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Mixed bag XR250/Mixed bag of ?'s

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Hi all,

I have acquired a wee bitza of a bike. No need to bore you with the details, other than it's good bits of this, good bits of that..done good. It's a pure joy to ride. It has an 84/5 XR250 motor, twin carb.

Starting from cold hasn't been a problem....full choke/no throttle, let it warm up. From warm, no choke/bit o throttle.

It rained last night, like the heavens opened, for 10 hours continuous.

Today the bike starts from cold as per but I can't touch the throttle when it's warmed up, any more than I usually can when cold. It's warmed, the choke is off, it's ticking over fine...but the slightest attempt to rev it chokes it instantly.

The bike has a flush, custom, fuel cap....looks cool but it leaks petrol with a full tank and, as I've now noticed, it leaves a well all around it that fills with rain water...it's too thin to be able to get in there and soak it up, so it just sits there until you need fuel....whereupon you pop the cap to watch the water disappear into the tank....smart!

Anyhow's, I'm thinking that if it leaks petrol out then it's likely to leak water in.... but can't quite believe it.....there's over a gallon of petrol in the tank, how little water in it do you need to block up the carbs after a couple of minutes ticking over?

I read elsewhere of failed CDI units causing similar symptoms....& I'm starting to worry as to where best to start?

Doesn't help any that I'm still in the dark re acquiring a plug spanner of course! Or that there's already two dead bikes out back, with no spark and CDI ignition that I find impossible to reason with.

Talking of which, could anyone please point me towards any thread, website or publication that might explain the very basics of bike electrics?

My bitza has a spark, s horn, stop/tail & main/dipped. There's no battery/fuses, no sign of remnant wiring for such. There's the spare wiring for front/rear indicators....and under the tank there's a whole bunch of stuff that I daren't even disturb.....rectifiers, regulators, relays, coil of course. I've just browsed through the Haynes manual of motorcycle electics.....?? Still buggered if I know...have I got an alternator, a dynamo, a magneto, never mind how all that other `stuff` comes into my equation here?

It would be some relief to get some grasp of the electrics.....it needs a digital speedo for instance, or I want one at least. But will it work? Do I perhaps need the Vapor with its ac/dc option, whatever that means, or will any other dc one be fine?

Thanks for reading/Steve

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The bike has a flush, custom, fuel cap....looks cool but it leaks petrol with a full tank and, as I've now noticed, it leaves a well all around it that fills with rain water...it's too thin to be able to get in there and soak it up, so it just sits there until you need fuel....whereupon you pop the cap to watch the water disappear into the tank....smart!

Anyhow's, I'm thinking that if it leaks petrol out then it's likely to leak water in.... but can't quite believe it.....there's over a gallon of petrol in the tank, how little water in it do you need to block up the carbs after a couple of minutes ticking over?

the water dosent mix with the gas in your tank,its heavier than petrol and sinks to the bottom of the tank,so you end up with a layer of water with a layer of petrol on top,if you got much water in there you'll be sucking mostly water when you open the tap,as i found out after jet washing my xjr1300 :busted: i'd drain your tank and get some fresh gas in there

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