I was always under the impression that timing had to be set on mopeds too. A friend of mine the other day was saying that the timing cant be off on a moped because its only one cylinder. I wasn't sure so i figured I would as yall. I also have a delima. The moped sparks good, and fires but wont start. There is gas because it drips out of the exhaust port because there is no muffler. What could be the problem and what can I try to fix it. By the way its on my 1974 Vespa Piaggio CIAO.
it might be because a engine needs back pressure to run correctly which the exhaust pipe and muffler provide by slowing the speed the exhaust escapes
The Ciao manual states'The timing on all Ciao models is preset by the manufacturer on assembly. As no provision is made for adjustment, it is normally impossible for the setting to be incorrect.'bruce
The Ciao Workshop manual goes on to state:
<i>...normally impossible for the setting to be incorrect. The exception to the above rule is when the contact breaker points or fibre heel become worn...</i>
You <b>do</b> need to set the contact breaker gap.
The workshop manual says:
<i>If the contacts are in good condition, measure the gap using a feeler gauge. A 0.4mm (0.015 in.) gauge should be a light sliding fit (the points <b>must</b> be within the range: 0.35 - 0.45 mm (0.013 - 0.017 in.)).</i>
Hope this helps!
almost all your questions are answered here >
Scroll down to the part about points and timing and read.
And YES... you can and SHOULD set the timing on a single cylinder engine with points.
The statement that ... " the timing is pre-set and can't change " is nonsense... the timing changes from day one because of wear of the points.
Only CDI's (electronic ignitions) don't change.
Fred, There is not an F mark or a T mark on a Ciao and I think the manual is saying that' yes the timing can change by means of a worn heel or worn points and must be set, this is the only adjustment there is. Are there not other ways to change the timing like turning a distributor ? I wish the Ciao did have timing marks so you could get it more accurate.bruce
Well Bruce... you can make your own marks on the flywheel.
First use a screwdriver in the spark plug hole... and get the piston at the top.
make a nice straight clear mark anywhere in plain sight on the flywheel.
Then... attach a wire coathanger under a bolt head somewhere near there.
Then... while the piston is at TDC... bend the coathanger till it lines up with the mark you made.
Next... measure your flywheel diameter... then tell me what it is... then I will give you a dimension to make another mark a set distance from the first one.
THEN... use an electrical meter and determine WHEN the points break... adjust the point gap till the points break when the second mark is lining up with the coathanger.
Also... if your points are mounted to a removable plate that is screwed to the motor (under the flywheel)... then it might be possible to slot those screw holes (if they are not already)... and rotate that plate to help you set the timing... (instead of relying on the point gap to set the timing).
Fred, The points assembly on a Ciao is fixed, no slots, and the pivot 'hinge' for the points, fits in an indentation so that it can not be repositioned. The points open when the cam lobe strikes the heel. With no adjustment of the heel then how can you change the time that the heel is struck by the cam lobe. If I set them the way that you say, will they still not open when the heel gets hit. I'm having trouble understanding how this setting can be changed by setting the points gap. Also, the Ciao flywheel can't be measured unless you remove the engine,it's buried under a cover and the frame. Anyone out there got a flywheel on a bench to measure. bruce
Well I'm sorry then Bruce... thats what I get for talking about something I've never worked on.
I have never seen a points ignition where you could not change the gap... (unless maybe old 4 stroke lawnmowers do that... can't remember).
if thats the case... then I guess it IS fixed... (as somebody said above)
if I misunderstood your statement above... and you CAN adjust the gap.. then you CAN adjust the timing...
.. bigger gap equals advanced timing.
.. smaller gap equals retarded timing
(casey says Crisis knows something about 'retarding" )... ; )
Fred ,thanks . bigger gap=advanced timing.... smaller gap= retarded timing. I can do that. Just no other adjustments.bruce
well hey Bruce...
... neither does my Honda have any actual 'adjustments' for timing... you have to play with the point gap to change the timing... almost ALL moped points systems are like that.
(because they are cheap and crude)
But I have changed my timing 6 times this year so far by altering the point gap... (mostly cuz I couldn't figure why it ran funky)
Then I check it with a strobe timing light.
If you flywheel is all covered up... (and you can't run the motor with the flywheel exposed... then I'd have to see the motor to see how it could be checked .. if at all).
Mine ?... change the gap... (don't even bother measuring it)... start the bike... hook up the strobe light... point it at the rotating flywheel and see where the "F" mark is in relation to the engine case mark.... Don't like where it is ??... shut it off and either widen the gap or close the gap... check again.
I am running about 2 degrees advanced right now.
The method of using a cig paper to check the point 'break' versus flywheel position is explained in 'the giude".
Is it too complicated ?
(its hard to word it simply and still cover all the bases)
What is that supposed to mean!
hehehe.. maybe you didn't see that a week ago Crisis... I said to you when you asked about changing your timing...
"how do you know where it is now... it might be 2 degrees retarded"... and casey said... "oh... Crisis is definitly 2 degrees retarded... I don't know bout his ped though"
thats what it meant... don't blame me
You can check the timing by measuring the piston height.
Most peds fire at 1-2 mm before top dead center. You can check this with a dial guage, or, if you are carefull, you can put marks on a wooden dowel.
This will not tell you what the timiong should be, but at least you will have a reference point for making changes.
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