NC23 Running problem

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IntenseJason
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NC23 Running problem

Post by IntenseJason » Wed May 16, 2018 3:38 pm

Hi, new to the forum, but not new to 400s, I have an NC23 that I have owned for about ten years, but it has sat unused for 5 years. I have been gradually bringing it back to life.

Its up and running up to a point but is suffering a weird stuttering problem - it runs fine up to about 6000 rpm then starts juddering really badly

I have a speedo convertor box and changed the CDI from a blue one to a Gold one so it shouldn't be a restrictor issue. (No resistors fitted however.)

Neither is it coming from the carbs - I have two different sets, one of them effectively new and it acts the same with both.

I changed the fuel filter and piping, so really the only place left to look is the fuel pump.

Should I be able to hear it running? Should I hear it prime when I turn the key? currently it is silent.

Thanks for any guidance.

J

dunkenb
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Bike owned: Cbr400rr nc29 type8 NSR250
Location: West Midlands
Re: NC23 Running problem

Post by dunkenb » Thu May 17, 2018 9:14 pm

Pump only runs when the engine is on. How’s the the charging system and battery?


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IntenseJason
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Re: NC23 Running problem

Post by IntenseJason » Fri May 18, 2018 7:46 am

Battery is a cheapo new one.

Will do some testing on the pump/alternator tomorrow - hadn't thought of that.

ta

IntenseJason
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Re: NC23 Running problem

Post by IntenseJason » Mon May 21, 2018 9:24 am

Ugh, what a weekend!

Checked pump and relay, seems to be fine, Alternator seems fine, checked fuel hoses for kinks again all fine.

Put it all back together and started running it up to temp, realised after a while I was standing in a lake of petrol - pouring out of the right carb overflow.

The temptation to 'solve' the issues with a match was strong.

dunkenb
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Re: NC23 Running problem

Post by dunkenb » Mon May 21, 2018 9:25 am

Time to check the carbs again


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stonecreator
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Re: NC23 Running problem

Post by stonecreator » Sat Jun 30, 2018 11:47 am

Always start with the basics! One problem I come across is inside the spark plug cap the seat for the spring and spark resistor builds up a corrosion, unscrew plug clip, extract resistor then spring, use a light to look inside and if it’s not bright use a long thin screwdriver to clean seat and blow out corrosion and refix..


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