OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Victa VSX160 fouling plugs every few months

Hi

I am really having difficulty figuring out why my Victa Corvette Series 700 VSX160 is fouling plugs, every 3 months or so it cuts outs not long after starting and then wont start until a new plug is fitted.

The plugs get black quickly with carbon and get wet with oil around the thread.

I am not sure what to do, I checked the front face of carby and all is clean and sealed, float is ok and needle is working.

Runs great after a new plug except it doesn't seem to rev as high as my dads VS160 it seems to rev lower on full throttle, maybe this is due to the governor?

I also put a new air filter on a few months ago and no help.

I run 200ml of oil to 5L fuel, 91 unleaded and Penrite Greenkeepers oil. Fuel is not old.

I'm contemplating changing piston rings however, I tested compression to 90PSI with the Decompressor on still, but it wouldn't hold the pressure there for long.

I've been told a blocked exhaust port or muffler?

Any help would be great.

I would check the exhaust system to begin with, but it sounds to me like it is running a little rich.

The VSX in my experience, rev's a little higher than the VS if anything, so check the air filter, air hose, and consider giving the carby a full cleanout.

Also check the throttle lever adjusting screw, it may have slipped, holding the mower away from "Run" this is the little screw where the air hose meets the filter block.

Igennerally adjust it so that when you pull up to stop, only about 1-1.5mm clearance is left.

Thanks Mr Davis, Will check the exhaust tonight hopefully, throttle has been lifted and adjusted, revs isn't really my concern, it does rev up more when it requires torque when cutting thick grass etc.

My biggest concern is the plugs fouling, bought it 2nd hand, I reckon the carb has been seller refurb'd but I could check that after the exhaust.

there was a guy with a similar problem below but he never came back with the results. Link to similar issue on Outdoorking

Mine starts with half a pull and operates great except for a little smoke sometimes but I guess it is a 2 stroke...

Any advice on what to check with the exhaust, Im aware of a partially blocked port and a heavy muffler being due to carbon, anything else?

Sorry, I should have made that clearer...

Low revs can be a symptom of running rich, along with the fouling.

So considering I would expect higher rev's from your engine, and the plug fouling, i suspect it is running rich.

my mower is identical to this one

The VSX variates from standard powertorque set ups mostly in regards to the intake.

The air hose is wider, the carburettor has different jetting, the intake manifold mount for the carby is straight, not dog-legged, on top of this, the muffler is an increased flow model.

It is designed to run at slighly higher revs, and overall produce an increased power output.

If the mixture is ritch this can indicate either excess fuel is comming from the jet, or not enough air is getting into the engine.

Due to the increased airflow, this engine can be more sensitive to a dirty air filter, or intake/exaust obstructions.

A rich mixture can cause less rev's and power than the engine is designed to produce, causing a lower temprature, this, combined with the excess fuel can lead to spark plug fouling, oil fouling of the muffler, carbon build up, and further obstruction to the engine.

The first step here is, in my opinion, to focus on the air flow through the engine, check the exaust port, the muffler, the air filter, air hose, carburettor inlet, body and mount, and if neccisary, the intake port, for any sign of obstruction.

Also checking the machine is corectly calibrated at the throttle is important, as it maybe sligly stuck in choke setting.

I prob should have also been clearer, revs don't change to much from 3/4 throttle to full throttle either

On a vsx there should be reasonable increase, once you hit run, the choke should be fully off, causing the mixture to lean back up, on a high airlow unit, this will bring the revs up, without that, it does indeed seem it is still running rich off choke

This is the exhaust port with muffler removed, not sure how bad that is?

It's fine, but there is oil build up.

How are the ports on the muffler?

Just out of interest what type of plug are you using? I find on the newer ones they seem to like a hotter heat range plug.

Ive used champion rcj8y, rcj8 n now an ngk bmr6a

Muffler was not restricted, can blow through it, was carbon on exit port of it

Top of piston i can see is saturated with gunk, will remove head n clean now

Looks like there is some scoring near the exhaust port inside the cylinder?

Starter seal was damaged a bit... Ordered a new one, may as well do the rings now...

Bump, any opinions on cylinder condition?

Hmm, I would hone it, and see how it's looking after that.

Anyone know if running a plug without a resister affects the running of a victa? i.e cj8 instead of rcj8

Suprised no one said the evidence looks like a leaking head gasket?

To me, it looks more like run out when it was opened

Could it be because the poopet valve wasnt set to the C? It was a bit off, could this cause it to run rich?

I dont use resistor plugs in any 2 stroke unless I happen to get some in the bulk lots I buy at auction, recently I have gone onto the very cheap and generic "carlton" plugs with fantastic results, I buy them in lots of 20 and get them in at less than $3 each.

Since it takes a few months to foul a plug, there are a few questions I have, Is the fuel tap always turned off after use? Do you use the start position on the throttle? do you always run it on full throttle?

With all of my 2 strokes, I always start and run them on full throttle, if the carb is working correctly they will start first pull, if the fuel isnt turned off whole the engine is stopped, it can cause flooding and therefore fouling of plugs, running them on a low throttle setting always seems to make them richen up, they are a 2 stroke they like to be revved!

Guy is this main jet normal? Seems to have some sort of hole on the head??

I run a precise mixture of 25:1, always turn tap of after use, run it and starts on full with only half a pull. Revs i believe are ok, just cant work out y its fouling, im guessing its got the wrong main jet or the cylinder is to scored.
I cleaned out the whole carby today n ensured it was set on C.

I heard there are bigger jets n smaller jets, showed mower shop n they rekon mine has the largest hole of the jets??

Hi Gaz01, there are a few jets available and the one i would suggest you try is the one i have circled. i believe it is a leaner jet and given yours is running rich it's worth a try. This particular jet normally comes out on the VE50 models. Replace the jet and read the plug for rich/lean condition after a couple of mows.

The other thing to note(and i'm not entirely positive about this)is the small bearing in the end of your jet is merely a "plug" to fill the hole after the jet was drilled from the factory. That jet appears to be off an earlier model as the later ones were cast solid on the front and all sizing was done from the other end.
Good luck.

Hi, thanks for the info on jets, would u be able to outline in order of size those 5 or so jets?

i.e smallest to biggest, mower shop was only carrying 3 ring jet

Sorry Gaz, i dont know the sizes, and very few can help us on this one. The early victa literature, which is what's more commonly available doent show the later stuff. i checked a couple of VSX160 mowers earlier today and the 2 ring jet was fitted to both of them. The newer jets don't have the ball in them, as far as i know, which is what leads me to believe that yours has probably been changed somewhere along the way.

My new machine!

Hi Gaz01,
And on your new beast...looks very nice...what a shame to get it dirty...
I hope it gives you hours of mowing pleasure mate,

Below is some information on the jets which only cover the later models with explanation.