Ever since rejetting, my bike takes LONGER to warm up. I kept thinking I could figure it out, but after tearing apart the carbs more times than I care to count, I think I need help. Quick overview:
When I got the bike, the jetting was stock, but the mix screws had been adjusted. I would start it w/ the choke and after about 3-4 min, the revs would climb, and I could close the choke completely, and it would idle perfectly.
I've since rejetted w/ 40 pilots, 150 mains (K&N, slip-on), and raised needle. Now, it still takes 3-4 minutes for the revs to climb, but once they do, the bike is NOT warmed up - it will die if I close the choke completely. I have to keep adjusting the choke to get it to idle. Even after I've ridden a couple of miles, it still doesn't want to idle. I'd say it takes a good 10 minutes before it will behave.
I currently have the mix screws set a 2.5 turns out. This seems to be the best setting for my bike when warm. More than that, and idle isn't as consistent and plugs begin to blacken. I've checked the float height 10 times and am fairly confident I have them in spec (measuring w/ the carbs apart, they're right on, but u-tube method shows fuel level slightly high).
The STRANGE part is the bike warms up quickly the FIRST time after I've had the carbs apart. Subsequent warm-ups go back to being excessively long. What does that mean???
I'll also mention that when I start the bike, I use about 4/5 choke, which seems to give me the max. If I go full, it will sputter when cold. I've checked the choke cable operation and it appears normal. Also worth mentioning, though probably unrelated: There is a significant flat spot around 1/4 - 1/2 throttle (most noticeable in a 6th gear smooth throttle roll-on).
Argh. Thanks for any help.
I'd lower the float level to where it is right when U tube check is made... that is the real test. I never could get my floats set right with the float tang measurement... There must be someway the floats must put enough pressure on the inlet before it closes off or some like that. You typically sound like you have one thing out of whack and have used another aspect to fix it, and that typically leaves you with a deficiency. High floats make it richer, but the air screws are set to where it works when hot. That effectively leaves you lean when cold. I'd drop the floats to where U tube shows at the top of float bowl, and open air screws to 3 or 3.5. Also is your carb synch good. Does the bike feel buzzy at idle but clear up ~4-6K... If so synch them. Else Leave it alone. I just think you have a lean air screw, but high float.
Cool.
Srinath.
Thanks for the info Srinath. I will adjust the float height and report back.
You may recall, though (from a post a couple months back), I had some problems getting accurate measurements w/ the u-tube. The fuel level in the tube would change depending on how much I opened the drain screw. I can actually get the level to be correct, w/ the screw open a couple of turns. If I open them a couple more, fuel starts dribbling out of the screw threads - but this is when fuel level reads high. So, I'll go w/ that though, and assume that's when i'm getting an accurate reading.
I synced the carbs during a few months ago. No noticeable vibration issues.
So, how about the thing where the bike warms up quick the first time after pulling the carbs apart? That really has me confused. For example, I usually work on the bike at night, so I pull carbs, adjust something, put them back together. The next morning, it starts up nice and quick - Idle picks up after maybe 1-2 minutes, then I finesse the choke for another minute or two and it idles perfect. Thinking I've fixed the problem, I start it up the next time it's cold and it's back to the 10 min ordeal. :dunno:
Well, I adjusted the float height slightly to lower the fuel level and turned the mix screws out another 1/2 turn to 3. It definitely helped, but warm up is still longer than it should be. Using the u-tube method, I checked the fuel level and the right side is perfect, but the left side is still high by about 3/16".
After repeteadly adjusting the float height, I can't get the fuel level to go any lower. I've pushed the tang pretty far in both directions and it's not affecting the fuel level. Is this a stuck float? It seems to move freely.
I've been working w/ the carbs on the bike - removing just the bowl/float, adjusting the tang, reassembling, switching to PRI to fill the carbs and measuring w/ u-tube.
Ideas?
Well if the float level isn't going down any more - where is the float level. The 2 carbs have to be equal. You set them differnt to one another and you have a whole new set of issues... one is rich the other is lean, and the bike shows sighns of both... bad. So what is the float level relative to the float bowl gasket. Also carbs on the bike is fine for setting the height. And you should have it in prime when checking float level, and 2-3 turns should have fuel dribbling out the screw... if so the O-ring is on the screw is bad. To set them equal is most important.
Cool.
Srinath.
Prior to adjusting, the fuel level was about 3/16" above the gasket on both sides using the u-tube method.
I then adjusted both equally to lower the fuel level. The right side is now level with the gasket, but the left side did not go down. Subsequent adjustments had no effect.
I could put them both back at 3/16" high, so at least they're equal, but then I'm back to square one. grrrr.
So I swapped the floats and when I put the right float in the left carb, the fuel level in the left carb was now 3/16" high. This same float was dead on in the right side. So, it seems the float is fine...
What now?
Weird goings-on, all right....
Don't shoot me, but your bike is vertical when you measure the float heights, right? On the centerstand? The only thing that makes sense to me with the higher readings on the left side is that the bike is leaned over on the sidestand.
Sorry if I'm coming out of left field - feel free to ignore this post....
Quote from: Kerry
Don't shoot me,
Definately a good thought (trust me, I wouldn't put it past myself to have overlooked something like that). But, yes the bike is on the centerstand and on level ground in my garage. I've meausred over and over w/ the u-tube, flicking it to make sure there's no air in it... but it still reads goofy.
sounds like you need new needle valves. The needle valve is the little plunger button that your float tab is pushing on. When you pull the needle valve out, it should look like a rubber cone on one end. If these are shot(or one), then it will let too much fuel into the bowl.
Yea however you can try swapping those side to side as well. They should pull out of the body easy. Need any of these parts hit me... I'll send it to you in exchange for your parts. However I dont see how youy canhave wear in any of those. You might have one sorta pulled out 1/2 way maybe.
Cool.
Srinath.
needle valves wear out alot. Especially if you have rust in the tank with no inline filter or the bike has sat for a long time. Once there is a groove in the rubber cone, you can forget about changing the float height because it just wont work. Most people just ride through it and think thier bike just isn't running very good, the problem is usually only at idle or low speed anyway.
Well read his post.... Well its not totally clear... now that I read it again.... The problem seems to follow the carb, but not the float... but did he change the rubber needle with the float???
Cool.
Srinath.
edited after re-reading post.
Quote from: seshadri_srinathWell read his post.... Well its not totally clear... now that I read it again.... The problem seems to follow the carb, but not the float... but did he change the rubber needle with the float???
Cool.
Srinath.
It confused me a bit too but when I re-read it, he said he took the right carb float (which measured fine on the right carb), and put it in the left carb, (which was reading 3/16 high with its original float) and it still read high in the left carb even with the right hand float. So that would lead me to believe its the float needle(or needle valve or whatever you wanna call the rubber cone :) )
Sounds like he has one bad one, that's why it's only happening in one carb. OR I read it wrong and I'm screwing everybody up :lol:
Thanks for all the input... Sorry for the confusion.
When I swapped floats, I swapped the needle valve as well. I have inspected the valve very closely, comparing it to the photos in Clymer and it looked to be fine. If there is any wear on the tapered end, it's not visible by eye. I do have an inline filter between tank and carbs.
OK The gloves are comming off this time... and we will fix it... Ok Carbs on the bike U tube method... mark off which is the right level carb. Then take off the carbs and take off the bowls and set then with the floats up on a flat table. Fit a fuel line to the inlet to the carbs and put it to your mouth and start blowing. Where the good one starts flowing... make a note of it. Then blow into the line, and lift the other one to the point where it starts flowing. Then bend the float tang and see if it changes... if so great... bend it and in a try or 2 they will both strat flowing at the same time. Stop.... and re fit them and check with U tube level.You also can eye ball the things from the side at the same time but that makes it a 2 man job.
Cool.
Srinath.
Quote from: seshadri_srinathOK The gloves are comming off this time... and we will fix it...
That's what I like to hear. Gonna get a little dirty...
But actually, before I read that, I adjusted the float height again with the carbs apart. Basically I put them both at max height w/ in spec (19/32"?). I put it back together and the left side carb still reads 3/16" high w/ u-tube... I don't remember what the right side was.
But, next morning it started up pretty quick. Then, this morning, it warmed up relatively quickly again. Started it w/ full choke, it idled low for about 20 sec, then revs climbed. I finessed the choke a little as I rode away and it seemed warmed up by the time I got to the fwy (maybe 3-4 min total - WAY qucker than before).
It was a bit warmer today, so I want to start the bike up when it's colder out before I count my chickens. But I think maybe the last float height adjustment may have done it. So, Srinath, it looks like your original assesment of fuel level being too high was right on.
I still don't know why the u-tube method reads funky - but for now, I don't care. If I still have problems, or the next time I pull the carbs, maybe I'll do your test. Thanks for all the help.
Yea no carb adjustment is complete wihtout you drinking up a few swigs of gas.... damn that 87 tastes rough.
Cool.
Srinath.
Ok to bring up an older post:
I'm having trouble going up long steep hills with my 91 GS. I'm thinking that the floats are set incorrectly since the bike will stumble and die on sharp inclines. I haven't yet done the U-tube test. To get more fuel into the bowls, I should raise the floats, right? Which is to actually "lower" them in the float bowl, since the carbs are upside down when you're working on them.
Adam
Quote from: Adam ROk to bring up an older post:
I'm having trouble going up long steep hills with my 91 GS. I'm thinking that the floats are set incorrectly since the bike will stumble and die on sharp inclines. I haven't yet done the U-tube test. To get more fuel into the bowls, I should raise the floats, right? Which is to actually "lower" them in the float bowl, since the carbs are upside down when you're working on them.
Adam
To raise the fuel level, you lower the float height (carbs upside-down). When right-side-up, the floats will be higher, raising the fuel level. Did that make sense???
Quote from: Adam RTo get more fuel into the bowls, I should raise the floats, right? Which is to actually "lower" them in the float bowl, since the carbs are upside down when you're working on them.
To get more fuel into the bowls, you really do want to raise the floats when the bike is in operation, which means lowering them
while the carbs are upside down. (That's what you just said, right?)
Page 3-11 in the Haynes manual shows the procedure. The float height mentioned in Figure 9.7 is listed as 14.6mm +/- 1mm. Whatever your current measurement is, to increase the operating level of the floats the measurement needs to go
down.
EDIT: Changed link from sisna.com to bbburma.net.
Since this topic came up again, I re-read it and noticed that nowhere is the idle screw mentioned.
Alright, tomorrow I'll tackle that problem, although I'm supposedly also going to be looking for a ultility trailer.