2 stroke wimp can't start 426

zsr

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#1
I've borrowed a mates YZ426 , converted to motard , but cannot start it. I know these things are a 'knack' but have no book to explain where in the stroke the piston should be etc

How do I start this 'kin thing?
 
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#2
If it's not been started for some time (cold, sitting overnight or longer), give it a couple twists of the throttle to get some gas in there - otherwise, don't ever give it any gas in the starting procedure. Starting cold for my bike consists of pulling the choke (enrichment button), pushing down the start lever until it is stopped by engine compression, pull in the decompression lever and push the start lever about an inch more, release the decompression lever and let the start lever return to top of stroke, and kick! Make it a full kick through the length of the stroke, unlike the short, quick sort of kicks used in starting 2-strokes. If it is in good running condition, going through this routine once or twice should do the trick (minus the throttle part - normally I never give the bike any throttle in starting - only when it's been sitting a couple weeks will I give it an initial prime). When my bike is warm, it's the same routine without the enrichment button, and starts first kick (hot start button not usually necessary). When stalled or dumped, the hot start button is added to the routine, and if it doesn't start right away, hold in the decompression lever with the hot start pulled and kick through about 10 or 15 times(no gas!), then try the start routine again - don't forget to push in the hot start button as soon as it fires up! Have fun!
 

zsr

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#3
Thanks S'Pad, pretty much what I was doing (minus the throttle twist - how does opening the slide without engine vacuum get gas into the cylinder?)

Still nothing. Managed finally to get that very convenient plug out and cleaned it up. First kick back it fired maybe 3 revolutions and died. Now its dead again.

Any other ideas? My R1 is seized, need a ride!
 
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#4
The carburator is a "pumper" carb - a special diaphram exists to squirt gas directly into the intake airstream to quickly counteract a lean condition in the mixture when the slide is opened rapidly. As far as what else to try, turn the idle screw clockwise half to a whole turn. A higher idle often helps light these.

Also I would ask what condition is it in? Has the air filter been cleaned recently? Has it ever been rejetted? How old is the gas in the tank? ...these things will seriously affect ones ability to start a YZF.

All else fails, jumpstart it.

- Sean
 

zsr

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#5
Condition? Hmmm. Gets used every day for commuting around London, therefore fuel is fresh, never re jetted, oil doesn't get changes as often as it should......air filter fresh today.

Bump it? Wanna see the skid marks up and down my road? Ive' tried every gear, choke on, choke off......Owner advised into 1st, clutch out roll back til it hits compression, clutch in, run like f@ck and .........dead.

Not to worry, too knackered to ride it now anyway and I don't think the residents of the sleepy little village where I live will think the pipe is as funny on the road as I do!

Thanks anyway, I wonder if those wheels will fit the 250, hmmmmmm
 
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#6
Originally posted by zsr
Condition? Hmmm. Gets used every day for commuting around London...


...well then, someone around you knows how to start it - get them to show you. :silly:

- Sean
 
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#7
If you are going to bump start it you'll need to flick the compression release as you dump the clutch to get the engine to spin up.

You mentioned that the air filter is fresh today? It's common for a freshly cleaned filter to cause starting problems on these bikes, and occasionally you'll see the jets in the air horn plugged from excess oil from a new filter.

Ultimately, it's a easy bike to start IF you follow the specific procedure. Failing that it's a plug fouling nightmare that will send you away annoyed at best.
 

zsr

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#8
The guy that owns (and starts!) the bike is 200 miles away. A mate near here has a WR 400 but he can't start it either.

As far as bumping it, the engine spins, but doesn't fire. We've just got back from a 400 yard hill, the engine turns most of the way down in 3rd, but it's as if the kill switch is on.

It can rot. Thanks for the help.
 

smarttoys

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#9
Why don't you install a new spark plug? I hope you don't think that cleaning up the old one is good enough. Some spark plugs can look fine but have a bad resistor or broken core. A bad plug can spark fine outside of the engine but not spark worth a damn under compression in the motor. A new spark plug is cheap and can save you alot of headaches and it should be one of the first thing you try. Just my $.02
 

07

Uhhh...
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#10
Turned out to be a fractured plug lead.

Now starts 2nd or 3rd kick every time - easy.

Thanks all .
 
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#11
ZSR aka 07 - Okie frowns on people who have multiple registrations out here.
 

07

Uhhh...
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#12
Rich - I know, he is aware of my re registration. My access to the board failed under zsr, I thought to be honest that you had pulled the plug on me, but he says not. He does not know the reason either, so it seemed easier to re register.

Don't worry, I'm not stupid to think I can create a different identity without changing ISP (and personality) - I'll still tell it how I see it, even if it does give you a headache, and I'm still open minded enough to learn.

Anyway, since my son quit after 10 years and I've now crossed the road to dirt divide as a rider, I can see things with a slightly better understanding of what people are talking about.

Chill.

Tony

:confused: