Yamaha SR250 problem

[gamgee]

Hey, theres something wrong with my bike what happens is when stopping at an intersection the bike won't idle and I have to hold the throttle on a bit to keep the revs up, I have tried upping the idle speed, cleaned out the carby (thoroughly with compressed air) and that hasn't worked, so I'm stumped, anyone got any other suggestions?

[Midnight 82]

Hey, theres something wrong with my bike what happens is when stopping at an intersection the bike won't idle and I have to hold the throttle on a bit to keep the revs up, I have tried upping the idle speed, cleaned out the carby (thoroughly with compressed air) and that hasn't worked, so I'm stumped, anyone got any other suggestions?

Did you make sure that the idle jet was clean the little hole in the end.

[Posh Tourer :P]

Have you got enough fuel, and enough battery charge?

[Fryin Finn]

Years ago I had an XJ650 and it had the same problem. It had rubber inlet manifolds and the bike shop said it had cracks from UV. They were replaced and the problem went away. Perhaps the same problem for your SR

[Paul in NZ]

Pardon me if I sound a little patronising because we have never met and I have no idea of your ability etc etc.

Are you sure that you cleared the idle jet? I tend to actually remove them all to clean them or you run the danger of just blowing the crud back into the carb and guess where it ends up again? Make sure you pull the float bowl and clean it.

Several items to check.

When you pull the carb off, undo the 4 screws on top of the unit and remove the slide / needle. The big rubber skirt thingy is the diapraghm (spelling?) and is crucial to the thing working properly (don't ask). Handle it gently 'cos they cost more than the bike is worth.

Hold it up to a strong light and check for any holes in it. If it is full of them, it's stuffed. I glued one up with tyre glue and silastic and it seemed to work.

There are also some vents into the venturi that need to be clear.

There will be a air bleed from the atmosphere side of the carb into the venturi. This allows the bike to idle with the throttle shut. Check this is clear with CRC or compressed air.

Check the float level and the doofrey that shut's off the fuel at the correct level.

Check the rubber mount for the carb is not cracked and leaking.

Check the fuel tap (vacuum) is working properly and there is no tank crud blocking the flow. While you are looking at it, check the little hose from the manifold to the tap is sound.

While you are at it. Adjust the valves (takes 10 mins) and change the plug.

If you get stuck I can lend you a carb for you to swap out.

Cheers

[FROSTY:Me]

Yea what paul said. Um one other thing--check that the choke aint stuck on . If it idles cold but not hot--could be a sticky choke

[gamgee]

Hey, it doesn't idle at all, the choke doesn't seem to work at all (maybe thats part of the problem) my dads a (car) mechanic, he pulled the carby apart completely, and spent about an hour cleaning it all out, so it's definitely not a problem there

[gamgee]

plenty of fuel, I'm starting to think the battery may be stuffed as I'm having problems starting it on cold mournings, I had to give it a push start yesterday (bugger) I think that may be the problem, so obvious and I didn't even think of it... just while I'm here, if it doesn't end up being the battery, what else could it be?

[gamgee]

Years ago I had an XJ650 and it had the same problem. It had rubber inlet manifolds and the bike shop said it had cracks from UV. They were replaced and the problem went away. Perhaps the same problem for your SR

will have a look at that tonight, thanks

[gamgee]

Pardon me if I sound a little patronising because we have never met and I have no idea of your ability etc etc.

Are you sure that you cleared the idle jet? I tend to actually remove them all to clean them or you run the danger of just blowing the crud back into the carb and guess where it ends up again? Make sure you pull the float bowl and clean it.

Several items to check.

When you pull the carb off, undo the 4 screws on top of the unit and remove the slide / needle. The big rubber skirt thingy is the diapraghm (spelling?) and is crucial to the thing working properly (don't ask). Handle it gently 'cos they cost more than the bike is worth.

Hold it up to a strong light and check for any holes in it. If it is full of them, it's stuffed. I glued one up with tyre glue and silastic and it seemed to work.

There are also some vents into the venturi that need to be clear.

There will be a air bleed from the atmosphere side of the carb into the venturi. This allows the bike to idle with the throttle shut. Check this is clear with CRC or compressed air.

Check the float level and the doofrey that shut's off the fuel at the correct level.

Check the rubber mount for the carb is not cracked and leaking.

Check the fuel tap (vacuum) is working properly and there is no tank crud blocking the flow. While you are looking at it, check the little hose from the manifold to the tap is sound.

While you are at it. Adjust the valves (takes 10 mins) and change the plug.

If you get stuck I can lend you a carb for you to swap out.

Cheers

yup he checked all that, checked diaphram, it was a little stretched, but no holes
he had a play with the air bleed, and when he took it off it seemed to go better, but he said he didn't know what it was, anyway, now we know, will have a go at cleaning that, thanks

other than that I think he cleaned everything

[Paul in NZ]

I'm pretty sure I have a soft copy of the manual some place if thats any use?

The choke is a nasty little knob you pull out to the left (sitting on the bike) under the tank and mounted on the carb it's self. (engine side)

I know Ross's SR is a pig to start if it is not run regularly, easy as if it is.

Also.. Have you got fresh gas in it? They really don't like stale fuel.

Also (2). One fast way to check the carb manifold rubbers is to get it running and spray a little engine start (ether) around the carb mounts. If it has a bad leak, the engine will speed up.

BTW. Have you checked the air filter?? If it's all clogged it won't run too well.

Paul N

I'm happy to bung you the spare carb to try....

[gamgee]

Hi, thanks for that, I found a service manual via google on www.sr250.com will check all those things you mentioned then get back to you, thanks for the help guys

[gamgee]

about that carb, I'll try everything else before trying that as postage would be about $15 each way, thanks though

[FROSTY:Me]

This problem of yours has been bugging me. I'm wondering if maybee the issue is an overtight valve. It'll run -ok when its cold but when it gets hot the valve tightens up and bingo.
Another maybee could be is a blocked air filter.
I second the blow EVERY jet and every orifice in the carb comment that jim made. Im also VERY suspicious of the choke onot working.Basicly if its connected properly it must its such a simple little choke. Maybee its actually got jammed on full

[Paul in NZ]

This problem of yours has been bugging me. I'm wondering if maybee the issue is an overtight valve. It'll run -ok when its cold but when it gets hot the valve tightens up and bingo.
Another maybee could be is a blocked air filter.
I second the blow EVERY jet and every orifice in the carb comment that jim made. Im also VERY suspicious of the choke onot working.Basicly if its connected properly it must its such a simple little choke. Maybee its actually got jammed on full

Yup, I was thinking about it too... particularly that the choke does not work.

Without looking at it tonight I can't remember if it's an enricher or a strangler but it could be the villian.

Cheers