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#Post#: 77317--------------------------------------------------
Re: pioneer 650
By: HolmenTree Date: May 9, 2017, 5:50 pm
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By looking at the 25 cent price on the front cover of that parts
manual I would think it's from the mid to late 1960's.
So I'm thinking by 1976 the 650 probably had a modern 2 or 3
piece crank without the bolt on caps on the lower con rod
bearing.
But my brothers Mac 101 kart saws have rod caps (I'm positive if
my memory is correct) and with a little weight balance welded to
the crank those Macs screamed past 16K. ;D
#Post#: 77365--------------------------------------------------
Re: pioneer 650
By: 1manband Date: May 13, 2017, 6:41 pm
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piston so far.
2.246, while the bore looks to be 2.252.
no luck sourcing a new one yet. if i cannot find a new one
going to send this one out for some work.
#Post#: 77366--------------------------------------------------
Re: pioneer 650
By: 1manband Date: May 13, 2017, 6:49 pm
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port mapped the jug and measured the con rod.
piston needle bearing is shot. believe it is a timken brand
bearing, but cannot find my magnifying glass to read the numbers
on it.
cannot remember what this king of bearing is called, but think
it is a high load/low speed type? hope it easy to find at a
bearing supply house.
#Post#: 77411--------------------------------------------------
Re: pioneer 650
By: 1manband Date: May 17, 2017, 6:34 pm
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no progress in the last few days. working some long hours.
my plans for the piston will most likely ruin it before it goes
up and down at all. hahaha.
side note: put a pair of rusty calipers (no dial) into the
vinegar jug....forgot about them. parts on them dissolved.
poof.
#Post#: 77413--------------------------------------------------
Re: pioneer 650
By: HolmenTree Date: May 18, 2017, 7:58 am
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1manband, any potential in the 650 being a race saw? ;)
#Post#: 77419--------------------------------------------------
Re: pioneer 650
By: 1manband Date: May 18, 2017, 7:38 pm
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[quote author=HolmenTree link=topic=6436.msg77413#msg77413
date=1495112314]
1manband, any potential in the 650 being a race saw? ;)
[/quote]
...do not know. also do not know what you consider fast/race
worthy.
if you throw enough money and time at something, sometimes it
works out. everything is fast for the first 2 weeks. that is
not my plan. will toss some money into it though.
baby steps for me. have to put the stock measurements into the
lotto machine to be able to first compare it to a more modern
saw of similar motor size. will concentrate my $ and efforts on
the piston to get it into shape. if luck is with me and it
works, will hopefully lead me to some options.
just thoughts on the following, i am not a chainsaw guy so take
it all with a grain of salt. some things that might not allow
going crazy with this motor: iron sleeve, don't think a large
overbore is possible to run anything but a custom piston.
re-sleeving maybe an option, but the aluminum around the liner
kind of thin. maybe nik plating would do it. piston is the
first hurdle. over bore would also diminish the size of the
transfer ports because they breath off the base. big end crank
has a split cage bearing...maybe one piece crank could replace
to run some kind of off the shelf piston. con rod little end has
a big hole, piston options again are issue because so far cannot
find a bearing that can neck down enough to run a more common
size pin.
again, maybe all these things can be overcome easily with
something i'm not seeing. thinking so far that there must be
better platforms to start from.
i'm digging this saw. just making it mine. hahaha. fun.
#Post#: 77420--------------------------------------------------
Re: pioneer 650
By: HolmenTree Date: May 18, 2017, 9:27 pm
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Always thought you were a saw guy.
The 650 has alot of similarities to a 105cc Stihl 090 . Same 40
mm stroke . Cast iron liner like on my YZ125 can be oversized
many times.
Whether you want it for a firewooder or a tuned pipe power
bucker in a hot saw race. It has good ergonomic potential for
both.
#Post#: 77435--------------------------------------------------
Re: pioneer 650
By: 1manband Date: May 19, 2017, 6:25 pm
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[quote author=HolmenTree link=topic=6436.msg77420#msg77420
date=1495160861]
Always thought you were a saw guy.
The 650 has alot of similarities to a 105cc Stihl 090 . Same 40
mm stroke . Cast iron liner like on my YZ125 can be oversized
many times.
Whether you want it for a firewooder or a tuned pipe power
bucker in a hot saw race. It has good ergonomic potential for
both.
[/quote]
too many different motors out there to learn for me to be a saw
guy.
thanks.....will have to look into the 090.
that's the rub. for the yz, they make oversize pistons up to
0.080. has a thicker liner. great platform with cheap off the
shelf parts.
my saw is past the wear limit, at least for me......0.006" after
i hone it it will be a no-go with the stock piston. there are
no 2.25" (57mm) oversize that i can find that have a 5/8" wrist
pin hole. cannot find even a new stock one. have to send the
the piston out to get it built up to get things tighter. still
checking bearing listings to see if i could get by with running
some other piston with smaller pin, but no luck so far.
-joe
#Post#: 77466--------------------------------------------------
Re: pioneer 650
By: 1manband Date: May 22, 2017, 6:48 pm
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whoever designed this motor was one smart cookie. the following
was easily seen by some, but i catch on slow.
IMO, they knew that the ring ends would snag on the ports if
they were too large, so they got around it in a cool way.
slanted the edge of the piston. as the slant passes by the
port, it opens the port sooner making these tiny ports flow like
they were a bit larger. funky head had to be.
specific time areas taken at 2500 rpm, because 5000 is max rpm
of motor listed on acres.
note: keep your eye on the jennings recommended numbers on the
right for an eye opener.
photo 1 = piston
photo 2 = time areas taken from top flat of piston crown as it
passes to open the exh and trans ports.
photo 3 = time areas taken mid-way down the slanted edge as it "
" " " " " "
photo 4 = time areas taken of bottom of slant as it " " " "
my guess is that it actually starts flowing somewhere between
the flat top and mid-way positions. what do you guys think
about all this?
#Post#: 77468--------------------------------------------------
Re: pioneer 650
By: 3000 FPS Date: May 22, 2017, 7:35 pm
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What does that slanted top above the piston do to the direction
of flow.
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