Villiers 425H

[Trevor van Andel]

Some very interesting discussions going on in here..... I'm hoping someone
can help me out here.
I have a Villiers Mark 425H No. 670X14406 on an old slasher/mower. The
engine had no spark. Now, I like to get my teeth into these sorts of jobs so
I began to rip it apart. After struggling to get the flywheel/magneto off, I
found the problem.....a broken roller on the points. Given that I haven't
got a manual and I've never worked on one of these before, my problem is
this...As I was removing the flywheel/magneto, I was surprised to discover
that the taper fit to the crankshaft had no keyway to properly align it for
the spark timing. When I begin to put the thing together, how do I fit the
flywheel so that it is positioned correctly? It has an arrow on the
flywheel/magneto and another on the backing plate. Do I align these two with
the piston TDC or is this the spark timing mark (ie: points begin to open)?
And what should the point gap be?
Any tips would be much appreciated.
tRev. (a small engine enthusiast from Hoppers Crossing, Vic Australia.)

[J. K. Siddorn]

From my recent experience with the MarVil, the flywheel mark represents TDC.
Position the piston, align the marks and the points should be opening
between 1.25" and 1.50" before TDC. You may have to fiddle with it to get it
right.

A foible is that the points spend most of their time shut, only opening,
closing and opening again just before ignition. Threw me that one .......

Make sure you have no oil on the taper when you do the nut back up and make
sure its tight.

--

Regards,

Kim Siddorn

"Non est tanti."
"Trevor van Andel" <tavan...@optushome.com.au> wrote in message
news:3dbfac97$0$12778$afc3...@news.optusnet.com.au...

[Trevor van Andel (aka tRev.)]

Thanks for that Kim, I'll (hopefully) be getting the new parts tomorrow. To
do this job setting up the flywheel and points, I suppose I'll have to
remove the head to make the measurements you so kindly posted for me. This
job keeps gettin' bigger! Bugger!
Thanks again....
tRev.

"J. K. Siddorn" <kim.s...@blueyonder.co.uk> wrote in message
news:apodo8$3hahu$1...@ID-151486.news.dfncis.de...

[J. K. Siddorn]

W-e-l-l, you can get out the degree disk, the micrometer clock gauge and
take the head off if you are picky, but a screwdriver down the plug 'ole and
a certain amount of common sense will be sufficient in all normal
circumstances..

Unless you are going to race it ......... ;o))

Regards,

Kim Siddorn

"Non est tanti."
"Trevor van Andel (aka tRev.)" <tavan...@Removethisoptushome.com.au> wrote
in message news:3dbfc290$0$13599$afc3...@news.optusnet.com.au...

[Trevor van Andel (aka tRev.)]

Kim, I want to be sure....So that means the piston has to be between one and
a quater and one and a half inches before it's TDC. I hate to seem to be a
dumb-arse, but that seems to be a fair bit of advance...!!!??? By the way,
the plug hole is not above the pot (its a side valve) and I can't get a
screwdriver down there so I think I'll have to take the head off. It
probably needs a decoke anyway.
tRev.

"J. K. Siddorn" <kim.s...@blueyonder.co.uk> wrote in message

news:apokci$3k1h9$1...@ID-151486.news.dfncis.de...

[Roland Craven]

TDC will be when the valves are just rocking or you can use a bit of bent
coat hanger through the plug hole :-) Before you take the head off, do you
have a spare head gasket or a sheet of 18gauge copper and a few hours spare?
Assuming (cos I can't remember) that the flywheel is 9" dia gives a
circumference of about 28". 1 1/2" advance is therefore about 19 degrees
of advance. By no means unreasionable in my view.
regards
--
Roland Craven
nr Exeter Devon, UK
rol...@petternut.co.uk
http://www.petternut.co.uk

"Trevor van Andel (aka tRev.)" <tavan...@Removethisoptushome.com.au> wrote

in message news:3dc05496$0$12778$afc3...@news.optusnet.com.au...

[Trevor van Andel (aka tRev.)]

Hi Roland, thanks for your input. I would rather not take the head off if I
don't have to so I'll try the bent bit of wire or something.
Also, I understand now that the measurement of 1 1/2" is on the flywheel,
not the piston travel in inches from TDC. (that didn't seem right to me).
Thanks again for your information.
tRev.
"Roland Craven" <pett...@clara.co.uk> wrote in message
news:10360155...@iris.uk.clara.net...

[Peter A Forbes]

On Thu, 31 Oct 2002 11:51:23 +1100, "Trevor van Andel \(aka tRev.\)"
<tavan...@Removethisoptushome.com.au> wrote:

>Hi Roland, thanks for your input. I would rather not take the head off if I
>don't have to so I'll try the bent bit of wire or something.
>Also, I understand now that the measurement of 1 1/2" is on the flywheel,
>not the piston travel in inches from TDC. (that didn't seem right to me).
>Thanks again for your information.
>tRev.

Not sure if the Mk25 is the same as your 425 engine, but the info for the Mk25
is as follows:-

Timing is 3/16" BTDC
Plug is Lodge CB3 gap 0.020" - 0.025"
CB Points gap is 0.012" - 0.016"
Oil capacity 2 pints
Bore 2.7565" 70mm
Stroke 2.625"
15.65 cu in capacity 256cc

A rough check on ignition timing is for the driving shaft keyway to be 20
degrees BTDC when the points are just opening.

As I have said, it may not be the same engine...

Peter

[Nick Highfield]

Info I have (Jack Sizer's book) gives the following:-

MK425H (1954)
Bore and stroke 70x67mm
Ign. timing 3/16" BTDC
Points gap 12-15 thou
Tappet clearance inl. 3 thou, exh. 6 thou
Spark plug type CB3

As Kim said, if drill is the same as for Villiers Mar-Vil, then correct ign
timing should be achieved by lining up marks at TDC.

Nick H.
--
n_hig...@hotmail.com

[Prepair Ltd]

I have the Mk20/Mk25 handbook if any further details are required,
plus I have a couple of new blocks I think...

Peter

Peter

Peter Forbes
Prepair Ltd
Luton, UK
email: pre...@easynet.co.uk
home: die...@easynet.co.uk

[Trevor van Andel (aka tRev.)]

Thankyou all ever-so-much for all your help. I just might have all the info
I need to get the old beast running again. I am waiting on parts at the
moment so last night I calculated the measurement Kim gave me earlier in
this thread. The flywheel is close enough to 7" Dia. So, 20 deg advance
works out to 1.22 inches at the flywheel. And I figure, if I set the point
gap to 12 -15 thou at TDC, then the time that they actually begin to open
(ignition), should be ~20deg btdc or ~1.22 inches btdc at the flywheel. I'm
not going to race the thing, so this should be close enough.
This group has been very helpful. Thanks again for all your generosity.
tRev.

"Prepair Ltd" <pre...@easynet.co.uk> wrote in message
news:qlm2sus41rdq6pbkt...@4ax.com...