Author Topic: carb tuning.... yes.... another one of those....  (Read 3425 times)

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Offline xsmooth69x

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carb tuning.... yes.... another one of those....
« on: November 12, 2011, 02:56:12 AM »
i need a detailed carb tuning walk through.

i completely rebuild my carbs from the bottom up.

1) so i need to now what those screws do that are by the arms of the carbs when they connect to the rack how much to screw them in our out and what do they do?

2) also the butterfly flap area screws how do they need to be adjusted?

3) also there are 2 screw things with springs on the carb rack itself. i know one is for adjusting the idle but does anyone have an idea how many turns in it usually sits? and what does the other screw do and who many turns is the basic position for that?

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things i have done to spec was

turn air fuel scew 1 1/2 turns ( close enough to 3/8 )

float heights are at 22mm

the carbs are clean and looking great

*******************************************************

couple of side notes is that i ran the bike and it was lean. i pulled out the spark plugs and they where a little white.
1975 CB550 (FINISHED?!?!?)
first motorcycle ever!!! ow and i dont know how to ride it either :D

raw rust rice venti quad shot cafe racing latte project aka my build..... http://forums.sohc4.net/index.php?topic=88853.0

black and white equation godzilla chalkboard 
1972 cb750 - next in line for some <3

Offline dave500

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Re: carb tuning.... yes.... another one of those....
« Reply #1 on: November 12, 2011, 03:14:49 AM »
pay for my flight and accomodation and im on it man,i dont think my keyboard would last .

Offline dave500

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Re: carb tuning.... yes.... another one of those....
« Reply #2 on: November 12, 2011, 03:20:35 AM »
i just got off the phone from my agent,ill bring all my tools and meters,,you have to supply hienekin.

Offline xsmooth69x

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Re: carb tuning.... yes.... another one of those....
« Reply #3 on: November 12, 2011, 03:31:53 AM »
lol honestly if i was a little more established and out of college i probably would fly you to the states or i might go to ausie land and just bring my bike and while im there scuba dive the great barrier reef  ;D
1975 CB550 (FINISHED?!?!?)
first motorcycle ever!!! ow and i dont know how to ride it either :D

raw rust rice venti quad shot cafe racing latte project aka my build..... http://forums.sohc4.net/index.php?topic=88853.0

black and white equation godzilla chalkboard 
1972 cb750 - next in line for some <3

Offline Gordon

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Re: carb tuning.... yes.... another one of those....
« Reply #4 on: November 12, 2011, 03:37:18 AM »
Your two most recent posts lead me to believe you either don't have or don't want to read a shop manual.  I'm not trying to scold because you're welcome to ask any sohc4 related question here, but these types of basic function questions are all covered in a decent manual. 

Also, knowing more of the basics of what you're working with will make it easier for others with more hands-on experience to help you. 
« Last Edit: November 12, 2011, 03:39:15 AM by Gordon »

Offline dave500

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Re: carb tuning.... yes.... another one of those....
« Reply #5 on: November 12, 2011, 03:56:52 AM »
with all due respect go away gordon,i want a free flight and beer!xsmooth,,carbs cant really be tuned by "x" amount of turns on a screw,,it might get close but more often than not itll only be ball park,which is often good enough,,,the major thing is get your ignition absolutley spot on,, repeat,,get your ignition absolutley spot on,this will mostly fix most poor running issues,,too many times carbs come off over and again for some ill thats in the easily fixed ignition,,youve been on here for a while now xsmooth,,,the basic bench synch,do that,,get the engine running,,you wont tune an engine that dosent run man!get riding the bike,,you aint gonna have a balls out going bike without some tuning,but it will be a good runner,,dive the yongala wreck before its off limits,,sank in 1911 and its getting unstable,45 metres down with a steady current over it.
« Last Edit: November 12, 2011, 03:58:58 AM by dave500 »

Offline dave500

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Re: carb tuning.... yes.... another one of those....
« Reply #6 on: November 12, 2011, 04:19:27 AM »
your top photo shows the balance screws,,these are whats adjusted to bench and or vac sync the carbs,they have a lock nut,the lower pic shows the choke sync tabs,,with the choke fully open you should adjust these untill the open flaps(think clean here)are all square and level,,close them and they should all shut together,,now brush up on ignition,,you must have your ignition spot on first.

Offline xsmooth69x

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Re: carb tuning.... yes.... another one of those....
« Reply #7 on: November 12, 2011, 11:42:23 AM »
to defend myself i did look at the shop manual on page 9 they talk about tuning the carbs and they only talk about what vaccum #'s you use but they dont really tell you how to adjust it nor do they say anything about everything i asked. i know where to hook up the vaccum lines and all that but i dont know what screw or bolt to turn to actually tune it.

dave500 i will look at the ignition system with a fine tooth comb. i did the point gaps but thats about it. i left the point plate where it was since i bought the bike so im on the assumption its right...... i have not hooked up a points light thing and checked that when the light comes on and all that jazz like how the shop mannual explains to make sure the engine is tdc1-4.

the only thing i did was adjusted the points gap looking at the highest point on the points lobe thing and did that.

i have the bike up and running.  it starts up with 1 kick with the choke on and an open throttle. but i do have the hold the throttle to keep it idling since i dont have the push pull throttle cables tightened properly or any of the screws on the carb rack correct to let the throttle go without the engine cutting out.

none of the carbs leak the carb float heights are good since its not leaking and all 4 cylinders are firing since the headers are evenly hot.

i also trouble shot a weird noise from cylinder 2 and noticed i didnt tighten the exhaust bracket hard enough and had an exhaust leak. after i tightened the bike sounds good.

holding a low idea i do hear some weird noises coming from the bottom end of the motor leaving me to believe it might be the primary chain or something dealing with the drive shaft thing in the motor.

i still need to figure out how to adjust the rear brakes with the little arrow and notch on the rear brake drum to make sure it work. i cant find anything dealing with that in the shop manual on how to tune the rear brake.

im currently waiting on a SS line from slingshot to finish my front brakes up.

im also trying to figure out how to route the clutch cable so its not kinked in a weird way when its seated on that engine bracket triangle thing. im thinking its supposed to be laced in between the 2 carbs (carb 3 and 4)

also my tach isnt working for some reason. it only reads from like 0-1000 rpm but when i  start reving the motor up it dosnt do anything. i have the tach drive in properly the cable in the tach drive with the bolt no kinks in the line then i screwed it into the tach and its not reading more than 1000 rpm. when i get home ill trouble shoot that more........ and also all the electrical gremlins but thats for another day

right now the on off switch on my right hand control works and the key ignition all function but i havnt done anything with the horn blinkers headlights the lights for both gauges etc etc dont yet



« Last Edit: November 12, 2011, 11:44:23 AM by xsmooth69x »
1975 CB550 (FINISHED?!?!?)
first motorcycle ever!!! ow and i dont know how to ride it either :D

raw rust rice venti quad shot cafe racing latte project aka my build..... http://forums.sohc4.net/index.php?topic=88853.0

black and white equation godzilla chalkboard 
1972 cb750 - next in line for some <3

Offline dave500

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Re: carb tuning.... yes.... another one of those....
« Reply #8 on: November 12, 2011, 03:57:33 PM »
did you get those carbs from the hulks garage sale?

Offline xsmooth69x

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Re: carb tuning.... yes.... another one of those....
« Reply #9 on: November 13, 2011, 05:47:05 AM »
did you get those carbs from the hulks garage sale?

hahahahahaha yes i did they give my bike like another 20hp
1975 CB550 (FINISHED?!?!?)
first motorcycle ever!!! ow and i dont know how to ride it either :D

raw rust rice venti quad shot cafe racing latte project aka my build..... http://forums.sohc4.net/index.php?topic=88853.0

black and white equation godzilla chalkboard 
1972 cb750 - next in line for some <3

Offline dave500

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Re: carb tuning.... yes.... another one of those....
« Reply #10 on: November 13, 2011, 11:47:14 AM »
do your riding gloves look like big fists?

72500john

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Re: carb tuning.... yes.... another one of those....
« Reply #11 on: November 13, 2011, 03:49:05 PM »
dave500 is 100 percent right about the timing. get the point gap and the timing right. if anything do the static timing with a test lamp. the noise you hear in the motor like the primary chain will most likely be your cam chain or the primary..and usally goes away after doing....
the point,timing,cam chain adjust, and the one that gets it as dave says spot on. the carb sync. but i agree with dave timing is VERY important.
did my bike and it was like a new engine!

Offline xsmooth69x

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Re: carb tuning.... yes.... another one of those....
« Reply #12 on: November 13, 2011, 04:57:41 PM »
holly batman i completely forgot about the cam tensioners!!!!!! i took out my cam gear to check the lobes re installed the bastard and i completely forgot about the tensionsers!!!! aghhhhhhhhhhhhhh so ya that is definitely the sound im hearing......   :P :P :P

ok ya im going to now adjust the cam tensioners properly and do the static timing with the light bulb and get that points plate in the right position and get the timing down and redo the points gap.


1975 CB550 (FINISHED?!?!?)
first motorcycle ever!!! ow and i dont know how to ride it either :D

raw rust rice venti quad shot cafe racing latte project aka my build..... http://forums.sohc4.net/index.php?topic=88853.0

black and white equation godzilla chalkboard 
1972 cb750 - next in line for some <3