Need advice on Victa Decompression valve problem. [solved]

[MrBedford]

Hi folks,
I'm new to this forum so excuse me if I've posted this question in the wrong hole.

I own an old Victa Utility lawn mower with the original Victa AE 054 AA90 Powertorque engine. The mower has been well maintained over the years and runs perfectly since it was built over 40 years ago. Lately though, the mower has developed the strange habit of blowing the foam filter out of the decompression valve. I have replaced it with a brand new decompression valve and it suffered the same fate and was destroyed. The foam rubber is blown out in several pieces through the four holes in the back of the decompression valve cover. The engine still runs fine by replacing the valve with an old spark plug to block the threaded hole, but I am wondering what might be the cause of the strange problem? It seems like it might be an engine timing issue but as the timing can't be adjusted on powertorque engines I am mystified as to the cause of the problem, and how to resolve it. Below is an image of my brand new decompression valve which, as you can see, has been rendered totally unusable. The engine compression destroyed completely the plastic vacuum hose fitting, and even tried to blow the diaphragm out the side of the valve!

I would be very grateful for any help the forum could give me to fix this problem.

Thankyou.

Thankyou..

 

[bertsmobile1]

It is happening because the signal from the carburettor is not holding the decompressor closed
The diaphragm is sprung normally open
A vacuum signal from the carburettor pulls the diaphragm up to close off the decompressor
Some times you can get little bits of carbon stuck under the head of the decompressor valve that also hold it open
RGS do a rebuidable decompressor so it can be pulled apart & cleaned
Also check the exhaust port
If you have been running the engine at the recommended 25:1 then you will probably find it is coked up
I run all my Victa engines 50:1 and they run a lot better
25:1 was the mix ratio for using BP energol engine oil & not modern ashless two stroke oils
The engineers at Victa wanted the Powertorque listed as 40:1 but management were afraid of warranty claims a they were all from the accounts department & had no understanding of mowrs or engines which is why they went broke & got bought out by Briggs & Stratton
Briggs & Stratton are no longer supporting the power torque engine so get some spares in hand
Coils re now NLA for all but the lattest version & even then they are $ 180 WHOLESALE .
For early models like yours you can fit a BSA Bantam coil over the original yoke but because the early engine had a remote Hall Effect trigger they rarely give any trouble
MR Woolworths has been employed by RGS and he is deleting a lot of Victa blades so get a good stock of blades because they will become NLA in the very near future, Stens have deleted most Victa blades so that just leaves RGS & the junk Jackmax ( made in China ) blades .
That engine will run till the end of time
I have 19 customers with 24" slashers running on powertorques and around 50 who have tossed away their new B &S powered engines now I have repaired their old Victas

 

[MrBedford]

Thanks very much for the informative reply. I was leaning towards a timing issue but your suggestion about the vacuum signal makes a lot of sense. I recently fitted a new carby kit but did not replace the hoses, so I will rectify that situation shortly and see if that makes a difference to the vacuum strength. I have always run this mower on the recommended 25:1, so it's interesting you say they run better on 50:1. I will give it a go. Thanks also about the pending shortage of parts. That's handy to know. I better do some shopping before it's too late. Thanks again.

Cheers.

 

[bertsmobile1]

Apart from blades the recommended service schedule is
New fuel & air lines every 5 years
new O rings every 10 ( including the one inside the recoil starter & the one inside the manifold )
New diaphragms in the carb & decompressor at 15 years
Decoke at 20 years
Air filter as required but most fall apart before they clog up .
Carb shims as required

The one thing that Victa did not mention is to return the throttle to the start position after the engine has stopped .
This prevents the cut out boot distorting to the off position as the boot is all that holds the ignition cut out wire in the on position.

Turning the fuel off & running the carb dry is also beneficial
I have some Mk I engines that are now 50 years old running like clockwork for some very happy customers.
I personally use twin that is 62 years old , a Vortex that is 36 years old & a couple of utes , one is a 125 and dates from 1969 and the other is a 160 powertorque of unknown origins because there is no date impression in the crankcase .

 

[MrBedford]

Thanks for all that information. After your first reply I took another look at my mower and found your advice was spot on. I realise now that after I'd fitted the new G4 carby kit I foolishly connected the vacuum hoses the wrong way round as I re-fitted the carby to the engine. I had the hose from the decompressor valve going to the port on the carby's snap on lid, where the crankcase hose should be. No wonder the decomp valve didn't work. A costly and stupid blunder, it shows what can happen when you don't take enough notice when dis-assembling parts. I've ordered a new valve and hopefully all will be good again. I'm really grateful for your help and advice, thanks a lot.

 

[bertsmobile1]

If you got the aftermarket one then you should be able to pull it apart & clean it
The foam is not critical and can be replaced from some old air filter foam
I cut out new ones from the old foam wraps found on ride on mower filters if I don't have any replacements in stock.
The the valve itself can say hello to a wire brush
RGS sell replacement foams
replacement foam
and full rebuild kits for the aftermarket decompressors
REBUILD KIT
Briggs & Stratton abandoned the Eco Torque ( EPA compliant Powerorque ) back in 2016 then closed down the engine factory in Adelaide the year latter , the last Powertorque Victa off the line was donated to the Powerhouse in 2020.
Briggs manipulated the price to make the Powertorque engined mowers $ 200 more expensive than the Chinese B & S engined mowers then claimed lack of sales support in order to abandon the release of the Eco Torque and close down the Power torque so Victa became just another "briggs on a bowl" vastly inferiour mower and lost 40% of the local sales & all of the exports ( real smart business move )
Bunnings dumped all of their Powertorque parts apart from blades & filters in 2020 as well.
Mitre 10 used to keep some but I have not been into a Mitre 10 or HardwearHouse for a very long time as I get all that stuff from the local unfranchised hardwear store ( till he closed down last year )

 

[MrBedford]

The the valve itself can say hello to a wire brush

As can be seen in the photo in my first post the very end of the valve stem where the retaining clip fits on is completely broken off, the plastic plug where the hose fits on was also destroyed. Rebuild kits don't supply these parts, so I ordered a complete decompression valve from Green Acres Mowers .

Thanks again for all your help in this matter.

Cheers.