Topic: help a noob make his 750 run :)

[worlddrum13]

k so heres the deal and im not a mechanic i just like my bike . i have a cb750k6, with 4-1 with not alot of baffles left, pods, 105mj, air screw out about 1 1/4 turns. when i start accelerating out of my driveway and up the road i have to "play" with the choke to get power. when i first take off he choke is almost all the way. then as i start to go up in rpms i let the choke out a little and the power surges through it then at the next gear i repeat that. as i said im not a mechanic and i dont really know what im doing when it comes to adjusting carbs. all the carbs are cleaned and im getting a strong spark. any sugestions? is it jetted wrong? any help would be great

[ekpent]

Looks like you are running pods also with the rather open 4-1 exhaust.Looks like a good cleaning of the carbs would not hurt,make sure you can see through the slow jet and emulsion tube holes on it and main, and a good chance you may have to do some rejetting with that combo.Lots of threads around on pods etc.Check timing and other settings also to eliminate other causes.   PS-Does that drive chain need some lube

[Johnie]

You said all carbs are cleaned? By who? Did they sync the carbs after the cleaning? Check the FAQ area on this board as there is some good carb info there. You may say you are not a mechanic, but you will be soon. Do not be afraid of the carbs...not that bad with the help of this board.

[xenoscr]

PS-Does that drive chain need some lube

Yikes... That bottom pic makes it look like it's a bit rusty doesn't it? I hope that's an old picture and you've already cleaned, lubed and checked for excessive wear or replaced that chain.

XeNoSCR

[worlddrum13]

yup, old pic. its got new chain and sprockets this april. as for the carbs, i cleaned them myself. i feel i did a pretty good job but im sure there are things i missed. all the jets were cleaned with toothbrush and guitar string(its what i had at the time but it seemed to work.) they actually didnt look bad other than a few small pieces of black stuff. not sure what it is. i put in line filters in and since found a little bit of said black stuff. not alot. so everything was cleaned inside, floats arent sticking. the main jets and whatever the thing is that the main jet screws into is cleaned. the slow jet was cleaned. the float jets were cleaned. am i missing something? what is the emulsion tube? where do i find that?

[xenoscr]

There are two emulsion tubes. They are the tubes that your main jet screws into and the on the top of the slow jet. It's the holes in the tubes that you want to make sure are free of crusty growth and gunk. The only question you haven't answered is, have you synced them? If you haven't synced them your bike will run horribly. Syncing can make a huge difference. For example if you take a synced set of cabs and adjust one of them up or down so it's out of sync you bike will start to run erratically and stall or rev out of control. It doesn't take much adjustment either way to affect how your bike runs.

XeNoSCR

[andy750]

Sounds like your main jet is too small - reject at 110 -->112-->115 etc to see where the optimal jetting is. Or just check your plugs after a ride and see if they are on the white side (lean)...

Stock K6 had a 110 main jet with stock exhaust/airbox etc...

[Johnie]

Here is a pic of the emulsion tube. Your main jet screws into the bottom of it. If you want your carbs to perform good you need to do the sync. A sync will ensure the carb slides are at the same position to mix air and fuel at the same amount in each carb. Your slides are the piston that moves up and down as you turn the throttle. You adjust them by the top bolt of the carb where it connects to the throttle arm. You need a vacuum sync gauge to do that. Many here use the Morgan Carbtune, but get what you can afford as long as it is reliable. You can do a search and find a lot about good and bad sync tools.

[worlddrum13]

i have the carbtune set up. i synced them to my best ability. thats another question. when i turn the adjustment thing on the top on the carbs, one or two carbs are alot more responsive than others. what causes that?

[fastbroshi]

  Not to step on anyone's toes here, but I think you might want to sort the jetting issues before you sync the carbs.    A very small adjustment can throw them off, not horribly but enough.  They're most likely good enough to get you by for now.  So if you sync them you may still be pulling carbs several times to jet for those pods, after which you may need to sync again.
 
  I could be wrong, I'm not intimately familiar with k6 carbs, or 750s for that matter. 

[xenoscr]

i have the carbtune set up. i synced them to my best ability. thats another question. when i turn the adjustment thing on the top on the carbs, one or two carbs are alot more responsive than others. what causes that?

What I think might be happening... this is just a guess. When you're adjusting the carbs the "unresponsive" ones have more play before they start moving because the others are holding the arm that ties them all together higher or lower than the one your adjusting. As you're syncing the carbs you should be blipping (give the throttle a quick short twist and release) the throttle occasionally. This will settle all the slides position. I also find it easier to sync them in pairs. Do the left two, then right two or vice versa. Slowly turn the adjustment nut, blip the throttle, repeat until they are all close enough to each other. I also find that if you hold the throttle around 2000 RPM while your adjusting things the reading are a bit more stable.

XeNoSCR

[BeSeeingYou]

The 105 is stock for the 76K with 40 for the idle jet.  I think it changed from 110 a year earlier.  So definitely with pods you will have to bump up but to where it seems to be a bit of trial and error.  It's obviously running lean.

[worlddrum13]

thanks for all the help. i have 110 main jets from a spare carb set i got so ill try those. as far as syncing some carbs, some i can turn the slightest amount and it makes a huge difference, others (carb 1 mostly) dont move much even after some  pretty extreme turns in comparison to the others. but ill try again. thanks everyone for the help. unfortunately i keep my bike at my dads so i dont have the convenience of just going out and trying it. i gotta drive 20 minutes first but ill keep you posted on any changes

also, although its not on the subject, the next cosmetic upgrade im doing is a seat cover. anyone got any sugestions for a good one? i would prefer to keep the honda logo on the back but it wont kill me if its gone.

[worlddrum13]

k so i put the 110 main jets on and it does seem better. still not perfect but better. i want to try going up in size. where can i find bigger jets and what size should i get?
thanks again

[worlddrum13]

also to add to that ^^ , should i be changing any other jet sizes as well? do i need other jets to be bigger if i make the main jet bigger?