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bobpara

Cold Starting Problem

12 posts in this topic

I have an '06 WR 450 with a carb (not FI)

I have checked all of the valve clearances a short while ago and they are in spec

 

If I have started the bike recently ( within 1 week) it lights almost instantly

If I have not run the bike in 1 - 2 weeks, it is incredibly hard to cold start.

Ambient outside air temp does not seem to matter too much ....ie, warm or cold out same problem

 

Here is my theory, and I'd like to bounce it off people who know and own this bike:

I think the fuel cock leaks just a tiny bit

I think the bike is basically a bit flooded when this happens

When I put the choke on to cold start it probably makes the situation worse.

 

To test this theory, If I have not run the bike in a few weeks I should start it as if it is a flooded bike and see what happens

Hold bike at WOT and hit the starter

If it starts better, my assumption is prob correct

If it does not, back to the drawing board I guess

 

Has anyone had a problem like this?

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I agree

Rebuild the float needle and polish the cavity it sits in and inspect the seat for pitting

 

 

If you hold the throttle wide open, hold the kill button down for several fast kicks, it will clear the cylinder before starting, making it start normally, afterwards

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Really depends on your jetting in the first place. Generally bikes either start well cold or hot but not often both.

As for flooding.... after sitting for a while your cylinder will be dry of fuel and your spark plug will be dry (ie. not flooded).

To test just try starting it cold and when it doesn't start after a few attempts... pull the plug...if it's soaked you are flooded.

I would guess it's more likely a slightly dirty or lean pilot is the problem. A cold bike is leaner than a warm one.

Get a new plug. I have found the "K" type plugs (CR8eK) most reliable when adjusting jetting. 

Try priming the fuel a bit first but turning the throttle 2-3 times. Accelerator pump will squirt some fuel into cylinder.

Then try starting.

My bike was always dodgy cold but starts better with a few twists first.

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The key part here is TIME

If I started it 1 week ago, it fires right up

If I started it 2-3 weeks ago, its a MoFo to start

It cold starts just fine so long as I started it less than a week ago

 

That is why I suspect a very small leak coming from the petcock or, as Ka Ra Nee notes, the float

I very religiously turn off the fuel cock when I park the bike

Perhaps the reason why I dont have a major flooded bike when I come back 2-3 weeks later

....not that I want to test it either

Imagine if Im right and the thing is all hydo-locked from fuel !

 

I think I have 4 things to rebuild/check:

1) Fuel cock

2) Float seat (carb coming out soon anyway)

3) Poss go 1 richer on pilot jet or clean it

4) new plug

 

Thanks for the advice!

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I hope your not trying to use the button to start it. Yamaha 's Electric start is a joke! I own a 12 wr450 13 wr250 and ride with a 14 wr450. None start worth a crap. I actually embarrassed to ride with other brands

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I hope your not trying to use the button to start it. Yamaha 's Electric start is a joke! I own a 12 wr450 13 wr250 and ride with a 14 wr450. None start worth a crap. I actually embarrassed to ride with other brands

 

 

You should be embarrased if you can't figure it out. 

 

Everything sucks, if it is ignored and treated like it owes you something...

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Well quite frankly I am. Valves are in spec earthx battery, 0-40 yamalube, co adjusted everywhere from -3 to 20 Rpm's set at 2100 and every combination of throttle position know to man. They all start ok when kicked. Who knows definitely not me.

I am tired of defending it. I've tried to fix it. Maybe mine is the only one with starting issues

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Raise your idle 50 rpm at a time

Change your plug

You probably need to adjust your TPS as well, as it is is probably to low of resistance. When it's higher, the ignition advances.

Edited by Kah Ran Nee

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