OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines S70 Decompressor, Servicing Guide date?

Hello all

Had previously assumed that the Series 70 Decompressor was introduced on the Mark Two engine in the 1971-72 Season.

Have a Pace Premier 160cc Engine # 7 70 2 3311 with Series 70 Mark 1 decals, it seems to be a 1970-71 PREMIER 160 Model 70PA also an additional engine # 7 70 2 4038 with a decompressor.

Does anyone have the publishing or effective dates of Victa Servicing Guides in particular No.79 (attached)

Was the Pace released "early" as a field test etc?

thanks

Mark

Hello MarkN
When I first read your post I was dismissive.
There was overwhelming primary evidence from Victa that the
decompressor was released in late 1971 for the 1972 season.

A huge marketing campaign - maybe Victa's biggest - ensued.
Everyone zipped on their doo-dahs ...

However, that Service Guide did throw a spanner.
Why would a non-Victa branded machine be the first ... ?

Because the 'Green Book' is a sort of Oracle at Delphi in
what it doesn't say, and ambiguous in what it does say,
I took a different approach....

I knew that central to the decompressor was Victa's new
[lighter] rewind starter. Victa's reliance on North American
starter designs prevailed in the 1960s, and the Victa Kirby 4-strokes
outsold their own 2-strokes for most of the 1960s.

So, when did the new Victa rewind starter first appear?
[The premise being it was designed with a decompressor in mind].

It would appear that it first appeared on ... Victa's Key-Electric in 1968.
That was a Kirby 4-stroke! [It was a back-up starter].

The first Victa 2-stroke to use the new starter was the 160cc Pace Premier
of 1970-71 [and the 125cc Utility of the same year].

I guess you see where this is going...

There is a real possibility - confirmed by your unearthing of SG79 -
that the Pace Premier was first used to trial the decompressor [and maybe
the 125 Utility]. Brilliant work!

No, I have not been able to date the Service Guide. Damn

Many thanks
----------------------------
Jack

p.s. I attach a collation of the V1 Green Book about this.

thank you Jack

I had noticed the 12-417 Starter although did not realise the significance.

I started out by trying to find when the Cylinder barrel 1-1063 with the vacuum connector was first used. The service guide doesn't mention the barrel part number although it does refer to the cylinder head 1-796.

Page B100 of A.L.5 doesn't differentiate for the barrel by model nor is the G2, G3 relevant model identified on page B101 for a Pace. The "Victa" version of the 7700 shows only the G3 on B96.

I was somewhat confused that Page A31 shows both the G2 and G3 Carburettors were used on the "Pace" 7700 engine, but both my 7 70 engines have, of course, the G3 and decompressor combination and both cowls have Mark 1 decals. Could the vertical line be too far to the right or was there the change mid stream for the same model engine?

I hadn't considered the 125cc and B92 reference for the decompressor cylinder barrel 1-1156 shows only 71 model engines and engine model 2700 has the 1-839 barrel.

Hence my confusion and the hope that someone had a date for the service guide etc

thanks again

Mark

Hi Mark and Jack

Here is the patent.


Cheers
Max.

Hello Mark and Max, and all
Max,
I won't say the usual ... but many of us have become
mechanical forensic historians.

The thing is we seem to advance understanding on ODK
and it is all member driven. Thank you!

Max, sincere thanks for the patent discovery of the Victa decompressor.
Members wonder whether you wear an everyday white lab coat or pajamas...?
You're that good!

I wonder what your thoughts are about my linking the
Zip start system to both a quick, simpler starter and a decompressor?
I'm saying it was a package and both were 'trialed' before mass production.

I was shocked when I realized the starter first appeared on a 4-stroke: -



This does support my speculation that Victa had a clear plan for the
1970s for fighting back against the 4-stroke dominance of the '60s.

Mark, I can only speculate...
I feel the A31 page does tell the truth.
Victa did introduce the G3 mid-season on selected models.

I feel that the G2 had service problems (rpm tune-ability] that could not be resolved.
[I mean, I know organ pipes are tuned by cutting metal, but carbies!]

Many thanks for the conversation.

----------------------------
Jack

Hi Jack , Mark and all,

I agree that the zip starter is a quicker and simpler starter and yes the introduction of the zip starter in 1968 is
the same year the decompressor patent was first lodged and both were trialed before mass production.

Mr Davis has mentioned Victa testing carbies before mass production here https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/99804/model-history-victa-vc-160.html

It looks like standard practice for Victa to field test certain mower parts before mass production.

I just can't think of the zip starter as a new starter or that it would need testing ,it's the same starter that was
used on 1960 Victa mowers .

The new zip starter has the same components as the alloy housing starter except now the outer housing is replaced with
a plastic starter housing,the only testing of this starter would be to make sure the plastic housing was durable.

The mechanical workings of the Victa starters are the same as the Villiers starters ,as we know so it was a new Victa starter
but an old designed starter that had already proven itself for durability.



Cheers
Max.

G'day Max, Mark and all.
Many thanks for your thoughts on this.

I most certainly agree with your comments.
Although this went beyond a simple 'field test' of prototypes, as you know.
I say this because ...

It was a 'real-world test' of production machines - if I understand this right.
I do feel Victa wanted to get this right ... for the new decade.

The Predicta and G2 may have resonated here ...?
I guess this was about the 2-stroke 'fight-back' of the 1970s.

I f someone were to ask what was the primary materials difference
between 1950-60 domestic mowers and the 1970s mowers, I would say
the extensive use of plastics used in later mowers.

Victa had its own Plastics Division from the early days.
[We're a bit more circumspect about plastics nowadays, and rightly so.]

When the VCs were introduced, I guess the dress cowls were the largest
plastic mouldings ever used on an AUS rotary lawnmower.

I think the new starter was a materials test for durability and serviceability.
I'm just speculating...

In any case, the case I make is that the new starter was complimentary
to the decompressor. This may have been a test of the combo.

The new ZIP starter had to compliment the new decompressor.
And Victa had to get it right for their greatest campaign ... of 1972.

ZIP Starting was a package deal.

Cheers
------------------
Jack

Jack, Max

Thank you both for the information and comment

Mark