slight hesitation at lower end of rpms

Ok guys I have a 1977 KZ650 with 4 into 1 exhuast and air pods.I have a Dyna S ignition with green dyna coils and the wiredGeorge coil mod.Im running 110 mains and 17.5 pilots in the carbs.Im getting a hesitation at the lower end of the rpm's.I checked my voltage to the battery at Idle and I only get 12 volts until I bring the rpm's up,then it will go up to 14.3 or so.Would that cause the hesitation?Or should I play with different jet's???

BoZ650 wrote:

Ok guys I have a 1977 KZ650 with 4 into 1 exhuast and air pods.I have a Dyna S ignition with green dyna coils and the wiredGeorge coil mod.Im running 110 mains and 17.5 pilots in the carbs.Im getting a hesitation at the lower end of the rpm's.I checked my voltage to the battery at Idle and I only get 12 volts until I bring the rpm's up,then it will go up to 14.3 or so.Would that cause the hesitation?Or should I play with different jet's???

That's completely normal. At idle, the alternator doesn't put out enough current to both feed the electrical system demand and also pump up the battery. If it goes to 14V +/- 0.5V at higher RPM, it's working right.

It can't cause throttle hesitation.

Thanks,Bountyhunter that will save me some time!But where should I start about the hesitation problem???

BoZ650 wrote:

Thanks,Bountyhunter that will save me some time!But where should I start about the hesitation problem???

depends;

Did this setup (pipes and jets) run good before and now doesn't?

Or, did adding the pipes make it run off?

Wired George is da man for jetting. Off the top of my head, a hesitattion at low end could be:

pilot jet size too small

needle position.

fuel level in the float bowl

I just got the thing up and going.So I dont have any history.I just got my dyna s back from Dynatek becuase it went bad on me.Ive never had the bike running for more than 1/2 an hour at a time.Today I put the ignition back in and set the timing and it started to hesitate after she warmed up for awile.Its still ridable but Id rather get it perfect!

i have a 79 kz650 b. i'm running 117.5 mains w/ 20 pilots. i have v&h 4-1 w/pods. i had a hesitation when i first would crack the throttle w/15's and then the 17.5's. went to a 20 pilot.. fixed it. also, i'm not sure but i'd bet your a little lean on the mains. i'd think you can run 112.5's or 115's.

Ill order some bigger pilots and give it a shot,it cant hurt!Ive had the carbs of and cracked open so many times that Im used to it,but I still hate doing it!Thanks for your suggestion vach!

Sounds to me like ur carbs might be out of sinc have you scincornized them lately since the new jetting and air pods?

No monsterman I havent synced them at all yet.But have been waiting to find a cheap set of gauges to do so.Or someone around buffalo to give me a hand!

I don't think #20 pilot jets are a great idea... they are generally a bit on the rich side and can foul plugs... depending on slide cut outs... I think a 77 will have 1.5 slide cuts outs if memory serves. I think it is a fine idea to sync the carbs but that won't effect off idle bogging. I don't know if your carbs have air screws or idle mixture screws but I would adjust these to richen the idle mixture just a tad which should cure your off idle bog... you can also ensure your jet needle is on the 4th clip slot if it isn't there already.

jet needle clip was positioned so the jet needle was raised up 1 notch,I cant remember if that was the 4th position or not.When you say richen you mean turn screw in to let less air in correct?It also seems to have little effect on the idle when I play with the air screws(The style on top of the carb throat).I started at 1.5 turns out from lightly seated.I checked the carb boots by spraying carb cleaner to see if they leak and there was no change in the idle so I suspect they are OK.I dont know if its related but the bike has always been hard to start after sitting for a couple of days.During one of my many carb disasembies I cleaned the choke circuts out and no change!As always wiredgeorge your opinion is worth its wieght in gold!!!Thank You sir!!!

Here's a diagram for reference.

Seems this model (1979 KZ650) could have come equipped from the factory with either type carbs, (1) side located pilot circuit air screw #42 (turn in clockwise to enrichen by reducing air in pilot mixture; turn out counterclockwise to lean by allowing more air into pilot mixture) OR (2) bottom located pilot fuel mixture screw #30 (turn in to lean by reducing mixture; turn out to enrichen by adding mixture).

[click to enlarge]



Edit-- am guessing the bottom located mixture screw version with the #32 limiter cap came on later models designed to comply with the then ever increasingly more rigorous EPA regulations.