TOPIC:

Well, I hate to burden you guys with a topic of such vaguery but I am at the end of my rope with my 650...

I JUST took apart the carbs and cleaned every jet, set em on the bike, and hit the go button to see if I improved on the very first startup. Figures that it wont fire OR run unless I have the choke on, and when it does start it can idle just under 1kRPM and rev somewhat roughly (with intermittent backfire/carbfire) up past 4.5k, the real problem is when I crack the throttle the bikes reaction is to fall flat on it's face, the power begins to drop instantly, and if I even jerk the choke on/off I might as well be hitting my kill switch. I don't know what could be wrong with my carbs? The throttle response is sluggish as well (stock 32mm CVs no airbox for testing).

I checked my plugs and it appears that two may be dead... I know I know, you say "well there's your first problem genius" but does that explain the huge starting problem (lean-ness?) and serious issue with my (main jets?) mid-high range fuel delivery? Damnit, I JUST cleaned out those jets.

I am considering both the coil mod and new plugs, but I don't know where else to go from there? Going cray zhee here.

Any words of advice?

-Jer

If your bike has been sitting for a long time then a simple cleaning will not do. You need to clean them really good including the internal passages in the carb bodies. What is happening is your idle circuit is partially or fully glogged with gas residue. That is why you need the choke to run. Good luck

Like I said, I pulled all the jets, except the float needles on 3 of the carbs, but they all worked well, I cleaned the pilots and mains and shot them out with compressed air...

did you remove the emulsion tubes?
and my yamaha wont idle at all without the airbox or atleast the rubber tubes that lead to it, it makes it too lean

btchalice wrote:

did you remove the emulsion tubes?
and my yamaha wont idle at all without the airbox or atleast the rubber tubes that lead to it, it makes it too lean

I honestly thought and still hope this as well as the plugs/ignition are the only issue. Cause they are CV carbs and they are running unrestricted so that would explain idle, but not how they die when you crack the throttle. I will have to check into removing the emulsion tubes, I'm not sure what you mean or if I already have though.

First, which plugs showed no signs of burn when you examined them?

Next, describe your current jetting, air box and exhaust pipe set up.

FWIW: The "emulsion tubes" is Harley-speak for the main jet holders on your BS series carbs. On other Mikuni carbs, there are two parts... the needle jet and the tube that the main jet screws into. On the BS carb assy, there is only the one piece with a combined function. I don't have any idea why these would be part of your problem, by the way but just wanted to share what was meant by emulsion tube.

I didn't look at my jet #s as I am virtually positive they are stock, everything on the bike is stock
The bike has 40k kilometers on it and I don't think it was ever opened up/messed with.

The dead plugs were #3/#4, so I don't think it's a bad coil, I will probably do your bypass mod to ensure the best ignition voltage though.

I am running stock KZ 650 4-2 megaphones w/ crossover, the airbox is not on, the carbs are full open.

Thanks for clearing that up, after disassemlby I blew out all the passages with compressed air/carb cleaner, I'm fairly sure there are no blockages.

Blowing carb cleaning into your carbs certainly won't clear up all types of blockages; espeically if a fuel rail is blocked. Next, you really need to check your jetting. With no airbox on the bike, it isn't likely to run very well with stock jetting. Either put the stock airbox on with the stock jets (AFTER you verify the jetting) or put some pods on and rejet. AGAIN, blowing some carb cleaner and compressed air in the carbs probably won't get the job done. They should be totally disassembled and every part cleaned including internal passageways with the problems you are having.

Are you located in or near the Okanagan nfswift?

Yea, It's possible there's more dirt in the carbs, but I think they should be in workable condition at the least. I expect that the Coil Bypass with new plugs and a proper airbox SHOULD fix things up. The problem is I don't have the airbox boots, I am going to have to find a suitable ID pool hose for a substitute which is why I didn't just fire it up with it on in the first place.

I'm not too sure about how much longer I want to use these carbs though, one of the little posts that hold the pin for the float in the float boal has cracked completely through and another one has a similar hairline fracture so I could only clean 1/4 floats up. The pins were siezed really bad, but I did the rest of the jets real good and hit all the passages I could with the cleaner and air, which is nearly the extent of my ability so...

Yea, sort of ankles, just North of Victoria on Vancouver Island.

I was hoping to cruise the mainland once I had maintainence wrapped up, but it's taken considerably longer than planned and I'm getting annoyed cause rings are the next thing I need and they are almost impossible to find, I JUST rebuilt the top end (clean, valve grind, gaskets) but had to skip piston rings half assing it with a light home-deglazing job on the walls.

I'm going bloody 810 next time I have to haul the head/barrels off.