are rolled! at least, its what i was told they were called back in the day.
while i like the idea of "A" in the diagram... it holds the pin in the hole... it would also require new rings of a type that dont actually exist.
sorry about the lousy pics. just threw my digi at the ground because it refused to take a pic at all when it did finally decide to turn on! not that it was much better than the phone cam anyways! why do i have such issues with cameras? gimme a good old SLR any day... grrrrr. at least they worked!
time to go clean the ports up in my new replacement cylinder finally use my dentist drills!
was it my 50:1 oil ratio?
no.
was it revving the poor lil thing to 8000+?
mmm, possibly. though no sign of ring flutter or any other type of damage everyone will tell you will happen if you do such things.
just the same old same old for me ...the stupid ring locating pin let go! i seriously hate it when they do that! i dare say it happened a week ago, due to the sudden loss of power and subsequent rattling noises, but the final straw must have been the circlip for the gudgeon pin snapping off today. bores a mess! pistons even worse! and i didnt even port this one this time! never even opened it! phooey!
everything else? perfect no shattered big end bearings, no play in anything other than whats normally there.
i blame it on my exhaust pipe :smug2:
was my bore, other than the dirty big gouges in it, worn at all?
no. surprising. someone on this site is adamant that running anything less than 25:1 causes excessive bore wear. ill stick with my preferred ratio, thankyou very much
i can now say a stock standard 48cc will take over a year of (almost) daily abuse at 50:1, revving its head off, only failing due to an inherent weakness... offset ring locating pins.
from jennings two stroke tuning guide...
"the “offset” ring-locating pin may prove prone to precisely the sort of loosening
and subsequent failure described in the preceding paragraph, which will lead you into a
piston modification that can be very tricky: installing a new locating pin in the back of
the ring groove. This gets tricky because in many cases the pin will be half-in, half
above, the ring groove and it is impossible to drill the hole for a new location after the
groove is machined. Impossible, unless you cut a small piece of aluminum to exactly fit
the ring groove, filling it flush, in which case you drill your hole half in the piston and
half in the filler piece. Then you remove the filler and your hole is ready for the pin -
which introduces yet another problem: what to use for a pin? Steel wire is a good choice
on grounds of strength, but is likely to work loose simply because the aluminum in which
it is pressed grows and contracts so much with changes in temperature. A small-diameter
“split pin” (which is like a rolled tube) is a better choice, but if suitable sizes are not
available, then a pin made of hard brass is at least as good."
i think im going to have to have a go at this, not relocate the pin itself, but simply replace the pin with something else... i call them "roll pins", also known as "spring pins"...a split pin, as ive always been aware, is the lil doodad you poke through a castellated nut, such as on the wheel bearings of cars. "roll pin" is far more apt, as the things are rolled! at least, its what i was told they were called back in the day.
while i like the idea of "A" in the diagram... it holds the pin in the hole... it would also require new rings of a type that dont actually exist.
sorry about the lousy pics. just threw my digi at the ground because it refused to take a pic at all when it did finally decide to turn on! not that it was much better than the phone cam anyways! why do i have such issues with cameras? gimme a good old SLR any day... grrrrr. at least they worked!
time to go clean the ports up in my new replacement cylinder finally use my dentist drills!