lean vs. rich question after rejetting - kinda long

[brandiwine]

i've got an issue i'm trying to fix without taking the carbs off straight away.  after rejetting, using the dyno jet kit, i'm having stalling issues at high speeds.  it's like a bucking horse feeling.  it happens usually after i'm going pretty fast, 90ish, for a few minutes and doesn't quit if i slow down, and continues through downsifting, but it's not as lurchy at lower speed.  on top of that it doesn't always continue to happen after restarting the bike and i've also tried putting the petcock on prime but that doesn't resolve the problem.  during the rejet, the idle screw was changed.  it does idle at 1200 rpm, but the weird thing about that is that it was idling ok, then yesterday after the stalling - lurching and i pulled off the road and came to a light, it idled too high like back when it was lean.  i turned the idle adjustment screw to idle at 1200 rpm again and the bike seemed to run ok, but i didn't speed on the way home to test for the lurching-stalling because there was too much traffic then.  i'm confused as to why it would idle ok with the idle adjustment screw way open but then idle high all of a sudden, then idle ok again after a readjustment to close it a bit.  i think i'm at a point where i might just take the dyno jet stuff out of the carbs and go with the main jet's  and pilot jet's suggested here, but if anyone can get any idea's of where to head without pulling the carbs off again, i'd really appreciate it.  additional info is that the dyno jet calls for tapping, which i did, and i plugged only one side.  and i used the 118
thanks!

[The Buddha]

Your description is a bit vague... But let me just try it anyway...
I think you are a bit lean up high, more lean down in the middle and about right at idle. Bigger mains and 1 notch higher on needle might do it. Just a guess.
Cool.
Srinath.

[The Buddha]

Info I'd need... 1. you accelerate to 90 and it does it when you hold throttle - that's in 6th gear I presume ... 2. what if you accelerate to 70 in 6th and hold speed... does it still surge. If yes in the first case and yes but not as much or not at all in the second case... 1 size bigger mains should be the next step. If step 1 is bd and step 2 is worse... then up mains and lift needle. Make sure you have floats set right and air filter is clean.
Cool.
Srinath.

[scratch]

Also, and Srinath correct me if I'm wrong, when our bikes get warmed up they will idle a little higher than when cold. But, it shouldn't be much. Maybe like 100 to 200 rpm, more.

[The Buddha]

That's right... however its still a hair lean in that case. Of course right down at idle you may be better off erring on the leaner side... you dont want it to be so rich it starts without choke when its 30 degrees... then you can never start a warm bike. Mine actually holds the same rpm cold or hot... it does sound smoother hot... but tach needle shows the same.
Cool.
Srinath.

[Hi-T]

Common problems to look for.

Make sure that your floats are set properly and are not stuck. ( I've heard tapping them with a hammer can giggle 'em loose and help them sit properly.

Fuel Starvation.  After I rejetted, I HAD to run a straight line from the tank to carbs.  I also had to make sure that it was a direct as possible (no bends or twists.  I had the same "bucking" especially at wide open throttle. but it went a way with a larger fuel line and a more direct approach from tank to carb inlet.

You may have junk in your bowls that my clog a jet.  This can happen if you have cut new line or added a fuel filter.  Sometimes rubber from the hose peels off and enters the carb.

Check your vaccum hoses and other routing.

[brandiwine]

thanks for all the input on this.  i'll definately check everything here.  good point about the fuel lines too.  i got some new line from the dealer but it was thinner diameter. hard as hell to put on but the parts guy said it would work.  i also added a fuel filter.  i'm picking up my air filter this week, so i'll get some bigger fuel line too in addition to putting petcock on prime.  i'll try all the easy stuff before opening up the carbs again.  thanks!  hopefully i won't have to update.  

[Gisser]

during the rejet, the idle screw was changed. it does idle at 1200 rpm, but the weird thing about that is that it was idling ok, then yesterday after the stalling - lurching and i pulled off the road and came to a light, it idled too high like back when it was lean. i turned the idle adjustment screw to idle at 1200 rpm again and the bike seemed to run ok, but i didn't speed on the way home to test for the lurching-stalling because there was too much traffic then. i'm confused as to why it would idle ok with the idle adjustment screw way open but then idle high all of a sudden, then idle ok again after a readjustment to close it a bit.

A couple thoughts about this problem.  First, if the hanging idle happens after the "lurching-stalling" episode, and it's assumed that the cause of these episodes is inadequate fuel flow at the petcock, then the cause of the  lean  or hanging idle may be low or empty float bowls.  Second, perhaps the idle mixture could stand another turn out.

[GT Eye]

I was just wondering if there's anything bad with leaving the bike in PRIME mode.

Thanks

[Anonymous]

If the float needle doesn't close completely fuel can run into the carbs and leak.

If you don't keep track of your miles you could run out of gas.

[scottpA_GS]

I am having a bucking problem as well. Seems to only happen above 50 or so, and not all the time. Sometimes I will be riding at 60, and it will just drop to 55. feels like im loosing gas.. then sometimes it will pick right back up, or start to buck a little, like jumping 1-2mph faster then slower. If I give it throttle it seems to respond and go back up to speed.. however this sometimes causes the surging to be more intense because.. I was going 60.. (didnt move throttle... bike slows to 55.. I give it more throttle.. back to 60.. now bike surges and bucks to 65

This bike is a 95 GSE stock and only has 700 miles on it now

Now this bike has sat for 10 years, I have the tank kreemed I cleaned the carbs and have had it well gone over at the dealer. I have to ride the bike on prime always, as I have the vacuum tube blocked due to bad diaphragm. Could the diaphragm be causing this? Even on prime?  can I just take the diaphragm and the spring out? maybe just cut the center of the gasket out and leave the outer ring to seal? I already have it stopped up on the vacuum side.

In a post I had made for this topic someone mentioned valve  shims? would I need those on a bike w/ 700 miles on it?

What else could this be? How can I check / fix


Thanks...