tuning my carbs

so, ive rebuilt my carbs last season, it was me and a friend who did it, and since then the bike hasnt run right. first the float levels were off, so i reset them to be as close as i can figure to get them. then i tried to set everything to factory settings, but all im getting is it firing okay on one cylinder and the other doesnt fire everytime like the other one. so when i take the diaphragms out to adjust the clips on the needle it seems one of them is covered in gas but the other is okay. it seems to run rich as it idles high as well, but if i put my hand over one carb to drop the idle, it will idle normal for a few minutes before raising back up. so at this point im stuck and dont know what to do. i dont know anything about jetting, all i know is i bought a rebuild kit that should be factory. also i may have an aftermarket exhaust, but i dont know, it is a megaphone style exhaust. also when i ride it or just rev it it seems to start popping out of the exhaust, its not as bad as it was now because i took the mechanical timing advance out and cleaned it up until it moved easily as it should. also it wont really rev past 4 grand when im riding, and no more than 7 just reving. so that is everything that its doing that i can remember right now and any insight on how to fix my problem would be greatly appreciated.

sorry we cant really help you if nobody knows what bike your talking about what make of carb's and size what are you using for filters

It sounds like you have a twin, of some kind, finding correct kits for the twins can be hard to impossible, depending on year/model. Need more info, like timebomb says. Any mods?pods?exhaust change?

sorry i forgot to list what kind of bike i have, i have a 76 kz750b1. dont currently have any filters on it, it came that way when i bought it and i plan to put a factory box on it when i can get ahold of one. also this morning i was lookin at a carb boot and one was cracked a lil, dont know if its all the way through or not, but incidentally it was on the side that isnt running so good, so just as a test i put a piece of electrical tape over the crack and it seemed to help a lil. i dont know too much about the exhaust i have on it, weather or not its factory i dont know, but i do know its a 2 into 2 megaphone style, looks older and i think i may replace it later when i can afford it, but it works for now i guess. also my carbs are mikuni bs38's from what i can tell from reading through the forum, but i do know for sure that they are mikuni's. anyhow i appreciate the responses and hopefully ill have it running right before the season. thanks

If you have stock jetting in the carbs without any filters on it it's never going to run right. Intake/exhaust mods require increased jetting to provide the correct fuel/air mixture. I dont' know much about that style carb, but needing to rejet is universal among all types of carbs. So, either get an airbox on there or increase your jetting so you're not running super lean. What do your spark plugs look like? I'm assuming white as a frozen ghost...

spark plugs are blackened, looks like its running rich to me, but as far as i know, the stock size jets were in the carb when i got the bike, i dont think its ever been rebuilt until i got it, but it ran fine with no filters, except it would load up at a stop light and sometimes stall out. like i said, it may be the intake boot, but ill look at it more tonight and see how it runs, i got some vaccum glue to see if its the problem. but the plugs have never turned white as long as ive owned the bike.

Keyster makes the full rebuild kits for the old 750 twins. I believe the same kit fits B1 - B4.

The stock jets are 45 pilot, 125 main. Needle clip osition should be center slot.

uummm wrote: " dont currently have any filters on it, it came that way when i bought it and i plan to put a factory box on it when i can get ahold of one. also this morning i was lookin at a carb boot and one was cracked a lil,..."

Something doesn't add up. You don't have an airbox but you have carb boots? By carb boots are you referring to the black rubber things between the carbs and the engine or on the rear of the carbs? The thingys between the carbs and the engine are carb holders. If you can see anything that looks like a crack on them they are no doubt shot. If they leak even a teeny bit between the carb and engine (usually at the mating surface between the holder and cylinder head where it can't be seen) the engine will run like crap. Also, with no filter on the carbs the mix will be so lean you will never get it running right, but if you did by changing stuff in the carbs, it would run poorly once you put on a filter. Also, running with no filter will quickly destroy the engine (it doesn't like eating foreign matter). If it was mine, I would get an airbox and filter on there along with new carb holders and use that as a starting point for getting it running right. Ed

oh i was planning on getting filters, and by carb boots, i do mean the manifold or the rubber piece between the carbs and the engine. i plan on replacing them, and i beleive the seal between them and the engine is good as i can see a long thin crack on the side of one. and i do understand the importance of a good air filter, i dont want mud or water in the engine, i know very well that water is not an engines friend. also its really not running lean, it seems to have alot of gas come out of the back sometimes or itll backfire through the carbs and be wet (gas mist) and the spark plugs are black from carbon buildup, therefore running rich and not lean. also backfires out the exhaust sometimes and for the most part shoots a flame when it does.

so i had a thought.... i remember reading somewhere (i dont remember where though) that 76 and 77 carbs have different rebuild kits or jets or something than the 78 and 79 models. if this is true then im wondering if its possible that i got the wrong rebuild kits when i did my carbs. if anyone knows i would appreciate any information on the topic.

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.

Im not sure either, but if you got the wrong rebuild kit it would make sense. I like that you said you will run an airbox when you find one, i have went back and forth with all three of my kz's with the pods and stock airbox, and have always returned to the airbox, i figure makaw designed it that way for a reason.