OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Victa Lawn Mower Frames Identify Victa Pro 550

What year would this Victa Professional 550 be?

The model number on the air filter is: WQ 197EX9

Is the motor the original fitment or an older retrofit?

There is no spark produced form the magneto even without the kill switch lead. The coil resistance is 9 ohm.

Are parts still available for this engine? If so, is there a parts list?

Does anyone know if the later c1990's victa power torque engine will fit the base?

LRT

Ps. How much compression should be expected with a Victa?

The engine spins over by hand easily and the compression stroke is barely distinguishable when spinning the flywheel by hand with the cover off. There is no compression rebound whatsoever.

Should be a decomp valve under the cover, I can't see the decomp tube coming up from the carby so anything is possible. Remove the cover, remove the decomp if it is there and put a spark plug in the hole and then see what compression is there

Hi Norm,

Thanks for your prompt reply.

Yes it does have a de-comp valve under the cover. I'll do what you suggest tomorrow & get back with the results.

When turning the engine over, it looks as though it has a bent crankshaft.

The owners description was it got harder & harder to start & then finally wouldn't start at all.

Caleb

those motors used a longer crank than a regular 18" engine, what makes you think the crank is bent?

When turning the engine over, the flywheel and centre of the shaft has a pronounced side to side wobble. There is no side play as if the bearings have worn.

I haven't had time to have a proper look at it yet though.

Caleb

fair enough, they are simple enough to strip and rebuild,
does the height of the blades vary on rotation ? ( from side to side )

No there isn't any noticeable height difference between the blades when they are rotated. Can you still get piston rings & the magneto from Victa?

G'day LRT, and a warm welcome to the ODK Forums.

From that model number, it's 86-87 year of manufacture; it's actually the 'Pro 550 Self Propelled' model. One of the very last of the full-crankshaft Victas; most of the model range had gone to the half-crankshaft PowerTorque engine by then. So it's the original engine I'd say, and no, a PowerTorque won't fit it.

Most parts are still available for this one, with the exception of the decompressor valve assembly. However, if that one has three clips holding the diaphragm chamber together, rebuild kits are available, e.g. HERE.

Piston rings are available in standard and three oversizes. That said, it's fairly rare for Victa 160's to get away with rings only when they're worn; the bores tend to wear oval, and they need to be rebored.

The basic service info on the engine and carby is available in the numbered sections HERE as free downloads; the lower 'Attachments' docos require a paid subscription for access.

This engine has electronic ignition; if it has the separate electronic module, the problem could lie in either the coil or the module.

Thanks Gadge,

Yes it does have a module that appears to have been replaced recently.

How to I test the module?

The coil resistance is 9 K Ohm.

Caleb

Try removing the coil from the body and clean where it attaches so that it gets a good earth and the module needs a good earth as well

Hi Norm,

I've cleaned all the contacts & checked for a good earth but there still isn't any spark. The module appears to be fairly new. Do the terminals on the coil have a polarity? The mower had been to several shops before I got the job so I don't know if things are connected up correctly.

Will a Victa MAO5617 universal module work?

http://www.gaspares.com.au/program/...20902102&GROUP=MW%20ELEC%20ECP%20VIC

Not sure if that module would work with the coil, probably would, but if you say the one you have looks fairly new I would think it is probably ok. Seeing you tested the coil I guess the plug lead is ok. Very annoying when you don't have boxes of bits to mix and match with to eliminate each component. Makes you wonder why it has been to several mower shops, I guess they figured it wasn't worth their time. Problem is once they start replacing bits the cost plus labor add up very quickly. Have you checked it for compression yet? I probably have a few of those motors kicking around here, quite a few I have never looked at so not really sure what is there, always happens when you pick up bulk mowers from ebay or gumtree. They just get pushed further back into the shed

There are basically two resistance readings for the coil; plug lead to earth or primary terminal, which should be 8.5-9.5 k ohm; and primary terminal to earth, which should read 0.2-0.5 ohms [if the meter will read that low].

The resistance across the module seems to measure around the 4.5 - 5.5 k ohm range.

The plug lead to primary or earth terminals: 9.0 k ohm

Between primary and earth terminals: 1 ohm

Between terminals on module: 4.5 k ohm

I purchased a NOS coil and it reads 8.5 k ohm on the plug lead to primary or earth. Otherwise it reads exactly the same as the current coil.

Does it matter which terminal is the earth or primary?


I haven't put the compression gauge on it yet, but it feels as though its got about 80 psi or so with the decompressor replaced with a spark plug.

Secondhand Victa's are virtually non-existent around here.

Caleb

Ok so dumb question what about the kill switch in the carby, pull the wire off that goes through the side first and the one through the rear second. You also need the throttle in the run position so you can pull the center wire out

Unfortunately Norm, both leads to the carby were out when I picked it up, so I don't know which goes where. There is no spark with the leads disconnected & isolated.

Just noticed both pins are different & can't be interchanged.

I've just put the coil back on and there still isn't any spark with the cut out lead off. I'll connect the oscilloscope with the secondary pickup & see if there is any voltage being produced.

Very odd as it technically should have spark.

The flywheel magnets are still strong enough as well.

The owners explanation was that it got harder and harder to start and then wouldn't go at all.

Attached below is a picture of the oscilloscope waveform with the original coil.

The secondary voltage is only 2.42KV



I then installed the NOS coil and the secondary voltage rose to 5.86KV



What is really odd is both coils test the same with the multimeter.

After some strenuous pulling of the cord, it backfired and ran up to governed speed.

It will cut 6" tall faster than you can push without missing or backfiring.

However, once the engine is turned off it refuses to start until 30 odd pulls on the starter cord. It then pops back through the air filter and slowly builds up to speed and then runs perfectly.

Is this more of a carby issue or still an ignition problem? Maybe the module?

Also, what is the maximum revs it should run at? It sounds like it is running twice as fast than our Victa Power Torque engine. It definitely leaves the Power Torque for dead!

Could the starting issue be the result of not connecting the hose to the vacuum control button on the cowling? This probably explains the high revs as I didn't have the cover on with the hose connected when I was testing it.

I can't obtain a replacement ignition module locally, so would need to order one in and then find it isn't part of the problem. The NOS coil I purchased could also be faulty.

More testing tomorrow...

The fact it runs makes me think the ignition side is ok, I would be leaning towards the carby with the hard starting, these can be a pig of a carby but once sorted they are very good

Yes it runs really well when it is going - no surging nor missing etc and pulls well under load. I'll pull it off tomorrow. How do I disconnect the throttle cable from the carby? Or is that only possible once it is apart?

LRT, the throttle cable is a bit tricky but once you know it is easy, problem is I'm not sure what you will find wrong in there, they are a great carby but I have to modify them to get them to work properly and that isn't easy to explain here. Anyway to get the carby off you have to twist it towards youand then pull it away from the barrel, be gentle with it. Move the throttle to run and remove the kill switch pin through the side, then you can remove the center wire/pin. Remove the snorkel hose and you will see the cable where it attaches to the carby body. Move the throttle control to the stop position, lift up the cable where it enters the carby body and pull it back out and it will release from the cam inside. Not easy and then once you have it apart, I will have to explain how to put it back together Go easy on the way the cable connects to the body you have to be forceful but delicate

Hi Norm,

I have removed the carby and disassembled it. The diaphragm spring is badly distorted, so I managed to track down a replacement to install.

I have a new poppet valve (part no.: CR03593A) on hand. Do I replace the existing one even though the existing valve looks ok? Also, what letter on the poppet valve should I line up on this mower?

I also have a new diaphragm. (part no.: CR03635A)

Caleb

Hi Caleb, I guess you have worked out that you need a plug socket or similar up inside the throat of the carb to hold the poppet up so you can remove the retainer disc. Then you can remove the diaphragm , spring and lifter. This then exposes the cam which you can lift out. I doubt you are going to find anything in there to cause the hard starting but you will have an idea as to how it works. I cut the lobes on the cam down and I have no trouble getting them to start, I'm not sure if cutting the lobes down makes starting easier, but it works for me. The re-assembly starts with the cam in the carb body, in the closed position, cable hole closest to the entry point of the cable/snorkel,throttle cable fully extended in the run position,poke the cable ball in though the body and clip the ball into the cam, rotate the cam full to the left and the cable will be sitting in the slot in the cam. Then clip the cable outer back into the carb body from the outside into the little recess in the body. Next comes is the stupid kill switch that I always fit a new rubber to and it often takes me several attempts to get the thing to work and even when I have them working they are prone to fail. The kill switch was just another one of Victas not so finest moments. If you have got this far then you can refit the carb to the motor. Then the next issue you may encounter is the float needle, I'm pulling my hair out with those at the moment. Good luck

Caleb I just saw that you can remove the center from some of those end caps, I had not noticed that before

Thanks Norm,

I've just finished cleaning it. No I didn't need a socket. It only needed firm finger pressure to hold it.

Are these the lobes you cut down? How much do you remove? I'll reassemble the carby and try out the mower first so I can see if the new diaphragm & primer cap fixes the problem.


I have also bought a cam (CR.03626A) that looks identical except for a pin moulded on the arm opposite the hole for the throttle cable. Is this an updated design? The existing cam part number is: CR03406