OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines VSX160 heat related power drop yoyo

Hi,

I've had a read of many of the threads and currently have my mower in pieces.

It's a VSX160 on a mustang alloy frame with a mulching blade base purchased new in 2003. The mower has worked well until recently and in the previous 8 years has been run on a diet of premium unleaded (98 ron) on a 25:1 mix with a few spark plugs in that time and an air filter. It's used for a 100m2's of lawn every 2-4 weeks.

Recently it started after running for a few minutes to start to drop the revs, it would increase almost straight away and would continue to do this every 5-10 seconds until it became progressively worse and would stop running after around 5 minutes (I suspect this is more to do with the load it's under when mowing and if left to run it would just decrease and increase speed for quite a while), when it's restarted it will run ok for 30-60 seconds and start again.

There is no oil leaking from the top oil seal, everything looks ok in that area but there was some oil sitting in the bottom near the piston and there was oil over the exhaust. There is no oil underneath the mower and all that area looks dry.

The pistons does appear to have a few minor score lines on them but runs fine with no noise apart from when the revs start dropping.

I have not pulled the carburettor apart yet as I'm not sure if this could cause the problem I mentioned.

Looking at the contacts on the side of the flywheel these seem ok but do have a little surface rust on them. The larger set of two contacts side by side with a gap in between are around 2mm gap whereas the other contacts which are smaller on the other side of the flywheel are closer.

The wire all "looks" fine with no sign of wear and the plug looks ok (about 18 months old).

Is it likely that the problem is the electronic coil that is playing up or should I look further, clean up the contacts on the flywheel and the coil along with the connections, replace the spark plug and put it back together and hope that it's resolved? If it's likely that it's the electronic coil I would rather replace it now, worst case is that it's not the electronic coil and I could sell the old one on ebay for probably half what the new one cost.

Any suggestions? Thanks in advance, I've learnt a lot from the posts on here. I can post photos of any relevant areas.