SRX250 won't start

**quickbuck** · 17th January 2009, 20:02

Originally Posted by FROSTY

Im beting that the little seive is full of crude--the one in the carby

Yep. It can look like white sugar, and be as hard as caramel. This substance will not let petrol past it.

**jleahy23** · 17th January 2009, 20:59

Originally Posted by quickbuck

Yep. It can look like white sugar, and be as hard as caramel. This substance will not let petrol past it.

I have had the carby appart twice now and havent seen a seive in it.
Anyone know where i should be looking?

**FROSTY:Me** · 17th January 2009, 21:32

Have a look between the fuel line and the float valve
I'd be checking that the float valve is goin up n down like its sposed to -thats an area affected by varnish build up
Also whe ya say youve cleaned out "all" the jets you have removed the needle and the pipe it slides down havent ya?
Im also wondering if you should pull your fuel tap out of the tank--maybee its also crudded up
Hey Um silly question but you are blowing all the orifices of the carb out with high pressure air arent you?

**Ixion** · 17th January 2009, 21:48

You said before that there was no fuel reaching the carb. Now, that fuel is overflowing out the overflow drain. That, to me, would point suspiciously tOWard a float or float valve that was jamming. Initially jammed in the closed position now jammed in the open position.

The SRX250 carb is a wierd and wonderful thing, basically a slide carb and a CV carb combined into one. It has many little passages. All must be claer. blwo them out with compressed air or canned air fROm a computer store

**jleahy23** · 18th January 2009, 08:02

I'm thinking of going to the Yamaha dealer here and ordering new jets, needles and float valves.

Does anyone think this is a good idea, and if so, is there anything else i should be ordering?

**xwhatsit** · 18th January 2009, 10:50

Originally Posted by jleahy23

I'm thinking of going to the Yamaha dealer here and ordering new jets, needles and float valves.

Does anyone think this is a good idea, and if so, is there anything else i should be ordering?

Stuff like that is easy enough to clean and see that it's clean. Those are just small brass removable bits you can pull out anyway. I'd check float height and whether the float valve is actually sealing first -- you can do this with the carb stripped and the float bowl off -- just plug it into the fuel line and manually move the float upwards with your finger and see where/if the fuel flow stops out of the float valve.

The float's not leaking, is it? It'll be plastic and they don't generally leak but just check there's no fuel sloshing around inside it anyway.

**Ixion** · 18th January 2009, 13:05

If the internal apssagewyas are blocked replacing the removeable bits won't help.

What you can do is find a dealer that has an ultrasonic cleaning bath. That'll clean all the bits that can't be reached .

**jleahy23** · 19th January 2009, 22:21

OK Guys,
I took it apart, and there was a bit of rubber in the float valve preventing it from closing properly. I cleaned it out and put it all back on.

Guess what - IT STARTS!

Now, tuning...lol.

When its running, warm and no choke it kinda pulses, as in it'll sit around 1500-2000rpm for a while then go up to 3-4000 revs, then back down.

Any Ideas?

**NinjaNanna** · 20th January 2009, 07:37

Originally Posted by jleahy23

OK Guys,
I took it apart, and there was a bit of rubber in the float valve .....

When its running, warm and no choke it kinda pulses, as in it'll sit around 1500-2000rpm for a while then go up to 3-4000 revs, then back down.

Any Ideas?

Find out where that rubber came from and you'll probably answer your own question

**Ixion** · 20th January 2009, 10:22

Originally Posted by jleahy23

OK Guys,
I took it apart, and there was a bit of rubber in the float valve preventing it from closing properly. I cleaned it out and put it all back on.

Guess what - IT STARTS!

Now, tuning...lol.

When its running, warm and no choke it kinda pulses, as in it'll sit around 1500-2000rpm for a while then go up to 3-4000 revs, then back down.

Any Ideas?

That is indicative of an air leak in the inlet tract. (ie air leaking between the carb and engine). Check the rubber manifoldy thing very carefully, they have a tendency to develop little cracks. Which let air leak in.

**jleahy23** · 20th January 2009, 20:08

Had a look at the inlet manifolds and both look in good shape, no cracks or anything. I have bought new O rings for where they join onto the head, just incase it's leaking there, also bought new O rings for inside the carb to replace the one that seems perished. Could it be a fuel hose with a nic in it or something?

Also, when it is running with choke on it idles fine, but doesnt rev nicely, choke off it surges but revs nice.

**Ixion** · 20th January 2009, 20:13

Fuel hose, no. Needs to be on the inlet side. Perished or torn diaphragm might. With the motor running , spray engine start carefully (carefully ! don't blow y'self up!) onto possible suspect points. A bit at a time and take it slowly. When the engine races, that's the spot.

It could be tight valves, but they don't tend to move much on those motors. Also try smearing some grease here and there, see if that stops it.

And also, sometimes the best fix for that sort of thing is to take it for a hard ride, cane it, then tighten everything up once it's cool again. It's sat round for years, it's all mucked up inside.

EDIT: Oh, and check the air filter.

**jleahy23** · 20th January 2009, 20:20

Yeah,
I have a new air filter on the way from yamaha, should arrive tomorrow. I'll chuck these new o rings on and see how it goes. Will also try that engine start trick. Could it possibly be the vacuum hose going from the secondary inlet to the fuel cock leaking?

**Ixion** · 20th January 2009, 20:22

Originally Posted by jleahy23

Yeah,
I have a new air filter on the way from yamaha, should arrive tomorrow. I'll chuck these new o rings on and see how it goes. Will also try that engine start trick. Could it possibly be the vacuum hose going from the secondary inlet to the fuel cock leaking?

Yes. that's a distinct possibility. Block it off , as near to source as possible, and run on the P tap setting, see if it fixes it. Any thing that lets air inot the engine without going through the carb.