On Tuesday, March 31, 2020 at 1:09:31 PM UTC+11, wrote:
On Monday, March 30, 2020 at 6:56:11 PM UTC-4, BillT wrote:
On Tuesday, March 31, 2020 at 9:08:25 AM UTC+11, SoaringXCellence wrote:
Just saw this on Reddit, looks like it might apply:

"Once I spent an entire weekend trouble-shooting an EX500 (twin cylinder Kawasaki) that would only run on one cylinder. The spark plugs, the float levels, the carb jets, the wiring harness, all connections, even checked the valve clearance and inspected all the valvegear.

Turns out an ant had crawled up a carb vent tube and wedged his tiny little body in just the right place in one little vent tube in one of the carbs. This mighty insect brought 600+ pounds of machine and man to a dead stop for an entire weekend. By weight, that would be like me stopping a cruise ship."

Thanks for the suggestions. I have bought new spark plugs (NGK B7HS) & will fit them for the next test flight. We tested the existing plugs (I won't call them old - they'd only run for 15') hoping we'd find one faulty - covering all possibilities. Rgds, Bill

If it is the pump I replaced mine on a Ventus CM (same engine block) with a Mikuni part no 14-2220 from Parker Yamaha in AZ for $18.42 in 2005 and it still works great 100+ engine hrs. later.

1MD

Apologies for the delay in reporting progress on this (many delays due Covid). Fitting the Walbro carburettor parts, (consisting of the diaphragms, gaskets and metering modules) ordered from SH, resolved the problem. The engine is now starting immediately and producing full power.
There was one hiccup however – initially the engine would start, run for 5 – 6 seconds, cut and then immediately restart. This would occur 6 – 7 times before stabilizing and producing continuous full power. After much deliberation it was realised the drive belts were slipping, causing the engine to over speed and the rev limiter to cut the ignition. Re-tensioning the belts solved this. Regards, Bill