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 think so when used in ally. Best to stick with grease in engine bolts, although the ali based anti sieze in a mix probably fine.
The problems come in the presence of electrolites(water).
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.
The improved running on fuel off isn't just at the last gasp - it will run for a minute or more - then if I fuel on and off again it will start to splurt as soon as the fuel enters then runs well as the fuel runs down. To me really suggests float level but it is set right - could it be the 10% incline towards the front (engine inlet) putting the level off just enough to muck it up. Only one way to find out ... crikey these things must be finicky about fuel level!!!
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
I made a small rubber seal to block the choke and can now count that out of the equation.
I think this is important - once fuel is switched off and the bowl starts to empty everything runs better - is the problem is float level however there are some issues confounding me:
the fuel isn't coming out the overflow - could this be affected by the 10 degree incline - or is too high but not high enough to flood
I know how to measure the level and it is set spot on according to what I have read ie: 15-17mm from gasket indent to tang touching needle
I guess not being certain of the model number doesn't help..
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.
Nice bike. What are the 240s like to ride compared to the 280cc? Sweeter I would imagine. Does anybody know where you can get the protector plate that sits under the kickstarter?
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.
Yes Hekto but in this set up doesn't the fuel have to negotiate the main jet in order to get to the needle jet... I am only guessing - to be honest I originally thought the setter was the main jet. With the o-ring around the setter how else does the needle jet get fuel - but through the main jet. Although I agree this wouldn't appear to address the air filter issue.
I also admit I am confused that the air filter is causing the engine to die (its clean) to me it means the mixture is still very rich - so I have to assume my o-ring isn't providing a suitable seal on the setter. This would allow the engine to suck fuel direct from the float bowl through the setter.
Eveything I have read about Mikunis on Montesa mentions main jets much bigger than the #90 I have at the moment and so I have tried to order a range of larger - foolishly tried some crowd in New Zealand ( SME ) cheap but hopeless communications.
I will try and pick up an o-ring tomorrow in Dorrigo - but I am not holding my breath
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.
Tighten until it doesnt stick and no play is present. Could be bushes are worn irregularly. Easy to make a new set with small lathe and a 14mm drill or Martin Matthews at motoswm could prob sell u some decent ones at a reasonable price...
Stu
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.
aha - there is no o-ring - well that explains everything .... I'll see what I have in my o-ring box.
Thanks again Ross for the offer and I may take you up - I just couldn't figure out how this carb could be so far off as to not even run badly and now I know why. I fitted an o-ring and away she goes.
It dies if I put the air filter on so my o-ring may not be sealing correctly - No amount of air screw adjustment affects it with air filter fitted but it works a treat without it. Anyway I have ordered some larger main jets - I guess that having the main jet on the feed side of the system means it affects the fuel flow for all stages but idle. I guess I also need the larger idle jet as well.
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.
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).
Just to add another opinion, i have run 60:1 full synthetic for 15 years in my SWM and again, have had no problems. The engine being very clean internally with minimal smoking.
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.
They are a noisy engine after a few years, piston slap being particulaly obviouse.
Get ear plugs, run mineral oil at 32:1, change the gear box oil regularly (check which is the drain plug)
Check the fly wheel nut is tight.
Routine maintenance.
Enjoy.
And check the kickstart allan bolt is tight.
''
Thanks ... sounds like I have to do it the same way I drive mu Ducati ... earplugs!
About the oil-mix. You recommend 32:1. Others say 40:1 and syntethtic. I'm sure that 32:1 is more 'safe' but are the any problems with it ... and why mineral oil?
I have acquired a TL320 this summer. I know these things are quite noisy - and nearly bullet proof. Inspections of clutch (to try solving the clutch'problem') and inspections of barrel and head, indicates that the engine is very fine. Anyway - it has a lot of mechanical noises and there seems to be some play either at the top-end or the big-end of the rod. I haven't measured it and it is just recognisable. (A lot of the noise is transferred by the fins on the head I have noticed)
Do anyone know where to find the specifications of service limits, wear outs etc. for the Rotax engine?
From a copy of a US maintenance manual I understand that there should be a kind of external stop for the kick starter to avoid damage to the left side engine (clutch-) cover.
I can't see any such mechanism on my SWM. Could anyone please describe it for me - if possible with a picture too?
Kawasaki kt 250
in Twinshock
Posted
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.