Sorry for the cross post for those of you who are also on pwctoday... just looking for some opinions on this one:

Hello everyone... just looking for ideas on why my old GPR maybe shutting down. This issue started just recently. Typically it seems to want to have issues after it has been running for a while and fully warmed up... especially if you let it sit for 10 minutes or so. Below are the two "odd" things that I've seen with it:

Condition #1 (seen this multiple times now) - Ride around the lake @ 50mph or so for 30 - 45 minutes, shut down to talk with friends for about 10 minutes, start the engine back up, idle for ~45 seconds or so, then gently give it a little throttle... as it hits about 3 - 4k rpms it'll die. (At about 1/4 throttle). It will then immediately restart and run fine.

Condition #2 (Only seen once) - Extended WOT the engine started loosing RPM's - it was @ 7000 and started dropping off to 5000 when I released the throttle. It instantly @ that time returned to idle after releasing the throttle and acted completely normal after that.

Ski details:

- Engine and carbs rebuilt last season, including new crank seals, case was pressure tested and has no leaks. Carbs were clean, all internal parts replaced with the exception of the needles and seats which were in perfect condition and showed no wear despite 240 hours of use. Crank has total of about 275 hours on it, but was in great condition last year when engine was rebuilt. About 35 hours since last rebuild, where cylinder #1 seized... never totally figured out what caused that, so just went though "everything".

- Stock jetting, with stock needles and seats

- Compression even and good across all 3 cylinders

- Running Amsoil Interceptor premixed @ 40:1, and 93 octane fuel

- Only modifications are D-Plate, Premix, Solas 13/19, carb T-handles, Pump plug kit, and Waveeater clips / couplers

- Carbs have been adjusted to SLIGHTLY richer (1/8 - 1/4 turn additional) than stock settings "just to be safe"

- I can see PLENTY of pistonwash on the tops of the pistons (via the spark plug holes), though it appears that #3 is running quite a bit more rich than #1 and #2. Spark plugs look fairly "clean" with the exception of #3 which is pretty dark. These readings are after some extended idling so I'm not sure how much they can be trusted. I haven't done a real "plug chop" since I tuned it last season.

- Spark plugs are BR8ES-11's

I'm pretty confident the issue is fuel related, but I can't determine if it's too rich or too lean. If it's too lean I'm thinking MAYBE the fuel selector valve... fuel filter looks very clean.

Keep in mind that none of the issues are consistent. Especially the issue that occurred @ WOT. I've run this thing PLENTY before and since that occurrence without it happening. Also that did happen when the fuel gauge had JUST dropped to it's "two bar" mark in moderate chop, so I can't help but wonder if it just sucked an air bubble.

Any ideas?