hekto

First of all - a zener diode can not solve the problem. It should handle alle the current when voltage comes over 12 Volts. You have to check all the wiring and especially the grounding wires and connections. Systems with 'light coils' are normally not regulated. The voltage (AND frequency) variates with RPM's (naturally). You therefore have to be sure that your meter can handle the frequency to get the correct values when you meassure. Start to meassure close to the wires comming from the engine. Then measure the voltage on the wire feeding the electrics still holding the refference to the engine case. Measuring any voltage across groundings or gound wires (say about 1 Volt) indicates brocken wires or bad connections.

I like it very much! Excellent job! Look forward to hear how it act's on the trail!

I have a pair of Rear Shocks for my SWM that I'm not able to identify (see pic.) Each have a hose fitted on it of about 150mm in length. The end of the hose is plugged. There seems to be no pressure in the hose. Does anyone know these schoks and what these hoses are good for? (if of no use I would like to remove them)

Just a comment: The Rotax engine is made by magnesium alloy. Magnesium reacts with water. So it has to be painted and i.e. stainless bolts needs grease not to seese in the threads. I would also use ordinary grease or one of the newer ceramic based anti-seese greases.

Just: WAUUUVV!!

It could be the float hight. Certainly. On my old Ducati both carburators at tilted forwards. They run with the standard float hight, and there are no recommended modifications from that. Somewhere there must be a specification of the float hight on the Mikuni

The float level is important. Too low and it will not pick up. Too high and it will give too much fuel. It doesn't necessarily have overflow. When you switch off the fuel and the bowl run empty it will on a certain point deliver the correct mixture - but it only indicates that the fuel mixture is too rich. Nearly all engines will rev up for a second when the bowl runs empty. If not it's the choke and if the float level is correct you may turn to the needle valve. Maybe that is fouled up and doesn't move freely or it even may be worn out.

Regarding the Kick-stop you may try Martin: http://www.motoswm.com/ Might be that I bought the last one!?

A 2-stroke engine where the piston controls the intake will always 'spit' out some fuel/gas of the intake. It depends on the timing and will normally be at low RPM's and during starting. This is due to the fact that the intake timing always will be symmetrical around TDP. Different arrangements with membranes and discs eliminates this. This is in general and I'm familiar with the actual design of your bike. How about the choke-system? Normally it's an independent air channel opened with some kind of a piston. It supplies fuel/air in a channel that surpasses the normal air intake. You write the fuel send backwards is building up? Is this during tick over or when you drives on it? It couldn't be oil that builds up in the crank? I can't see that the o-ring should do these problems.

I'm most familiar with Dell Orto - Italians freak u' know! I think that Mikunis works very close to how Dell Orto's do. If you don't know where you are with the mixture it can be a good idea to start with the standard jetting and take it from there. Then make a 'tape tuner' for your gas grip, with marks for 25%, 50% 75%, 100%. There can be a great difference in what you feel is the throttle position and what it actually is. It take some while to get it optimal. This manual is very detailed and gives a lot of excellent explanations: http://www.guzzitek.org/documents/carburateur/DellOrtoMAJ01.pdf

Thank you Stu. The bushings seems OK. It was the mix of lubricating nipples and rubber bushings that confused me. I remember that a scooter with an bearing arrangement of the same kind at the front wheel should be tightened so that it only moved in the rubber. Further the swing arm should be positioned in a specified angle so that the damping from the rubber contributed to the overall damping.

About the main jet your assumptions are wrong. The main jet only affects the mixture when you are running full throttle.The needle and the needle jet covers most of the throttle positions. But the idle jet (pilot) also affects the size and position. More info: http://www.dansmc.com/carbs2.htm

I have a question about the remounting of the axle for the swingarm. How much do I thighten it? To a specific torque or just as much as it moves freely? It's a SWM and I'm pretty sure that the 'bearings' for the swingarm are some 'rubber-thingies' like silent blocs. The center-bushing of them seems to be a little bit wider than the outer bushing (with the rubber inbetween).

I think it might be welded with some luck; but it will need some machining afterwards. You could also go with 3 springs?

Hmmmm ... 3% ... 2,5% ... 1.6% It seems that the Rotax engine is very tolerant. I don't have that much experience with it to say how much it will foul up the exhaust. I think I will stick with the 2,5% (40:1) for a while. The modern 2-stroke oils are a lot better than in the older days; but I have had en Yamaha RD350 that ran 60.000 Km's on plain Castrol mineral 2-stroke oil with out any problems. (the I sold it) The gas pick up on the SWM is as you point out .... very slow. I can see that it is recommended to remove 500 Grams. I will try that some time.