tuning my carbs

cafe750 wrote:

I have a 78 twin I rebuilt the carbs and the thing that the floats push on to stop the fuel has a 2.0 on it dunno if that helps I have the same exact setup with exhaust and all as you do. my bike has not really run right since the rebuild either, same exact symptoms.

well, i got my bike to run halfway right. i replaced the o-rings on the needle jets and it seems to run better, also i adjusted the timing so it was a lil more advanced than it was and it will run out to 8 grand with out any problems. the only thing its still doing is its idleing around 3 grand. i adjusted the idle screw all the way out and i have the mixture screws almost all the way in. it seems that when i put my hand over one carb its hardly sucking in any air, thats the cylinder thats running good, but on the other one when i put my hand over the carb its sucking in a lot of air. does anyone know if thats a carb issue or maybe a valve issue or something. id really like to get this thing running how it should before summer. and to cafe750, where the main needle goes into the carb that brass piece can be tapped out with a hammer and a punch, it might be worth while to take them out and inspect the o-rings, if they are bad i would reccomend replacing them, if they are bad i read somewhere that fuel can get by them and cause a rich condition and cause it to run badly still. thanks to everyone who has helped me out so far. i really appreciate the advise.

Did you sync the throttle plates to make sure they are open the same amount at idle?

Just an observation here... if the plugs are black with dry soot, then it sounds like incomplete combustion. The typical solution for this symptom is the WG Coil Repowering Mod (worked wonders for me).

See WG:

Link

How I implemented mine:

Coil Power Upgrade

IMHO, all these 30 year old bikes need this mod.

Best of success.

ok then, two questions, first is, how would i sync my carbs because that has not been done yet and i have no clue how to do it, however i understand it requires a special tool and i dont know anything about doing it. second, i like the idea of the coil wireing mod, but im kind of confused, does it remove the points from the system and if it does, then how is the bike timed? i think a weak spark could be some of the culprit as i put in a fresh set of plugs and it made worlds of wonder. and syncing the carbs would be good for me to do cause i was messing with it just trying to "eyeball" the butterflies to get them close, but that was probably a mistake as i had no idea what i was doing at that time. thanks for the advice and i do plan on trying the coil mod if i can.

uummm, you should consider getting a Maintenance Manual for your bike. I will come in handy for basic procedures. They are available on ebay and here:

Z1 Ent.

The manual method of carb synching is done with a wire or drill bit placed in each carb... not while running! At least that's the way it’s done on my KZ650-B1. The idea is to get the carbs to open together, as much as possible.
The advanced method of carb synching is done with one vacuum gauge (there are several types to chose from and at different price points) connected to each carb vacuum test point and this method, when done well, is much more accurate.

Remember, your carbs could be completely different from mine so... reader be ware.

The Coil Re-powering Mod can be installed on Points and Electronic Pickup ignition systems... no problem.

If you checked out the link to my Photobucket site posted above, you will have notice that I have several diagrams. Most show the Points ignition version and one shows the Electronic Pickup ignition version of the Coil Re-powering mod.

Best of success.

hey thanks, i appreciate the info, and after i took a good look at the diagram last night i realized that you dont do anything with the points wire when you perform the mod. so i beleive i have a pretty good grasp on how to do both now and i really appreciate the info. as for the book, times are tight right now, and i know they are like ten bucks, but im married, so ten bucks is hard to come by lmao. i know i need one of those too though. thanks again.

ok, so im at about my wits end. i did the ignition mod and it worked great as far as seeing a better spark, but the bike still runs like crap. i had it idleing pretty good for a while, but now its not so good, and it wont rev very well past 3000rpms unless your really on the gas in 1st and it catches up. so ive tossed around the idea of rejetting, i think i have aftermarket pipes and i plan on getting a new set, most likely aftermarket, and i wanna do pod filters. so far im still at stock jetting and i was wondering which pilot and main jets i should buy to "tinker" with it or what kind of carbs could i get to replace performance wise? thanks to everyone for being patient with me.

The carbs need to be cleaned. It's not getting enough gas from plugged passages and so it's hanging up at 3000 for a while. You'll want to put a test light on the points to make sure they are breaking at the right time. If they are not breaking on the fire mark the power band will be no fun atall. Check the valve clearance too it's too easy not to.