I don't know the status of the carbs, but I suspect they need to be cleaned and possibly synched. Is this what causes irratic idle? I get good response from throttle even at low RPM but setting idle has been an act of futility. It seems to idle at a different RPM every time I ride it, and if I try to set idle below 1500, it bounces between 1K and 1.5K, sometimes running up to 1800 and back down again. It won't sit still. It's not what I would call 'rough' idle, just irrratic. If I set it to idle a little higher (around 1800), then itgets steadier. Suggestions?

I've only put in a new set of NGKs..nothing else has been messed with yet.

Thanks

 

The first step I would take is to synchronize the carbs. If that doesn't work, check for vacuum leaks. Otherwise the carbs should be torn down and cleaned.

That's what I'd do.

 

hmm, true on the carb sync, it only takes a minute to plug in your gauges.

I have not had an erratic idle bounce though with a bad carb synch. In which I prefer to thoroughly clean the rack. Check float height, and make sure that idle screws are the same. Spraying starter fluid around the vacuum lines will also aide you in seeing any cracks in lines accordng to some riders. I prefer to just pull each and every line with the rack on or off for a visual.

 

After reading the how-to on carb synching, I've elected to have it done professionally. There are a lot of things I venture to do, but this doesn't sound like one of them. I'll probably just take it somewhere and tell them to fix the erratic idle, whether it be synching,cleaning, etc. Me and carbs have never gotten along and I rather not f it up and then have to truck it to a mechanic.

Such a strange problem. It idled smooth and steady all the way to work this morning, but yesterday it refused to settle. Do they have a cure for 'moody'? :-)

 

I got ambitious last night and built a home-made carb synch tool. Clear tubing, 2 snapple bottles,2 corks and some water. While it was a fun job to attempt, I think it highlighted some engine problems I may be having.

I synched them at idle speed, but if you blip the throttle or just raise engine speed, one sucks harder than the other. I'm sure that's not a good thing. I elected to keep them synched at idle instead of trying to synch at elevated rpms.

Something else I noticed is that during a throttle blip, I get a white fog in both bottles. It disappears quickly, but I'm wondering if that isn't blow-by.

My erratic idle seems to have subsided a bit, but it's still there. The bike seemsto run the same as before. All vacuum lines are firmly connected and in good shape.

Anyone have input on my findings?

Thanks

 

so you elected to have it done professionally. Do tell what you found?

 

your homemade apparatus is quite amusing!! LOL

hmm.. the fog.. don't let it vex. its not blow-by persay in the oil sense (which is what i associate the word with..). its merely the accumulation of atomized fuel. it has no where else to go when the valves are shut, and the charge velocity is still at above-idle speeds.. it'll force its way into the bottles and condense. if you run your motor at an iff-idle speed, kill it, then open the butterflies, you'll see the same fog rise up from the carb throats.

oh.. be VERY careful when blipping the throttle.. the sudden vacuum surge WILL draw any liquid into the chamber will it will NOT be compressed and will NOT agree with a piston or its components coming at it at a high rate of speed. if you were to use mercury, Hg weighs849lbs per Cu. Ft.. lol.. bad stuff to suck into a motor.. water weighs in at 62.4lb/Cu.Ft..(yup.. genius.)

i do believe you have CV carbs with vacuum pistons incorporated? check the slide travel and smoothness of them. also check choke engagement and play.. sync will kinda throw off idle, but it'll idle high for a while after an off-idle state.. it'll take 5 or 10 seconds sometimes to settle to the idle speed. i'm thinking to maybe do a compression check.. if one cylinders loading faster than the other, or has more vacuum or whatnot, there may be a potential problem brewing.. definitely check float height like Drag stated.. (if you opt to do this yourself..)

pay close attention to the ambient temp when this idle fluctuation occurs.. you said it was fine on the way to work, but not home?.. check the weather to see the temp and dewpoint when ya left and returned.. dewpoint could (i think, personally) lead to an A/F change.. (density ratios and all..) as well, or course, as temp.. also note the engine temp.. cold motor/ cold morning= good, stable idle?

keep us posted man.. i'm not too sure what else to tell ya. and i'm REALLY tired..lol can't think no mo'..

oh.. bt.. if you feel experimental, you can map blow-by with a flow meter hooked up to your crankcase breather or oil-fill hole. at some point in the RPM range, it will exponentially rise, exposing the RPM that ring flutter is occuring at. typically its around 9,000 RPM or so..

 

Hey,
The way the bottles are set up, it's impossible to suck water out of them. The only tubes submerged in water are the ones that transfer water from one bottle to the other. The vacuum tubes coming from the carb stop at the top of the bottle.

I encountered yet another problem yesterday, but it's strange that it took a day to manifest itself. I synched the carbs tuesday night, andon the test-ridethe bike behaved pretty much like it always had, with a slightly smoother idle. One thing my bike ALWAYS does is fire right up. If it's warm, one touch of the starter and it's going. Same when cold...choke it, touch the button, and it's lit. It ran fine for the rest of the night after the carb synch tuesday night, it acted normally wednesday morning, and again when I left work wednesday night. I went to Lowes after work, and when I attempted to leave Lowes, it nearly didn't start. I had to use heavy throttle to get it started - VERY unusual for this bike. Idle was quite low as well. Since then, it's been a royal bitch to get started. It seems to idle ok, but shut it off and try an immediate re-start, and it just cranks and cranks until you give it throttle....then it reluctantly fires. This morning on cold-start, I choked it and had to throttle it to get it started.

I find it odd that if I messed up the carb synch, that it took a full 24 hours to show up. It's very much like Jekyll and Hyde. Anyone have any ideas? I nearly got stranded with it this morning at a convenience store. I can't be sure if it's gonna start back up every time I shut it off. I guess I'll be elbow-deep in it again today after work.

 

Not sure, but costs nothing to see what the gauges tell ya.

 

wow.. very, very strange..

you just can't win, can ya!?

i think maybe checking the float levels, jet needles and the general health and fitment of the carbs and it's components should be somewhere in your machine's future..

process of elimination, sir!