yz250f starting woes... again...

[stormer94]

I gave a quick look for answers and didn't find any.

I know we've all had trouble learning the starting procedure. I know the starting procedure. Mine's been working well. 1-2 kicks every single time. BUT, that was when it was 50 degrees outside.

Here's what I did tonight. I went out it was, 70 degrees. Pulled the cold start, first kick, blammo, off it fired where I let it idle with cold start out while I put on my boots, and got my helmet. I'm guessing maybe 3 minutes, 4 minutes max.

Just before I got on, I pushed in the cold start, and it quit instantly, never to fire again (no hands on the bars, just standing next to the bike). I gave up kicking after about an hour. I initially tried to start it with the cold start pulled out. I gave up and tried a few minutes with the hotstart out. Finally shut the gas off as well, hoping it was flooded and that might cure things. Never did fire. I had no tools with, and no spare parts like a plug. (it's been so dang reliable, that I kind of forgot about the agony I had when I first got it). I was reminded of that agony tonight.

It was a first kick bike.... :( Where did I go wrong? What happened?

I'm thinking this is related to outside air temperature in some way. What's the dealio? How should I start it and what's the ritual as the temperature outside gets warmer?

Many thanks,
Bob

 

[dmp437]

I feel your desperatation. I was three days starting my WR after I got it home from the dealer (the dealer left it on reserve for the hour long ride home). You will almost certainly need a new plug. Get ready for the reaming. I've purchased new NGK's for my Stihl trimmer, TTR90, and Raptor 660R (a quad), and they've all been less than $3. The plugs for the 250F are $6, that's at two diffefent bike shops and a motorcycle supply shop.

As a start I would change the plug (be sure to check the gap), set idle for five turns out and the fuel screw at 1 3/4 turns out. The idle is very important because usually it's set to low, and the idle adjustment controls air volume at starting. My idle is set about 1900-1940 RPM's right now.

For more detailed FCR information and all the carb information you could ever want, check out www.thumpertalk.com in the Yamaha 250F forum. It was instrumental for me to get mine running. Carb jetting is a popular topic as quite a few people have problems getting it dialed in for their area/temp/altitude/mods.

 

[BikeDstroyer]

A couple of things I would check. First I would put a new plug in. I think you let it idle way too long with the choke and it fouled a plug. I never let mine run with the choke on for more than a minute. Since you went from 50 degrees out to 70 then you may have to lean the pilot out. This summer I had to go one step leaner on the pilot. As you probably already know that the fuel screw adjustment is very critical in the starting of these little blue babies. If the ciruit is too rich it will be a bear to start. Hope this helps some.

 

[webbrace]

It sounds like you may have either to small of pilot jet or you may have a plugged pilot jet. If the bike sat for awhile, the jet may be restricted down and the bike is running to lean.

 

[stormer94]

webbrace,

everybody is leaning toward a rich setup, how do you get lean? Although I can see the theroy, ran on the choke, quit when not. But that was a one time thing, normally it's fine.

The guys I was with thought we had some overflow out of the carb. And really thinking about it, it seems it's always outta gas. Now either I'm heavy on the gas or the bike is really rich, or I'm having so much fun that I hav no concept of how long I've been on the bike when riding and the tank is always empty.

I'm leaning toward rich 'thoughts'. The trick is to figure out where to first look and then pinpoint how to go about figuring it out.

It's kind of like the "flooded technique", I don't know it, but would like to hear about it.

Many thanks,
Bob

 

[Hick]

Originally posted by stormer94
What's the dealio? How should I start it and what's the ritual as the temperature outside gets warmer?

Many thanks,
Bob

My only thought is that at 70 deg. it shouldn’t need the choke to idle or warm up. I turn the idle up instead and don’t leave the choke on any longer than necessary.

By “cold start” I’m assuming you mean the choke...

 

[webbrace]

If it will run with the choke on, but quits when you turn the choke off, you are not getting enough fuel through the pilot jet. If the bike sat for awhile, or if you sucked up a little dirt, and its stuck in the jet. It will make it to lean to run on the pilot circut. It dosent take to much to restrict a pilot jet. The other problem maybe that you just fouled a plug by letting it run to long on the choke..Change the plug, if it fires with the choke on, but dies when you flip it off, then the jet is pluged.
Also, if the carb is overflowing, you probably have some dirt stuck in the needle valve assy. And if you have dirt comming through the needle valve, its a good chance you sucked some dirt into the pilot jet. Clean the tank and carb..

 

[webbrace]

By the way, i get about 35 miles to the gallon, racing. Trail riding i can get much better. I hope this helps you out.

 

[truespode]

Temperature effects jetting a lot. Try richening the pilot a tad... less than a 1/4 turn and go from there.

Ivan

 

[Dr.Zaius]

Just push the button silly!
Oh wait, its a YAMAHA! hehe, had to KICK that one in there. Good luck :)

 

[BikeDstroyer]

Originally posted by Truespode
Temperature effects jetting a lot. Try richening the pilot a tad... less than a 1/4 turn and go from there.

Ivan

Yes temperature effects jetting a lot, but when it gets warmer it makes your bike run richer which means you want to lean it out.

 

[stormer94]

Okay, I got the plug out, and it was just black soot. Put in a new plug and 4th kick she was fine. I think I might change my starting ritual to include using the cold start to fire it, and then using the throttle to keep it running for a bit to warm it up before you start flogging it down the trail.

I think the whole thing must be just nasty rich. I'm basing this on the hard starting if I miss something in the sequence or drop the bike, and awful mileage. I go out and ride with the kids, and I'll run out of gas twice before they do once with the same size tank. Granted, I'm not afraid to twist the throttle... ;)

Great, it's rich now, warmer making it richer (You're right, I hadn't thought about that scenario yet)... :( Looks like I'm gonna have to break down and make some changes I was hoping to avoid. Not that I'm afraid to wrench, it's just that this bike is so finiky I'm afraid to even monkey with it, what if I can't get it back and I make something worse? The ol' 2 smokes were pretty cut and dried.

 

[truespode]

Originally posted by BikeDstroyer


Yes temperature effects jetting a lot, but when it gets warmer it makes your bike run richer which means you want to lean it out.

Ooops... that is what I meant. Richer, leaner, just tern the farn screw :)

Ivan

 

[BikeDstroyer]

Stormer,

Go buy you a little notepad and write down your settings. Note the air temp and elevation as well and how the bike ran with those settings. My book is full of the different jetting changes for the different elevation changes and temp changes I ride in. It's very helpful for me it may be for you as well.

 

[stormer94]

Went out and rode some today. 70 degrees. Fired second kick, with the cold start out. Never killed it. Each time I shut it off, I started it without any carb help on the first kick. Well, I did manage to stall it once, but pulled the hot start, and it firec first kick. I think from now on, when it won't fire, and it was running, the rule of thumb will be to pull the plug, which were $6.50 each BTW!!! My sons KX100 $9 a plug... yikes! (trying to support the local shop) :think:

Thanks for the advice to all who took the time to post.
Bob

 

[skthom2320]

NGK CR8E plugs can be found at O'Reilly Auto Parts for $3. Their part #1273. [Oops - that was supposed to be #1275].

I pay close attention to how my bike is running (lean/rich) and rejet often for temperature changes. Nevertheless, I occasionally foul a plug as well - usually it is if I try and start my bike when the jetting is off a little. If it doesn't start in less than 5 kicks I just pull and replace the plug. Never fails - it will start first kick after that, then I adjust the fuel screw and/or whatever else it needed.