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Porks bike carbs and boost project

OP
OP
pork

pork

Club Member
Dead easy, switched live, engine earth and signal to neg side of coil. ;)
Sweet,

I would like the fuel pressure gauge inside car to, but bit nervous about running fuel line inside car next to all the live wires
 
Reckon that'll be long red n black-power supply, short red n black-illumination and green signal. Does it not come with destructions? ;)
 
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pork

pork

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I got brave and went outside to put carbs back on after adjusting idle mixture,
Still doesn't idle, I've been gradually adjusting the mixture.......but still won't idle, I have the idle speed screw wound in, and still have to keep a but off throttle to keep it running, I have no idea of the revs yet as I'm still to attach tacho. Also is sounds very tappy (if that means something to someone :( )

Here a vid off it running, skip to 2:23 for how I have to get it started still.

Yes, I know I'm an idiot, and yes, I have made this a bit hard for myself, so hope someone can help :)


Thanks for any input :D
 

Skinner_87

Club Member
I got brave and went outside to put carbs back on after adjusting idle mixture,
Still doesn't idle, I've been gradually adjusting the mixture.......but still won't idle, I have the idle speed screw wound in, and still have to keep a but off throttle to keep it running, I have no idea of the revs yet as I'm still to attach tacho. Also is sounds very tappy (if that means something to someone :( )

Here a vid off it running, skip to 2:23 for how I have to get it started still.

Yes, I know I'm an idiot, and yes, I have made this a bit hard for myself, so hope someone can help :)


Thanks for any input :D
Nice work Pork!

Do your carbs have a choke? If its as cold as it is at the minute i have to leave the choke open a good while longer before it will happily idle by itself (after much faffing with the idle screw)
 
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pork

pork

Club Member
It's a right faff to adjust these screws, they're not very accessible in my bay :(
I spose it is a bit chilly, it won't start with choke, I have to blow down pipes like in the video
 
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pork

pork

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I know I'm probably being a right menace, but I'm proper stuck now, anyone got any tricks I can try?
 

frank

Club Member
it sounds like its only running on 2 to me neil, have you checked if the 4 exh primaries are getting hot ?
 
OP
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pork

pork

Club Member
Yeah, all firing up ok, (once blown into tubes as in video) jus wont idle, revs up fine though.
I've got idle mixture screws nearly all way out, and idle speed screw all way in.

Exhaust still ain't hooked up so that's why it's sounds but loud. Also it's very tappy sounding from under rocker
 

frank

Club Member
does,nt sound like its running on 4 to me mate, and the mixture screws will only alter the idle mixture eh (they wont alter 1/2 or full throttle mixture)
 
"Also it's very tappy sounding from under rocker"

Thats sounds like valve clearances then neil. Did you not have this head stripped fully? Recheck rocker arms etc?
 
Tried pulling any ht leads off while its running to see if it makes any difference? I also think it sounds like its not running on all cylinders
 
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pork

pork

Club Member
"Also it's very tappy sounding from under rocker"

Thats sounds like valve clearances then neil. Did you not have this head stripped fully? Recheck rocker arms etc?

I made sure I put all valves back in same place, never touched the rockers, il have to get correct shimmy thing to check that :)
 
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pork

pork

Club Member
Tried pulling any ht leads off while its running to see if it makes any difference? I also think it sounds like its not running on all cylinders
Il try that to tomorrow.

Keep 'em coming, bound to be something extremely Simple I'm forgetting
 

frank

Club Member
i set our kart tappets by adjusting the clearance down to zero, then back it off 2 flats of the nut neil (1/3rd of a turn) you could set yours like that for now :)
 
OP
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pork

pork

Club Member
i set our kart tappets by adjusting the clearance down to zero, the back it off 2 flats of the nut neil (1/3rd of a turn) you could set yours like that for now :)

Cool, thanks :)


Anything else you can think of for idle issue?

Someone said raise fuel pressure back up, it's now at 4 psi, was at 0.5 psi, but that ain't worked.

Not something stupid, like the fact it's freezing lol?
 
OP
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pork

pork

Club Member
Are all 4 carbs flowing correctly? Maybe leaning out on a couple of cylinders? o_O

See, I have no equipment for testing anything right now :( all money goes on parts lol

It did just pop into my head whist typing this that there's a bloke up the road who repairs bikes, so ay have to kidnapp him and make him repair my car in return for freedom
 
What about if you disconnected coil and spun engine over then pulled plugs and make sure they're all wet with fuel as you have individual cabs for each pot??
 
I'm not saying thats a good thing to do (and its probably not!) but its what I'd do in my ghetto style with limited (no) resources!!
 
by blowing down the overflows your effectively pressurising the float chambers and pushing fuel down the inlets. From playing with my carbs id say you have blocked pilot jets
 
OP
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pork

pork

Club Member
by blowing down the overflows your effectively pressurising the float chambers and pushing fuel down the inlets. From playing with my carbs id say you have blocked pilot jets

Strip down and carb cleaner marathon....... Again! :(


First set if carbs sufferered with over fuelling, these the opposite. I might be able to make a decent set from the 2

Thans
 
mine where well blocked i ended up having to feed a single strand of copper wire ( copper is soft so wont enlarge the jets)down the jets to unblock them.
 
OP
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pork

pork

Club Member
I shall have a go at that too.

The last set off carbs I stripped down, those jets (with flat head slot in) they were VERY tight in there, even snapped one if them.

Hope these are a littke more forgiving
 
I shall have a go at that too.

The last set off carbs I stripped down, those jets (with flat head slot in) they were VERY tight in there, even snapped one if them.

Hope these are a littke more forgiving
yeah those jets can be white knuckle tight, make sure you have a very good fitting screwdriver, with relation to the idle mix screws a good starting point is to screw them all the way in the unscrew them 3 turns out. i think mine are currently 2.5 turns out i think :-/
 
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pork

pork

Club Member
I e been all over the cbr forum lookin for answers, not to keen to help tho with car builds
 
OP
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pork

pork

Club Member
This is what I've found so far from a post:

I highly suggest downloading the service manual and balance the carbs!!!!!!!! The service manual clearly outlines how to adjust the carbs ( page 55 section 6-14)

If you don't have California model OR Canadian and don't live above 6,500 ft, then the manual states:
1. Turn each pilot screw clockwise until it seats LIGHTLY, then back out the screws to 2-1/8 turns

2. Warm up the engine to operating temp (10 min)

3. Attach a Tach (built-in tach isn't accurate enough)

4. Adjust idle speed (knob on side of bike) to 1200 RMP + or - 100 RPMs

5. Turn all pilot screws 1/2 turn counterclockwise from initial setting

6. If engine speed increases by 50 RMP or more, turn all screws out in 1/2 turn increments until the engines speed doesn't increase.

7. AGAIN Adjust idle speed (knob on side of bike) to 1200 RMP + or - 100 RPMs

8. Turn number 3 carb pilot screw IN until engine speed drops 50 RPM

9. Turn number 3 carb pilot screw counter clockwise from that point.

10. AGAIN Adjust idle speed (knob on side of bike) to 1200 RMP + or - 100 RPMs

11. Perform the steps 8, 9, 10 for carbs 1, 2 and 4.

That is nearly verbatim of what is in the service manual.
 
i think the first port of call is to try clean the jets then refit them with the pilot screws three turns out to get it running then take it from there
 
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