MZ/MuZ Riders

Hello all,
Just been to try to start my Baghira and it turns over fine, strong battery, but wont fire at all, jsut a muffled thud, thud, thud.

Tried it with choke on, off, throttle open, shut etc.

The only thing I can think is that I left it for 2 weeks with the fuel turned ON (i'm used to bikes with vacuum fed fuel taps so the fuel stays on all the time)

Presume therefore its flooded????

So, whats best to do????

Get the plug out and give it a clean???

Is there any knack to getting the plug out, it looks like the side bodywork and radiator need moving or removing????

Thanks.

It can't be flooded because you left the petcock open. The float needle valve sguts when the level is reached. Ehen it doesn't seat, the gas runs out on the floor thru the bowl overflow and that is lower than the the throat of the carb. I never close the petcock: my Skorpion doesn't have one and the SZR's is unreachable.
It can be flooded cause you overdid it. Leave it alone for an hour or two.
If you have misgivings that the ignition sparks, pull the wire from the plug and try any old sparkplug, grounding it against the engine somewhere. Easiest way to take out the plug is to take off the tank. (on the SZR, the only way) Using the original plug wrench that came with, you can remove the plug under the tank - a pain and not it.
Normally the problem is simply stale gas in the float bowl. The stock Teikei carb has no functioning accelerator pump(the thing it has is a bad joke) and is touchy to start, with or without choke. Many Skorpionisti shut the petcock and let the engine run until it dies. That way, the bowl is empty. When you open the petcock, it gets fresh gas.
With the SZR, I go out, pull the choke, twist the grip 2-3 times and turn it over 10-15 times, then turn it off and go back in an put my druck on. Takes at least 5 minutes. It usually starts then.
With a decent carb like a Mikuni flatslide, I go out, turn it on, twist the grip once, no choke, and push the button. Bums.
No matter how long it's been unused.

Cheers for that Bill. I understand what you are saying about flooding, thanks.

I managed to get the plug out with the toolkit spanner without having to take the tank or anything else off and the plug looks clean and dry and a grey colour.

Fuel is only two weeks old, so shouldnt be stale yet.

I think I will treat it to a new plug anyway, then remove the plug cap and use the new plug to test if there is a spark but I am thinking there probably isnt....

Fuel is only two weeks old, so shouldnt be stale yet.

I meant the gas in the float bowl, not in the tank. The surface where the fuel oxidizes is quite large in this case, since there ar two chambers, only one of which is a true float bowl, the other has no float, just gas.
OTOH, starting with choke only involves the real float bowl, i.e. the left side of the carb so in fact some stale gas is in fact drained back from the right side before the needle valve actually opens to any extent. Without any intake vacuum the right side does nothing at all. thus,m it takes longer than with a normal carb to suck fresh gas into the bowl and that is why many opt to close the petcock and let the engine run until it runs out of gas. When you then open up, the left side fills immediately with gas from the tank. This can only work with a manual petcock, not with a vacuum or electric one.
I have never done this myself, however. If you regularly use the bike, there are no problems. I do not own a car.

Run a piece of hose from the bowl drain into a container and open the drain screw. Let it run for a bit and then shut and retry starting the engine. At least this gives you fresh gas to start with. I do this trick on my nighthawk (4carbs) if it sits for a month between floggings and it works every time.

OK, had another go at it today and it still wont start

Got a new spark plug. Pulled off the cap and tried the new plug outside the engine, earthed on the cylinder fins and it sparks OK.

Took the old plug out to swap with the new one and tried this one outside the engine also, and that sparked fine too.

Pulled the petrol pipe off the carb and turned the fuel tap on the tank to "on" and fuel cam through so...

1. Tank has fuel in it.

2. Fuel is getting to carbs ok.

3. Plug is sparking ok.

4. Battery is charged up and strong.

So could it really be down to stale (three week old) fuel in the float bowl causing it to not even fire up at all, not once, as you say Bill??

I will drain the float bowls next and then try again, but any other ideas?? Anyone??

dave

Do drain the bowls you might be surprised.

When you pull the plug is it wet?

Will it fire on starter fluid?

Mmmm... when did you last do a compression test?

from distance, it strikes me that the is being turned a lot in trying to start - an aweful lot more than the normal battery will take.
Compression test?
that isn't possible with this engine due to the auto-deco.
Check the valve tolerances now (0,10mm intake, 0,15mm out). The outlet valves tend to get too close.

before fooling around more, take out the float bowl plug screw on the underside.
Once drained, open the petcock and check that the flow is sufficient out that hole.
If not, remove the carb entirely and dismantle it. Clean the passges with petroleum and air pressure.
The needle valve has a very small sieve which clogs easily.
Wipe out the bottom of the airbox. How much oil was in there?

I have encountered all of this.

Plug is not wet when I take it out, even after I've tried to start it for a while. Its a grey colour.

Maybe it should smell of petrol more when I take it out after I've been trying to start it for a while.....? No fuel?

Carbs were taken off very recently and completely stripped and cleaned because the bike had been standing for 6 months. (see my other thread...)

Then I put them back on, fresh fuel in the tank and went for a blast, and it rode and ran great.

Originally, the air box had a fair bit of oil in the bottom when I took the filter off when I did the carbs. I presumed this was oil that had dribbled out of the air filter after it had be re-oiled by someone. I cleaned out the airbox and put the filter back in 'dry' so I will check in there again tonight.

I'll also drain the bowls and see if they refill ok whith the petcock on.

Probably need to charge the battery too.

I want to check everything obvious that I (or you) can think of before I start ripping the motor apart or taking the carbs off again.

Thanks for eveyones help so far. I will report back soon!!

dave

Try some starting fluid to see if it fires up,spray into the left carb,it should start..silly,but is the choke on?

Chip

Well, its still not running Got a good spark and a charged battery, but still seems to be no fuel.

Took the carbs off AGAIN (loosing another two knuckles!) and stripped them down AGAIN

The float bowl was pretty much empty (Its difficult to tell as some fuel spilt out when I took them off).

I know fuel was flowing from the tank, so I'm thinking maybe the small valve that the float presses up on to cut off the fuel flow was stuck up, or maybe the float itself was stuck up, so no fuel was getting in.

Had all the jets out of both carbs and blasted them through with carb cleaner and all was/are clear.

Got to re-assemble now and see what happens.....!!

BTW I need a new rubber gasket for between the carb and the float bowl. Rang Yamaha and they can do one (for the SZR/XTZ) for £7.50UK.

Anyone know where I can get one cheaper??



Dave.

still say try some starting fluid...spray into left carb...should fire up...chances are the pilot jet may be plugged up...but if ya cleaned it all shouldnt be that way

If you have doubts that fuel is getting into the carb you do not need to go thru mounting them on the engine to prove it. With your carb horizontal on the bench just fill a piece of cheap vinyl tube with gas and hook it to the carb. Raise the tube above the carb and you should be able to see fuel flow into the carb bowl. Keeping adding fuel in this manner till it no longer flows. If the fuel flow stops before anything flows up into the carb throat you can be fairly sure that the float and needle are working properly.

I have also checked the float needle by very lightly blowing in a clean fuel line and with the bowl off, slowly raise the float (mimicking what fuel should be doing) when the float gets to the right height you should "feel" the needle seal in the seat by a little back pressure in the tube in your mouth. Be gentle there is no benefit in forcing things.

Hope this helps.

know one has mentioned the filter hidden behind the float needle inside the carb
what a pain
dave

Is this the mystery 'tiny mesh filter' ?

I've searched on here and seen it mentioned, but cant find any info on where it is. I cant see it on the carb diagram someone kindly posted up either.

Where will I find it??

Dont want to put the carbs back together and back on if I've not checked it first.

Can someone point it out in any of these pics?









Cheers, dave