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Post by 8bridge on Oct 2, 2021 10:24:50 GMT
Hi folks. My name is Stephen from Needham Market,Suffolk,UK. Introductions as a new member to your forum.
I have recently purchased a 1983 250N Superdream,and having massive problems! I have been unable to get running properly since I bought it on 10/9/2021.I originally suspected Ignition faults,but having now eliminated this,I realise it is carburation. I have just finished a rebuild/strip/clean of the 2 Keihin VB30B carbs,and upon reinstalling and getting petrol pouring out. It 's coming from the 2 inside facing air vents,and the overflow pipe under the bike. I have removed and checked floats etc,and still have same problem! Any member out there got an idea please where my problem lies? Many thanks in anticipation-Stephen.
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willy3pigs
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Post by willy3pigs on Oct 2, 2021 11:37:28 GMT
The float valves are not shutting off the fuel flow. You'll need to clean the seating area, everyone has their own preferred method, I use a slither of Scotch Brite pad, others use metal polish on a cotton bud etc.
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Post by reversespin on Oct 2, 2021 12:43:52 GMT
As Willy said above.
Also when rebuilding the carb if the Needle valves are not rubber tipped I tend to bed them in with a very slight tap of a small hammer.
As willy said everyone have their preferred method, however, if using a cotton bud make absolutely sure it doesn't deposit any strands as that will cause it not to seat properly.
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Post by 8bridge on Oct 2, 2021 17:56:12 GMT
I thank you both for prompt replies.
I am at a loss then as needle valves are new and carbs have just been sonic cleaned!
I replaced the gaskets 'O' rings as well.
Stephen
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stevegbr
Administrator 
ADMIN
BIRMINGHAM
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Post by stevegbr on Oct 2, 2021 18:53:32 GMT
hello and welcome to the forum.
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ian
Member Of The Year 2019 
Isle of Man
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Post by ian on Oct 2, 2021 20:40:31 GMT
Hi Stephen, welcome along. I'm with the other 2, most likely suspect is float valves, I've had similar problems on all my SDs at one time or another. It's more likely the seats than the valves themselves & I reckon they need more of a polish than cleaning, so it's worth giving Solvol or similar a try. Less likely, but worth checking the float heights & it's also possible the new float valves are poor if they're pattern types (got pattern ones on some of mine & they're fine, plenty are, but that's not always the case with pattern parts)
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Post by 8bridge on Oct 4, 2021 18:57:57 GMT
THanks ,seems sorted now-all good advise!
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