CBF500 ABS - 30 MPG

[Nobby the Bastard]

Why would a compression test help in any way when diagnosing a rich fuel mixture cause?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[PotatoHead202...]

There was oil on the plugs so was concerned about an internal issue. I've ordered a few parts off of ebay.
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Honda VFR1200F, Honda CBF500 ABS, CZ125 now CZ175

[ThunderGuts]

I'd abandon 99 RON fuel; it's a carb'd bike, so unless it's been tuned to take advantage of that fuel, it's just wasted and if anything probably won't as well as on 95.

Sounds like it's running really rich - get someone to follow you when it's warmed up and open up the throttle; black/grey smoke can indicate overfuelling (pump the "prime" button on a running petrol lawnmower to get a similar effect).

FWIW, my old 2006 ER5 which is very similar config bike used to manage around 50mpg on an urban 8 mile commute, and I'm pretty sure the carb tuning left something to be desired too (but it was a hack and it worked ok so I lived with it).
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TG.

[PotatoHead202...]

Yeah the guy that looked at it said as much. I've done a fair bit to it (new clutch, brakes, suspension etc) but carbs are a bit too complicated for me on my own.
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Honda VFR1200F, Honda CBF500 ABS, CZ125 now CZ175

[P.]

[PotatoHead202...]

As I said, they are stock. The jets are the standard size. Everything is standard. The airbox is sealed and a second hand one is on order.
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Honda VFR1200F, Honda CBF500 ABS, CZ125 now CZ175

[P.]

I don't think you've had the carbs off.

[sickpup]

[PotatoHead202...]

Thanks. I've got it partially stripped down and will carry on when I get home this evening. Guess it's just checking every part I can. I'm just reticent to get another set of it's knackered as well. When you say fueling there do you still mean main jet?
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Honda VFR1200F, Honda CBF500 ABS, CZ125 now CZ175

[sickpup]

[PotatoHead202...]

Yeah I've since managed to find one for a reasonable amount. Had it on and off multiple times now. No way to change needle height unless there's a different spring.
Fuel pissing out of the bad carb again now. Took them off, checked float height, checked float actually stops fuel when pushed back up (it does). Needle valve is about six months old and seems fine.
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Honda VFR1200F, Honda CBF500 ABS, CZ125 now CZ175

[jaffa90]

R.U. bench checking the carbs with a long fuel pipe and a header tank (big funnel) and tapping / vibrating the carbs simulating riding conditions before fitting?

[PotatoHead202...]

Not that precise but preety much. I have an auxiliary fuel tank and have checked the floats and various angles.
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Honda VFR1200F, Honda CBF500 ABS, CZ125 now CZ175

[jaffa90]

""" Needle valve is about six months old and seems fine"""

I bought 6 brand new ones from "JAPG power", using a watchmakers glass all had ridges on the viton rubber tips some bad so i sent them back for a refund and bought some from "RACING PLANET" and they were all perfect.
Valve seats need to be cleaned & polished, i use WD40, cotton buds soaked in varnish remover and cocktail sticks dipped in BRASSO with a twisting action for very small carbs.
Then fit a very fine new fuel filter mesh.

[sickpup]

[Nobby the Bastard]

[jaffa90]

Have you old guys never heard of a 6 cylinder motorbike?

Joking apart i have more than 6, i have used 2 and have 2 carbs ready with 2 spare.

You cannot repair any carb/s without spares.

See pic. hopefully.

[Nobby the Bastard]

Why would you need to have multiple carbs in readiness? Are they a known weak point on your bike?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[jaffa90]

""Are they a known weak point on your bike?""

Who mentioned my bike?

[ThatDippyTwat]

[PotatoHead202...]

I'm guessing the needle valve/it' seat is the only culprit then? It's driving me a bit insane now.....
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Honda VFR1200F, Honda CBF500 ABS, CZ125 now CZ175

[sickpup]

You do realise this is disturbing?

https://www.bikechatforums.com/download.php?id=103202

[GettinBetter]

[jaffa90]

[jaffa90]