[byggd]

I rebuilt my carbs, got them in sync and adjusted the idle screws (2 ¾ turns out). This eliminated all popping on deceleration and for the most part the bike starts and runs perfect. But about every now and then when taking off from a stop I will get a slight hesitation. Also if I run the RPMs up and then close the throttle (like when you take off from a stop and just before you shift you notice the light up ahead is turning red) when I come to a stop the bike will sometimes stall. The bike is stock except the Jardine pipes and 170/45 jets in both carbs. Any ideas? maybe I need to back the idle screws out a bit more?

-Don

 

[93gc40]

What brand 170 jets are you using. Number is meaningless without the brand. Kinda sounds like the floats are sticking or misadjusted. Sounds like you have a fuel supply or delivery issue

 

[byggd]

What brand 170 jets are you using. Number is meaningless without the brand. Kinda sounds like the floats are sticking or misadjusted. Sounds like you have a fuel supply or delivery issue

Of that I have no idea. The bike was jetted before I bought it. I double and tripple checked the float settings. Knowing what a PITA the carbs are to remove I was super careful on the rebuild. I have yet to change the fuel filter. Could it cause both issues?

 

[Cbjr]

Up your throttle speed then re-sync the carbs again (post idle screw adjustment) changing air/fuel after a sync pretty much changes the sync. Anyway it's cheap and easy to do and sets a the bike to a more predictable baseline.

Mine acted in bizarre ways at, or around idle, when the sync was way out.

 

[apbling]

Almost sounds a bit too rich... my 0.02

 

[byggd]

Up your throttle speed then re-sync the carbs again (post idle screw adjustment) changing air/fuel after a sync pretty much changes the sync.

This doesn't make sense to me. Unless I’m mistaken the function of the sync screw is to synchronize the 2 carb butterflies. How can adjusting the idle mixture screws change this? It seems to me you should sync the carbs first and then fine tune the idle mix screws.

 

[byggd]

Almost sounds a bit too rich... my 0.02

That is possible. I need to take it on a good run and then pull the plugs and read them.

 

[apbling]

When you rebuilt them... what did you all do? New needles, seats, gaskets...but did you put different jets in? If so, if you took out a DJ jet and put in a rebuild jet of a different make, maybe they aren't the same? Off the top of my head, I think my 170 jet (I ended up using the 165 anyway) from DJ was somewhere in the neighborhood of a 190 keihin jet. Also, going with what was said before about the needles...I got bit once by that. Never noticed it, but the new needle that came in the rebuild kit was a different length than the stocker! The spring tension even felt different. Took forever to get it set properly. This was on an old KZ inline 4, so you could measure actual fuel level using a clear tube.

Also, not sure about the 88 model, but did you double check to make sure all your vacuum lines were hooked up and not pinched?

 

[byggd]

When you rebuilt them... what did you all do? New needles, seats, gaskets...but did you put different jets in? If so, if you took out a DJ jet and put in a rebuild jet of a different make, maybe they aren't the same? Off the top of my head, I think my 170 jet (I ended up using the 165 anyway) from DJ was somewhere in the neighborhood of a 190 keihin jet. Also, going with what was said before about the needles...I got bit once by that. Never noticed it, but the new needle that came in the rebuild kit was a different length than the stocker! The spring tension even felt different. Took forever to get it set properly. This was on an old KZ inline 4, so you could measure actual fuel level using a clear tube.

Also, not sure about the 88 model, but did you double check to make sure all your vacuum lines were hooked up and not pinched?

One of the bowl gaskets developed a leak so I purchased two gaskets sets that included all the gaskets, o-rings and needle/seat. The jets were installed by the previous owner when he installed the pipes so I have no idea what brand they are but the plugs have always looked good. The only hoses going to the carbs are the fuel lines and a hose that goes to a plastic T that runs from one carb to the other (I assume its emissions related). It only hesitates one out of maybe 10 times just as I come off the line. The stall only happens after a loooong engine braking stop. If I blip the throttle as I pull the clutch in it doesn’t stall. Other than that the bike runs great at all throttle positions/gears/speeds.

 

[apbling]

hmmm...odd that you would have that problem with just new needles/seats and a gasket. That tee you speak of is what caused me 2 weeks of grief. I took the extension off mine because it looked cleaner. Well, at higher speeds it ran like complete crap. Put the extension back on and away we went! My tee'd line went down the right side, between the cylinders to the left and went all the way back by your left calf.

My thoughts are if you only replaced those parts, you either have a vacuum leak or misrouted line or you have some tinkering yet to do with your float height. I know just tiny differences in float height can make a world of difference sometimes. I just wish there was a good way to measure the actual fuel level with a clear tube instead of just measuring the float height.

 

[byggd]

I'll check the sync again and see what that shows. I'll also see if I can follow that hose and check for cracks then spray carb cleaner around the connections and see if the idle changes. If not I guess I get to pull the @#%#@ carbs off again.