MZ/MuZ Riders

I've had a persistent problem with starting my Skorpion after it has stood for a few days. It has standard engine and carbs. I have removed the fuel pump, cleaned the carbs, removed the "hidden filter" in the float bowl to no avail. If I leave it for more than a couple of days I have to crank it for ages until it will fire unless I squirt fuel directly into the cylinder. Choke is operating OK. As soon as it fires it behaves perfectly and if I don't leave it for more than a day or two it starts first turn. Anyone else experienced this?

Try replacing the pilot jet with something that will flow more fuel. The stock Tekei pilots are hard to find but the Mikuni VM28/486 #40 will work. It doesn't look anything like the original but it works and your local shop either has one or can order it for you. It may even be a size too large so pick up a #38 too if you can. It runs fine with the #40 but my dyno guy ran out of adjustment on the pilot screw when trying to dial it in.

Is the "choke" or enrichment plunger moving freely? Remove the assembly and make sure it isn't sticking or the rubber has perished

at start up my rotax 500 and rt 125 both get upset if i happen to open the throttle any
when cranking a cold not ran engine that set for a few days

sort of like it does not let them suck in a fresh shot of fuel
dave

I`ve long got into the habit of switching the fuel tap off with the engine running on my return from a ride in order to empty the carb of fuel before garaging the bike.
This was after having the very same problem as you have, usually more like weeks than days though.
Once running it was fine (like yours) which suggests jetting is fine.

breakwellmz wrote:Once running it was fine (like yours) which suggests jetting is fine.

I beg to differ. A bike will idle fine with a lean pilot jet but will be a bear to start when cold or after sitting for a while. There are several threads on this site regarding the pilot jet replacement to resolve cold starting issues. XT225 had the same issues. Unfortunately the search engine on this site is crap so I can't find the threads anymore, but it was discussed quite a bit back when I first joined up.

I take your point.
I suppose i should have said that my poor starting was cured by having fresh (from the tank) fuel in the carb rather than by any re-jetting.

DAVID THOMPSON wrote:at start up my rotax 500 and rt 125 both get upset if i happen to open the throttle any
when cranking a cold not ran engine that set for a few days

sort of like it does not let them suck in a fresh shot of fuel
dave

If it's an enrichment jet rather than a choke flap (which most are) then the enrichment system is ineffective if the throttle is opened at all.

I also tries to switch of the petcock of the fule-line half a minute before stopping the engine. If it does not want to start, open the drain-screw of the bowl so it gets emptied. A trick I've heard from several sources has to be applied to this engine.
But be very careful with the drains-screw, it's very easy to ruin the head if you don't come 100% straight onto it with the screwdriver. And if the head gets ruined it's VERY hard to get the screw out.