OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Power Torque muffler getting hot. Melting cowling.

Hi guys,

I need some advice. I recently swapped out a badly scored 1996 chinese power torque for an earlier aussie power torque in great condition. I swapped the starter from the chinese engine and the coil and set the air gap to 0.25mm. I serviced the carby and fitted the red deluxe cowling from the chinese engine. It starts with the slightest pull from cold and is one of the smoothest running power torques i've come across. I run it at or near full throttle however the muffler is getting so hot it is melting the cowling above. At the time i was using 98ron so i switched back to 91 but its still happening. I swapped to another 'good' muffler but its still happening. Have tried experimenting with oil/fuel ratios from 25:1 to 40:1 with no avail. It doesn't appear to be running lean, it runs and sounds great, i've rechecked the piston and it looks great, no scores just a nice film of oil. Any other ideas? Does the aussie engine run hotter?

Cheers,

Dan

Too hot = too lean. Check manifold o-rings, also starter o-ring.

Re-read your post...if you serviced carb ensure that the "C" is directly next to the spray jet / primer side of the carb

Definitely set to "C", i replaced the starter oring when i swapped the starter. I haven't looked at the other orings because it will happily idle really nice and low so i figure theres no vac leaks? Spark plug doesn't really indicate she's lean either, maybe i should try setting "A" see if it helps?

Hello Dan265 and Dieselboy,

I have seen Victa documents explaining the differences between these
engines. One point made was that the newer engine was cooler running.
I'm hoping a member will remember and produce that document.

Hope this helps.
------------------------------
JACK.

Long shot, remove Chinese cowl and run "bare" .....does it still run hot?

Hi Jack, i believe that document refers to the newest power torque 2/eco torque engines. I have a couple here they have the revised cooling fins and extra webbing and run cooler despite being leaner.

Dieselboy it's hard to say these motors do get bloody hot, i only its too hot by the fact the cowling was melting above the muffler. Whether the engine itself is running hot or just the muffler is getting really hot, i'm unsure. Gonna try another muffler again and see how we go.

My thoughts are that the cowling is not the original and may be too close to the exhaust. The exhaust does get very hot, hence carbon been formed by over rich conditions. If you have access to a non contact thermometer, I will measure a couple of my motors running under load....

Good point i'll check its location on the original motor. I might be able to get hold of one but will be interesting to see the temps either way. I may have found atleast part of the problem, seems my cowling is missing the black shield above the muffler as seen on this mower. Also stumbled across a picture of another mower missing the shield and the cowling was badly melted.

Damn just found a note in the manual "NOTE - DELUXE COWL HEAT SHIELD DISCONTINUTED 6/00" Might not be the original cowling, original engine stamped 1996, original cowling probably melted lol.

Well i believe i found the problem. I knew it was revving fairly hard but it sounded fairly comfortable doing it and i put brand new genuine springs in the carb (red 150g) so figured thats how it was. As it turns out she's been revving over 4800rpm! lol 3100rpm is about half throttle! Quick check shows the vacuum nozzle on the block is stuffed, does nothing at all. Sucking on the diaphragm cap drops the revs as it should, time to swap the nozzle off the original motor and see how it goes.

No change, original nozzle was fine anyway, no blockage. Why would it not produce enough vacuum to control the governor? Tired swapping slightly different bottom plate also.

G'day Dan265 definitely keep the poppet valve on C that's the richest tune, going to A or B will lean it out more and with that comes more revs and heat...Try putting brass spacers in the carb (see pic) I've run up to two to bring revs down, yours may have one if so try two,I don't know part numbers or what Victa call the brass spacers but that's there job take any wear out and bring revs down worth a try.. As you have said with the missing black heat shield that would be why the cowling is melting.. Cheers Chris

Valve is on 'C' mate. I dont think it needs the washers as it happily idles very low. Like i said ive got no vacuum to the governor, disconnecting the hose does nothing. Have tried new hose, other vacuum nozzles still nothing.

Ok well as long as the vacuum control button is installed the correct way all should be good on that side of things..My guess is it has the wrong spring and is holding the poppet valve open...I'd try a known good carb to start eliminating things.

Thanks to all who replied, finally got there in the end not 100% sure how lol tried another vacuum nozzle made sure it was nice and tight against the block and cleaned all around. Refitted original baffle plate, then thought why not check the inlet manifold, screws were completely loose, no cracks or leaks, oring looked fine, so added a smear of loctite 515 and refitted it, tight this time. Bingo! governor is now controlling revs 3400rpm, no more melted cowling.

I'll be following the information on this thread to see if this sorts out the exact same issue I have with the same engine/cowling configuration on an original 160cc PowerTorque motor.
Swapped over the base from a blown Tecumseh 4-stroke as original base was knackered and noticed the cowling had started to melt over the muffler. It wasn't until I got the motor running and mowed a section of lawn that, when I had run out of fuel, I noticed smoke coming out from the cowling and found the larger hole melted above the muffler.
The mower was running at extremely high revs on full throttle, would idle reasonably low, could vary revs using the throttle and there was no noticeable blue smoke, being a 2-stroke.
Fuel is a minimum 25:1 mix, as I added the oil myself, but took a chance on a 5L tank of fuel that I got from someone else. I don't know if it is 98, 95 or E10 and they said it was for their old 2-stroke mower they had recently sold. In my mind, the fuel was too clear to have had oil in it, so I added oil to be sure it was at least 25:1. I know this was not the right thing to do, and I should have just used the fuel to clean engines and parts, but it seemed too much to waste.

Photo below shows how bad the overheating effect on the cowling is on the machine I am working on.


Here's the colour of the new CJ8 spark plug after a tank of fuel had been used when mowing yesterday.


Based on the colour of the plug, machine appears to be running lean so, according to the above post information, changing the Poppet Valve position to C should correct this.

Will start by: -
1. Changing the position of the Poppet Valve from A to C
2. Check Vacuum Nozzle, as the machine was revving very high on full throttle and didn't appear to have any speed variation from the governor/vacuum
3. Remove and check Inlet Manifold internal O-ring as the external manifold O-ring looked fine. I did notice the top screw on the inlet manifold was a fraction loose (about 1/8 of a turn) when I was fixing the cut-off wiring and the bottom screw was tight.
Hopefully, these will sort out the issue I am having.
Although this post is 12 months old, I will advise outcome of these changes to help others who may be having the same issue, now being summer and all, with heat during the day not helping.
Thank you.
Daryl

Hi mate, the mower from my post is still running great with no over revving or melting. Disconnect the governor hose and blow through it to check the nozzle isn't blocked. If ok, disconnect the hose at the nozzle, with the engine running suck on the hose and confirm it brings the revs down. If ok, replace both inlet manifold and starter orings. If no change remove and inspect the governor diaphragm. It's the over revving that causes the excessive heat and melting.