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Vfr 400 fuelling issue :-( help lol

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chalky143
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PostPosted: 18:11 - 02 Jun 2012    Post subject: Vfr 400 fuelling issue :-( help lol Reply with quote

I bought a vfr 400 race bike last month and it doesn't run right, it's sluggish At low Revs and then past 6k it just doesn't really go anywhere. It revs all through the rev range but slowley for parts then takes off then dies again.
I took the carbs off, cleaned them, drained fuel, cleaned fuel tap. It fired straight up, still ran naff. Better but naff. I thought it may be the vacum pipe, not letting enough fuel through.

Now after it running for a little bit it then died and now doesn't start at all..... Help Sad
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Current bike :: sv650 minitwin race bike
Previous bikes::cbr600 steelie race bike, 1989 Honda vfr750f, 2013 Honda fireblade, 2013 Ducati multistrata 1200s, 2012 Triumph street triple R, 1999 yamaha r6, vfr 800, ducati 600ss, vfr 400x2, ntv 650, bandit 600, cagiva mito 125, aprilia rs 50, honda c90x2, honda hornet 600x2, cbr 600, aprilia rx50, suzuki katana
My bike pics: https://www.bikepics.com/members/chalky143/
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Walloper
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Joined: 24 Feb 2005
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PostPosted: 18:20 - 02 Jun 2012    Post subject: Reply with quote

Shit.

In the system.

Remove.
Clean.
Install.
Rip.
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Billing
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Joined: 12 Mar 2009
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PostPosted: 21:18 - 02 Jun 2012    Post subject: Reply with quote

What size main jets and what exhaust has it got? (full, 1/2, cut stock or full stock)

Pull a plug from one of the rear cylinders and check the colour, that should give an indication as to the fuelling. Make sure that vacuum line is good too, they can cause no end of problems.
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'84 TS50X, '91 TZR125, '89 CBR400RR, '91 VFR400R NC30, '98 R1
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chalky143
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PostPosted: 11:51 - 03 Jun 2012    Post subject: Reply with quote

I dont know what size they are to be honest. The can is just a unbranded de baffled race can. Nout special, looks like a standard one. I took both plugs out from rear cylinder and they had a brown liquid on them, looked like oil but did put some
Carb cleaner fuel mix in tank too. So
Would that be why? What colour is it sposed to be? Thing is it doesnt even run at all now...
____________________
Current bike :: sv650 minitwin race bike
Previous bikes::cbr600 steelie race bike, 1989 Honda vfr750f, 2013 Honda fireblade, 2013 Ducati multistrata 1200s, 2012 Triumph street triple R, 1999 yamaha r6, vfr 800, ducati 600ss, vfr 400x2, ntv 650, bandit 600, cagiva mito 125, aprilia rs 50, honda c90x2, honda hornet 600x2, cbr 600, aprilia rx50, suzuki katana
My bike pics: https://www.bikepics.com/members/chalky143/
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Billing
World Chat Champion



Joined: 12 Mar 2009
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PostPosted: 15:09 - 03 Jun 2012    Post subject: Reply with quote

Get the plugs cleaned off, I've put them in the oven before when I flooded mine. Then try starting it again, using full choke, no throttle, see how that goes.

If that fails, carbs off, float bowls off and check the jets sizes, seems a lot of people forget to change the jets when putting an end can on these, early ones ran 110s which in reality were too lean to begin with. for a race can I think the recommended setup is 115f/118r (bigger rear jet to compensate for the rear cylinders not getting such a good air flow IIRC)

Also check your air filter is nice and clean, it sounds to me like it was running far too rich as it was bogging out, whereas IIRC lean lets it rev, but makes it feel like it has no power.
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'84 TS50X, '91 TZR125, '89 CBR400RR, '91 VFR400R NC30, '98 R1
"Hey copernicus! Why don't you navigate yourself to the back of the line with your feet and stand there with your shit."
BCF Eastern members map here ---> g.co/maps/2tm8b PM me to be added to it!
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