Discussion:
question about a 250 bike
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C***@deathtochristianity.pl
2019-04-12 18:09:20 UTC
Permalink
Anyone have any idea or even your best guess at a 250 cc carb will get
in gas mileage and top speed?
--


"There are idiots among us, and they all believe in a god"
~Toidi Uoy
C***@deathtochristianity.pl
2019-04-12 18:44:51 UTC
Permalink
On Fri, 12 Apr 2019 13:09:20 -0500,
Post by C***@deathtochristianity.pl
Anyone have any idea or even your best guess at a 250 cc carb will get
in gas mileage and top speed?
Also air cooled. Is there a chance it will overheat on long rides?
Post by C***@deathtochristianity.pl
--
"There are idiots among us, and they all believe in a god"
~Toidi Uoy
--

____/~~~sine qua non~~~\____
Dennis Lee Bieber
2019-04-12 22:59:21 UTC
Permalink
Post by C***@deathtochristianity.pl
On Fri, 12 Apr 2019 13:09:20 -0500,
Post by C***@deathtochristianity.pl
Anyone have any idea or even your best guess at a 250 cc carb will get
in gas mileage and top speed?
Also air cooled. Is there a chance it will overheat on long rides?
No idea of the air-cooled, but by nature -- it is more likely to
overheat when you stop moving (heck, even water-cooled can heat up with
standing still -- but they usually have an electronic controlled fan to
force air over the radiator). After a long cruise at upper speeds, you
might want to spend some time at lower road speeds before shutting down...
All of mine have bee water-cooled.

As for fuel mileage, et al...

My previous -- Vespa GT200 -- tended to run close to 60mpg at middling
speeds (not full-out, but not city stop&go). Top speed was sufficient for
65MPH Interstate freeway (which meant, allowing for speedometer error, are
reading of around 72MPH [10% error]). BUT -- expect to lose 5-10MPH as soon
as you hit a moderate climb. No problem on 45-55MPH mountain roads.

My current -- 2006 Aprilia Scarabeo 500 ABS [a 460cc engine] -- gets
close to 50MPG /at 55MPH/ -- freeway speeds drop it to about 45MPG. Freeway
speeds here are 70MPH (or near 80 on the speedometer -- the Vespa had a
more accurate speedometer). I have not discovered the top speed (there is
around 1000-1500RPM left on the tachometer before redline, 70MPH is around
4500RPM as I recall, and if the CVT is not in the top ratio, the remaining
1000+RPM might be another 20+MPH)
--
Wulfraed Dennis Lee Bieber AF6VN
***@ix.netcom.com
C***@deathtochristianity.pl
2019-04-12 23:26:04 UTC
Permalink
On Fri, 12 Apr 2019 18:59:21 -0400, Dennis Lee Bieber
Post by Dennis Lee Bieber
Post by C***@deathtochristianity.pl
On Fri, 12 Apr 2019 13:09:20 -0500,
Post by C***@deathtochristianity.pl
Anyone have any idea or even your best guess at a 250 cc carb will get
in gas mileage and top speed?
Also air cooled. Is there a chance it will overheat on long rides?
No idea of the air-cooled, but by nature -- it is more likely to
overheat when you stop moving (heck, even water-cooled can heat up with
standing still -- but they usually have an electronic controlled fan to
force air over the radiator). After a long cruise at upper speeds, you
might want to spend some time at lower road speeds before shutting down...
All of mine have bee water-cooled.
As for fuel mileage, et al...
My previous -- Vespa GT200 -- tended to run close to 60mpg at middling
speeds (not full-out, but not city stop&go). Top speed was sufficient for
65MPH Interstate freeway (which meant, allowing for speedometer error, are
reading of around 72MPH [10% error]). BUT -- expect to lose 5-10MPH as soon
as you hit a moderate climb. No problem on 45-55MPH mountain roads.
My current -- 2006 Aprilia Scarabeo 500 ABS [a 460cc engine] -- gets
close to 50MPG /at 55MPH/ -- freeway speeds drop it to about 45MPG. Freeway
speeds here are 70MPH (or near 80 on the speedometer -- the Vespa had a
more accurate speedometer). I have not discovered the top speed (there is
around 1000-1500RPM left on the tachometer before redline, 70MPH is around
4500RPM as I recall, and if the CVT is not in the top ratio, the remaining
1000+RPM might be another 20+MPH)
was your vespa fuel injected?

Also do you know if CVT gets better mpg or a manual clutch
transmission?

--

____/~~~sine qua non~~~\____
Dennis Lee Bieber
2019-04-13 20:32:20 UTC
Permalink
Post by C***@deathtochristianity.pl
was your vespa fuel injected?
Fairly certain it was carburetor -- but it's been over 13 years, and
the only thing I ever had to do to it was tweak the idle-speed screw -- it
tended to work out resulting in stalling when the choke went off but the
engine wasn't fully warm.
Post by C***@deathtochristianity.pl
Also do you know if CVT gets better mpg or a manual clutch
transmission?
I think that's part of why some autos tried them (and in an auto, they
could add computer control systems to optimize the CVT even more). The idea
being that, based on the load at any given road speed, the pulleys will
adjust the ratio. You won't be spinning any tires or doing "wheelies" with
one though, as you can't gun the engine and then drop a clutch. The CVT
uses weight rollers on the engine pulley -- the faster the engine runs, the
more the weight move out, pressing on a slanted surface to squeeze the
front pulley narrower -- forcing the belt to the outermost diameter. The
rear pulley has springs with try to force it to narrower, along with a
diagonal slot and pin. When you come to a stop, the front pulley isn't
forced narrow, and the springs squeeze the rear pulley -- "low gear"
configuration. The diagonal slot and pin handles change in load (going up
hill, say) as the load increase makes the pin move sideways in the slot
(helping the springs move the pulley) reducing "gear".

There is also a centrifugal clutch in the rear hub, between the pulley
and the wheel -- needed to allow the pulleys to rotate at all times.


Automotive CVTs didn't really have the torque handling ability for
heavy duty. Instead we now find things like 9-speed automatic transmissions
(in the Jeep Cherokee). Again, the design intent is to keep the engine in a
narrower performance band, instead of having to swing to high RPM, then
drop to somewhere above idle and work back up...
Post by C***@deathtochristianity.pl
--
____/~~~sine qua non~~~\____
--
Wulfraed Dennis Lee Bieber AF6VN
***@ix.netcom.com
C***@deathtochristianity.pl
2019-04-14 13:51:14 UTC
Permalink
On Sat, 13 Apr 2019 16:32:20 -0400, Dennis Lee Bieber
Post by Dennis Lee Bieber
Post by C***@deathtochristianity.pl
was your vespa fuel injected?
Fairly certain it was carburetor -- but it's been over 13 years, and
the only thing I ever had to do to it was tweak the idle-speed screw -- it
tended to work out resulting in stalling when the choke went off but the
engine wasn't fully warm.
Ahh good to know. I thought my scoots was a piece of crap because it
does that
Post by Dennis Lee Bieber
Post by C***@deathtochristianity.pl
Also do you know if CVT gets better mpg or a manual clutch
transmission?
I think that's part of why some autos tried them (and in an auto, they
could add computer control systems to optimize the CVT even more). The idea
being that, based on the load at any given road speed, the pulleys will
adjust the ratio. You won't be spinning any tires or doing "wheelies" with
one though, as you can't gun the engine and then drop a clutch. The CVT
uses weight rollers on the engine pulley -- the faster the engine runs, the
more the weight move out, pressing on a slanted surface to squeeze the
front pulley narrower -- forcing the belt to the outermost diameter. The
rear pulley has springs with try to force it to narrower, along with a
diagonal slot and pin. When you come to a stop, the front pulley isn't
forced narrow, and the springs squeeze the rear pulley -- "low gear"
configuration. The diagonal slot and pin handles change in load (going up
hill, say) as the load increase makes the pin move sideways in the slot
(helping the springs move the pulley) reducing "gear".
There is also a centrifugal clutch in the rear hub, between the pulley
and the wheel -- needed to allow the pulleys to rotate at all times.
Automotive CVTs didn't really have the torque handling ability for
heavy duty. Instead we now find things like 9-speed automatic transmissions
(in the Jeep Cherokee). Again, the design intent is to keep the engine in a
narrower performance band, instead of having to swing to high RPM, then
drop to somewhere above idle and work back up...
Post by C***@deathtochristianity.pl
--
____/~~~sine qua non~~~\____
--

____/~~~sine qua non~~~\____
C***@deathtochristianity.pl
2019-04-14 14:08:36 UTC
Permalink
On Sat, 13 Apr 2019 16:32:20 -0400, Dennis Lee Bieber
Post by Dennis Lee Bieber
Post by C***@deathtochristianity.pl
was your vespa fuel injected?
Fairly certain it was carburetor -- but it's been over 13 years, and
the only thing I ever had to do to it was tweak the idle-speed screw -- it
tended to work out resulting in stalling when the choke went off but the
engine wasn't fully warm.
Post by C***@deathtochristianity.pl
Also do you know if CVT gets better mpg or a manual clutch
transmission?
I think that's part of why some autos tried them (and in an auto, they
could add computer control systems to optimize the CVT even more). The idea
being that, based on the load at any given road speed, the pulleys will
adjust the ratio. You won't be spinning any tires or doing "wheelies" with
one though, as you can't gun the engine and then drop a clutch. The CVT
uses weight rollers on the engine pulley -- the faster the engine runs, the
more the weight move out, pressing on a slanted surface to squeeze the
front pulley narrower -- forcing the belt to the outermost diameter. The
rear pulley has springs with try to force it to narrower, along with a
diagonal slot and pin. When you come to a stop, the front pulley isn't
forced narrow, and the springs squeeze the rear pulley -- "low gear"
configuration. The diagonal slot and pin handles change in load (going up
hill, say) as the load increase makes the pin move sideways in the slot
(helping the springs move the pulley) reducing "gear".
There is also a centrifugal clutch in the rear hub, between the pulley
and the wheel -- needed to allow the pulleys to rotate at all times.
Automotive CVTs didn't really have the torque handling ability for
heavy duty. Instead we now find things like 9-speed automatic transmissions
(in the Jeep Cherokee). Again, the design intent is to keep the engine in a
narrower performance band, instead of having to swing to high RPM, then
drop to somewhere above idle and work back up...
Post by C***@deathtochristianity.pl
--
____/~~~sine qua non~~~\____
Well the reason that I am asking is because I was looking at a 250 CC
bike with a 5 speed shift. But it is the same brand of Chinese that I
have now, and I was a bit weary because it keeps stalling. But from
what you told me that could be normal for a small 1 cylinder engine. I
was also worried that a 250 cc bike may not get that good of gas
mileage which is the entire reason I bought one in the first place.
I bought mine in November and have over 3000 miles on it not adjusted
for error. but divide that by lets say 60 mpg and that is about 50
gallons of gas.... multiply that by 2.50 <avg price of gas during that
time> you get 125 dollars

now do that again for my truck 3000/10 = 300 x2.50 = 750

125$ vs 750$

that is a lot of money saved. The cheap Chinese scooter that I bought
for about 750$ (550 + shipping) has almost paid for itself

That other 250 cc bike that I am looking at costs about 1000 dollars
plus almost 300 for shipping and I was concerned that if it did not at
least get 50 MPG it would not be worth it

--

____/~~~sine qua non~~~\____
Dennis Lee Bieber
2019-04-14 16:16:51 UTC
Permalink
Post by C***@deathtochristianity.pl
Well the reason that I am asking is because I was looking at a 250 CC
bike with a 5 speed shift. But it is the same brand of Chinese that I
have now, and I was a bit weary because it keeps stalling. But from
My stalls were temperature and idle speed related -- the tachometer
showed that the bike was trying to idle about 300RPM slower than it was
supposed to. When fully warm, it would handle that slow idle. And, fully
cold, the choke provided enough fuel.

Your stalling problems sounded like they were independent of engine
temperature, which lead me to believe it was a problem in the mixture jets
transitioning from idle to run... You should have seen the junker used by
the school when I took my motorcycle driver's class: I stalled it
practically everytime we did a stop&go move -- until I learned I had to
crack the throttle, WAIT while the engine sputtered, and THEN open the
throttle while releasing the clutch to start moving. Going from idle to
attempted run speed without the pause always stalled the bike -- too much
air got in before the run mixture jet could start providing fuel.

{It also had the grabbiest front brake around, with soft front suspension
-- a result being that as one applied the front brake lever, the nose would
dive severely, and that pulled the handlebars and brake lever even
tighter!}
--
Wulfraed Dennis Lee Bieber AF6VN
***@ix.netcom.com
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