OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions on Other Engines Masport utility 460 2 stroke

This mower feels like its got zero compression. Took the muffler off, piston and bore are almost spotless.
I can't see a decompressor on these, is there another explanation for the lack of compression on this?
It says easy start on the mower but this is ridiculous.

When you pull the starter cord out its full length, you should feel two definite compression pulses.

As a decompressor, this engine has a small hole in the exhaust port (spark plug side).
You wont see it, if it is blocked with carbon. But it is there.

I have had one of these with a partially broken ring, that couldn't be seen through the port.

Not feeling any pulses at all on this Mark. Rings look ok from what i can see, not getting any spark either, this one may be parts only.

It's a Suzuki engine and have been told that it's near impossible to get parts for it.

You could check the online store HERE for Suzuki parts. They still have a few left.

As I'm not getting any resistance when pulling the cord, I thought I'd remove the starter unit and sure enought it doesn't engage the crankshaft, when you spin the blade plate there's plenty of resistance! Is this starter unit broken, I haven't worked with one of these before but others have lugs that engage the crankshaft unit, I can't see any lugs, am I missing something?

Hello tiger,
With your starter, if the single lug that engages the starter cup is not throwing out when you pull the cord, I would strip and clean it.
If you have done other starters, it wont be too much different.

Undo that centre nut and it will all come apart.

If you just want a quick fix to assess your engine, spray some WD40 inside, it should throw out enough to test your engine.

Oh, I also inspect the lugs inside the starter cup for wear, I have doctored them up with a file in the past.
Cheers

Thanks Mark, the lug/dog that is suppose to throw out was getting caught on the starter cap (?) so I bent the starter cap slightly for some clearance and now the lug/dog can spring out, it looks as though there should be 2 lugs and that one may be missing but the one there does engage the crankshaft most of the time. I can't see a petrol primer button on this machine I assume there should be one????

Hello tiger,
The starter only has one pawl that throws out.

There is no primer on this engine, it has a choke.

Try this thread, it will give you some idea of what your up against.

https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=49918#Post49918

The manual for this engine is on this site and available on the web.
cheers

Thanks Mark for clearing that up, it looks like there is a spot for another pawl but it does engage the crankshaft. Thanks for clearing up the primer bit, i suspect I'm going to have issues with the automatic choke, we'll see.

G'day tiger,

Just to clear up a point, this engine has a choke plate that closes with the throttle control. Not automatic.

That mower may have been discarded because of the failed starter.
or
The starter failed because the engine was hard to start.
Anyway, it may run now.

To proceed/assess engine:
Prove you have spark.
Put some 25:1 mix in the plug hole and see if it will fire and run.

Other things to do:
See how clean the fuel tank is.
Do you have fuel (50:1 mix)going from the tank, through fuel tap and out the needle and seat.
(remove fuel bowl or screw in fuel bowl to prove this).

Prove muffler is not blocked.

Before disturbing the carby and governor springs, I would spray carb cleaner into the galleries I could get to. (a bent spray tube can help here).
You will have to remove the air filter box to do this.

Try and start it, ensure your choke plate is fully closed before wasting any of your energy.

I normally remove the air filter box and then replace the 2 x 10mm nuts to hold the carby on. (I know you shouldn't run an engine without a filter, I do it on clean concrete for testing purposes)

See how you go
Mark

G'day Mark, this is an interesting mower. The starter unit does not sit nicely on the mower. As soon as you tighten the 4 bolts the starter cord jams. If the unit is off the mower it retracts perfectly, anyway what I did was put some spacers down under the starter unit/cowling and now it seems to work ok. Got spark, put some petrol in the plug hole and it fires and runs but it shakes a lot and is very loud even for a 2 stroke. Muffler is approx 40% blocked with carbon. Will check the carby tonight. Thanks for all your help, it is invaluable.

Mark, I need to make a point about safety. I agree that running an engine briefly for test without an air cleaner in a clean area will not suck enough dirt into the intake to cause any problems, but there is a safety issue here.

Particularly with an engine that has or may have problems, you have to consider the possibility that the engine will produce a "spit", a symptom of lean mixture which causes a puff, or a blast, of partly vaporised, possibly burning, fuel to be spat out from the intake. Aside from the (probably small) risk of a general fire, when we are working on engines we are often standing close to them. A blast of burning petrol onto a person, especially the person's face and eyes, can have horrific effects.

I confess I sometimes do start an engine without the air cleaner, usually to see if it is the air cleaner that is causing the problem I'm investigating. I shouldn't do this: the way to check for a filter problem is to remove the filter element then put the air cleaner housing back together. However if I do take this rather hazardous short-cut I always do it with the possibility of a spit at the front of my mind. I have seen a lot of spits over the years, and seen a few small fires, some of which badly damaged the bonnet of a car. The ejected fuel often bounces off the hood and ignites the carburetor generally. The fuel in the float bowl will vaporise, causing a steady emission of fuel into the venturi. Sometimes the under-hood insulation burns as well, in which case the whole car will probably be destroyed. Do not perform such tests in close proximity to anything that might be damaged by a blast of burning petrol - especially yourself. And don't ever use an engine, especially a car engine, routinely without at least a flame arrestor over the carburetor. I can recall a greatly-prized Bolwell which was driven to the local shops by the owner's wife, who then stood there saying "Oh dear" while the fibreglass bonnet was burned to uselessness, after the engine spat during startup.

Thanks for explanation Grumpy.
Yes,I fully agree.
Must work safely to avoid personal injury and fire.
I will be very careful in what I advise in the future.

Still had issues with the starter assembly but I think I've got it right now however the cord jerks along rather than a nice smooth pull, any ideas as to why this would be?

If the jerks are consistently every half-revolution of the engine, it sounds as if they are just due to the compression pressures. That is quite a high compression, crankcase-induction two stroke, so you should expect it to feel rather like a chainsaw.

Thanks Grumpy, ironically the mower says EASY START on it but you're right it does have high compression, may get the gauge out and check it.

If you refer to the older thread that Mark posted a link to earlier, you'll find the minimum acceptable pressure is 90 psi and the nominal is 120 psi. This is a lot more than you'll find on a Briggs, for example, because of their EasySpin feature. Also, the Suzuki has a decompression port below its exhaust port, and this may be blocked by carbon build-up on your engine. You could easily check that by removing the muffler: see the other thread for details.

No sign of any decompressor but i've put that on the backburner for now, there is a rubbing/grinding noise that occurs once every revolution of the flywheel/blade plate. It occurs in the same spot, i thought it was the coil rubbing the flywheel but after taking the coil it made no difference. Any ideas as to what this could be? Bent crankshaft?

G'day Tiger, you have eliminated the coil being the cause of the grinding noise.

Those utility mowers can be treated pretty poorly, so crank being bent is a possibility.

To investigate:
Remove spark plug lead.
Remove the blade plate.
Look to see if the crank is baldy bent by rotating the engine, you should notice a badly bent crank with your eyes.
Use your senses to try and find the noise.
You can detect a slightly bent crank using a dial gauge or clamp something close to the crank shaft, rotate the engine whilst noticing the gap.

While your there, grab the crank and check it for movement. Your noise could be bearing related.

Thanks Mark, my senses tell me that the flywheel is rubbing against something but can't see without taking the flywheel off which despite a few attempts including the air hammer/chisel would not come off, looks as though the crankshaft is ok.

I have a collection of these plates to get flywheels off now.
They just pop off, using this method.
Weasel some spray down into the joint.
Thought I would show you under the flywheel.
With the Suzuki there is no need to tap threads.(use the 3 x starter cup bolt threads)

Ok Mark, will fabricate something soon and try it out.

Mark, do you know what the thread size is in the nut/bolt that holds down the cup over the flywheel, I think i've buggered up the thread and nothing spins on it properly.

The size of that screw is M5, not sure of the pitch.

It must be another because it's got a diameter of approx 10 mm.