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Tank fuel flow issue??

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Farmingstock
Trackday Trickster



Joined: 17 Jun 2016
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PostPosted: 17:47 - 29 May 2017    Post subject: Tank fuel flow issue?? Reply with quote

Having issues with my nsr misfiring, kind of like it's got a sporadic rev limiter.

So after doing all the General bits and bobs I thought I'd try riding a temp tank (zipped into my jacket and piped straight to carb with no filter)

This cured the issue and the bike revved round till it ran out of fuel!

So I did a little experiment:

With the temp tank 300ml of fuel took 15seconds to drain out!

The nsr tank took 45 seconds to drain the same amount out with tank cap off!

So I'm guessing the standard tank isn't flowing fast enough to keep up with the need of the carb which is leading to running if of fuel momentarily at high revs.

Could this be an issue and if so how do I cure it??
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Chris45
Nitrous Nuisance



Joined: 23 Oct 2016
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PostPosted: 19:53 - 29 May 2017    Post subject: Reply with quote

Quote:
Having issues with my nsr misfiring


If it's a fueling problem the engine would simply die surely? A bit like when the tank goes from On to Res. However you say the engine is misfiring? Which is more of a timing/electrical issue?

Anyway, I would persist with the fuelling side first. Check the tank breather, fuel tap and line. Remove lines and gently blow through, also check for any splits etc. My guess is a fuel tap problem...
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Farmingstock
Trackday Trickster



Joined: 17 Jun 2016
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PostPosted: 20:18 - 29 May 2017    Post subject: Reply with quote

It's kinda like when your running out of fuel the bike will go then splutter if you know what I mean? But at high revs it just misfires, but if I let off it will ride fine.

I have tried putting the choke on at speed when its doing it but that makes it just bog down and run worse.

However when I ride it with a free flowing temp tank, it runs absolutely perfect.

Could it still be an electrical issue if it runs perfect with the temp tank on?

I tried it to try and iliminate that but are you saying it could still be an electrical issue?
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Chris45
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Joined: 23 Oct 2016
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PostPosted: 21:01 - 29 May 2017    Post subject: Reply with quote

Quote:
However when I ride it with a free flowing temp tank, it runs absolutely perfect.


There's your answer...

It's deffo a fueling problem. Putting the choke on at speed is NOT a bright idea, too rich a mixture when the engine is hot. Besides, that's a carb side issue. Nope.... keep digging through the tank, fuel lines side of things.

It's not an electrical problem.
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jaffa90
World Chat Champion



Joined: 06 Apr 2016
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PostPosted: 21:56 - 29 May 2017    Post subject: Reply with quote

NSR what????????????????????????
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Farmingstock
Trackday Trickster



Joined: 17 Jun 2016
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PostPosted: 22:17 - 29 May 2017    Post subject: Reply with quote

It's an NSR125
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 22:27 - 29 May 2017    Post subject: Reply with quote

Hiya

By coincidence I had a similar problem this weekend. Turned out to be corrosion in one of the pipe connectors on the fuel tap.

Katy
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Farmingstock
Trackday Trickster



Joined: 17 Jun 2016
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PostPosted: 22:53 - 29 May 2017    Post subject: Reply with quote

Was thinking of just replacing the whole tap, pipe, filter for new as my reserve is none existent anyway!

There are new nsr250 taps on eBay cheap!! not sure if they will fit but no cheap 125 taps
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 23:09 - 29 May 2017    Post subject: Reply with quote

Hiya

Taps are normally fairly easy to strip down and clean out. I would do that first

All the best

Katy
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Farmingstock
Trackday Trickster



Joined: 17 Jun 2016
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PostPosted: 07:52 - 30 May 2017    Post subject: Reply with quote

I have already done that, stripped, cleaned, blown out. But no change, so just thought but new.

The flow is to slow, it just trickles out, like it's not a full tube of fuel coming out if you know what I mean?
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 10:01 - 30 May 2017    Post subject: Reply with quote

Farmingstock wrote:

The flow is to slow, it just trickles out, like it's not a full tube of fuel coming out if you know what I mean?


Yep, that is exactly the symptom I had.

All the best

Katy
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Chris45
Nitrous Nuisance



Joined: 23 Oct 2016
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PostPosted: 11:20 - 30 May 2017    Post subject: Reply with quote

Quote:
I have already done that, stripped, cleaned, blown out. But no change, so just thought but new.

The flow is to slow, it just trickles out, like it's not a full tube of fuel coming out if you know what I mean?


Check if the tank has a fuel breather. Also, does the fuel flow more freely with the petrol cap open? Might be a vac building on the tank side for some reason.
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Farmingstock
Trackday Trickster



Joined: 17 Jun 2016
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PostPosted: 12:13 - 30 May 2017    Post subject: Reply with quote

Hi yes it has a filter, I'm going to replace for new if I can find one for a good price, the tank it clean but has some internal rust patches which won't be helping things!

I took the in-line filter off which made the fuel flow much better, it maybe restricting flow but it's not perfect so will dig deeper again! Full tank of fuel in it too, nightmare!
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