OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines super 24 70 series

Recent 2nd hand purchase, worked for a while then stopped. Replaced carb o-ring, white back plate and needle, o-ring carb-to engine, new decompressor, new top cup and starting rope etc. Dismantled and cleaned carb.
So it starts and goes for maybe 10 minutes, then stops and wont start again. If i leave it for an hour or so, it will start, go again for a while then stop. Running out of patience! Seems like its a heat related problem?
Any thing else i can check before I go and buy a proscape or similar??
Thanks.

bejes,

When it stops does it seem like it is running out of fuel i.e. revs high before it stops or just stops straight away.

When it stops do you check for spark at the plug. One test is have a new plug ready and then check to see if you have spark.

Myself I would be looking at a faulty plug as well as fuel flow from the tank to the carby.

Thanks bruce, plenty of fuel getting to the carby if i take the hose off from the back of the carby.It flows fine, and they are new hoses also.
It does sort of go to low revs, stays there for a while, then slowly dies. So no, it doesn't stop suddenly. The spark plug seems pretty new, guess it wouldn't hurt to try a new one. I have also tried taking the plug out, making sure its not wet etc.
Would you know the correct plug for this engine? I think its a denso plug in there at present.
Thanks.

It is more likely to be the ignition module than the spark plug. A bad spark plug mostly makes it hard to start, sluggish when revving up, and reduces maximum power. However one of the tests for a bad ignition module is checking the spark at a known good spark plug when the module is hot and has been running long enough to give trouble.
Bear in mind that you can have trouble with bad module earthing - it isn't always a bad module.

Could be right grumpy. Will try new plug first, though it is pretty new. Today mower worked for about 15 mins, then stopped wouldnt start. As if there was no spark so could be right about the module(or the plug). If it is the module how do you go about fixing it?
Some photos

The symptoms are just about a perfect fit for an ignition module failure. They don't fit anything else very well. Victa 2 strokes are Bruce's and Joe's territory, and they can give you much better details than I can. Also, before you blame the module, you should try everything easier/cheaper to fix, including the spark plug and the ignition "kill wire" that goes to the carburetor. It is unlikely that the kill wire would ground itself every time the mower gets hot then unground itself when it cools, of course.
To find the ignition module, trace the spark plug lead, or the kill wire from the carburetor backward. Both those wires lead to the module.
If you can lay hands on a replacement module from some abandoned Victa on a nearby nature strip, swapping it for the one on your mower is a good way to test whether that is the source of the problem.

Grumpy, removed top flywheel, checked the points gap. THere was no gap! Set it to correct gap, power is back. Almost running too fast now, maybe some carb leak problem? Now i notice a banging noise, belt too loose? and also the top alumnimum flywheel has a crack in it. And the starting cup is starting to slide around on top of the flywheel, but if i tighten it any more it will make the crack worse!. And its a bit loose where the key slides in. Think I'm going to get a new mower, not worth all this time and expense!.

Now you can see why I said Bruce and Joe are the guys - I thought 70 series engines had ignition modules. Of course a closed-up breaker gap has the same symptoms as a module failure. Loss of gap is usually due to failure to lubricate the cam on the crankshaft that operates the points.
You may have an induction air leak, which defeats the governor setting. You said you replaced the two inlet pipe O-rings: does that engine have an O-ring under the starter, sealing the crankcase? That is a common cause of induction air leakage.
What is this belt of which you speak?
If the flywheel is cracked it has to be replaced, or the engine scrapped. If it is a hub-area crack, it may have been caused by overtightening the crankshaft nut. With the flywheel cracked at the hub, the flywheel has no proper axial location, which is the reason the starting cup is loose. If the crack is at the keyway, it is also the reason for the loose key. All these problems can be cured in a couple of minutes by replacing the flywheel with one from a junked Victa - and the world seems to be full of those. I agree you wouldn't go looking for a flywheel that cost much for an old mower, but a more or less free one is a sensible solution - you haven't mentioned any faults that a flywheel change won't cure.

Yes the flywheel is cracked there, at the key point. I got this mower from a 'guy' who seemed to know about two strokes. But as i have had to replace all these parts, i'm not so sure. Think i will be paying him a visit... I'm not sure about the o-ring under the starter, i would have to take the starter bits off, which i didn't want to do. I replace the one where the carby joins the engine, and the one for the back plate of the carb with the primer bulb.

The belt: its a 24inch cut, and its belt drive. From the engine to the blades: 2:1 reduction.
I think the flywheel is cracked from over tightening, but unless its tight the cup slides around on top of the flywheel. Is there a torque setting for this joint?
Well ill see if i can find an old flywheel... But im starting to see the attraction of a new four stroke...

OK, things become a bit clearer. The O-ring under the starter may not apply to your engine (I have only a vague idea what a series 70 is) but it is an unreliable component on the engines that have it, and it does cause an induction leak. The other possible cause of over-revving is that some activist may have messed with the part of the carburetor that operates the governor. If you have an induction air leak you would probably have hard starting and/or loss of power.
The reason for your loose cup is the cracked flywheel. You cannot tighten the retaining nut properly because the crack just opens up and lets the flywheel move down the taper. The only way to improve the situation is to replace the flywheel. The loose cup is probably also the reason for the clattering noise you complained about. The belt isn't likely to cause a noise like that.
Don't get too enthusiastic about a new four stroke. The affordable ones mostly have poorly-made engines that might make you long to have your Victa back. A flywheel change might result in a complete cure of everything you have reported. And it will give you a chance to smear a little grease on the breaker-point cam, if you forgot to do so when you reset the points.

Thanks grumpy. I did actually put some grease on the cam re: points.
Yeah i will chase up a flywheel then. Before i fixed the points, there wasnt the issue of overreving... And also the damn throttle cable in this thing: keeping it inside the carby and working is a constant challenge!

With the points just about fully closed up before you reset them, the engine was running with retarded ignition and that would make it reluctant to rev up. It is possible that someone had reset the governor in an attempt to overcome that problem.

The over revving fixed, last time i removed the carb diaphragm cover to get the throttle cam in the right position i didn't seal it properly so there was a leak. That's fixed now. I think the banging might have been the flywheel moving around possibly as its not really fixed to the shaft with the crack in it.

Hi grumpy, the Series 70 and Series 80 Victas are both full crank models....the starter 'o' ring is only applicable on the half-crank "Powertorque" engine.

I was starting to suspect that it was full-crank, from the age (since it has breaker points). All the more reason to fix the cracked flywheel - it should end up a better mower than the average Chinese 4 stroke. (Of course it still couldn't compare with a real mower, using a pre-China Briggs. However those have to remain exclusive, for we true enthusiasts.)

If you need a flywheel I can post you one as long as you cover the postage.

Hey Bruce. THat would be great. Sure i will cover postage. Will send you a pm with address.Thanks!

No problem glad to help.

HI Bruce, sent you a pm with address details for flywheel. Would be great if you could post it. Let me know the cost. THanks

bejes,

Sorry for the delay but I don't have enough hours in the day to stay on top of everything.

As long as you make a donation to the forum of at least $12.50 (that will cover postage) I will post tomorrow by Express Post.