Author Topic: Idle problems (Read 5300 times)

echomadman · « **on:** June 10, 2005, 07:07:35 AM »

Ok, I rebuilt the b250 last night but i'm having some problems.
It starts, and runs at very low rpm for a few seconds, then immediately revs up to 8000rpm and stays there.

I discovered this after push starting it as the battery died trying to start it again after a month lying idle, vroom "excellent, it started" VROOOOOOM "holy shit clutch in and swerve to avoid that car"

if you open he throttle it stumbles then revs up again. I took the tank and airbox off again and started it so i could have a look at what was happening with the carbs. The slides arent coming up much at all unless you crack the throttle, so this insane idle is coming from the idle circuit.

help me carb gurus.

PitterB4 · « **Reply #1 on:** June 10, 2005, 08:36:35 AM »

Echo - it might be helpful to know what you had done to her while you had her apart.

echomadman · « **Reply #2 on:** June 10, 2005, 10:05:16 AM »

degunked the carbs as was seen in this thread.

prior to that i fitted a new can , and on starting it afterwards the really low idle problem started, except it wouldn't rev at all, then the petcock on the tank broke and the bike was flooding constantly so it's been apart for ages now.
the carbs were disassembled completely and cleaned out, i think i buggered up the idle mixture, those are the screws on the bottom of the float bowls right? as i took them out and sprayed cleaner into them.

esentially what i need is a "set up your carbs from scratch" guide.
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PitterB4 · « **Reply #3 on:** June 10, 2005, 10:20:56 AM »

As is CLEARLY evident by my posts here, I'm not a carb guru but did you synch the carbs yet? Poorly synched carbs can cause weird idle and throttle response issues.

echomadman · « **Reply #4 on:** June 10, 2005, 11:43:00 AM »

you need to be able to set an idle speed first :) My idle adjuster is all the way out,
I think there's way too much fuel getting in somewhere, the butterfly valves are closed and the slides are down when it's idling.
I'm sure its those little screws, i never intended the bandit to be disassembled for som long, but i ended up buying the SV650 so the urgency of the repair went out the window and now i cant remember what the hell i did to it :(

Red01 · « **Reply #5 on:** June 10, 2005, 07:18:33 PM »

Screw "those little screws" all the way in until they lightly seat, then back them out 2.5 turns - that should give you a pretty good starting point for totally stock bike.

echomadman · « **Reply #6 on:** June 15, 2005, 01:12:30 PM »

ok, some digging on japanese websites reveals that the stock setting on the 250 for the pilot screws is only one turn out, i had them out way too far, i'll have a gouge at them again on saturday and hopefully make some progress

echomadman · « **Reply #7 on:** June 26, 2005, 09:22:56 AM »

all pilot screws are at 1 turn out, bike still wont idle, just starts, revs up to 6K and sits there.
Anyone got any other suggestions (apart from worn out carbs)
everything looks ok, for a 15 year old bike with 37000kms on it that is.

theslyfox · « **Reply #8 on:** June 26, 2005, 01:49:11 PM »

Would it be anything to do with the choke or the choke settings?

Jamesobrady · « **Reply #9 on:** June 28, 2005, 12:13:36 PM »

Ed sorry i missed this one fer so long....
Its your idle screws plain and simple.....
Or at least(and this parts the disclaimer!!) this sounds exactly like the problem i had with my bandit twice.
Close the screws(all 4 of them) then open them by quater turn increments. I find the best way is to get a suitable screwdriver...put some masking tape on the shaft of it...and make a zero position and then quaterly increments....so obviously...from zero facing you...you can tell what a quater turn is very accurately.

Best thing to do is get one of your mates to help you out with balancing the carbs at the same time as thats half the battle.

Dont get too wound up by having it set up by the book it seems....i think mine are about 1 3/4 turns open.

HTH
ME.

ps...that'll teach you to take them out!

echomadman · « **Reply #10 on:** June 29, 2005, 08:59:46 AM »

yeah, bad news is carb 3's screw (the one thats always been the dodgy cylinder) decided it was having none of this adjustment business and in inimitable suzuki style has rounded out.

I'm going to epoxy a small hex screwdriver bit to it and hope it'll hold enough for me to get the pilot screw out so i can dremel a better slot in it.

theslyfox · « **Reply #11 on:** July 01, 2005, 06:17:17 AM »

Jesus man your havin a nightmare there

raptorsc · « **Reply #12 on:** November 20, 2005, 06:04:54 AM »

My 250V is obviously different to this older model but typically most carb manufacturers go for about 1.5 turns out from bottom, that is what mine is set at.

Something you can do once you get this far to optimize the tune is to run the screw in and out half a turn getting the best possible tune for the individual cylinder. As you turn the screw you will quite easily be able to tell at which point the engine is happiest. Do the same for all cylinders when engine is warm, not hot and you will be the happiest fellow.

The above does not specifically address your issue in that I have not experienced it like that. Something to be sure about is double check the idle emulsion tube jets in carbs, VERY FINE hole and must be perfectly clean, if not you can twiddle the screws forever and get no effect.

If they are clogged you can get some electrical wire (automotive) take of the insulation and seperate an individual strand for the purpose of running through the jet to clear obstructions