Kikuyu grass keeps clogging the deck on an old Briggs rotary

[Mxolisi Jaxa]

Hi all, first post. I'm in Gqeberha in South Africa, so some of what I describe might be a bit different from what you get in the UK, but the machines are mostly the same.

I've got an old 18 inch rotary with a Briggs & Stratton 3.5 hp side-valve, no brand name left on the deck, bought second hand years ago. The lawn is kikuyu, which if you haven't met it is a thick runner grass that grows like mad in summer. If I leave it more than ten days the mower bogs down and the underside of the deck packs solid with wet clippings, then it starts throwing them out in clumps and leaving stripes.

Things I've tried: sharpened and balanced the blade, cleaned the air filter, cutting higher and doing two passes. It helps, but after about half the lawn I'm on my back scraping the deck again.

Is it worth fitting a mulching blade or a higher-lift blade on an engine this size, or will that just make it bog down more? And does anybody put anything on the underside of the deck to stop the build-up? I've read about silicone spray and also about people painting them, not sure what actually works.

[Mxolisi Jaxa]

Quick update in case anyone else with kikuyu finds this thread.

I did the cheap things first. Scraped the deck back to bare metal, wire brushed it, and gave the underside two coats of silicone spray, letting the first one dry for an hour. Cutting on Saturday it went the whole lawn with only a thin layer stuck near the chute, which is a lot better than before. Not sure how long the spray lasts, I'll see after a few more cuts.

The other thing that made a difference was timing. I used to mow late afternoon after the sprinkler, and the clippings were basically paste. Mowing before lunch when the grass is dry, with the wheels one notch higher, the engine hardly bogged at all.

I haven't changed the blade yet. A high-lift one for this model is about R350 at the local spares shop, so I'll try it once the current blade needs replacing and report back on whether the 3.5 hp copes with it.