OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Victa Tornado Surging

Hi All,
Had an issue with my Victa Tornado 2 Stroke a few months back where it just shut down and refused to restart. No idea why as all the usual suspects (i.e. I ran it out of fuel, bad spark plug etc.) seemed fine. Figured it was about time to do a full rebuild on it so pulled the engine apart and put it back together with all new parts including:

• Diaphragm
• Needle (Black)
• O-Rings *3 to overhaul G4 Carby
• Electrical Boot
• Primer Cap
• Air Filter
• Fuel Tap (and filter)

Assembled the engine and it would start and run but after about 30 seconds would start surging badly. The top of the revs in the surge seemed "normal" but the lower bounds of the surge would usually cause it to shut down/stall. Checked the needle and found out there are multiple different types of needles (thanks to this Forum for this one). Mine was pinkish in colour but supposedly the yellow one was longer and more in line with the length of the previous one. Put that in, still no luck. Rechecked the jet and gave it a good blow out/fine piece of wire to make sure nothing small was in the hole but again no luck.

Tried a compression test and was getting 50psi with the decompressor plugged up. Seemed low from what I had read elsewhere/experience from previous engine rebuilds etc. so went deeper and replaced the following:

• piston
• rings
• starter housing o-ring
• decompressor (decompressor was fairly gunked up and was cheap so just replaced it)

Still the same issue (starts first pull though now so it's an improvement). Rechecked compression and was still getting 50psi with the decompressor plugged up.

At this point I was running out of ideas so tried the old pinkish needle and it seemed to work MUCH better. Now it's running and usable but it still surges albeit not as aggressively. It appears as though the top of the surge is now possibly a bit fast as it gets quite a rattle up before slowing down (not too dissimilar to pushing through a thick patch of grass). It doesn't shut down/stall now though when it hits the bottom of the surge.

I'm seriously at a loss as to why this is happening. I did have a quick feel of the main bearing/crankshaft when I had it apart for the piston and it didn't seem to have any play in it. Has anyone had similar experiences or issues or can anyone offer any suggestions on where to look at next? It's a seriously good mower but it is quite annoying when you have to be careful how much grass you're cutting/how fast you're pushing near the bottom of the surge to stop it from stalling. Did have a bit of a search again through these forums and the manuals, which I now have access to, before posting for help however nothing was jumping out as being something I've missed or haven't already done.

Any help would be much appreciated.

Tyler

I think the surging problems are connected to the carb.....I've had a few I couldn't fix, changing parts etc...
Maybe change the O-ring on the carb manifold and check the screws a firm. Check you haven't got the diaphragm installed a bit off on one side, and you have all springs and that flat plate at end of poppet on. I forget parts sometimes.....
speedy

Hi Tyler (good to have another Tyler on board haha)

Most definitely, as you have found, part of the issue is those terrible black plastic needles. I suggest buying one of the carby masters metal needles, soak it in 2 stroke mix for a few days, then let it dry to cure the viton tip.

They usually work out of the box, but sometimes the soak helps.


I have a technical service bulletin released by victa regarding the tornados with 2ring jet surging, will post this afternoon

Regards
Tyler

Hi Tyler,

That's a great dedication and love of your Victa machine to go over that far of repair especially rebuilding the engine and changing the decompression valve because of surging and with only 50psi compression which is normal compression. Surging happens if when the delivery of jetting fuel and diaphragm vacuum is not been controlled similar to electronic feedback e.g. AVL or automatic volume control. Make sure you didn't swap the control and return springs, check setting of the poppet valve, check the diaphragm cap lip if not damaged, check diaphragm cap plug if secured and sealing properly, check the governor hose or tube if not damaged, check the governor vacuum nozzle on the base of the engine if not blocked with grass or dirt which could restrict the vacuum. Check the vacuum tube attach to the carby by applying 10psi pressure and it should maintain and hold that pressure if there is no leak. You can view my YouTube below for check valve setting. Anyway you've done a good job!

CM

The other thing to note is many of these tornados utilise a 2 ring main jet. They leaned them out from the typical plain face jet.

You could try a different jet if you have to use it, but since you are probably close to finding the actual cause, I would keep looking.

Haven't found the TSB from victa, but one thing I remember it saying was plastic swarf at the air filter housing inlet (where the snorkel attaches to.

Also check for bits of the old foam sealing ring getting stuck in the pipe inlet - you wouldn't be the first to have that happen

Wow to completely rebuild the engine because of tuning issues?? Baby with bathwater stuff.

It's nearly always ancillary issues. Rebuild motor if it's decades old and tired or been straight fuelled or damaged in some way, not because it surges or stalls!

At least you know your motor is not the problem now!

Hi all



50 psi sounds a little low to me with new rings ,I would be checking that the head gasket is not leaking compression,
when the head is removed you can check how straight it is with a steel ruler (straight edge) .

When the motor is complete you can use soapy water around the outside of the gasket then pull the motor over
with the plug lead disconnected and see if there are any bubbles or put some oil in the plug hole then put the plug back in
and spin the motor over to see if any oil spills out between the gasket.

Start the engine., feel around the head/cylinder joint for streams of escaping exhaust gasses. If you find places where a highly pressurized stream of hot gas is escaping it means the head gasket is leaking.

https://www.hunker.com/13404541/how-to-diagnose-a-2-stroke-head-gasket-leak




Cheers
Max.

Wow, didn't expect so many replies with so much detail so quickly. Will give all these ideas a good crack this weekend and see what I can find with each. Regardless if it works or not I'll come back with results for all tests/checks for future reference (always hate it when someone posts something, gets answers, then never actually bothers to confirm what worked or not).

If you want to use it as a mower to slash through anything do the carby mod you won't have any surging problems. Could have saved you a heap of money and time.

Ok belated reply seeing as the weekend and first half of the week got away from me.


I'll start with the poppets, that's one detailed video. Can confirm I'm using the middle white with A/C poppet. Can also confirm that it's set on "A" and has been the entire time. What I can't confirm is what it was set on before I took the thing apart the first time (will know for next time I work on one of these engines to check it). Could try C seeing as the two are nearly identical in terms of RPM from your tests however not sure it would make any difference?

I'll pull the carby apart again proper later (ran out of time doing other checks) however all the hoses were replaced as one of them was looking quite stiff/sad and they gave me heaps of the tube so figured I'd refresh them all. Are there any special tricks for checking the governor vacuum nozzle or will poking a bit of wire through the hole to make sure it's clear be sufficient? You also mentioned to check the vacuum tube attached to the carby by applying 10psi pressure and it should maintain and hold that pressure, any suggestions on how to do this easily? Can probably get creative and rig something up to test it but wanted to see if others had easy at home solutions I could use.

As for the 50psi, I'd read elsewhere that 50psi was low (and experience from other engines was that 50psi was also low) and the new piston rings was only like $40 so wasn't too worried to swap them out as I'd rather have this work than buy a new mower which isn't as bulletproof.

Is there a way to determine the difference between the control and return springs when I pull the carby apart next?




Checked the intake and the air filter housing inlet including the hose that goes from the filter to the carby and it all seems clear. Bit oil/fuelly but clear none the less.




Ok tried to compression test again (have used a lot of Pushmowerrepair's videos as guides and bought most of the parts from his shop) with an old spark plug in the decompressor. Got 50psi cold. Tried the soapy water trick around the head and spun the motor a few times, couldn't see any bubbles forming. Then pulled the head off to have a look at the gasket and if the head was straight, head gasket seemed intact (until I destroyed it trying to take it off to check the head face). The head was most certainly straight with the steel rule. Did note that the head gasket I'm using is more of a "paper" type gasket rather than the metallic one that was on there originally, not sure if that's good, bad or indifferent. Regardless, reassembled the head and tried another compression test with the new head gasket and it got 60psi, so slight improvement. Did give the head a good clean (including scotch brite to make sure everything was removed)

Haven't checked the hot streams of exhaust gas yet. Will do the carby checks suggested by some others then I'll do that when it's back together again.



Will keep going with the carby later today or tomorrow and see if there is anything else I find along the way. After that I'll try running it again, do the exhaust gas leak check and maybe try the "C" setting for the poppet and see how it goes.