Hi all,

Help needed, any opinions would be appreciated...

I recently bought an NSR250 in Thailand and it was in pretty bad shape. Initially it was running really rough and blowing a lot of smoke and it would drip oil from the join between the exhaust and cylinder. First thing i did was pull the carbs off and clean them, they were filthy, never seen anything like it... Put them back on and it started first kick and sounded much better but after warming up on low revs it was blowing heaps of smoke. Turned it off and the plugs were very oily. My thinking was the oil injection was feeding too much oil so I disconnected it and ran premix 30:1 (95 octane). It ran well on this and the smoke problem was fixed so I assume I was correct. The engine revved up all the way to 12000 and pulled hard from 7000 but it was sputtering under 7000.

The carbs were leaking a little petrol from the seals so i took them off again and adjusted the floats. I lost the 95 octane fuel as I put the fuel tank on the grass and it was not turned off properly (my foolishness). Anyway I put the carbs back on and this time put in 91 octane fuel with 5% ethanol. Started up sweet and took off with the engine feeling good for maybe 1 minute and then the engine cut out. Pulled over and gave it a kick and it started up again but after accelerating for a couple of gear changes it cut out again. This happened a few more times on the way home.

I looked up this forum and found that maybe it was electrical so I checked the battery with a voltmeter. With engine off its around 12.7v, engine on and its up to 14.2 or so, revving to 5000 and its up at around 14.6 and fairly steady. With the headlights on it goes down to around 12.9 at idle and up around 13.5 with the revs up. So I'm assuming the electrical side of things is ok.

I tried riding it a few more times and the same thing happened, it would run sweet for a minute or 2 and then cut out but it is now even worse. For a while it was better with the choke on but now choke on or off it doesn't want to go anywhere and I had to push it home.

So I'm wondering, could the wrong float setting cause these symptoms? Or low quality fuel? Or a mixture of both? Or could the carb jets be clogged again? Or could it be something else entirely? Any ideas??

cheers,
Tim

Have you tried a new battery and searching the forum on "battery"

A fresh battery does make a difference. Try charging it with an intelligent charger if you have one or if you can borrow one
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Why do things simply when you can complicate them

so when it cuts out is it a sudden cut out or a surge in revs at idle or a loss in power or running on one cylinder?

It goes from running normal to loss of power to no power at all within around 10 - 20 seconds. Once there is no power it won't start again while rolling but once I stop and wait 10 seconds or so it will then kick start. Last time I tried it got to a point where it would not start up well enough to ride at all so i pushed it home. Once home I got it to start but fairly rough and checked the battery and it was as before, 12.7 with engine off and 14.5 or so with engine on.

I charged the battery the other day and it didn't make a difference when I tried to ride it. Maybe its the kill switch or a short circuit somewhere?

Maybe start at the top and work your way down from the tank. Check the tank is clean. The fuel tap unbolts and should have a filter on the top
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Why do things simply when you can complicate them

It sounds a lot like a fuel pipe is kinked or bad float level adjustment.
Your voltage measurements sounds fine by me.
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2t-racelab.com

As per the advice above, it sounds like fuel starvation so make sure all your hoses are routed correctly, check you can drain your carbs, look inside your tank for rust, check condition of filters if fitted, crack open the carbs again to check if you've installed the internals correctly and for contaminants.

Thanks for the advice.. I will do it today and let you know how I go...

I checked the fuel line and all was good there. I took off the carbs and noticed one of the tubes I used to cover the oil intake when disconnecting the oil injection was cracked so air would have been getting in. Could this be the cause of the symptoms?

I haven't checked the float levels yet, I'll do that tomorrow and put the carbs back on and see how it goes..

The carbs looked fine and the floats were set correctly. I put it all back together and got it going again. It went really well for around 2 minutes and revved up to 10000 nicely then it started sputtering and would not rev past 7000. I slowed down and pulled over and put it in neutral and noticed the neutral light was dimming and kind of flashing as I was revving it to keep it from stalling. It didn't cut out completely but stayed rough with no power all the way home. Once home I checked the battery again and again 12.7 with engine off and 14.3 - 14.5 with engine on so it still seems the battery and regulator are ok?

Does anyone know what could cause the neutral light to dim and at the same time cause the engine to lose power and run very rough? Any more help would be greatly appreciated...

cheers,

Tim

The bike running volts sound a bit high, there is a link in the workshop area to a good guide to battery and regulator rectifier troubleshooting so look at that and follow it.

Have you also checked if all your ground connections are secure? It almost soundsike a loose connection causing an intermittent problem.

Regulator/rectifier up the duff!
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Andy.
NSR-WORLD.COM

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Thanks for the replies.. I cleaned up the earth connections and then tried the engine again. It runs ok but when i rev it up to 6000 it becomes rough and the neutral light dims and flashes. I unplugged the rectifier and the engine reacts in exactly the same way with it plugged in or not. Does this mean it is not the rectifier causing the problem? Any ideas what else could cause this? I haven't tried riding it again.

I've ordered a new regulator anyway but probably won't receive it for a few weeks as the postal service here is pretty slack..

.

So the engine ran fine on 95 octane, and now keeps cutting out on 91 and 5% ethanol?

A stock NSR250 should run OK on 91, but it's far from ideal.

The way the rev ceiling is dropping, I would put money on the reg/rec.
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Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

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