Kissy
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| posted on 29/3/05 at 09:36 AM |
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Fuelling on Carb'd BECs
What have people with Carb engined BECs done about correcting the fuelling for new airboxes/filters and exhausts? I'm fairly confident that at
least the main jets will need upping on mine. Also, what have people done about feeding fuel to the carbs? The CBR1000F uses gravity feed via a
vacuum operated tap. I have a Red Top pump by the tank, and a Malpassi regulator by the carbs. Originally I had a single line to the carbs, but the
tickover was dead uneven. I fixed up a bottle over the carbs to replicate a tank a la bike, and hey presto problem went away. I installed a return
line to minimise the pulsing effect and all seems pretty good, just not sure it's the best I could do, and whether I will run out of fuel on
extended excursions toward the red line. I will eventually go F/Inj (have nice shiny set of R1 bodies in garage) with MegaSquirt+Spark.
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ChrisGamlin
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| posted on 29/3/05 at 10:27 AM |
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If you are running an open air filter the mains will need upping, and on the blade at least, the pilot hole will need blocking. Im not sure exactly on
doing this as I had mine done for me, but this link to Dan Bromilow's
site shows how to do them on Blackbird carbs and Im sure its all but identical.
As to the fuel pump, I would personally junk the red top and just run a bike pump, you dont need a regulator then as they just pump to the correct
pressure. Your combination can be made to work (Westfield use a similar setup) but for simplicity you cant beat a bike pump.
[Edited on 29/3/05 by ChrisGamlin]
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Jon Ison
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| posted on 29/3/05 at 11:06 AM |
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cocktail sticks block the holes nicely but its worth having it jetted properly, i was 40bhp down on cocktail sticks and std on TTS's dyno, as
for fuel pump with carbs as Chris says stick too a bike pump.
you will prob find your carbs are very dirty inside too if they have been stood a long while, TTS recomended that i drain the carbs if stood for 2
weeks or more.
[Edited on 29/3/05 by Jon Ison]
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Kissy
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| posted on 29/3/05 at 05:46 PM |
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Cheers Gents, all good sound advice. Didn't know the bit about blocking the pilots. Off to ebay for a pump and to sell a red top now.
How far do I jet up as a rough guide? I have a set of 128's which could replace the 122's in there already, or is that not enough?
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Kissy
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| posted on 29/3/05 at 05:47 PM |
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...oh and Blackbird carbs are the same Keihin VP Flatslides as the CBR1000F IIRC.
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ChrisGamlin
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| posted on 30/3/05 at 12:12 PM |
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E-Mail Simon Neil (chaos999) and ask him about jetting, he used to have a CBR1000 Striker and played around with the jetting a lot.
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Kissy
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| posted on 4/4/05 at 07:19 AM |
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Top advice boys - bought a pump on ebay for under 20 quid, upped the mains from 122 to 128 (all I've got) & added 2 cocktail sticks
(I'll solder the jets up in due course). Engine now starts better and revs cleanly through to the red line - very happy! Now found out
I'm down on compression on no.2 pot! Not too bad, as soon as the throttle is opened it cleans up.
Red Top pump and pressure reg now on ebay!
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ChrisGamlin
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| posted on 4/4/05 at 08:31 AM |
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Good to hear its running better now 
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locoboy
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| posted on 4/4/05 at 01:31 PM |
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Kissy,
What pump are you using? i need to source one for my CBR1000 too.
ATB
Locoboy
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ChrisGamlin
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| posted on 4/4/05 at 01:42 PM |
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Most big bikes seem to use the same one, its a Mitsubishi made pump as found on the early blade.
There are quite a few on Ebay, for example
ZX9
ZZR 1100
CBR600
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locoboy
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| posted on 4/4/05 at 03:53 PM |
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surely thay CBR600 pump wouldnt pump enough to run a CBR1000 would it?
ATB
Locoboy
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ChrisGamlin
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| posted on 4/4/05 at 04:04 PM |
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As far as I know they are all the same pump. Don't forget that they pump to pressure so they arent necessarily running flat out from a flow rate
perspective when supplying fuel, especially on the smaller engines.
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Kissy
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| posted on 4/4/05 at 04:18 PM |
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If the Haynes manual is correct the 600's pump 650cc/min, and the 1000's 900cc/min. I bought a VFR750 pump (ebay 15 quid + P&P), and
it seems fine, no issues with over pressure, and no constant clicking as with the red-top. Only got to sort the final drive ratio (major headache on
the CBR1000F with 13" wheels) and the propshaft which is off to Bailey-Morris soon (and the missing no.2 pot!)
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ChrisGamlin
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| posted on 4/4/05 at 04:20 PM |
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I stand corrected, will have to slap wherever I got that info from (the BEC list somewhere).
Ive heard loads of people say CBR600s are the same as blade pumps etc though, so maybe its year dependent or something.
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ChrisGamlin
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| posted on 4/4/05 at 06:23 PM |
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Just thinking, which CBR1000 is that, cos I thought someone on here said that the old CBR1000 was gravity fed with no pump? Maybe those numbers are
from the fuel injected engines?
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locoboy
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| posted on 5/4/05 at 12:36 PM |
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i dont know much about my engine but i dont think there was an injection version?
As for gravity feed, my haynes manual for the CBR1000 shows where the pump is located.
Just out of interest how do you feed fuel to a normally gravity fed bike engine when its in a car?
Seperate smaller fuel tank up front somewhere that is pump fed from the main tank?
ATB
Locoboy
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ChrisGamlin
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| posted on 5/4/05 at 02:08 PM |
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I just had the pump at the back near the tank and low down in the back corner of the chassis. Either at the front or back they seem to work OK as ST
install them near the engine generally, but from what Ive been told the fuel pumps generally push better than they pull so Id say at the back is
better. I certainly didnt have any issues with it there even when draining the tank and re-filling - no need for syphoning or bleeding it through etc.
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Kissy
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| posted on 5/4/05 at 09:32 PM |
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The early thous and all 600s were pump fed. The later thous had a vacuum tap. I think this only applied to the VP45 flat-slide carb'd (FP
onwards?). You're right Col, someone did make the comment - me! Anyway whatever Honda's reasoning it's solved my probs, and I
stand to make on the old pump. Bonus!
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Kissy
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| posted on 5/4/05 at 09:35 PM |
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...and no, you cannot easily put a header tank up front as it needs to vent to atmosphere, otherwise it is merely a fat piece of fuel line! I
didn't realise how few of the 'eligible' carb engines use pumps over gravity.
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