Carb Balancing

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viper911
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Carb Balancing

Post by viper911 » Fri Feb 23, 2018 6:20 pm

Hi All, can someone point me in the right direction to the link that explained how to balance carbs it seems to of vanished. It was a really good post with pictures of the screws to adjust

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Miles
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Re: Carb Balancing

Post by Miles » Fri Feb 23, 2018 8:39 pm

Is it not up on the workshop section on the main website

nevzzn
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Re: Carb Balancing

Post by nevzzn » Tue Apr 02, 2019 11:10 pm

Hi guys can you help with sending the link for carb balancing

Ewetea
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Re: Carb Balancing

Post by Ewetea » Wed Apr 03, 2019 8:34 am

Hi.
Underneath the carbs are two small black pipes. One links cylinders 2 and 3, and the other bridges 1 and 4. They are held in place with small clips, and can be pulled off to leave four stub pipes connected to the inlet ports on the cylinder head. The carb balancer pipes should be attached to these. When balancing, use the spring loaded adjusting screw between the carbs 1 and 2 to obtain the same reading on the two left hand gauges. Then use the adjusting screw between carbs 3 and 4 to balance the two right hand gauges. Finally, use the adjusting screw between carbs 2 and 3 to balance the readings on the left hand side with those on the right hand side. To do all this you will need to run the engine, which requires fuel. Ideally you need a small reservoir so that the tank can be removed to give you access. I use an old coolant reservoir as the outlet at the bottom is the right size for the fuel pipe to the carbs (the fuel pump is not needed as gravity supplies the fuel since the reservoir is suspended from the garage roof, so disconnect the supply to the pump for the testing, but don't forget to reconnect it!). Oh - there should be restrictors on the pipes, which need to be almost closed to reduce the needle vibration caused by the suction pulses. It'll all become clear when you start. I'm also assuming that you have a carb balancer consisting of four gauges and flexible pipes. Also the air box needs to be removed for easy access - you're only balancing the carbs, not tuning them.

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banner001
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Re: Carb Balancing

Post by banner001 » Thu Apr 04, 2019 7:30 am

All the main site workshop topics have gone, I'll make some new ones in time
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EvilSpike
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Joined: Mon Oct 24, 2011 4:00 am
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Re: Carb Balancing

Post by EvilSpike » Sat Apr 20, 2019 11:28 am

Thanks Ewetea for that description, and Banner001 for when you get round to making the new links.

I'm off out to the garage, what's the worst that could happen...?

EvilSpike
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Re: Carb Balancing

Post by EvilSpike » Sat Apr 20, 2019 10:41 pm

Hmmm, well to answer that, the bike now won't pull very hard over about 50mph. I suspect it's fuel starvation, so enemy number one is either a kinked hose or the £4.95 ebay special fuel filter is to blame. I'll buy an OEM one and see if that makes a difference.

I emptied the tank and removed the fuel tap and filler cap so possibly I've fouled the breather. I've changed the air filter for a Pipercross and the fuel filter for a new (non OEM) one and had a clean behind the engine so I might have knocked something. I'm sure the vacuum pipes went back on and there is no popping and banging so I don't think air is getting in anywhere.

I'll have to take the tank and airbox off on Tuesday and see if it's anything obvious. :/

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banner001
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Re: Carb Balancing

Post by banner001 » Sun Apr 21, 2019 1:56 pm

Just FYI, the hose on the tank is a water drain pipe...the tank "breathes" through the key slot...
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EvilSpike
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Re: Carb Balancing

Post by EvilSpike » Fri Apr 26, 2019 12:08 am

Ah ok, thanks. Well I drained the tank with the fuel cap on and it merrily poured out so it's not a breathing issue but it's nice to know where it gets atmospheric air from.

I've got a new OEM filter, the lines don't look kinked at all, the four vacuum ports had their 2/3 & 1/4 connecting balance tubes correctly installed when I removed the airbox and I've tested the fuel pump and it's working correctly.

What engine speed should I be balancing the carbs at, I'll try again with this new filter in the morning but I'm guessing about 1500rpm?

Ta :)

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