Yamaha SR250 starting issues

[Soul.Trader]

A few months ago, my 2005 SR250 had been sitting around for a couple of weeks, and it wouldn't start (inexplicably). I wasn't too worried about it, because I haven't needed to bike lately, so it's been sitting around now for at least 10 weeks. I'm trying to get it back on the road, but cannot get it started. Here's the issue:

It had been running perfectly fine, although occassionally just wouldn't start - cranks fine, battery is fine, but won't fire. If I left it for a while and came back, it would start first time. Now it won't start at all - the battery is strong and it cranks well, but never fires. At first I'd assumed it was an ignition problem, but I've confirmed it's getting a strong spark from a new plug. So it must be a fuel issue? I've drained the float bowl for a minute or two on prime and tried again, but no difference.

What could be the issue here? Thanks.

[98tls]

When you crank it are you getting a strong fuel smell,just thinking maybe the float is sticking and its flooding,try cranking it with throttle wide open.

[FJRider]

Its gotta get air too...check the air filter. Could be full of shit / wet etc.

[Soul.Trader]

Had another crack at draining the bowls - drained them dry with the petcock in the "On" position, then let them refill on "Prime", and it started right up :niceone:

[FJRider]

Old petrol, let us know if problems REoccur

[Soul.Trader]

To be honest I'm not sure I buy the "old petrol" thing, as it has only been sitting for around 10 weeks. It seems incredibly unlikely that petrol would go bad in that time frame. Also, the petrol that came out appeared to be in good condition.

It seems more likely that the carb was badly flooded. The bike hasn't done many K's, so the seals in the carb are still in good condition, so it's not overly surprising it didn't drain itself over time.

[FROSTY]

if its an SR whip the bowl off and have a looksee.

[Soul.Trader]

Went to go for another ride today, and it wouldn't start again. sigh. Not too sure what the issue is, but I'm fairly certain no fuel is making it into the cylinder. It's gotta be an issue with either the carb or the petcock, so when I get a chance I'll pull those apart. Funny, though, as it was running really well yesterday.

[xwhatsit]

Fuel goes off quickly in small quantities. The stuff in your carb bowl can go off very quickly (my bike is slow to fire, it's quite sensitive to stuff like that), so 10 weeks probably isn't much just to make the stuff in the float bowl rubbish -- which then fouls the spark plug eventually, even when you start getting better fuel from the tank.

[FJRider]

Had another crack at draining the bowls - drained them dry with the petcock in the "On" position, then let them refill on "Prime", and it started right up :niceone:

1. Check if ANY fuel is coming out when drain is open and fuel tap is on prime.
If there is, it may be flooding.
2. On prime, with drain open, turn motor over.
This will check if vaccum is working.
3. Try turning fuel off (if you can) and turn on just before you try to start.
4. Try leaving on prime.

First two questions are to see if its the fuel TAP thats the problem. Vaccum hose may not be attached (at one or both end)
Fuel can go off in 10 days...if it can get air.

[Soul.Trader]

1. Check if ANY fuel is coming out when drain is open and fuel tap is on prime.
If there is, it may be flooding.
2. On prime, with drain open, turn motor over.
This will check if vaccum is working.
3. Try turning fuel off (if you can) and turn on just before you try to start.
4. Try leaving on prime.

First two questions are to see if its the fuel TAP thats the problem. Vaccum hose may not be attached (at one or both end)
Fuel can go off in 10 days...if it can get air.


I thought fuel was supposed to flow in Prime? I will check these though. However, the vacuum pipe appears in good condition. What should happen when I crank the engine in Prime with the tap open?

[TimeOut]

I thought fuel was supposed to flow in Prime? I will check these though. However, the vacuum pipe appears in good condition. What should happen when I crank the engine in Prime with the tap open?

Try starting and running on prime all it does is bypass the Vacuum pump, won't do any harm it's just as a safety to stop the fuel flow when stopped.

I've had a vacuum hose kinked and not working properly, the new fuel does go off quickly.

[Soul.Trader]

I've confirmed the operation of the tap is just fine. Fuel flows on Prime, and when in the On position fuel only flows when I suck on the vacuum pipe. The bike wont start in Prime either.

So the problem must lie in the carb, which I'll remove and clean later today.

[FJRider]

I've confirmed the operation of the tap is just fine. Fuel flows on Prime, and when in the On position fuel only flows when I suck on the vacuum pipe. The bike wont start in Prime either.

So the problem must lie in the carb, which I'll remove and clean later today.

But does fuel flow when the BIKE turns over on "on" Check float levels...

[Soul.Trader]

But does fuel flow when the BIKE turns over on "on" Check float levels...

From the tap, yes. The issue lies somewhere after the tap.