[wristpin]

Very interesting about the flywheel positioning / timing issues. As per my earlier post, I have fitted many Meco units and never experienced a similar issue but will log your work around for any future problems. It would be interesting to know the final positioning of the original Villiers timing marks with the flywheel in the position that gives satisfactory running.

EDIT. Just occurred to me, are you referring to a Mk25, which is a four stroke, or actually to a Mk25C, two stroke?
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[wristpin]

Depending on the interference fit of the new guides in the block they will “shrink” a bit when pressed in. In some instances the guides then have to be reamed to achieve a working clearance.
By all means space the ring gaps for the initial start up, but unless they are pinned as on many two strokes, they move around on their own when running – cyclic rotation.

[wristpin]

I would not advise spot heating with a blow torch . Heating, if needed should be the whole block and over an extended period so as not to set up local stresses.

[wristpin]

In an ideal world guides should be pressed out rather than bashed, but…..! Use a good quality punch that is just a gnats under the outer diameter of the guide or even better find a man with a lathe to make you a stepped drift that locates on the id and nearly covers the od.
Before you even start, and assuming that the guides are not flush with the base of the ports, measure the protrusion of the guide into the valve chest or even make a block that just fits under them so as not to push the new guides to far.
Perhaps putting the new guides into the coldest part of the deep freeze would be more acceptable to her indoors than the smell of roasting cylinder block. Even better, do you know anyone with some dry ice or liquid nitrogen?

[wristpin]

Running the engine without the crankcase breather valve could be counter productive in that while providing an exit for the air displaced on the downward piston stroke, it should seal on the upward stroke creating a negative pressure area in the crankcase to keep the engine oil tight. It’s possible that some of your oil burning is due to the ball valve not sealing properly and not creating that negative pressure.
The F15 used two versions of the breather, the ball one that you have and a (later?) poppet valve similar to that used on the F12 Sloper. That was integral with the valve chest cover, so is an easy swap. Paul at Meetens is the man to advise whether it might be worth doing.

I too had noticed the difference in the amount of useful information provided in the earlier Mk series manual compared with the F15 one that I posted, but in fairness it does mention oversized valve stems and reaming – buried in the text at the foot of page 13.

Attachments:

1. Villiers-F15-crankcase-breather0001.pdf

[wristpin]

One of my F15s is 50 years old . Around 20 years ago although it was running fine, I did a top end overhaul and the valve stems were so worn that no measuring was needed – just Mk1 eyeballs .Put it back together and ordered new valves which are still in their wrapping, still running fine with no smoke!
If you want to repair yours I’d settle for o/s valve stems it might even be that there’s not enough metal available to accommodate inserted guides and you could end up ruining a good engine.

[wristpin]

So how do the valve stems measure up against the book spec?
Might be worth asking Paul at Meetens whether there are any over size valves stems . Then it would just be a reamer job.
As far as getting guides goes, an engine reconditioners, possibly one specialising in motor cycles may be a good starting point.

[wristpin]

Have you actually removed the rings and measured the gap in the bore

If you have a look at “spec page” of the F15 manual scan that I posted there is quite a lot of info on ring sizes and end gaps – 6 – 11 thou, I think.
Take each ring off the piston – keeping them in order and correct orientation and poke each one in turn into the running section of the bore using the piston upside down to keep them square and then check the end gaps . Then push them down to the unworn area at the bottom of the bore ( remember that the oil control ring is at the very bottom of the piston) and check / compare again. That will give you an idea of what and where the wear is but, of course it is more meaningful if you have some new rings as a “control” .

[wristpin]

For F15 parts, Paul at Meetens is your best bet, but I see that L&S Engineers have some new old stock F15 parts including standard and certain oversized rings.

https://www.meetens.co.uk/

https://www.lsengineers.co.uk/

[wristpin]

The oil ring on that engine is below the gudgeon pin near the bottom of the piston, so although, as you’ve mentioned, the cross hatching is still visible, that ring is running on the out of sight area of the bore. I believe that the issue is unlikely to be resolved without dismantling and micing the bore at all areas where the rings run.

[wristpin]

Assuming that the crankcase breather is functioning correctly, I would suspect a worn oil control ring.
If it comes to pulling it apart this may be of assistance

https://www.dropbox.com/s/qcj176ljzvt47vb/Villiers%20F150001.pdf?dl=0

[wristpin]

I believe that there was a link between Westwood and Templar but don’t quote me without some corroboration. Westwood was founded by Gerry Hazelwood and I believe that his brother was the man behind Templar. They also made a hover mower.
Just a point of order – Rotavator ( spelt that way) is / was the trade mark of Howards. What you have there is a rotary cultivator or even a rotorvator !

[wristpin]

Almost certainly a Flymo DM and, yes, that lever was the release for the tipping body attachment. Many of the Flymo cultivators were derived from the Norlett models but most (all?) of those had split chaincases . As has been said that welded chaincase is reminiscent of the Westwood Gemini.
Presume that the engine blower housing with the recoil is missing, but if it’s in a box of bits it should have the BS Model, Type and Code Numbers on it. The Code number will date the engine to the day of manufacture which will give an approximate build date for the chassis. If you have that, I have possibly got the appropriate DM illustrated Parts manual.

[wristpin]

Do you have an image of one or a parts book illustration? There’s a possibility that it may have been a proprietary item and used on another manufacturer’s machine.

[wristpin]

Maybe I’ve been lucky, but over the years I’ve fitted dozens of Meco modules to a variety of engines including many old Villiers, and never experienced a problem – other than on one. That exception was a two-stroke Allen Scythe with the centrifugal governor system operating on the contact breaker points. Fitting the module effectively by- passes the governor, resulting in spectacular rpm! We worked out a way around the problem, but that’s another story.

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